Alum sludge is produced in massive amounts through the process of water-works due to the use of aluminum sulphate as a coagulant. The possibility of twining cadmium sliver ferrites named CdAgF and cadmium cupper ferrites named CdCuF fabricated by a simple co-precipitation route with alum sludge (AS) based waste is accompanied. The prepared ferrite materials are mixed in a 50 % proportions with a modified AS (AS400) and labeled as AS400F-CdCu and AS400F-CdAgand introduced as adsorbent material. The surface functionalities, structure and morphology of the prepared adsorbents are evaluated via scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) surface area analysis. The prepared composites are applied in the removal of two types of dyes from wastewater stream as a simulated textile effluent named Synozol dyes Red K‑HL and Synozol dyes Blue K‑HL. Initially, the isotherm time is located at 1 h of contact time. Then, the adsorption parameters are investigated and the optimal operational parameters are recorded at natural pH of the aqueous effluent (7.0) and the economic adsorbent dose used is 1 g/L. the dye concentration is evaluated and the studied range (20-100 mg/L) reported that increasing the dye concentration increasing the adsorption capacity. Thermal effect has a negative behavior on the adsorption capacity. Langmuir and Freundlich isotherm models are evaluated to check the experimental data and the results are best fitted with Langmuir model for the both dyes. The greatest monolayer adsorption capacity is associated to CdAgF and its composite form AS400-CdAgF that is recorded as 149.031 and 102.564 mg/g, respectively for KHL Red dye and 79.744 and 32.414, respectively for KHL Blue dye. Also, the kinetic model is investigated and the data is following pseudo-second-order kinetic model. Finally, the recyclability of the catalyst showed its effectiveness for sustainable use.
Research Article
Efficient augmentation of superparamagnetic ferrite with alum sludge as a sustainable nanoadsorbent matrix for promoting dye removal: preparation, characterization and application
https://doi.org/10.21203/rs.3.rs-4667492/v1
This work is licensed under a CC BY 4.0 License
You are reading this latest preprint version
- Alum sludge waste by-product result from the water-works plants is converted into a value-added material
- Different magnetic nanomaterials are used as a core-shell with alum sludge
- The composites are employed as adsorbents for eliminating Synozol dyes from aqueous effluent
- Magnetized adsorbents recognized as a superior win-win substance for pollutant elimination
- successive cycles of adsorption–desorption revealed the material sustinability
Although water is abundant on the globe, searching for a freshwater is still remaining a concern. At he meantime, toxic organic and inorganic substances are continuously leaking into soil, air and water that causing a sever damage to the ecosystem. Dyes are referred to as common pollutants that are frequently released in huge quantities by industries such as textile, leather, paper, rubber, food and plastics industries [1]. Annually, approximately 100 tones of dyes are dumped into water bodies in the form of wastewater effluents. Around 7x105 tones of commercial dyes are generated annually across various industries [2]. Such dyes are carcinogenic in nature and they have adverse environmental impacts since their release into water even in low concentrations. Dye presence in the watercourse might reduce the sunlight penetration into the water bodies, change water color and affect the photosynthetic reaction that harms the aquatic life [2]. Thus, treating such effluents is a must. Various biological, physicochemical and chemical techniques have been used to eliminate such dyes from aqueous solutions, including bio-sorption, chemical and physical treatments [3] is signified as the minimum cost treatments such as adsorption process. Adsorption is a cost-efficient system due to its cheap operational cost, versatility, convenience for use and effectiveness in eliminating various harmful contaminants from wastewaters [4–6]. However, the chemical use and the excessive sludge production are still limiting their real applications [3] [4].
Alum sludge (AS) is a waste by-product result from the water-works plants since aluminum sulphate is utilized as a primary coagulant [7]. The result is massive quantities of inevitable alum sludge that universally is treated as a waste for decades. But, with the global need of academia and researchers is to attain a sustainable world, converting a waste into a valorized material is essential to satisfy the required standards. Generally, alum sludge in Egypt is exposed for landfilling as a direct disposal to the environment without treatment. It is noteworthy to mention that recently, engineers have attracted much attention for using such waste AS in the adsorption systems [4, 5, 8]. Up to now, the most system is focused on using alum sludge in its pristine form. Unfortunately, because saturated adsorbents are typically hard to regenerate, their adsorption capacity will be significantly diminished, resulting in the limited service life of the AS adsorbent. This is the fundamental reason why the AS sorbent's useful life is being limited. According to Zhao et al. [8], the lifespan of an AS filter employed in artificial wetlands is from for to seventeen years [5]. Therefore, scientists are becoming more interested in creating new composites and adsorbing materials for the removal of wastewater from textile dyeing processes that might be used in large-scale industrial technology.
Magnetic (Fe3O4) nanomaterials can be used as a core-shell in a variety of compromises to improve their recyclability [6]. Magnetic nanoparticles (MNPs) are type of nanomaterials that can be manipulated using a magnetic field. Large surface areas, high number of surface active sites as well as strong magnetic characteristics of such MNPs signified them as high efficient adsorbent materials besides they are simple in operation and quick separation after treatment via magnetic field. The recovered MNPs can be successively used after separation because the impurities are easily removed from nanoparticles by the adsorbent agents [7]. Among magnetic nanoparticles, spinel ferrites have recently received the researchers’ attention in the field of wastewater treatment industry. Spinel ferrites have the general formula MeFe2O4, where "Me" stands for the trivalent iron ion Fe3+ and "Fe" for the divalent metal ions Fe2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Mg2+, and Cd2+. The oxygen ions in ferrites form a very compact cubic structure with two distinct cation lattice sites, one of which is a tetrahedral A site and the other an octahedral B site [8]. Ferrites have been prepared by several methods [9], [10], although co-precipitation method is still signified as an efficient preparation method. Co-precipitation posses various advantages including high homogeneity and small particle size, that stands the method as one of the best synthesis processes. Also, such method could result in a production of ultrafine, highly pure, crystalline and high-yield of nanoparticles [11]. Cadmium ferrite is signified as a kind of geometrically frustrated system in such system cadmium ions occupies the tetrahedral A-site. Commonly, it is considered that the addition of cadmium into ferrite improves its magnetic characteristics, such as saturation magnetization [12]. Previous research conducted experiments that substituting various cations of ferrites to improve its electrical and magnetic characteristics. Since Cu2+’s when occupied the spinel lattice declines the ionic radius and potential for creating a lattice distortion, thereby that substitution can significantly improves the magnetic characteristics of ferrities[13]. Moreover, Ag+ is appealing for use in water filtration systems due to its very low toxicity to humans when compared to other metals [14].
Thus, adsorption by MNPs materials, ferrites and their composites has been regarded as a practical and cost-effective technology for treating wastewater, and it is the primary topic of research for the elimination of dyes. Bayantong and his co-workers [15] fabricated MFe2O4@GO (M = Cu, Co or Ni) adsorbents for the removal of Methylene blue (MB) dye [12]. Dong et al.[16] prepared carbon/cobalt ferrite (C/CFO) nanocomposite which used for the removal of both cationic dye and anionic dye. Nickel ferrite nano composite activated carbon was fabricated by Saravanan for adsorption of Malachite green [17]. However, to the best of the authors’ knowledge, so far there is no report of the Alum sludge/spinel ferrite composite for the removal of both cationic and anionic dyes from water.
Herein, the current investigation is aimed to the fabrication of new magnetic composites augmented with the modified alum sludge waste as sustainable recyclable adsorbents. The composites are employed as adsorbents for eliminating Synozol Red KHL and Synozol Blue KHL dyes. XRD, SEM, TEM, EDX, VSM and FT-IR characterize such adsorbent materials. Isotherm time is located as well as the adsorption parameters including adsorbent dose, working pH and thermal effect are investigated. Various isotherm models are applied to define the composite adsorption mechanism.
2.1. Materials
Synozol Red KHL (R K-HL) and Synozol Blue KHL (B K-HL) are a water-soluble, reactive dyes supplied by Kisco International, Turkey, are used as a simulated textile adsorbate effluent. A separate stock solution of 1000 ppm is initially prepared from the two dyes, which is then diluted to the required concentrations as required. Also, diluted NaOH and H2SO4 are used to adjust the pH of the aquoues effluent, if needed, to the desired values. Cadmium nitrate (tetrahydrate) Cd(NO3)2.4H2O, ferric nitrate nonahydrate Fe(NO3)3.9H2O, cupric nitrate trihydrate Cu(NO3)2.3H2O, silver nitrate AgNO3 and sodium chloride (NaCL) are of analytical grade and used for nanoferrite preparation. All chemicals are used as received without any further purification.
2.2. Preparation of AS400-ferrite composites:
AS as an Aluminium- based waterworks residue was collected from the largest water treatment plant in Southern Shebin El-Kom City, Menoufia governorate, Egypt. The plant is based on using raw water from the River Nile reservoir by pumping. Such plant generates roughly 40,000 m3 of drinkable water per day for the western part of the city, where reservoir water is flocculated via the use of aluminium sulphate as the main coagulant. The fresh sludge was immediately removed from the sedimentation tank's underflow channel and taken to a lab for analysis. The excess water is then removed from the sludge by gravity settling, and the moisture content is then reduced to 10.8% using air drying. The resulting sludge cake is then washed to get rid of contaminants. Subsequently, such sludge is treated through an overnight oven drying (105°C) process to remove any water content. The resulting dried sludge is ground into a fine powder though a ball mill for one hour. The sample is labeled as raw alum sludge (AS). Afterwards, AS is then calcined in an electrical furnace for 2 h of calcination time at 400°C and the sample is named as (AS400).
On the other hand, nanosized Cd0.5Cu0.5Fe2O4 ferrite particles is prepared by co-precipitation routes as a fast simple method prepared at mild temperature range. The required metal reagents masses of Cd(NO3)2.4H2O, Cu(NO3)2.3H2O and Fe(NO3)3.9H2O were attained and dissolved in distilled water in a (1: 2) molar ratio. Then, NaOH (3 mol L) was gradually added until a precipitate was produced. The reaction mixture was heated for 2 hours at 80°C and then the mixture is vigorously stirred for 1 hour at room temperature. The samples are then first dried, followed by magnetic decantation and many washes with distilled water to produce soft ferrite particles. Subsequently, the attained powder is exposed for overnight drying at 80°C and the attained material is signified as CdAgF. Furthermore, it is essential to mention that Cd0.5Ag0.5Fe2O4 ferrite (CdCuF) are prepared by the same technique [16]. Then, the prepared ferrites are mixed with AS400 in (1:1) ratio to attain AS400F-CdAg and AS400F-CdCu that is then used as recyclable adsorbents.
2.3. Determination of Point of Zero Charge (pHpzc)
The point of zero charge (pHPZC) is signified as a crucial characteristic and applied to investigate the adsorption capacity of the adsorbent surface and the type of surface binding active center. pHPZC is determined through by salt addition method to investigate the electro kinetic properties of a surface referred as pH level at which the charge on the adsorbent surface approaches zero. In such method, approximately, 0.15 g of adsorbent was added to 25 mL of 0.01 M NaCl in 50-mL plastic tubes. The pH was adjusted using a pH meter (C5010, Consort, Belgium) to 2–12 (± 0.1) via 0.1 H2SO4 and 0.1M NaOH. The mixture was agitated for 24 h in a shaker (Orbi shaker BT3000, Benchmark, USA). The final pH was located and the difference between the initial and final pH are plotted against initial pH.
2.4. Characterization of the prepared adsorbents
The X-ray diffraction (XRD) is signified as an effective tool for analyzing the phase structure of the prepared samples as well as the crystalline and amorphous characteristics of the material under study. In this regard, the samples were analyzed through X-ray powder diffractometry (XPERT-PRO diffractometer) using Cu-Kλ radiation at room temperature (λ = 1.54060Å) run at 40 kV and 30 mA. The specific surface was obtained from measurements of adsorption–desorption isotherms of N2 at 80 K (BEL SORP MAX- Made in Japan). The SEM-EDX analyses were acquired at an accelerating voltage of 25–30 kV. Scanning electron microscopy was performed using an SEM model Philips XL 30 (Eindhoven, Netherlands) equipped with an EDX device (energy-dispersive X-ray spectroscopy). The morphology examination was investigated using a high-resolution Talos F200i-transmission electron microscope (HR-TEM, Thermo Fisher Scientific Co., Eindhoven, and the Netherlands). A transmission electron microscope (TEM) instrument (Talos F200i) operating at 20–200 kV was used to analyze the nanoparticle morphology. The hand-made VSM DMS-880 device, from the Physics Department of the Faculty of Science at Tanta University in Egypt, was used to measure the magnetic characteristics.
2.5. Experimental methodology:
The adsorption test is conducted through a jar test using an orbital shaker. The variety of operating conditions are carried out including contact time (0–300 min), initial pH of the aqueous (2–10), adsorbent dosage (0.5-5 g/L), initial Synozol Red KHL dye and Blue KHL dye concentrations in the range of 20 to 100 ppm, and solution temperature (40–60°C). Initially, the aqueous dye solution in a certain concentration is poured into sealed bottles. Thereafter, the essential amount of adsorbent material is added in order to conduct the adsorption experiments. H2SO4 or NaOH solutions were added to the dye solutions to change their initial pH values. The residual dye remaining after treatment in the aqueous effluent after treatment is measured and compared with the initial concentration using spectrophotometric technique (Model Unico UV-2100, USA) at the highest absorbance wavelength of 525 nm and 620 nm for Synozol Red KHL dye and Synozol Blue KHL dye, respectively. Then, the adsorption capacity of the prepared samples (qe) was determined according to the following equation:
\(\:{\text{q}}_{\text{e}}\) = ( \(\:{\text{C}}_{\text{o}}-{\text{C}}_{\text{i}}\:\))\(\:\frac{\text{V}}{\text{m}}\) (1)
Where Co and \(\:{\text{C}}_{\text{i}}\) (mg/L) are the initial and equilibrium concentrations of dye solution, m (g) is the mass of the adsorbent used, and V (L) is the volume of dye solution. The percentage of dye removal R (%) was calculated with the Eq. (2)
R = \(\:\frac{(\:{C}_{o}-{C}_{i})}{{C}_{o}}\) x 100% (2)
The adsorption test and the material preparation are illustrated graphically represented in Fig. 1.
2.6. Mathematical models:
Adsorption isotherm models:
Four isotherm models were used to determine the adsorption capacity of the adsorbent materials namely those of the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D-R).
Langmuir adsorption. The Langmuir adsorption is based on the notion that the adsorbent's homogenous sites are the only places where adsorption may take place. No more adsorption takes place at a site after a dye molecule has occupied it. To get the maximal adsorption capacity that corresponds to complete monolayer coverage on the homogeneous adsorbent surface without any interaction between the adsorbent and dye, the Langmuir equation is used. Both chemical and physical adsorption can be explained using the Langmuir equation. The following equation often describes this equation's linearized version [18].
$$\:\frac{{C}_{e}}{{q}_{e}}\:=\:\frac{1}{{Q}_{0}}\:{C}_{e}+\frac{1}{b{Q}_{0}}$$
3
Where \(\:{q}_{e}\:\)is the amount of adsorbate adsorbed per unit mass of adsorbent (mg/g), Ce is the retained adsorbate concentration at equilibrium (mg/L), \(\:{Q}_{0}\) is a measure of adsorption capacity (mg/g) and b is the Langmuir constant, which is a measure of energy of adsorption.
The equilibrium constant \(\:{R}_{L}\), also known as a separation factor and can be used to define the key properties of the Langmuir isotherm. It can be calculated by
$$\:{R}_{L}=\:\frac{1}{(1+b{C}_{0})}$$
4
where \(\:{C}_{0}\) is the initial concentration of adsorbate (mg/L) and b is the Langmuir constant. The separation factor \(\:{R}_{L}\:\)indicates the isotherm shape and determines whether adsorption is favorable or not. If \(\:{R}_{L}\) = 0, adsorption is irreversible; if 0<\(\:\:{R}_{L}\)<1, adsorption is favorable; if \(\:{\text{R}}_{\text{L}}\) = 1, adsorption is linear; and if \(\:{R}_{L}\)>1, adsorption is unfavorable [18].
Freundlich Isotherm the Freundlich model is an empirical equation that assumes the interaction between the adsorbed molecules and the adsorbent's diverse surface. Furthermore, a multilayer adsorption process is described by the Freundlich isotherm model [19]. The heterogeneity constant (1/n) classifies the Freundlich model as being applicable to highly heterogeneous surface systems. The linear form of the Freundlich isotherm is written as the following equation by plotting log \(\:{C}_{e}\) versus log qe [20].
\(\:\text{ln}{q}_{e}\) = \(\:\text{ln}{K}_{f}\)+ \(\:\frac{1}{n}\) \(\:\text{ln}{C}_{e}\) (5)
Where \(\:{K}_{f}\) is Freundlich constant that relates to the adsorption capacity of the solid (L/g). The heterogeneity constant, 1/n, assesses the strength of adsorption and indicates whether or not it is favourable. Advantageous adsorption conditions are represented by n larger than unity [20].
Temkin isotherm. The Temkin isotherm model is based on a variety of hypotheses and includes a component that explicitly considers the interactions between adsorbing species and adsorbate. The study's use of the linear form is indicated by the following equation [21],[10].
\(\:{q}_{e}\) = B \(\:\text{ln}A\) + B \(\:\text{ln}{C}_{e}\) (6)
where B is related to the heat of adsorption (B = \(\:\frac{RT}{b}\:\)), T is the absolute temperature (K), R is a gas constant (8.314 J mol−1 K−1), A is the equilibrium binding constant [10].
Dubinin–Radushkevich (D–R) Isotherm. This model, which is restricted to a monolayer, is used to examine the nature of adsorption and can estimate adsorption energy. It does not, therefore, model a homogenous adsorption surface or assume a constant sorption potential.
$$\:\text{ln}{q}_{e}\:=\:\text{ln}{Kq}_{m}+\:{K}_{DR}{\varepsilon\:}^{2}$$
7
$$\:{\varepsilon\:}^{2}\:=\:\text{R}\text{T}\:\text{ln}(1+\frac{1}{{C}_{e}})$$
8
Where \(\:{q}_{e}\) is the monolayer saturation capacity (L/g) and \(\:{K}_{DR}\:\)is the constant of adsorption energy used to calculate the average free energy (E). E value confirms the chemical or physical type of adsorption [22]
E = \(\:\frac{1}{\sqrt{2{K}_{DR}}}\) (9)
2.7 Kinetic models
Pseudo-first- and pseudo-second-order kinetic models were employed in this study to fit the experimental data points. The linear form can be used to express the pseudo-first-order kinetic model as follows:
\(\:\text{ln}({\text{q}}_{\text{e}}-\:{\text{q}}_{\text{t}}\) )
Where;\(\:\:{\text{K}}_{\:1}\:\)is pseudo-first-order constant (min− 1). The values of the adsorbed amount of dyes at the equilibrium (\(\:{\text{q}}_{\text{e}}\)) and \(\:{\text{K}}_{\:1}\) were calculated from the intercept and slope of \(\:\text{ln}({\text{q}}_{\text{e}}\)- \(\:{\text{q}}_{\text{t}}\)) versus t plot, respectively.
The linear version of the pseudo-second-order kinetic model is as follows.
\(\:\frac{t}{{q}_{t}}\) = \(\:\frac{1}{{K}_{2{{q}_{e}}^{2}}}\) + \(\:\frac{1}{{q}_{e}}\)t (11)
Where; \(\:{\text{K}}_{\:2}\) (g/mg min) is pseudo-second-order kinetic model constant. The plot of \(\:\frac{t}{{q}_{t}}\) versus t was used to calculate the value of\(\:{\:\text{K}}_{\:2}\) from the intercept and the value of \(\:{\text{q}}_{\text{e}}\) from the slope [23].
3.1. Characterization of AS-Ferrite composites:
3.1.1 XRD Analysis:
XRD patterns of the prepared powder, AS-Sorbents that calcined at 400°C and their ferrite composite are given in Fig. 2. The synthetic materials' XRD spectra show that the material is a multiphase system shows crystalline and amorphous phases, which, in turn, give the background and sharp diffraction peaks, respectively [24]. Sharp peaks appear in the XRD of the AS-sorbent (Fig. 2a) are visible in the pattern data suggesting the presence of a crystalline structure. Calcite (CaCO3), quartz (SiO2), and albite (NaAlSi3O8) are the main crystalline inorganic materials found in the raw alum sludge [25]. Quartz, or silicon oxide (SiO2) is the primary crystalline inorganic material in such sludge. Its crystal shape is hexagonal. Based on the hkl planes, the highest intensity peaks of SiO2 are identified as shown in Fig. 2 (a). Since the only coagulant used in this water treatment plant is aluminium sulphate, the quartz particles may have originated from suspended particles in the raw water, such as sand and clay. Additionally, the AS400 Sorbents contain the anorthic crystal structure of calcium aluminosilicate (CaAl2Si2O8). AS400 also contains the crystalline rich-silica zeolite ZSM-12 (sodium aluminium silicate, Na1.16Al2Si77.4O158.38), which has a monoclinic crystal shape. Al2O3 and SiO2 are thought to be the primary zeolite precursors. Due to the usage of Al2(SO4)3 in the water treatment process with the presence of NaOH and the presence of sand, those compounds have high concentrations in alum sludge [20].
Figure 2 (b and c) shows the XRD pattern of AS400-Ferrite composites. The same signals of quartz [SiO2], graphite, calcite and albite [Na Al Si3 O8] in the same values of 2θ were appeared in both samples of (AS400) and their composites. In addition to the band characteristic associated with the presence of amorphous silica and albite in the nano-composite sample, there was evidence of nano-ferrite characteristic bands. The peaks which were precisely indexed to the lattice planes (220), (311), (422), (440), and (533) have been matched with the plane of CdCu and CdAg ferrite (JCPDS documents 591–0028 and 153–9598) and the results are in good agreement with the result reported by Mangood et al. (2023) [11]. This XRD pattern indicating the coexistence of ferrite and AS400 in the composite.
3.1.2 Scanning electron microscopy (SEM):
The physical morphology of the ferrite materials, ferrite composite as well as the pristine AS400 substance is illustrated in Fig. 3. Also, the SEM image of the ferrite composite after the dye adsorption is supported. The SEM micrographs depict the physical morphology of the prepared AS-Sorbent material and their composites with the prepared ferrite particles. The microstructure SEM images of the composite materials reveal spherical quantity of magnetite nanocrystals with few irregular shapes as illustrated in Fig. 3 (a) and (b) [23]. Figure 3 (d) shows the SEM images of CdCuF that display the prepared ferrite is spherical in shape and there is aggregation between the particles that indicating the magnetic nature of the prepared ferrites and this result also confirmed by VSM analysis [9]. The modified AS-Sorbent (AS400) posses a heterogeneous structure and has a non-uniform porous shape mixture and rough surface morphology as shown in the micrograph Fig. 3 (g) [20], [26]. The image explores that the material structure is porous in nature that confirms the material is efficient in the adsorption process [23].
Furthmore, the SEM images after adsorption is checked and the micrograph is represented in Fig. 3 (c). The graph shows a discernible smooth surface in comparison to the rough surface of the material prior adsorption. This is due to the dye molecules’ that have been occupied on the surface of the sorbent surface [20].
3.1.3 Transmission electron microscopy (TEM)
The morphology and crystallite size of AS400F-CdCu and AS400F-CdAgcomposites prior and after adsorption were investigated under transmission microscope as displayed in Fig. 4 (a), (b) and (c) respectively. It was shown from Fig. 4 (a-c), that the prepared composites are spherical in shape after modification with CdCuF and F-CdAg, different spherical nanoparticles were detected. The TEM images also confirm the porous nature of the prepared composites. Mesopores were arranged and aligned to generate backbones of coagulated nano-ferrites. These results are in good agreement with the result obtained from SEM studies. Additionally, Fig. 4f displayed the synthesized adsorbent's selected area electron diffraction (SAED) pattern, which included prominent diffraction rings that indicated the strong crystallinity of the made nano-adsorbent [4]. Using the IMAGEJ 1.48 V program, the particle size distribution is also measured. As shown in Fig. 4, the AS400F-CdAgsample has low particle size relative to the other samples' particles allow it to have the largest surface area. Generally, high surface area helps in conducting an efficient adsorption process.
Additionally, the particle size distribution were investigated and explored through digital TEM images that were analysed using the, IMAGEJ 1.48V program. Ferrite composite materials’ images as well as the solo AS400 and Ferrites are signified to calculate their particle size distribution in the histogram in the inset of Fig. 4. The particle size distribution of Ferrite, AS400 and Ferrite composite displayed an average particle size in the nano size range. The solo CdCuF and the pristine AS400 substances displayed a particle size of 11.6 and 18.7 nm, respectively. The average size of 14.5 nm and 4.2 nm for AS400F-CdCu and AS400F-CdAg compsites, respectively. Also, the average particle size distribution of AS400F-CdAgcomposite that is loaded with dye recorded 11.3 nm, which confirms the material is still in the nano size after it is occupied with the dye molecules. This reasonable size offers a high surface area for the material that signifies its efficiency as an adsorbent material through wastewater elimination.
3.1.4 Fourier transforms infrared spectroscopy (FTIR):
The various forms of bonding present in calcined sludge AS400, ferrite and the prepared composite material augmented with AS and ferrite, i.e. AS400F with and without dyes might be identified using Fourier transform infrared (FTIR) transmittance spectrum analysis. As shown from Fig. 5 (a), the absorption bands around 3443.15 cm− 1 are assigned for the Si-O-H and O-H bonds in surface water molecules. These samples have the Si–HO–HSi stretching vibrations (silanol) at 1110.01, 1102.75, 1094.78, 1103.20 and 1094.20 which indicate the presence of quartz in those samples [1]. The type of silicate network can be inferred from the location and strength of the Si—O—Si stretching band. Such amorphous silica peak is signified at 1094.20 cm− 1. The Al—O stretching and bending vibrations of the water molecules that are chemically bound to Al(OH)3 are correlated with the absorption bands of Al(OH)3 at 550, 1600, and 3518 cm _1 [25]. The absorption band of carbonate appears at 1388.19 cm− 1 [1]. Si–O–Fe is included in the composite because it shows identical band intensities at about 539 cm− 1. All the spectra from 1094 to 476 cm− 1 show the same peaks, though, belonging to quartz (Si–O) and other oxides (Si–O–Fe, Al–O–Si) are presented close to such band [27]. Additionally, the majority of the AS400 distinctive peaks can be seen in the composite's FTIR spectra, which is another indication that the AS400F composites were prepared successfully. The composite samples also show two strong peaks, respectively at 476 and 616 cm− 1 band. These peaks are caused by the stretching vibration mode linked to the metal–oxygen absorption band (Fe–O links in the crystalline lattice of Fe3O4) and are attributed to the formation of the ferrite phase. This happens as a result of contributions from the stretching vibration bands associated with the metal in the octahedral and tetrahedral sites of the oxide structure in these locations [11]. That is in good agreement with the results reported by Thabet et al. and that was the same bands appeared at FTIR spectrum of CdCuF and CdAgF ferrites. The FTIR spectra of the susbtsance after adsorption is signified by a shift on the groups and vanished, indicating that the dye molecules are adsorbed on the surface of the adsorbents.
3.1.5 Energy dispersive X-Ray spectroscopy (EDX)
The elemental composition of the prisitne AS400 and the synthesized nano-ferrite composite were investigated by EDX technique as found in Fig. 6. Solo AS400 displays three sharp peaks linked to silicon (Si), oxygen (O) and (Al). Such elements posses a typical structural framework of alumino silicateminerals (i.e., zeolites group) as seen in Fig. 6 (a). Such group is also observed in all the prepared composites compromised of AS400 prior to or after adsorption. AS400 also contains carbon and iron elements. The carbon in the water sludge was derived from the soil organic matter (SOM), which was created by microbial activity during sludge storage. The presence of iron and other minor metals indicated that aqueous sludge had the capacity to exchange cations [28]. After modification with CdCu ferrite and CdAg ferrite, other peaks that asscoiated with Cd, Cu, Ag elemtns are obsserved as displayed in Fig. 6 (b from Fig (b-e). Such results verify the fomation of alum sludge ferrite composites. It is noteworthly to mention that their proportions are differs according to the solo AS400 or composite augmented with ferrite according to the data represented in Table 1.
|
Elements (wt %) |
C |
Si |
Al |
O |
Fe |
Cd |
Cu |
Ag |
|---|---|---|---|---|---|---|---|---|
|
AS400 |
7.56 |
25.78 |
13.81 |
39.23 |
7.43 |
- |
- |
- |
|
AS400F-CdCu |
15.12 |
16.48 |
8.92 |
29.77 |
15.53 |
5.46 |
4.06 |
- |
|
AS400F-CdAg |
1.47 |
20.77 |
10.86 |
28.68 |
20.07 |
6.70 |
- |
6.58 |
|
AS400F-CdCu after dye adsorbed |
24.34 |
12.35 |
6.08 |
27.89 |
17.36 |
5.74 |
4.06 |
- |
|
AS400F-CdAgafter dye adsorbed |
23.26 |
13.64 |
6.57 |
27.25 |
17.52 |
6.12 |
- |
4.91 |
3.1.6 Vibrating sample magnetization (VSM):
Up to now, vibrating sample magnetization (VSM) test is still the most significant technique to evaluate the magnetic characteristics of a substance. In this regard, the hysteresis loop os the substances are investigated, the larger the hysteresis loo is related it the greater magnetic susceptibility value of such substance. Dissimilarity, the magnetic susceptibility value decreases with a smaller hysteresis loop [27]. Based on the data in Fig. (7) and the results tabulated in Table 2, CdCuF showed a 29.392 emu g− 1 saturation magnetization, while their composite type (AS400F-CdCu) showed a 7.026 saturation magnetization. The smaller or absence ferrite mass in the nanocomposite was the cause of the composite's lowest saturation magnetization value [29]. The presence of porous AS400 may be a major factor in the decrease of magnetic saturation but the final imbedded material still posses a good superparamagnetic properties, which depicts the enhancing of the nature of non-magnetic behavior of AS400 [27]. On the other hand, it was found that (AS400F-CdCu) has saturation magnetization value greater than its ferrite. The magnetic properties of these ferrites in their solo or composite form with AS400 signify them as a good sustainable candidate adsorbents since their easiness in recover technique and reuse opportunity.
|
Material |
Magnetization, Ms/emu g− 1 |
SBET/m2 g− 1 |
|---|---|---|
|
CdCuF |
29.392 |
94.9230 |
|
AS400F-CdCu |
7.026 |
92.943 |
|
CdAgF |
2.889 |
146.3849 m²/g |
|
AS400F-CdAg |
3.507 |
105.42 |
3.2 Wastewater adsorption
3.2.1 Adsorption time-profile:
Initially, in order to the study the adsorption matrix, it is essential to investigate the adsorption time. In this regard, the time profile of the two simulated wastewater dyes, i.e. Red and Blue KHL Synozol dyes are studied, at room temperature, using AS400F-CdAg and AS400F-CdCu composites as well as the pristine AS400, CdAgF and CdCuF substances. Figure 8 is illustrating simultaneously the time profile and a comparison of the pure AS400, CdAgF and CdCuF and the composite ferrites AS400F-CdCu and AS400F-CdAg. The results are displayed in Fig. 8 (a) and (b).
Overall, CdAgF and its AS400F-CdAg composite exhibit the maximum sorption tenancy for both Red and blue K-HL, with the majority of the dyes adsorbed during the first one hour of contact time. As silver nanoparticles are thought to be a special kind of adsorbent that can be utilized to remove pollutants due to their high specific surface area at the nanoscale nature [30]. Surprisingly, all the prepared adsorbents exhibit complete saturation of their accessible active sites with both the two used dyes molecules after a protracted reaction time of more than one hour of contact time. Adsorption capacity increases, rapidly, in the initial contact time; ascribed to the availability of large number of vacant adsorption site. Thereafter, the adsorption capacity slows down due to the exhaustion of adsorption site. Eventually, equilibrium is attained after 1 h, as the entire vacant site gets occupied by dye molecules.
3.2.2 Effect of initial dye loading on sorption capacity
For real scale applications, it is essential to investigate the effect of pollutant loadings on the adsorption capacity. In this regard, the effect of the initial dye concentration is shown in Fig. 9 (a and b). The experimental results displayed in the Fig. 9 show the effect of the initial dye loading ranged from 20 to 100 ppm using various adsorbents. Generally, for all of the employed studied adsorbents, both dyes explored noticeable increases in the adsorption capacity and decrease in removal efficiency with the increase in the dye loading. This might be caused by an increase in the interaction between the dye molecules and the prepared adsorbents at greater dye concentrations. The improvement in the adsorption capacity can be attributed to the fact that an increase in the initial dye concentration causes an excess of the dye molecules that surrounding the adsorbent sites. Thereby, an enhancement in the mass transfer rate between the adsorbent material and the adsorbed solute is achieved [1]. The decreases in removal percentage with increase in initial dye concentration is attributed to the fact that for a fixed weight of adsorbent, the free binding site available on the surface of the adsorbent get reduced. This result well correlated with reports of Sabarish Radoor et al [31].
3.2.3 Effect of adsorbent dosage on the dyes adsorption
The amount of both dyes absorbed by the prepared adsorbents is significantly influenced by the optimal adsorbent dose. In the current investigation, different adsorbent doses in the range of 0.5 to 5 g /L were employed, while keeping all other parameters constant, were applied. It was observed from Fig. 9 (c and d), for both dyes, the adsorption capacity increase when adsorbent dosage increases. The might be attributed by the total number of active sites of the prepared ferrite and their composites increase with the increase in the amount of adsorbent. Therefore, significantly large amount of blue and red dyes can be adsorbed resulting in higher dye adsorption capacity, which is in good agreement with the previous data reported in the literature [5], [32].
3.2.4 Effect of temperature on the dyes adsorption
Since most textile dye effluents are produced at very high temperatures, temperature influence plays a significant role in influencing the suggested adsorptive dye removal process in real-world applications. In order to determine whether the adsorption process was endothermic or exothermic in nature, set of similar experiments were carried out in the temperature ranges of 313, 323, and 333 K. The results showed in Fig. 9 (c and f) illustrate that increasing the temperature, the amount of Red dye adsorbed onto adsorbents is increased as well. This might be suggesting that the process is endothermic in nature (Fig. 9 (c). The increase in temperature-dependent adsorption capacity of produced adsorbents might be attributed to two factors: an increase in dye molecular mobility and an increase in the number of absorbable active surface sites on the material due to pore widening [32] [28]. On the other hand, the results showed that as the temperature increased, the adsorption capacity of produced adsorbents for the Blue dye adsorption decreased, suggesting that the process is exothermic in nature (Fig. 9 (d). this might be associated with the different nature of the dye molecules affecting the thermal trend of the adsorption system.
3.2.5 Effect of pH on the dyes adsorption
Aqueous solution pH is one of the most crucial parameters on the adsorption systems since it influencing on the adsorption properties of the adsorbent material. pH might be affects the chemistry of the polluted effluent. Also, pH posses an influence on the ions in the solution that could be competing the absorbent material in the solution. Furthermore, the activity of functional groups and the surface charge of the adsorbent also impacted by the pH value. In addition, the characteristics of the adsorbent, the adsorption process and the dissociation of dye molecules can all be influenced by the pH of the aqueous medium. Not only can the pH of the solution alter the adsorbent, but it can also alter the dye's chemical structure. The degree of ionization and surface charge of the adsorbed ion are changed by pH [34].
Figure 10 (a and b) displays the variation in the adsorption quantity of Synozol Red and blue K-HL via the suggested adsorbents with the initial solution pH ranging from 2.0 to 10.0. It is deduced from Fig. 10 (a, b) that increasing the pH value from the acidic (pH 2.0) to the alkaline (pH 10.0) results in a reduction in the adsorption capacity. For the object of comparison such effect is applied for all the studied adsorbents and the comparative investigation is displayed in Fig. 10. According to the data illustrated in the figure, the acidic pH medium increases the adsorption capacity at the same time as decreases adsorption capacity found at alkaline pH values.
In order to examine such pH trend, the type of the surface charge of the adsorbent materials’ might be studied to be a guide to verify such adsorptive behavior. The pHPZC of the AS400 and their composites with the prepared ferrites were found in the range of (7.4–9.33) as shown from Fig. 10. As the solution pH is above pHPZC, the adsorbents’ surface is mainly negatively charged, while the surface of the adsorbents posses a positive charge at the pH below this range [35]. This could be linked to the Synozol Blue KHL dye is an anionic dye that is negatively charged. Thereby, there is an electrostatic attraction between such dye and the positively charged adsorbents indicating the higher adsorption capacity in acidic medium. In contrast, at higher pH values (pH > pHPZC) there was repulsion between negatively charged (OH−) on the surface of the adsorbent and anionic blue dye. The reduction in the adsorption capacity for Synozol Red KHL dye may be due to the loss of the active sites of the adsorbent material. Such investigation is in accordance with the earlier findings referenced in the literature [9].
3.3. Isotherm Models
The experimental results were applied to the linearized form of various isotherm models, Langmuir, Freundlich, Temkin, and D-R in order to explore the Synozol Red and blue KHL dyes adsorption mechanism on the adsorbent materials. Thereby, various isotherm constants and parameters were calculated using such proposed abovementioned models and the data is listed in Table 3. The best-fitted model is governed according to the correlation coefficient (R2) values. According to the data listed in Table 2, adsorption isotherm for Synozol Red KHL adsorption is following monolayer Langmuir and Freundlich isotherm models according to the highest R2 values. But adsorption isotherm for Synozol blue KHL adsorption is best fitted to the monolayer Langmuir isotherm only [36]. Further the values of RL for both two dyes are in the range of 0 and 1. Such data indicating that the adsorption process is favorable .The adsorption is favorable when the n value is ranged from 1 < n < 10, as shown from Table 3. The n values are greater than unity, which verifies the adsorption is favorable [21]. Remarkably, the low values of the mean free energy of adsorption (E), which are less than 8 kJ mol− 1, suggest that the adsorption of the dye molecules on the adsorbent substances is physisorption [20]. Such physisorption is contributing the physical sorption process that may be represented by Van der Waals forces that contribute to the adsorption process. The adsorption of the Red and Blue K-HL dyes onto the prepared adsorbents may be predominately controlled by chemical adsorption mechanism, which agrees with the well-fitted Langmuir monolayer adsorption isotherms and pseudo-second-order kinetics. Therefore, such results suggested that the adsorption is in between physisorption and chemisorption mechanisms [19].
|
Isotherm parameters |
CdAgF |
AS400F- CdAg |
CdCuF |
AS400F-CdCu |
AS400 |
||||
|---|---|---|---|---|---|---|---|---|---|
|
Synozol Red KHL |
|||||||||
|
Langmuir |
|||||||||
|
Q0 (mg/g) |
149.03 |
102.56 |
91.66 |
52.30 |
40.95 |
||||
|
0.038928 |
0.043747 |
0.123374 |
0.368259 |
0.048876 |
|||||
|
R2 |
0.95 |
0.98 |
0.99 |
0.98 |
0.99 |
||||
|
Freundlich |
|||||||||
|
KF |
7.9619 |
10.2894 |
9.444 |
12.3124 |
6.3752 |
||||
|
n |
1.869718 |
2.245929 |
2.318841 |
3.538696 |
2.696145 |
||||
|
R2 |
0.96 |
0.94 |
0.96 |
0.97 |
0.94 |
||||
|
Temkin |
|||||||||
|
B (J/mol) |
31.52844 |
23.43355 |
20.21028 |
10.30284 |
9.1516 |
||||
|
A (L/g) |
5.47619 |
3.53265 |
3.51167 |
1.24236 |
2.26984 |
||||
|
R2 |
0.96599 |
0.95781 |
0.9844 |
0.96204 |
0.95723 |
||||
|
D–R |
|||||||||
|
qm (mol/g) |
88.789 |
77.568 |
66.231 |
43.219 |
34.326 |
||||
|
KDR (mol2/J2) |
70.27907 |
42.77259 |
35.66965 |
43.54258 |
5.60474 |
||||
|
E (KJ/mol) |
0.10311 |
0.11047 |
0.11411 |
0.15000 |
0.12084 |
||||
|
R2 |
0.97055 |
0.99376 |
0.98731 |
0.87431 |
0.9964 |
||||
|
Synozol Blue KHL |
|||||||||
|
Isotherm parameters |
F-CdAg |
AS400F-CdAg |
CdCuF |
AS400F-CdCu |
AS400 |
||||
|
Langmuir |
|||||||||
|
Q0 (mg/g) b R2 |
79.7448 0.328530 0.98152 |
32.4149 0.261507 0.99981 |
29.0866 0.092518 0.98416 |
27.0343 0.0491254 0.97638 |
10.0867 0.069481 0.97638 |
||||
|
Freundlich |
|||||||||
|
KF n R2 |
6.12611 2.0351 0.99691 |
31.94066 3.4370 0.9826 |
46.750408 3.8448 0.99538 |
24.29821 3.1904 0.99223 |
31.30317 17.2592 0.60475 |
||||
|
Temkin |
|||||||||
|
B (KJ/mol) A (L/g) R2 |
16.38333 3.50816 0.99805 |
6.79689 1.201149 0.99068 |
5.44555 1.52425 0.98539 |
5.408 1.23014 0.97898 |
0.60296 5.34667 0.61903 |
||||
|
D–R |
|||||||||
|
qm (mol/g) KDR (mol2/J2) E (J/mol) R2 |
51.326 70.27907 0.084347 0.98534 |
31.132 42.77259 0.108119 0.99823 |
25.753 35.66965 0.118396 0.94334 |
22.254 43.54258 0.107159 0.95253 |
10.405 5.60474 0.298681 0.40425 |
||||
3.4 Adsorption thermodynamics
The intrinsic energy changes associated with the adsorption process are thoroughly explained by the thermodynamic parameters. A thermodynamic research was done to determine the spontaneity and nature of the adsorption process. To ascertain the nature of the adsorption process onto the prepared adsorbents, changes in free energy of adsorption (ΔG), enthalpy change (ΔH), and entropy (ΔS) were calculated. The thermodynamic parameters were investigated though using the following equations from the Langmuir isotherm parameter,
ΔG = -RT Ln KL (12)
KL = \(\:\frac{{q}_{e}}{{C}_{e}}\) (13)
Ln KL = \(\:\frac{{\Delta\:}\text{H}\:}{\text{R}\text{T}}\) + \(\:\frac{\varvec{\Delta\:}\mathbf{S}}{\text{R}}\) (14)
where KL is the equilibrium constant, qe is the amount of dye adsorbed on the adsorbent per liter of solution at equilibrium (mg l− 1) and Ce is the equilibrium concentration in solution (mg l− 1). R is the universal gas constant (8.314 Jmol− 1 K− 1) and T is the absolute temperature (K). ΔG (kJmol− 1), ΔH (kJmol− 1) and ΔS (JK− 1mol− 1) indicate changes of Gibbs free energy, enthalpy and entropy, respectively.
The plot of Ln KL versus 1/T resulted in a straight line and the values of ΔH and ΔS calculated from the slopes and intercepts of such plot along with ΔG values (Fig. 12). The thermodynamic parameters for the removal of both dyes by the studied materials are presented in Table 4. Negative values of ΔG indicate the fact that the adsorption of both two dyes adsorbed onto CdAgF and its composite is a spontaneous process, while the other prepared materials had positive values of ΔG indicating the process is not spontaneous. This explains the lowest values of both two dyes removal by AS400, CdCuF and their AS400F-CdCu [37].
The positive values of enthalpy change ΔH for Red dye removal attributes to the endothermic nature of adsorption process which led to an increase in the degree of adsorption with increasing the temperature [21]. The values of ΔG dropped as the temperature rose, suggesting that high temperatures were ideal for adsorption [15]. While, The exothermic nature of the blue dye removal process is indicated by the negative values of ΔH, indicating that the dye adsorption onto the materials is slowed down by high temperatures [37]. Furthermore, as a result of the adsorption process, there is an irregular rise in the degree of randomness at the solid-adsorbate interface, as shown by positive entropy change values for Red dye [23]. Conversely, a negative value for ΔS of blue dye adsorption denotes a decrease in randomness in the adsorption process during the molecules' transit from the adsorbent to the adsorbates [38].
3.5. Adsorption Kinetics
Two types of kinetic models were studied for determining the adsorptive removal mechanism of Red and Blue K-HL dyes onto the prepared adsorbents. These models are (i.e. pseudo-first-order and pseudo second- order models) and the parameters of each model are displayed in Table 5. It was clear from the correlation coefficient (R2) attained that the pseudo-first order kinetic model could not adequately describe the adsorption process as it posses a lower R2 value than those of pseudo-second-order model. Furthermore, as compared to the pseudo-first-order model, the calculated adsorption capacity (\(\:{\text{q}}_{\text{e}}\)) of the pseudo-second order model is substantially closer to the experimental one (\(\:{\text{q}}_{\text{e}}\)) as seen in Table 5. This demonstrates that the proposed adsorption process may be described by the pseudo-second-order model. Given that the experimental adsorption data fits the pseudo-second-order model well, it can be concluded that the characteristics of the adsorbent and adsorbate materials influence the adsorption mechanism [39]. The pseudo-second-order model is based on the hypothesis that rate-determining step may be chemical sorption or chemisorption involving electron sharing or exchange between prepared adsorbents and two proposed adsorbates, i.e. Synozol Red and Blue dye K-HL dyes [18].
|
Red KHL dye |
|||||||
|---|---|---|---|---|---|---|---|
|
Pseudo-1st - order |
Pseudo-2nd - order |
||||||
|
Adsorbents |
\(\:{\mathbf{q}}_{\mathbf{e}}\) (mg g− 1) |
k1 (min− 1) x 10–2 |
R2 |
\(\:{\varvec{q}}_{\varvec{e}}\) (mg g− 1) |
k1 (min− 1) x 10–3 |
R2 |
|
|
CdAgF AS400F-CdAg CdCuF AS400F-CdCu AS400 |
6.4350 12.3607 16.8974 22.0151 7.2088 |
3.386 3.958 2.913 2.62 1.443 |
0.8334 0.9120 0.9600 0.9790 0.7762 |
33.0906 33.1016 32.2684 32.2268 18.6776 |
29.374 11.663 5.704 2.753391 7.768 |
1 0.9999 0.9999 0.9991 0.9992 |
|
|
Blue KHL dye |
|||||||
|
Pseudo-1st - order |
Pseudo-2nd - order |
||||||
|
Adsorbents |
\(\:{\mathbf{q}}_{\mathbf{e}}\) (mg g− 1) |
k1 (min− 1) x 10–2 |
R2 |
\(\:{\varvec{q}}_{\varvec{e}}\) (mg g− 1) |
k1 (min− 1) x 10–3 |
R2 |
|
|
CdAgF AS400F-CdAg CdCuF AS400F-CdCu AS400 |
6.1455 8.3343 6.81222 11.8363 5.63681 |
4.075 4.225 4.068 3.674 3.472 |
0.8932 0.9397 0.9338 0.9566 0.9709 |
20.3500 17.8826 16.5480 15.9718 10.6621 |
25.432 16.437 21.564 6.802 20.261 |
0.9999 0.9989 0.9999 0.9999 0.9999 |
|
3.6. Adsorbent recyclability:
Further, one of the most necessities for materials utilized in eco-system is to be degradable or recoverable. As reusable materials reduced costs. The recovery process may ensure that the adsorbent agents may be collected after the dye removal process to avoid secondary pollution. Due to the magnetic properties of the ferrite and their composites, they could be restored and washed for several times and dried before being used once more, which is vital to reducing their costs. Figure 13 (a,b) illustrated the reusability of the prepared adsorbents over five cycles. The adsorbent displayed relatively stable adsorption performance for Red dye in multiple adsorptions/desorption cycles. The removal of blue dye drop after each cycle due to the loss of dynamic sites during the whole adsorption–desorption process. The results showed good reusability of the above adsorbents.
Comparative investigation with various adsorbents
Comparing the current work with the data from literature is essential to evaluate the current study performances. Removal capacity of Synozol Red KHL compared by other ferrite composites is listed in Table 10. The removal of Red by CdAgF and its composites (AS400F-CdAg) is greater than previously reported literature in terms of higher adsorption capacity (149.031 and 102.56mg/g). Compared to the adsorption capacity of different dyes by other adsorbents, CdAgF and its composite (AS400F-CdAg) are considered as an effective adsorbent for removal of toxic dye from aqueous solution due to their higher effective surface area, having more adsorption active sites and the presence of calcium and sodium aluminosilicate (Zeolite), which is indicated by the X-ray diffraction result (Fig. 2), These components are useful in dye adsorption. Also, compared to the other suggested processes, the current system is ecologically friendly since both Alum sludge and ferrite are environmentally benign
|
Adsorbenrt |
adsorbate |
Adsorbent does |
Dye Conc |
Adsorption isotherm time |
Adsorption capacity(mg.gl− 1) |
|
|---|---|---|---|---|---|---|
|
MgFe2O4-SiC composite |
Azo dye direct black BN |
1.5 g/L |
20 PPm |
120 min |
84.637 |
[40] |
|
carbon/cobalt ferrite (C/CFO) nanocomposite |
Methylene Blue, MB) |
0.6 g/L |
50 mg/L |
- |
43.05 |
[41] |
|
CuZnFe2O4–biochar composite |
BPA SMX |
- |
20 mg/L |
60 min |
101.5 99.99 |
[42] |
|
sawdust/magnetite composite (SF-(2:1)) |
Synozol Red KHL |
1 g/L |
20 |
5 min |
21.71 |
[6] |
|
fly ash/NiFe2O4 composites |
Congo red |
0.1 g/100 mL |
25 mg/ L |
180 min |
23.33 |
[43] |
|
NiFe2O4 nanocomposite activated carbon |
malachite green |
0.5 g |
50 mg/L |
60 min |
83 |
[17] |
|
CoFe2O4–chitosan composite |
Methyl Orange (MO) |
240 min |
66.18 |
[44] |
||
|
CdAgF AS400F-CdAg |
Synozol Red KHL |
1 g/L |
20 PPm |
60 min |
149.031 102.56 |
This work |
This study showed the efficient and effective magnetic AS400F-CdCu and AS400F-CdAg composites synthesis and application that are both used for the Synozol Red and Blue dyes oxidation. The experimental data revealed that the ferities based absorbents offering the benefits of easily recoverable and separation substances for successive and sustainable use. To add up, the batch adsorption test was studied and the experimental parameters including pH, initial dye concentration, contact time, adsorbent dosage, and temperature are assessed. The adsorption capacity of AS400F-CdAg composites was 102.56 and 32.41 mg/g for Red and blue dye, respectively. Also, adsorption kinetics and isotherms models are evaluated and the experiments are fitted to the pseudo-second-order kinetic and Langmuir isotherm models, respectively for Synozol Blue dye. But, Langmuir and Freundlich isotherm models are well describing the Synozol Red dye. The thermodynamic parameters verified the adsorption of the both studied dyes is an endothermic process and spontaneous in nature. Up to five successive cycles of adsorption–desorption were demonstrated by the regeneration investigation that validate the stability and reusability of these composites. According to the research's findings, ferrites and their composites with calcined alum sludge can be used as efficient adsorbents to remove Synozol Red and Blue dyes red from wastewater. However, more future work is essential to study the real scale treatment facilities.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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