In this research work, a novel guar gum based membrane was fabricated that was further reinforced with tungsten oxide (WO3) nanoparticles (NPs) respectively for the removal of methyl violet (MV) dye from aqueous solution. The membranes were characterized by Fourier Transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) which confirms the presence of functional groups, rough and smooth surface morphology with porous structure and X-ray diffraction (XRD) shows specific peaks approves the NPs of WO3 respectively. The swelling study of membranes was performed by using various parameters i.e. maximum swelling were attained at neutral pH 7, water transport mechanism was followed the Fickain diffusion and the gel content was linearly increased 91–95%. The adsorption efficiency of membrane for virulent dye (MV) was investigated by following parameters i.e. the adsorption of dye was maximum at pH 10 and 96% of dye was removed at 60 mins. The kinetic data for adsorption process was best fitted with pseudo first order kinetic model which shows the physisorption of dye and isothermal data for Langmuir-Freundlich model shows multilayer adsorption. The negative ∆H values indicates the exothermic reaction. Furthermore, pre and post analysis of water samples (drinking tap water and contaminated water) were used to examine the physiochemical parameters such as colour, odour, pH, conductivity, TDS and DO (dissolve oxygen) by using the synthesized membrane. The fast uptake capacity of dye removal and the physicochemical parameters of contaminated water was observed by friendly nature of membrane.
Research Article
The impact of tungsten oxide (WO3) nanoparticles, embedded in Guar gum based hydrogel for water treatment applications
https://doi.org/10.21203/rs.3.rs-2080318/v1
This work is licensed under a CC BY 4.0 License
Version 1
posted
You are reading this latest preprint version
Adsorbent
crosslinking agent (TEOS)
Guar gum (GG)
Methyl violet (MV)
polyvinyl alcohol (PVA)
Tungsten trioxide (WO3).
Water is essential for the survival of living creatures as well as technological sector for economic development (Sharma and Sanghi, 2012). The industrial waste, agriculture run-offs, radioactive substantial, garbage disposal and rapid population growth are responsible for contamination of natural and anthropogenic sources (Yaqoob et al., 2020). So, the release of pollutants such as many gases, dyes and micropollutants badly affects the bionetwork and human health. Polluted water is major problem that effects the ecosystem and cause the diseases like typhoid, cholera, dysentery, dermatitis and many more. Thus, efficient and economical methods are used for the wastewater treatment to overcome the complications of industrial sectors (Besha et al., 2020; Chowdhary et al., 2020).
The contamination of water resources with dyes has becoming a major environmental problem world-wide. On the basis of chemical and natural properties, different classes of dyes such as cationic, anionic mordant and vat dye are used in textile, paints, pulps, and printing industries which can adversely affect the human health, ecosystem and water organisms (Nandi et al., 2009). Meanwhile the methyl violet is a cationic dye that highly soluble in water, non-degradable, gives intense color and ability to react directly with fiber substrates to form strong covalent bond (El-Barghouthi et al., 2007). The structural or fundamental stability and complexity of dyes are difficult to degrade and needs to be treated before release. Cationic dyes are more toxic, carcinogenic and mutagenic than acidic dyes. So, its hazardous nature that can directly influence the ecosystem and life. It may trigger many harmful diseases in human and also affects the crops and its production while used for irrigation purposes and damage the soil as well (Bonetto et al., 2015; Krishnappa and Badalamoole, 2019; Midya et al., 2019). Physicochemical parameters are used to detect the quality of water before used for drinking, domestics, industrial and agriculture purposes. Physical and chemical properties of water alters by contaminations and examined by the water quality by color, temperature, pH, TDS, EC, and DO and biological parameters that are used for microbial contamination and Total Coliforms (Hunter et al., 2002; Toufeek and Korium, 2009).
A broad range of technologies has been established for exclusion of dyes and to check out their physiochemical features for drinking and waste water treatment. Hence, the various techniques are consist of physical, chemical and biological methods that are used to eliminate the pollutants and improve the water quality (Saleh et al., 2020). Membrane separation, electrolytic process (Mouli et al., 2004), Ozonolysis treatment (Guin et al., 2017), Nanofiltration (Shi et al., 2021), Precipitation and Coagulation (Ozyurt et al., 2019) and Adsorption (Costa et al., 2022) are frequently used techniques for the treatment of dye polluted wastewater. Techniques has its own pros and cons not only in costs but also in the term of efficacy, feasibility, sludge and toxic by-products production, pre-treatment requirements, and environmental impact (Crini and Lichtfouse, 2019). Adsorption is physical process that extensively used in industrial applications such as water purification, synthetic resins and many more. Because it is inexpensive, extremely efficient and well known cleansing technique for the removal of organic and inorganic pollutants (Ariffin et al., 2017; Peralta et al., 2020). Adsorbents plays a vital role in the adsorption process and its effectiveness is depends upon the porosity, number of sites, surface area and possible interaction among the contaminants (Al-Ghouti and Da'ana, 2020). Different types of adsorbents such as siliceous material (Walker et al., 2003), zeolite (Armağan and Turan, 2004), clay materials (Alkan et al., 2005) and activated carbons (Demirbas, 2009) are used in the water purification and wastewater treatment because of high adsorption surface area. Such adsorbents have been limited due to its high cost and low availability (Singh et al., 2018). So, the biopolymers have potential candidate for the adsorption of dye from wastewater. These biopolymers have the advantage of biocompatibility, low cost and easily available (Yaashikaa et al., 2022).
Natural based polysaccharides like guar gum is biodegradable and economical, it has plenty of hydroxyl functional group attached to polymeric backbone which provides the scope of modification. Bio and synthetic polymers used to fabricate the membranes or hydrogels which are modified by different nanofillers or crosslinkers to act as a best adsorbent for the removal of dye with high adsorption capacity.(Dragan et al., 2012). Gum ghatti-graft (4-acryloylmorpholine) hydrogel was incorporated with nanoparticles of magnetite. So, the hydrogel was used to remove the metal ions such as Cu(II) and Hg(II) and dyes (methylene blue and rhodamine 6 G) from the wastewater respectively has been reported in literature (Kulal and Badalamoole, 2020). Guar gum (GG) is one of the most abundant polysaccharide which is commercially available. It is non-toxic and highly hydrophilic biopolymer which is functionalised or grafted in a versatile manner to synthesize the materials (adsorbents) for diverse applications like removal of dye and heavy metals from the wastewater. This is because of a large number of hydroxyl groups present in the polymer backbone that forms the hydrogen bonding in aqueous solution (Mathur and Mathur, 2005; Mudgil et al., 2014; Sharma and Katwal, 2016; Sharma et al., 2018). Guar gum based composites play a vital role in the waste water remediation due to their superior properties such as large surface area, high active site availabilities and biodegradable through adsorption and photo-catalytic degradation processes (Saya et al., 2021). Synthetic polymers widely used in polymer blending because of its excellent physical and mechanical properties (Aslam et al., 2018). Polyvinyl alcohol (PVA) is synthetic, nontoxic, hydrophilic, thermally stable, non-corrosive nature and biocompatible polymer that used in industries for many applications such as drug delivery, adsorption, biosensors, antimicrobial surfaces etc. Tetraethoxysilane (TEOS) is mostly used as a crosslinker agent because it is nontoxic and biocompatible as compared to previous cross-linkers such as glutaraldehyde epichlorohydrin, borate, and tripolyphosphate (Jena et al., 2008).
The properties of polymeric composites are tuned by the incorporation of nanofillers such as graphene oxide, carbon nanotubes (CNTs) and metal oxide i.e. iron oxide, titanium oxide, zinc oxide, molybdenum oxide and many more(Saritha, 2022). Among these nanoparticles, the tungsten metal oxide nanostructure has various advantages such as strong adsorption, low cost, high thermal stability and excellent chemical properties used in environmental areas like photocatalysis and water purification (Parashar et al., 2020; Supothina et al., 2007).
The aim of this research work, is to be fabricate the GG/PVA based nanocomposite and explore its application for exclusion of the MV dye from aqueous solution, also for the physicochemical analysis. The swelling behaviour, kinetic modelling and equilibrium data were studied for the adsorption capacity of dye onto the polymer based nanocomposite membrane. Secondly, we study the pre and post analysis of water samples by using the physiochemical parameters such as colour, temperature, pH, TDS, EC, and DO. As a result of post analysis, synthesized membrane gives better results for the quality of water samples. Synthesized nanoparticles and membrane were characterised by using different techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) as well as UV-Visible spectroscopy technique.
Materials
Guar gum (GG), hydrolysed Polyvinyl Alcohol (PVA) MW = 146,000–186,000, 2% Tetraethyl-orthosilicate (TEOS), Methyl violet (C23H26N3Cl), sodium hydroxide, calcium chloride, sodium tungstate dihydrate salt and nitric acid were purchased from Sigma Aldrich.
Synthesis of Tungsten Oxide
Tungsten trioxide nanoparticles were synthesized by acid precipitation method. Sodium tungstate dihydrate (Na2WO4.2H2O) and solvent nitric acid were used. Washed and centrifuge the precipitate it with distilled water (DI) and ethanol for many times. The resultant precipitates were dried at 80°C for 12 hours in oven and then finally fine yellow powder were calcined at 350°C for 6 hours.
Synthesis of membrane
0.4 gram (g) PVA was dissolved into 50mL of distilled water at 80°C by using magnetic stirrer. On the other hand, 0.6g GG was dissolved in 50 mL distilled water with constant stirring at 50°C. Then, PVA solution was mixed into GG solution with continuous stirring at 60°C. After that, the TEOS solution and sonicated tungsten oxide NPs were added into the solution mixture at 60°C for 5 hours. After 5–6 hours the resultant solution were poured into petri dishes and left it for dry in dust free environment at room temperature that was shown in the schematic Fig. 1. Same procedure was used to synthesize the other sets of membranes with different amount of WO3 nanoparticles shown in the table 1.
Swelling study
In swelling experiment, an appropriate amount of sample was immersed into the distilled water. After specific time, water was removed from the membranes and clean petri dishes before weighing. The swelling of the membrane was calculated by using Eq. 1.
$$\text{S}\text{w}\text{e}\text{l}\text{l}\text{i}\text{n}\text{g} (\text{g}/\text{g})= \frac{{(\text{W}}_{\text{s}} {-\text{W}}_{\text{d}})}{{\text{W}}_{\text{d}}}$$
1
\({W}_{d}\) Is initial weight and \({W}_{s}\) is the weight of sample after swelling.
Swelling studies of water into membrane is depends upon the diffusion process by both external media and polymeric chains. The diffusion mechanism is described by the Eq. 2.
$$\text{F}=K{t}^{n}$$
2
The water diffusion is measured by the value of n and k that is obtained by the swelling data of membrane. Where F is the swelling fraction that determined by the swelling ratio of weight at time t and weight of material at equilibrium time. K is the rate constant which is changes according to membrane network structure and n is the diffusion exponent (Ostrowska-Czubenko et al., 2015).
Gel content of sample was determined according to ASTM 2765, known weight of sample was placed in stainless steel cloth. Membrane was carried out with distilled water for 8 hours in Soxhlet Extractor. Then extracted the membrane samples and dried in vacuum at 60°C and weighed the membrane after time interval once it gets constant. So gel content was measured by weighing the amount of insoluble parts of membranes by applying Eq. 3 (Karoyo and Wilson, 2017).
Gel fraction % = (Wg / Wo) × 100 (3)
W g is the obtained weight of membrane and Wo is the weight initial of membrane sample.
The swelling study of membrane was determined at various pH (2, 4, 6, 8, 10, and 12) by pH meter. The non-buffer solution, 0.1 M solution of NaOH and HCl were prepared. Absorption study was examined by the sample amount with weight of the petri dishes. Buffer solutions were prepared by standard method (pH 2, 4, 7 and 10) and calibrated the values of pH by-pH meter.
Swelling of membranes were also studied in different electrolytes (NaCl and CaCl2) having different range of concentrations (0.1, 0.2, 0.4, 0.6, 0.8, 1 M).
Batch (Adsorption) Experiment
Batch equilibrium method is used for the kinetic adsorption measurements of the dye by using GG\PVA\WO3 based adsorbent. In kinetic study, stock solution of 1mmol/L dye (methyl violet) was prepared in distilled water. Then, take the appropriate amount of membrane in 15ml of dye solution, agitate it in thermal incubator at 25°C. Shaking speed was fixed at 150 rpm during whole batch experiment. After the specific time of agitation, filtrate the dye by using Watts’s man filter paper and concentration was estimated with help of UV-VIS spectrophotometer SPECORD 200 PLUS at maximum absorbance wavelength called λmax (584 nm). The adsorption capacity (qe) and adsorption proficiency (R %) of the membrane was calculated by using the equation.
$$\text{q}\text{e} = \frac{\text{C}\text{o} – \text{C}\text{e} }{\text{m}}\times v$$
4
$$\text{R} \text{\%}= \frac{\text{C}\text{o} –\text{C}\text{e}}{\text{C}\text{o}} \times 100$$
5
q e (mg/g) is the quantity of dye adsorbed on per unit mass of adsorbent or equilibrium capacity of dye and R % is percentage adsorption (dye removal efficiency).
Where Co initial concentration and Ce is the concentration at equilibrium time ‘’t’’, m is the mass of adsorbent and V is the volume of adsorbate solution.
The pH of solutions were adjusted at 2–12 pH and monitored by pH meter. For adsorption analyzation, different pH solution was prepared by taking the 15 ml of dye solution and then putted into shaking incubator. The temperature was maintained at room temperature (25°C) and 150 rpm speed. Each sample was collected after 1 hour. Then, samples were filtered, and adsorbed concentration of dyes was estimated using UV-visible spectrometer.
Determine the influence of adsorbate concentration on adsorption efficiency, prepared the different dye concentrations like 0.025, 0.05, 0.1, 0.2, 0.4, 0.6, 0.6, 0.8, 1 mmol/L and checked the adsorption efficiency of the sample by the UV-visible spectrophotometer.
Temperature parameters play a profound role in adsorption. The isothermal experiment was conducted at different temperatures (25, 35 and 55°C) under the pre-optimized mass of adsorbent, dye concentration and agitation time. This analysis indicates, with the increase of temperature the value of adsorption of dye solution may also increase or decrease.
Analysis for the physiochemical Parameters
For the analysis, water samples were collected from different sources one from cafeteria of COMSATS University Islamabad and other is tap water sample. 500mL of the contaminated water and tap water samples were collected in Sterilized sampling bottles for physiochemical analysis. After the pre-analysis of wastewater samples, add the synthesized membrane in wastewater for 1 to 2 hour to check the post analysis of samples.
The water samples were analysed to determine their physicochemical characteristics such as temperature, colour, pH, electrical conductivity (EC), total dissolved solids (TDS) and dissolved oxygen (DO). Temperature is important parameter of water quality because it exerts the major effect on water chemistry. Temperature value was must found in the range of standard limit.
Colour of wastewater sample was observed with naked eye. The pH reading of water samples were recorded using Hanna Instrument pH meter. Each measurement was taken by standard procedure mentioned in the manual of instrument. Standardized the pH meter with known buffer solutions 4, 7 as well as 10 before recording the sample reading. Initially, the pH value of a three-time collected untreated samples of water was found to be 8.5–8.9. Others parameters such electrical conductivity (EC), amount of total dissolved solids (TDS), and dissolve oxygen (DO) were checked and calibrated.
The GG/PVA was blended and crosslinked with fixed amount of crosslinker (TEOS) with different amount of NPs. The resulted polymeric network structure (membrane) is quite stable in different studied of environments.
Characterisation
FR-IR analysis was done to investigate the functional groups present between polymeric membrane based on GG, PVA, TEOS and WO3 nanoparticles (NPs). The broad peak at 3247–3736 cm− 1 indicates the O-H stretching of inter and intra-hydrogen bonding of hydroxyl groups which present in polymeric membrane. The absorption of C-H at 2919 cm− 1 that recognized the stretching of alkyl groups, stretching of primary alcoholic groups (C-OH) at 1050–1150 cm− 1, peak of C-O was spotted around the range of 1000–1100 cm− 1, C = C, Si-OH at 1653 cm− 1 and C-H bends at the range of 700 to 610 cm− 1. Siloxane bond and Si-O-C were observed in region of 1100–1020 cm− 1 and siloxane (-Si-O-Si-) linkages confirms the crosslinking of TEOS with GG and PVA. In the spectra, peak around the 870 cm− 1 shows the mannose and galactose polysaccharides and (1–4), (1–6) linkages of galactose and mannose, respectively. Below the region of 1500 cm− 1 deformation of molecules was observed. Crystallinity of polymer is represented by region between 700 − 500 cm− 1 (Iqbala et al., 2019; Irani et al., 2011). Tungsten oxide vibrations are found in IR region around 1453 − 600 cm− 1 and about 3454 cm− 1 which corresponds the stretching and bending modes (Díaz-Reyes et al., 2008). Hence, all functional groups and spectral peaks confirmed the formulation of membrane successfully was shown in table 2 and Fig. 2.
Scanning electronic microscopy (SEM) technique was used to study the morphology and porosity of NPs and membranes. In Fig. 3, the particles of pure WO3 shows the nano shape like material that is interconnected with the nanoflakes like morphology. whereas SEM of Fig. 4 showed the aura of interconnected porous structure through rough surface and Fig. 5 illustrates the extremely rough surface with the agglomeration of nanoparticles in membranes because the membranes are consist of substantial amount of WO3 in set 3 as compared to set 1.
The Fig. 6, XRD confirmed the monoclinic structure and the angles. The peaks appeared at 23.07o, 23.63o, 24.30o, 26.55o, 28.72o, 34.17o, 41.74o, 44.8o and 55.82o belongs to plane (002), (020), (200), (120), (112), (202), (222), (400) and (420) appropriately. The peaks were fitted with the standard JCPDS card no. 01-083-0950 and a sharp triplet peak linked with plane (002), (020) and (200) are the proof of WO3. The crystalline size of the nanomaterial was calculated by the help of Scherrer formula (Klug and Alexander, 1974).
$$D=\frac{K\lambda }{{\beta cos}Ɵ}$$
6
The term D is crystallite size, K is constant and K = 0.94. β is the full width half maxima, λ is the wavelength of X-ray source and λ = 1.540562Å. The average crystallite size for the tungsten oxide is 23.8 nm.
Swelling study
In the polymer matrix (crosslinked membrane), porous structure provides the diffusion, due to good water holding capacity with maintaining the structure because of chemical or physical cross-linking of individual polymeric chains. Swelling properties are greatly affected by hydrophilic or hydrophobic functional groups in the membrane (Sharma et al., 2015; Shruthi et al., 2016; Singha et al., 2018).
Effect of time on swelling
Swelling behaviour of membrane is directly correlated with diffusion and the diffusion depends on pore size, morphology and hydrophilicity or hydrophobicity of membrane as well as volume of membrane. Water absorption capacity increases with time and show more swelling behaviour in membrane due to presence of hydrophilic units inside the membrane and also by internal osmotic pressure, electrostatic repulsion and diffusion rate (Singh and Dhaliwal, 2018).
Swelling behaviour of the cross-linked membrane was studied in deionized water at different time intervals. Swelling ratio increases with time and maximum swelling was attained at 80 minutes in set 3 and after 80 mins it attains the constant state that shown in the Fig. 7a. The active sites are occupied and no more sites are available for accommodation of water molecules with the passage of time. So, higher swelling ratio was observed in set 3 (0.043 g/g) because of free sites and volume inside the network was available for rapids diffusion of solvent ions as compared to in set 2 (0.035 g/g) and set 1 (0.033 g/g) correspondingly and no more swelling was recorded at equilibrium point.
Swelling of membrane is controlled by the diffusion mechanism. Polymer chains have high mobility that permits to penetrate the solvent into the polymeric system (Masaro and Zhu, 1999). These membranes showed the value of n is less than 0.45 indicates the Fickian diffusion mechanism. Because in Fick Law of diffusion the solvent rate of diffusion is slower than the relaxation rate of membrane (Ostrowska-Czubenko et al., 2015). The graph between the ln (F) versus ln (t) is shown in Fig. 7b, diffusion parameter and regression coefficient were calculated from slopes and intercept are given in the table 3.
The gel fraction (or gel transition) is forming the gel from polymeric system. Polymers forms the network between the chains due to various functional groups. The gel fraction of crosslinked membrane determines the degree of crosslinking that was shown in table 3 which is linearly increased in all sets and provides the proper crosslinking of TEOS in polymeric network of membranes.
The swelling capacity of membrane was measured at different pH solutions. In Fig. 7c, maximum swelling (0.04 g/g) was observed at 7 pH and lesser capacity was found in low acidic medium as well as basic medium. In set 3, maximum swelling of membrane is observed as compared to set 2 and set 1. Swelling goes up with acidic pH, due to the hydrophilicity and diffusion of membrane increased and reduced with increasing of pH at basic pH (Sami et al., 2018) .
Absorption of membrane was increased when pH increases and maximum swelling attained at pH 7.0. Maximum ion-ion repulsion was observed between the polymeric chains by increasing of pH values that indicates the more uptake of fluid in more space. One more possibility, increasing of pH values may decreased the H+ ions screening effect. So, the ion-ion repulsion decreasing the Na ion screening effect which dominates at higher pH and reduce the swelling factor (Chandrika et al., 2016).
Swelling study of membranes were recorded in buffer with different pH solution (2, 4, 7, and 10). The difference in their behaviour is due to functional groups that are protonated and deprotonated that shown in the Fig. 7d.
In swelling reaction, the salt concentration has an essential effect on membrane such as NaCl and CaCl2 were used to determine the swelling behaviour and the graph was drawn between the % age of swelling and concentration in Fig. 7(e, f). The results confirms the maximum swelling was shown in low concentration after that minimum swelling was in high concentration. The amount of solute (salt) in solvent which lowers the osmotic pressure in all sets. Thus, the process of diffusion reduced and lower ionic strength shows better swelling. The membrane was ionic in nature and their swelling behaviour depends on their chemical nature as well as media ions. So, increasing the concentration of external ionic strength leads to decrease the osmotic pressure along with electrostatic forces between the polymeric membrane and external solution (Mittal et al., 2016).
ADSORPTION STUDY
Batch study
Kinetic/ batch study is used to determine the efficiency of adsorption process with the contact time of adsorbent with adsorbate. In other words, we can say that there is chemical interaction between adsorbate (dye solution) and functional groups of adsorbent surface (Altintig et al., 2021). For adsorption mechanism, mass transfer process, diffusion process, availability of adsorbent’s surface, surface area, porosity and active sites of adsorbents are the important factors for determination of equilibrium capacity and rate (Bhattacharyya and Sharma, 2004). Absorption of methyl violet (MV) versus contact time on membrane was shown in Fig. 8a. It indicates that rapid adsorption capacity (qe) of MV was observed in set 1 (0.037 mM/L) as compared to set 2 (0.020 mM/L) and set 3 (0.013 mM/L) for the period of increasing time because of high vacant active sites and permeability of adsorbent. After 60 mins, adsorption capacity was gained at equilibrium in all sets because different %age of NPs are used to average out the best concentration from the present results. So, the set 1 shows the maximum adsorption of MV dye as compared to other sets. It might be possible that higher concentration of nanoparticles blocks the pores of membrane and dye cannot be permit through the pores or active side for adsorption.
Simulation of kinetic data
In order to know the adsorption behaviour of dye onto membrane, the experimental data was simulated by apply different kinetic model which are Pseudo First (PFO) and pseudo second order (PSO) kinetic models.
Pseudo First Order Kinetics (PFO)
The pseudo first order (PSO) kinetic model was firstly proposed by the Lagergren (Lagergren, 1898). So, PSO model shows the uptake of solute with time that is directly proportional to the difference in amount of solid uptake and saturated concentrations and applicable to initial phase of adsorption process. The PFO was describe in the Eq. 7.
$${\text{Q}}_{\text{I}}={\text{Q}}_{\text{e}}\left(1-\text{exp}\left(-{\text{k}}_{{\alpha }}\text{t}\right)\right)$$
7
Where Qe related to quantity of dye adsorbed at equilibrium, \({Q}_{I}\) shows adsorbed weight of dye at different time interval and ka is the PFO model parameter.
Pseudo Second Order Kinetics (PSO)
Ho and McKay introduced the PSO kinetic model and provides the correlation of the experimental data. The rate limiting step is the chemisorption in PSO model, which predicts that the behaviour is over the whole range of adsorption. In this condition, rate of adsorption depends on the adsorption capacity not on the adsorbate's concentration. The equation of Pseudo second order is in Eq. 8 (Ho and McKay, 1999)
The kinetic models of sets are in Fig. 8b. The PFO and PSO kinetic models closed to the value of experimental data that explains the adsorption mechanism of MV on to membrane. The best fitted model is PFO, its correlation value 0.99 and Qe (0.0381 mmol/g) value is very close to experimental value (0.0375 mmol/g) was shown in the table 4. It shows that adsorption of dye on to (GG/PVA/WO3) adsorbent is physisorption (Bilgili, 2006).
Influence of pH
The pH of dye solution play a vital role in the process of adsorption, especially on adsorption capacity. It was studied that the pH within the range of 2–12 effects the adsorption of dye onto membrane. In acidic media the surface of membrane get protonated which repel the positively charged cationic dye that reduce the adsorption efficacy. But in the case of basic medium, the deprotonation of membrane and electrostatic interaction in adsorption of cationic dye occur. Hence, increasing of adsorption capacity was observed in basic media that was shown in the Fig. 8c. It is concluded that the adsorption of dye was highly depends on solution of pH and pH solution affects both aqueous chemistry and surface binding sites of adsorbent. Adsorption rate of dye gradually increased as we move from acidic to basic media because of oxygen containing functional groups and electrostatic interactions (Hameed, 2008; Keyhanian et al., 2016; Sharma et al., 2019).
Concentration studies
Adsorption rate was determined by different concentrations of dye solution at constant temperature, pH and agitation rate. Adsorption efficacy was increased by increasing the concentration of MV from 0.025 mmol/L to 1 mmol/L. At low concentration, dye uptake was slowly increased on the active site of adsorbent. But at the higher concentration of dye needs to diffuse the adsorbent surface and steric repulsion between the molecules of solute would slowdown the adsorption process (Gupta et al., 2014; Hameed, 2008). So, adsorption rate was gradually increased by increasing the concentration of dye (in Fig. 8d) and adsorption equilibrium was attained at 0.2mmol/L because number of active sites of adsorbent were occupied by the dye molecules.
Adsorption Isotherms and Thermodynamics Study
Adsorption isothermal is important parameter for optimisation of adsorbent usage and the relationship between adsorbate concentration in bulk and adsorbed amount at interface. Factors are obtained from different models to provide the information of the adsorption mechanism and also gives the data for surface properties and affinities of adsorbent. In this study, three models such as Langmuir, Freundlich and Langmuir-Freundlich isothermals models were used to simulate the experimental data of adsorption.
The thermodynamic study predicts the nature of adsorption process that was based on temperature in terms of ∆H, ∆G and ∆S and performed at (25°C, 35°C and 55°C) different temperatures.
Langmuir Isotherm Model
Langmuir isotherm model represents the homogenous adsorption of the adsorbate on the surface of adsorbent and assume that the adsorption occur only once at particular sites. This model can be describe in the Eq. 9.
$${\text{q}}_{\text{e}= \frac{{\text{q}}_{\text{m}\text{a}\text{x}. \text{b}{\text{C}}_{\text{e}}}}{1+\text{b}{\text{C}}_{\text{e}}}}$$
9
Where the qe is the amount of adsorbate in adsorbent at equilibrium, b (L/mg) is the Langmuir isothermal constant, Ce is equilibrium concentration (mmol/L) and qmax (mmol/L) shows the maximum monolayer coverage capacity (Ayawei et al., 2017).
Freundlich Isotherm Model:
Freundlich isotherm model states that the adsorption capacity of any adsorbent depends on heterogeneous or multilayer surface. The isotherm defines the surface heterogeneity with all the active site having different adsorption potential (Ayawei et al., 2015).
The Freundlich isotherm is in Eq. 10 used for finding the maximum adsorption capacity of adsorbent (Boparai et al., 2011).
$${\text{q}}_{\text{e}= {{\text{K}}_{\text{F}}\text{C}}_{\text{e}}^{1/\text{n}}}$$
10
K F is adsorption capacity and 1/n represents the intensity of adsorption. Hence, this model indicates the heterogenous site of adsorbent and relative distribution energy.
Langmuir-Freundlich Isothermal Model
Langmuir-Freundlich (LF) isothermal model is also known as Sip model (Wang and Guo, 2020). This model is used for speculating the monolayer adsorption in homogenous as well as in heterogenous system because it avoids the limitation of increased concentration of adsorbate that associated with Freundlich model. The LF model provides the great accuracy of adsorption isotherm due to the incorporation of both Langmuir and Freundlich characteristics. The LF equation was describe in Eq. 11.
$${\text{q}}_{\mathbf{e}= \frac{{\text{q}}_{\text{m}\text{s}.{{\text{K}}_{\text{s}}\text{C}}_{\text{e}}^{\text{n}\text{s}}}}{1+ {\text{K}}_{\text{s}}{\text{C}}_{\text{e}}^{\text{n}\text{s}}}}$$
11
q ms (mg/g) shows maximum adsorption capacity, sip isotherm constant Ks (L/mg) and exponent of sip model also called a heterogeneity factor (Chen et al., 2022).
Adsorption rate provides the different mechanism as we increasing the temperature from 25°C to 55°C. As a result of increasing the temperature, diffusion rate of MV dye molecules decreases. Because of increasing the kinetic energy of dye molecules get strikes on surface of membrane and it might be possible to reduce the chance of capturing the dye molecules was shown in Fig. 9a. The effect of adsorption temperature mainly depends on the nature of adsorption either it is exothermic or endothermic process. In endothermic process, adsorption capacity increases with increasing of temperature due mobility of dye molecules on active site increases. While in case of exothermic adsorption process, with temperature increased adsorption efficacy decreased because of low adsorptive forces between the dye (Nandi et al., 2009; Soliman et al., 2020).
Langmuir-Freundlich isothermal model was best fitted as compared to other models on the experimental data and R2 = 0.99 close to unity was shown table 5. This means that the adsorption of MV onto the membrane is multilayer adsorption process. Maximum adsorption capacity of dye was performed with exothermic process in Fig. 9b. Furthermore, the thermodynamics parameters were studied by using model data which show the exothermic process from ∆\(G\), ∆S and ∆H. So, which are calculated by following Eq. 12 (Mahto and Mishra, 2022) and tabulated in table 6.
$$\varDelta G= \varDelta H+T\varDelta S$$
12
Analytical Application
The practical applicability and efficiency of the synthesized GG/PVA/WO3 membrane was tested in the water samples. For the physiochemical analysis, water samples were collected from the different sources such as tap water and other sample was collected from the COMSATS University cafeteria waste water. The pH ranges from 7-8.5 reveals that water sample falls within the allowable pH range (6.5–8.5) as stated by World Health Organization (WHO). In the study area, the average temperature of water samples lies in range of 25-26.5°C which was found within acceptable limit of WHO (Organization et al., 2004). The desirable limit of TDS is 500 mg/L and maximum limit in 1000 mg/L both prescribed for the drinking purposes that shows the water with high TDS values is highly mineralized. The recovery values were found satisfactory. So, overall result indicates that the tap water and contaminated water lies within the desirable ranges after the treatment. All the recovery values of samples were displayed in table 7.
The Nano-based polymeric membrane was successfully fabricated by solution casting technique. The FTIR analysis revealed the intermolecular hydrogen bonding is present between the polymers, which are porous in nature and pores are uniformly distributed. Swelling system of membrane follows the Fickians diffusion model. The kinetic adsorption of methyl violet was best fitted to PFO kinetic model and isothermal studies of methyl violet revealed that the adsorption process was perfectly followed the Langmuir-Freundlich isothermal model. In thermodynamic study, negative value of ∆G supports the feasibility and possibility of adsorption process. Nanocomposite membrane have been used for 96% removal of methyl violet from the aqueous solution. All recovery values of water samples were found satisfactory. Thus, the guar gum based nanocomposite would be most suitable for the removal of MV in wastewater at commercial level. In the future, this polymeric based membrane will be recommend for biological parameter (physiochemical analysis) of water quality.
Acknowledgments
COMSATS University Islamabad, Islamabad campus, Pakistan
Funding Information
There is no funding found with authors
Conflict of Author Interest
The authors declare that they have no competing interests that can influence the work reported in this research paper
Author Contribution
Alishbah Iftikhar Ahmad and Aun Abbass: Designing of experiment, synthesis of material, Syeda Sitwat Batool: Characterization and analysis of the material, Zahid Imran: Figures, review and formal analysis, Safia Hassan: Methodology Conceptualization, Writing editing and review, Supervision
- Al-Ghouti, M.A., Da'ana, D.A.J.J.o.H.M., 2020. Guidelines for the use and interpretation of adsorption isotherm models: A review. 122383.
- Alkan, M., Çelikçapa, S., Demirbaş, Ö., Doğan, M.J.D., Pigments, 2005. Removal of reactive blue 221 and acid blue 62 anionic dyes from aqueous solutions by sepiolite. 65, 251-259.
- Altintig, E., Alsancak, A., Karaca, H., Angın, D., Altundag, H.J.C.E.C., 2021. The comparison of natural and magnetically modified zeolites as an adsorbent in methyl violet removal from aqueous solutions. 1-15.
- Ariffin, N., Abdullah, M.M.A.B., Zainol, M.R.R.M.A., Murshed, M.F., Faris, M.A., Bayuaji, R., 2017. Review on adsorption of heavy metal in wastewater by using geopolymer, MATEC Web of Conferences. EDP Sciences, p. 01023.
- Armağan, B., Turan, M.J.D., 2004. Equilibrium studies on the adsorption of reactive azo dyes into zeolite. 170, 33-39.
- Aslam, M., Kalyar, M.A., Raza, Z.A.J.P.E., Science, 2018. Polyvinyl alcohol: a review of research status and use of polyvinyl alcohol based nanocomposites. 58, 2119-2132.
- Ayawei, N., Ebelegi, A.N., Wankasi, D.J.J.o.c., 2017. Modelling and interpretation of adsorption isotherms. 2017.
- Ayawei, N., Ekubo, A.T., Wankasi, D., Dikio, E.D.J.O.J.o.C., 2015. Adsorption of congo red by Ni/Al-CO3: equilibrium, thermodynamic and kinetic studies. 31, 1307.
- Besha, A.T., Liu, Y., Fang, C., Bekele, D.N., Naidu, R.J.C.R.i.E.S., Technology, 2020. Assessing the interactions between micropollutants and nanoparticles in engineered and natural aquatic environments. 50, 135-215.
- Bhattacharyya, K.G., Sharma, A.J.J.o.h.m., 2004. Adsorption of Pb (II) from aqueous solution by Azadirachta indica (Neem) leaf powder. 113, 97-109.
- Bilgili, M.S.J.J.o.H.M., 2006. Adsorption of 4-chlorophenol from aqueous solutions by xad-4 resin: isotherm, kinetic, and thermodynamic analysis. 137, 157-164.
- Bonetto, L., Ferrarini, F., De Marco, C., Crespo, J., Guégan, R., Giovanela, M.J.J.o.W.P.E., 2015. Removal of methyl violet 2B dye from aqueous solution using a magnetic composite as an adsorbent. 6, 11-20.
- Boparai, H.K., Joseph, M., O’Carroll, D.M.J.J.o.h.m., 2011. Kinetics and thermodynamics of cadmium ion removal by adsorption onto nano zerovalent iron particles. 186, 458-465.
- Chandrika, K.P., Singh, A., Rathore, A., Kumar, A.J.C.p., 2016. Novel cross linked guar gum-g-poly (acrylate) porous superabsorbent hydrogels: characterization and swelling behaviour in different environments. 149, 175-185.
- Chen, X., Hossain, M.F., Duan, C., Lu, J., Tsang, Y.F., Islam, M.S., Zhou, Y.J.C., 2022. Isotherm models for adsorption of heavy metals from water-A review. 135545.
- Chowdhary, P., Bharagava, R.N., Mishra, S., Khan, N., 2020. Role of industries in water scarcity and its adverse effects on environment and human health, Environmental Concerns and Sustainable Development. Springer, pp. 235-256.
- Costa, T.C., Hendges, L.T., Temochko, B., Mazur, L.P., Marinho, B.A., Weschenfelder, S.E., Florido, P.L., Da Silva, A., de Souza, A.A.U., de Souza, S.M.G.U.J.J.o.P.S., Engineering, 2022. Evaluation of the technical and environmental feasibility of adsorption process to remove water soluble organics from produced water: A review. 208, 109360.
- Crini, G., Lichtfouse, E.J.E.C.L., 2019. Advantages and disadvantages of techniques used for wastewater treatment. 17, 145-155.
- Demirbas, A.J.J.o.h.m., 2009. Agricultural based activated carbons for the removal of dyes from aqueous solutions: a review. 167, 1-9.
- Díaz-Reyes, J., Dorantes-García, V., Pérez-Benítez, A., Balderas-López, J.J.S.y.v., 2008. Obtaining of films of tungsten trioxide (WO3) by resistive heating of a tungsten filament. 21, 12-17.
- Dragan, E.S., Perju, M.M., Dinu, M.V.J.C.p., 2012. Preparation and characterization of IPN composite hydrogels based on polyacrylamide and chitosan and their interaction with ionic dyes. 88, 270-281.
- El‐Barghouthi, M.I., El‐Sheikh, A.H., Al‐Degs, Y.S., Walker, G.M.J.S.S., Technology, 2007. Adsorption behavior of anionic reactive dyes on H‐type activated carbon: Competitive adsorption and desorption studies. 42, 2195-2220.
- Guin, J.P., Bhardwaj, Y., Varshney, L.J.A.R., Isotopes, 2017. Mineralization and biodegradability enhancement of Methyl Orange dye by an effective advanced oxidation process. 122, 153-157.
- Gupta, V., Pathania, D., Singh, P., Kumar, A., Rathore, B.J.C.p., 2014. Adsorptional removal of methylene blue by guar gum–cerium (IV) tungstate hybrid cationic exchanger. 101, 684-691.
- Hameed, B.J.J.o.h.m., 2008. Equilibrium and kinetic studies of methyl violet sorption by agricultural waste. 154, 204-212.
- Ho, Y.-S., McKay, G.J.P.b., 1999. Pseudo-second order model for sorption processes. 34, 451-465.
- Hunter, P.R., Waite, M., Ronchi, E., 2002. Drinking water and infectious disease: establishing the links. CRC Press.
- Iqbala, D.N., Tariqa, M., Khanb, S.M., Gullb, N., Sagarc, S., Azizd, A., Nazira, A., Iqbala, M., 2019. Synthesis and characterization of chitosan and guar gum based ternary blends with polyvinyl alcohol.
- Irani, M., Keshtkar, A.R., Mousavian, M.A.J.C.e.j., 2011. Removal of Cd (II) and Ni (II) from aqueous solution by PVA/TEOS/TMPTMS hybrid membrane. 175, 251-259.
- Jena, K.K., Raju, K.S.N.J.I., research, e.c., 2008. Synthesis and characterization of hyperbranched polyurethane hybrids using tetraethoxysilane (TEOS) as cross-linker. 47, 9214-9224.
- Karoyo, A.H., Wilson, L.D.J.G., 2017. Physicochemical properties and the gelation process of supramolecular hydrogels: A review. 3, 1.
- Keyhanian, F., Shariati, S., Faraji, M., Hesabi, M.J.A.J.o.C., 2016. Magnetite nanoparticles with surface modification for removal of methyl violet from aqueous solutions. 9, S348-S354.
- Klug, H.P., Alexander, L.E., 1974. X-ray diffraction procedures: for polycrystalline and amorphous materials.
- Krishnappa, P.B., Badalamoole, V.J.I.j.o.b.m., 2019. Karaya gum-graft-poly (2-(dimethylamino) ethyl methacrylate) gel: an efficient adsorbent for removal of ionic dyes from water. 122, 997-1007.
- Kulal, P., Badalamoole, V.J.J.o.E.C.E., 2020. Efficient removal of dyes and heavy metal ions from waste water using Gum ghatti–graft–poly (4-acryloylmorpholine) hydrogel incorporated with magnetite nanoparticles. 8, 104207.
- Lagergren, S., 1898. Zur theorie der sogenannten adsorption geloster stoffe.
- Mahto, A., Mishra, S.J.P.B., 2022. The removal of textile industrial Dye-RB-19 using Guar gum-based adsorbent with thermodynamic and kinetic evaluation parameters. 79, 3353-3378.
- Masaro, L., Zhu, X.J.P.i.p.s., 1999. Physical models of diffusion for polymer solutions, gels and solids. 24, 731-775.
- Mathur, V., Mathur, N., 2005. Fenugreek and other lesser known legume galactomannan-polysaccharides: scope for developments.
- Midya, L., Das, R., Bhaumik, M., Sarkar, T., Maity, A., Pal, S.J.J.o.c., science, i., 2019. Removal of toxic pollutants from aqueous media using poly (vinyl imidazole) crosslinked chitosan synthesised through microwave assisted technique. 542, 187-197.
- Mittal, H., Maity, A., Ray, S.S.J.A.S.S., 2016. Gum karaya based hydrogel nanocomposites for the effective removal of cationic dyes from aqueous solutions. 364, 917-930.
- Mouli, P.C., Mohan, S.V., Reddy, S.J., 2004. Electrochemical processes for the remediation of wastewater and contaminated soil: emerging technology.
- Mudgil, D., Barak, S., Khatkar, B.S.J.J.o.f.s., technology, 2014. Guar gum: processing, properties and food applications—a review. 51, 409-418.
- Nandi, B., Goswami, A., Purkait, M.J.A.C.S., 2009. Removal of cationic dyes from aqueous solutions by kaolin: kinetic and equilibrium studies. 42, 583-590.
- Organization, W.H., WHO., Staff, W.H.O., 2004. Guidelines for drinking-water quality. World Health Organization.
- Ostrowska-Czubenko, J., Gierszewska, M., Pieróg, M.J.J.o.P.R., 2015. pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling. 22, 1-12.
- Ozyurt, B., Camcioglu, S., Firtin, M., Ates, C., Hapoglu, H., Treatment, W.J.D.W.T., 2019. Boron removal from industrial wastewaters by means of optimized sequential chemical precipitation and coagulation processes. 172, 292-300.
- Parashar, M., Shukla, V.K., Singh, R.J.J.o.M.S.M.i.E., 2020. Metal oxides nanoparticles via sol–gel method: a review on synthesis, characterization and applications. 31, 3729-3749.
- Peralta, M.E., Ocampo, S., Funes, I.G., Onaga Medina, F., Parolo, M.E., Carlos, L.J.I., 2020. Nanomaterials with Tailored Magnetic Properties as Adsorbents of Organic Pollutants from Wastewaters. 8, 24.
- Saleh, I.A., Zouari, N., Al-Ghouti, M.A.J.E.T., Innovation, 2020. Removal of pesticides from water and wastewater: Chemical, physical and biological treatment approaches. 101026.
- Sami, A.J., Khalid, M., Jamil, T., Aftab, S., Mangat, S.A., Shakoori, A., Iqbal, S.J.I.j.o.b.m., 2018. Formulation of novel chitosan guargum based hydrogels for sustained drug release of paracetamol. 108, 324-332.
- Saritha, D.J.M.T.P., 2022. A concise review on the removal of heavy metals from wastewater using adsorbents.
- Saya, L., Malik, V., Singh, A., Singh, S., Gambhir, G., Singh, W.R., Chandra, R., Hooda, S.J.C.P., 2021. Guar gum based nanocomposites: Role in water purification through efficient removal of dyes and metal ions. 117851.
- Sharma, G., Katwal, R., 2016. Fabrication, characterization and cytotoxicity of guar gum/copper oxide nanocomposite: efficient removal of organic pollutant, Materials Science Forum. Trans Tech Publ, pp. 88-102.
- Sharma, G., Kumar, A., Sharma, S., Ala'a, H., Naushad, M., Ghfar, A.A., Ahamad, T., Stadler, F.J.J.S., Technology, P., 2019. Fabrication and characterization of novel Fe0@ Guar gum-crosslinked-soya lecithin nanocomposite hydrogel for photocatalytic degradation of methyl violet dye. 211, 895-908.
- Sharma, G., Sharma, S., Kumar, A., Ala'a, H., Naushad, M., Ghfar, A.A., Mola, G.T., Stadler, F.J.J.C.p., 2018. Guar gum and its composites as potential materials for diverse applications: A review. 199, 534-545.
- Sharma, R., Kalia, S., Kaith, B.S., Pathania, D., Kumar, A., Thakur, P.J.P.D., Stability, 2015. Guaran-based biodegradable and conducting interpenetrating polymer network composite hydrogels for adsorptive removal of methylene blue dye. 122, 52-65.
- Sharma, S.K., Sanghi, R., 2012. Advances in water treatment and pollution prevention. Springer Science & Business Media.
- Shi, G.M., Feng, Y., Li, B., Tham, H.M., Lai, J.-Y., Chung, T.-S.J.P.i.P.S., 2021. Recent progress of organic solvent nanofiltration membranes. 123, 101470.
- Shruthi, S., Bhat, C., Bhaskar, S., Preethi, G., Sailaja, R.J.G., chemistry, s., 2016. Microwave assisted synthesis of guar gum grafted acrylic acid/nanoclay superabsorbent composites and its use in crystal violet dye absorption. 6, 11.
- Singh, J., Dhaliwal, A.J.V., 2018. Synthesis, characterization and swelling behavior of silver nanoparticles containing superabsorbent based on grafted copolymer of polyacrylic acid/Guar gum. 157, 51-60.
- Singh, N., Nagpal, G., Agrawal, S.J.E.t., innovation, 2018. Water purification by using adsorbents: a review. 11, 187-240.
- Singha, N.R., Dutta, A., Mahapatra, M., Karmakar, M., Mondal, H., Chattopadhyay, P.K., Maiti, D.K.J.A.o., 2018. Guar gum-grafted terpolymer hydrogels for ligand-selective individual and synergistic adsorption: Effect of comonomer composition. 3, 472-494.
- Soliman, N., Moustafa, A.J.J.o.M.R., Technology, 2020. Industrial solid waste for heavy metals adsorption features and challenges; a review. 9, 10235-10253.
- Supothina, S., Seeharaj, P., Yoriya, S., Sriyudthsak, M.J.C.I., 2007. Synthesis of tungsten oxide nanoparticles by acid precipitation method. 33, 931-936.
- Toufeek, M.A., Korium, M.A.J.G.J.o.E.R., 2009. Physicochemical characteristics of water quality in Lake Nasser water. 3, 141-148.
- Walker, G., Hansen, L., Hanna, J.-A., Allen, S.J.W.R., 2003. Kinetics of a reactive dye adsorption onto dolomitic sorbents. 37, 2081-2089.
- Wang, J., Guo, X.J.C., 2020. Adsorption isotherm models: Classification, physical meaning, application and solving method. 258, 127279.
- Yaashikaa, P., Kumar, P.S., Karishma, S.J.E.R., 2022. Review on biopolymers and composites–Evolving material as adsorbents in removal of environmental pollutants. 212, 113114.
- Yaqoob, A.A., Parveen, T., Umar, K., Mohamad Ibrahim, M.N.J.W., 2020. Role of nanomaterials in the treatment of wastewater: A review. 12, 495.
Table 1. Preparation of membranes with different weight of nanoparticles.
|
sample code |
Guar gum (g) |
PVA (g) |
WO3(g) |
|
Set 1 |
0.6 |
0.4 |
0.1 |
|
Set 2 |
0.6 |
0.4 |
0.2 |
|
Set 3 |
0.6 |
0.4 |
0.4 |
Table 2. Infrared band position and relative vibrational assignment
|
Wavelength (cm-1) |
Bond |
wavelength (cm-1) |
Bond |
|
3736-3247 |
O-H stretching of hydroxyl groups of membrane |
1053 |
C-OH stretching vibration |
|
2919 |
C-H stretching of CH2 group |
1020-1021 |
Si-O-Si,CH2 deformation, C-O stretching |
|
1993 |
C-H stretching of CH |
894 |
Galactose and mannose |
|
1716 |
C=O of acetate group |
760 |
(1–4), (1–6) linkage of galactose and mannose, respectively |
|
1653 |
C=C, ring stretching of mannose, Si-OH |
679 |
W-O-W deformation mode |
|
1558 |
C=O group |
655 |
CH out of plane |
|
1074 |
ester carbonyl (C-C-O, C-OH,C-O-C) stretching modes of polymer backbone. |
|
Table 3. Diffusion parameters and Gel content of the membranes.
|
Parameters |
Set 1 |
Set 2 |
Set 3 |
|
N |
0.01758 |
0.02498 |
0.01236 |
|
Intercept |
-11.11699 |
-10.71842 |
-10.6916 |
|
Slope |
0.47435 |
0.41886 |
0.44589 |
|
Regression (R2) |
0.97471 |
0.9422 |
0.97406 |
|
Gel content (%) |
91 |
93 |
95 |
Table 4. Kinetic parameters for the removal of MV dye onto membrane
|
Kinetic models |
sample no. |
qe (exp) mmol/g |
qe (cal) mmol/g |
Kinetic constant(b) |
R2 |
|||||
|
PFO |
Set 1 |
0.0375 |
0.0381 |
0.034 |
0.990 |
|||||
|
Set 2 |
0.0149 |
0.0155 |
0.049 |
0.967 |
||||||
|
Set 3 |
0.0173 |
0.0194 |
0.045 |
0.924 |
||||||
|
PSO |
Set 1 |
0.0375 |
0.0396 |
0.7373 |
0.980 |
|||||
|
Set 2 |
0.0149 |
0.0161 |
2.528 |
0.940 |
||||||
|
Set 3 |
0.0173 |
0.0201 |
2.667 |
0.951 |
||||||
Table 5. Parameters of Langmuir-Freundlich Isothermal model on membranes.
|
Parameters |
R2 |
Q (cal) (mM/g) |
Q (exp) (mM/g) |
|||
|
25°C |
35°C |
25°C |
35°C |
25°C |
35°C |
|
|
Set 1 |
0.996 |
0.985 |
0.461 |
0.1412 |
0.469 |
0.1327 |
|
Set 2 |
0.997 |
0.982 |
0.337 |
0.1107 |
0.315 |
0.1032 |
|
Set 3 |
0.992 |
0.981 |
0.304 |
0.1106 |
0.268 |
0.1024 |
Table 6. Thermodynamic Parameters for membranes.
|
Parameters |
∆H° (KJ/mol) |
∆S° (Jmol-1K-1) |
∆G° (KJ/mol) |
|
|
Set 1 |
-5.98 |
-90.58 |
-5.78 |
|
|
Set 2 |
-1.02 |
-88.12 |
-1.13 |
|
|
Set 3 |
-8.45 |
-70.42 |
-8.13 |
Table 7. Physicochemical parameters of tap water and contaminated water.
|
Parameters |
Pre and Post treatment of tap water set 1 set 3 |
Pre and Post treatment of contaminated water set 1 set 3 |
||||||||||||
|
|
|
mean |
Median |
St.dv |
mean |
median |
St.dv |
|
mean |
median |
St.dv |
mean |
median |
St.dv |
|
pH |
8.5 |
7.8 |
7.9 |
0.2645 |
7.8 |
7.8 |
0.1 |
8.9 |
8.1 |
8.1 |
0.115 |
8.2 |
8.3 |
0.057 |
|
Temp (°C) |
26.5 |
26 |
26.5 |
0.7505 |
26 |
26.3 |
0.859 |
27.5 |
26 |
26.4 |
0.723 |
25.8 |
26.4 |
0.8717 |
|
TDS(mg/L) |
510 |
503 |
510 |
11.547 |
503 |
500 |
5.773 |
540 |
526 |
530 |
5.773 |
516 |
540 |
50 |
|
EC(μS/cm) |
1040 |
1033 |
1010 |
20.816 |
1020 |
1010 |
17.32 |
1100 |
1066 |
1070 |
32.145 |
1090 |
1090 |
10 |
|
DO(mg/L) |
5.5 |
5.3 |
5.2 |
0.404 |
5.0 |
5.0 |
0.3055 |
4.5 |
4.7 |
4.5 |
0.173 |
4.6 |
4.7 |
0.35 |
No competing interests reported.