Preparation of crosslinking-grafting cationic starch flocculant and its study on textile dyes removal

doi:10.21203/rs.3.rs-3219699/v1

Download PDF

Research Article

Preparation of crosslinking-grafting cationic starch flocculant and its study on textile dyes removal

https://doi.org/10.21203/rs.3.rs-3219699/v1

This work is licensed under a CC BY 4.0 License

Journal Publication

published 23 Jan, 2024

Read the published version in Journal of Polymers and the Environment →

You are reading this latest preprint version

In the aim of textile printing and dyeing wastewater efficient and environmental friendly treatment, a cross-linked grafted cationic starch flocculant CGSt was prepared to study its removal performance of textile dyes. Here in, corn starch (St) was used as raw material, methacryloyloxyethyl trimethyl ammonium chloride (DMC) and N.N'-methylenebisacrylamide (MBA) were used as cationization grafting monomer and crosslinking monomer, respectively, and an environmentally friendly Fenton initiation system was adopted. The chemical structure and physicochemical properties of CGSt were characterized SEM, XPS, XRD and FTIR. The flocculation performance of CGSt on acid light yellow G, direct lake blue 5B and reactive brilliant blue KE-GN was investigated. The removal rate RR of CGSt to Acid Light Yellow G, Reactive Brilliant Blue KE-GN and Direct Lake Blue 5B reaches 97.2%, 96.3% and 97.2%, respectively. CGSt has a wide flocculation window from 5 g/L to 12g/L. It maintains good flocculation performance in a wide pH range from 4 to 9, and the RR was the highest when pH was 9, which is beneficial for the treatment of textile printing and dyeing wastewater with high alkalinity, complex composition and variable water quality by CGSt.

starch based

crosslinking

grafting copolymerization

flocculation

dyes removal

Due to the development of modern society, textile industry has become one of the major polluters of water[1]. Printing and dyeing wastewater contains complex components, large emissions, inorganic salts and heavy metal ions, and has great biological toxicity. The complex components make the treatment of printing and dyeing wastewater difficult and have a serious impact on the environment. Dye is one of the main pollutants in printing and dyeing wastewater. There are many kinds of dyes in textile printing and dyeing, and their biodegradability is also different. Most of them are organic matter, and contain chromophoric groups, which increase the organic content and chroma of printing and dyeing wastewater. In the textile printing and dyeing industry, the most used anionic dyes are anionic dyes, including reactive dyes, direct dyes, acid dyes, etc., which are dissociated into negatively charged colored anions in aqueous solution. Among them, the most used are reactive dyes[2], which are commonly used in the dyeing and printing of pure cotton, viscose, Tencel and linen fabrics. Direct dyes are more used in silk and wool[3]. Acid dyes are mainly used for dyeing nylon, silk, wool and protein[4]. The dyes in wastewater could absorb sunlight, reduce the transparency of water bodies, affect aquatic organisms and microorganisms, and cause serious damage to the environment[5–7].

At present, the secondary treatment of textile printing and dyeing wastewater can be divided into three categories: advanced oxidation method[8–10], biological method[11, 12] and physical method[13, 14]. Advanced oxidation process will produce disinfection by-products, and the cost of biological method is high[15].As one of the physical methods, the flocculation method is widely used on account of its simplicity, high effi-ciency and reasonable price[16–18].

Flocculation is a process of particle aggregation and sedimentation caused by adding a small amount of chemical substances. Small or dispersed particles gather together to form a large settling floc, which is separated from water. The flocculants currently used are mainly polymer polyelectrolytes, including organic and inorganic polymer flocculants[19, 20]. Inorganic polymer flocculants include PAC[21, 22], PFS[23, 24], etc. Organic polymer flocculants include synthetic and natural polymer modification. The former is more common in PAM[25, 26], PDMC[27, 28], modified PVA[29, 30], etc., and the latter is more common in various modified starch-based, cellulose-based flocculants[31, 32].

Natural polymer modified flocculants mainly refer to a series of polymer electrolytes with flocculation effect prepared by introducing different functional groups or polymer segments into the main chain of natural macromolecules. Natural polymer modified flocculants are generally non-toxic products with a wide range of sources, low prices and biodegradability. Starch is an economical raw material for natural polymer flocculants. It has the advantages of rich and easy availability, biodegradability and high stability. It is an ideal principle for preparing natural polymer flocculants and is widely used[33, 34]. Starch-based flocculants include include nonionic, cationic and anionic flocculants.[35–37]. Because cationic starch flocculant has good charge neutralization and destabilization effect on negatively charged dye ions and organic colloids and suspended particles in water, it has good flocculation effect. Cationic starch flocculants are also divided into three main types, including cationic starch ethers[38], cationic modified starch grafted acrylamide[39], and graft copolymers of starch and cationic monomers[40]. The first is due to the low degree of cationic modification, and the flocculation effect is relatively limited. The second is due to the complex preparation process and the need to use formaldehyde, and the formation process is easy to cause pollution. The third is equivalent to the introduction of a positively charged polymer chain segment in the starch macromolecules, which can change the surface charge properties and quantity of the starch macromolecules, and design its molecular structure to obtain better flocculation effect. Hongjie Zhou[41] synthesized a cationic flocculant with cationic degree of 1.51 mmol/g by KMnO₄/HIO₄ initiating starch grafting acrylamide and dimethyl diallyl ammonium chloride, the flocculant has a good removal effect on anionic reactive dyes and disperse dyes. Pan Hu[42] et al. synthesized three series of co-grafted cationic starch-based flocculants with different cationic degree, graft chain length and graft chain distribution by graft copolymerization of [(2-methacryloyloxyethyl) trimethyl ammonium chloride] and acrylamide, experiments show that charge neutralization is the main flocculation mechanism.

In this work, a starch-based natural polymer flocculant CGSt was prepared by cross-linking-grafting modification on corn starch with DMC and MBA monomers under the action of Fenton initiation system. The innovation of this work includes two aspects: ① Through the cross-linking-grafting one-step reaction, the positive charged grafting chain segments are introduced into CGSt macro-molecules, and its molecular structure is regulated to give full play to its electrical neutralization, bridging and net trapping of dye ions in water, so as to improve the flocculation effect. ② The adoption a Fenton initiator in preparation of CGSt, which has mild reaction conditions, high initiation efficiency, safe and clean preparation, and environmental friendliness. The chemical composition and physicochemical properties of the CGSt were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and its flocculation performance to textile dyes including acid yellow G, direct lake blue 5B and reactive brilliant blue KE-GN was investigated.

2.1 Materials and reagents

Corn starch, from Binzhou Jinhui Corn Development Co., Ltd. Methacryloyloxyethyl trimethyl ammonium chloride (DMC), purity 75%, containing 600 ppm inhibitor, from Shanghai McLean Biochemical Technology Co., Ltd. N.N'-methylenebisacrylamide (MBA), from Tianjin Institute of Fine Chemicals, Hydrogen peroxide (H₂O₂), purity 30%, from Tianjin Fengchuan Chemical Reagent Technology Co., Ltd. Ferrous chloride (FeCl₂·4H₂O), from Tianjin Damao Chemical Reagent Factory.

2.2 Preparation of CGSt

10 g of St was firstly dispersed in 50 ml distilled water and poured into a three-neck flask, then 0.68ml of DMC solution (0.04 mol/L) was added, and 5ml of MBA aqueous solution (40 wt%) was slowly added, the suspension liquid was stirred in a 35 ℃ constant temperature water bath for 5 min, then a Fenton initiator solution of 5 mL (containing 0.875 mmol H₂O₂ and 0.125 mmol FeCl₂•4H₂O) was drop-wisely add, and the crosslinking-grafting co-polymerization reaction was carried out at 35 ℃ for 90 min. Then same amount of DMC, MBA and Fenton initiators were added in the same manner for another 90 min reaction. The reactant was precipitated with ethanol, centrifuged at 4500 r/min, washed three times with 50% ethanol aqueous solution and dried at 65 ℃ for 3 h, and CGSt was obtained. The sample was crushed, passed through a 100-mesh sieve, dried and stored.

2.3 Flocculation performance test

The prepared CGSt was gelatinized and prepared into flocculant diluent with 5% concentration. The diluent was dissolved in a water bath at 80 ℃ for 10 min, and then a certain volume of diluent was added into 50 mL of dye solution with a concentration of 300g/L (direct lake blue 5B, acid light yellow G, active brilliant blue KE-GN) respectively.The solution was shaken in a water bath oscillator at 25 ^oC for 20 min, then pour into a 50mL colorimetric tube, standing for 3 h to observe the floc formation and precipitation conditions. The supernatant was taken to measured the absorbance by an ultraviolet-visible spectrophotometer at their respective maximum absorption wavelength. The removal rate RR was calculated according to the following formula to evaluate the flocculation effect.

\(\text{R}\text{R}=\frac{{C}_{0}-{C}_{1}}{{C}_{0}}\) ×100% (1)

Where: C₀ is the concentration of the initial dye solution; C₁ is the concentration of supernatant after flocculation.

3.1 Effect of synthesis process on flocculation effect

3.1.1 Effect of temperature

The removal rates of three dyes by flocculants synthesized at different reaction temperatures are shown in Fig. 1. It can be seen from the figure that, under the same other synthesis conditions, the removal rates increase with the increase of reaction temperature, and decrease when 35 ℃ is reached. On the one hand, an appropriate increase in temperature can help Fenton trigger the decomposition of hydrogen peroxide in the system, so as to generate a certain amount of hydroxyl radical, activate the hydroxyl group of starch macromolecules, and then trigger the graft reaction with the two monomers. On the other hand, appropriate increase of temperature, starch swelling degree increases, conducive to various reaction reagents to the internal diffusion of starch particles, to reach the reaction site. As a result, the number of cationic structural units in CGSt macromolecules increased, the number of positive surface charges increased, and the electric neutralization ability and flocculation ability of anionic dyes were enhanced. When the temperature further increases, the decomposition rate of hydrogen peroxide accelerates, excess free radicals lead to the acceleration of chain termination reaction, and the graft rate decreases, so the flocculation ability decreases.

3.1.2 Influence of initiator dosage on flocculation effect

The effect of Fe²⁺ addition in Fenton initiator on the removal rate of dyes is shown in Fig. 2. It can be seen from Fig. 2 that the RR increases with the increase of of initiator. Below Fe²⁺ concentration of 0.025 mol/L, the removal rate decreases with the increase of initiator addition. The concentration of initiator has a great influence on the grafting reaction. Fe²⁺ and H₂O₂ can generate active hydroxyl radicals (•OH) via redox reaction, which can initiate the grating co-polymerization of DMC and MBA on starch back bone. This is due to the more initiator dosage produced sufficient free radicals for the copolymerization[43]. When the concentration of Fe²⁺ is low, the amount of free radicals in the system is insufficient, lead to low grafting ratio and low RR. The increase of Fe²⁺ can promote the decompose of H₂O₂ and formation of •OH radicals, thus improve the grafting ratio and RR. When the concentration of initiator is too high, the excessive primary free radicals in the system will cause reaction rate of double base termination reaction increase, and it will also lead the increase of side reactions such as homo-polymerization. thus initiation efficiency decreases. As a result, grafting rate has a downward trend, so the flocculation effect is weakened.

3.1.3 The effect of the amount of crosslinking agent on flocculation effect

The effect of crosslinking monomer MBA addition on the removal rate of dyes is shown in Fig. 3. It can be seen from the figure that the RR increases with the increase of MBA. When the concentration of added MBA was 0.26 mol/L, the RR reaches a maximum, then with the further increase of dosage, the RR tend to be stable. MBA is a crosslinking monomer with bivinyl groups, it can form crosslinking points among the starch backbone, as well as grafted side chains. Therefor, the macro-molecular configuration of CGSt can be rebuild, to obtain a more complicated three-dimensional network structure. This crosslinked 3D structure with higher molecular weight and branching coefficent is considered more benefit to improve the adsorbing, bridging and netting capacities of CGSt to dyes ions, thus the RR increases. While, too high crosslinking degree and molecular weight is considered has negative effects to the water solubility and flocculation capacity of CGSt.

3.1.4 Effect of different monomer addition on flocculation effect

The effects of different DMC addition amounts on the removal rates of three dyes are shown in Fig. 4. It can be seen from the figure that the RR increases with the increase of the addition amount of cationic monomer DMC, and approaches the peak value when the concentration of DMC in the system is 0.08 mol/L, with the further increase in DMC addition, the improve in RR is no longer significant. In this study, the three dyes are anionic dyes, with sulfonic acid group in their molecules, they dissociate into anions in water, and exist stably via homologous charge repulsion. After graft co-polymerization of DMC, the positively charged PDMC grafted branch chains are introduced into starch backbones, makes CGSt transforms into cationic electrolytesto with increase zeta potential and isoelectric point PI. The macro-molecular chains of CGSt can thus combine with negatively charged dye ions via electrostatic force, making the anions destabilized by electrical neutralization to form microfloc. Then, the size of flocs increases via bridging and trapping of CGSt macro-molecular chains, settle under the action of gravity. When the monomer addition amount exceeds 0.08 mol/L, there are too many monomers in the system, side reactions including chain termination and homopolymerization reaction accelerated, making graft ratio no longer significantly improve, thus the flocculation capacity of CGSt no longer significantly improve, this result is also consistent with the Zeta-potential test results.

3.2 Zate-potential analysis

The effect of different DMC additions and different pH on the Zeta-potential of CGSt is shown in Fig. From the figure, it can be seen that with the increase of cationic monomer DMC addition, the zeta potential of CGSt and the isoelectric point PI have a gradual trend to increase, when the addition amount increased to 0.08 mol/L, the PI increased from 5.63 to 7.10. Native starch is a polysaccharide substance, with the dissociation of hydroxyl group in its glucose structural units, its carries negative a certain charge. The PI of St is 5.63, so it has an electrostatic repulsion effect with anionic dyes in water, and thus cause a poor flocculation capacity to the above dyes. Through graft co-polymerization of DMC, a positively charged PDMC grafting chain segment with a certain length was introduced into the CGSt backbone. With the increase of monomer addition, grafting ratio increase, making the positive charged DMC structural units in CGSt backbone increases, so the PI tends to increase. CGSt is thus transformed into a cationic polymer electrolyte, increasing the ability of electrically neutralizing and destabilizing to anionic dyes in water, which is the main reason for the improved flocculation capacity of CGSt on the above dyes. When the monomer addition was 0.08 mol/L, the pI of CGSt increased significantly, from 5.63 to 7.10. Further, as the DMC addition continued to increase, the increase in pI no longer significant, it is considered to because the chain termination and homo-polymerization side reactions intensified when the DMC monomer concentration was too large, making the grafting efficiency decreased, and thus the positive charge no longer increased significantly.

3.3 Fourier infrared spectroscopy characterization (FT-IR)

The infrared spectra of St and CGSt are shown in Fig. 6. and the structural changes of starch before and after modification are analyzed. The C-H stretching vibration is near 2930 cm^− 1, and the intensity of this peak increases significantly in the CGSt spectrum, which is due to the presence of a considerable number of methyl and methylene groups in the backbone and monomer units on the grafted PDMC side chains. And the peak intensity is also enhanced at 1460 cm^− 1, which is caused by the bending vibration of C-H. The characteristic absorption peak near 1709 cm^− 1 is the stretching vibration of C = O, which is due to the presence of acyl groups in the DMC structural unit, which can be taken as direct evidence of the introduction of PDMC into the CGSt backbone. Peak at 1157 cm^− 1 is assign to the stretching vibration of C-N, which are present in the quaternary ammonium groups in DMC structural unit. The results of the IR spectra were in general agreement with the NMR analysis.

3.4 Nuclear Magnetic resonance spectroscopy Characterization (¹³C NMR)

The NMR spectra of St and CGSt are shown in Fig. 7. The chemical shift value of 101.5–71.5 ppm is the six carbon atom peaks of the starch glucose ring: C1 (anomeric carbon) is located in the lowest field (δ101.5). This is because C1 is directly connected to two strongly electronegative oxygen atoms and is strongly shielded. The peak at δ81.9 belongs to C4, and the strong peaks near δ71–74 are caused by the overlap of C2, C3 and C5. The chemical shift of C6 is at the highest field. Compared with native starch, the NMR spectra of starch flocculant had a series of obvious changes after crosslinking grafting modification. At the lowest field, the chemical shift value of the Sp² hybrid carbon atom peak at 176.2 ppm is attributed to the carbonyl carbon atoms C10 in the cationic monomer DMC and C16 of amide group in the crosslinking monomer MBA structural units. Because the chemical shift values of the two carbon atoms are relatively close, a moderate intensity peak is formed at 176.2 ppm. At the highest field, a variety of new saturated carbon atomic peaks appear in the chemical shift value range from 48.6–29.1 ppm, which are assigned to tertiary carbon C8, C15, secondary carbon C7, C14 and primary carbon C9, respectively, exist in the backbone and structural units of the grafted side chains. The result indicated a certain amount of positively charged polymer chain segments have been introduced in the CGSt backbone, and make CGSt transformed to a cationic polyelectrolyte.

3.5 X-ray photoelectron spectroscopy characterization (XPS)

The surface chemical composition of St and CGSt was detected by X-ray photon spectrometer. The C1 s in the spectrum was fitted with several components, and the results are shown in Fig. 8 and Fig. 9. The surface chemical composition of St is shown in Fig. 8. The peaks of the spectrum appear at 284.58 and 286.38 eV, corresponding to C-C / C-H and C-O, respectively. It can be seen from Fig. 9 that the C1 s peaks of CGSt appear at 284.68, 285.28, 286.48 and 288.48 eV, corresponding to C-C/C-H, C-N, C-O and C = O-C, respectively. The elemental composition of the two starches is shown in Table 1.The data showed that the C-C/C-H and C-O contents of CGSt decreased, and C-N and C = O were introduced. Therefore, the increase in the content of C-N and C = O indicates that St successfully grafted the quaternary ammonium cationic monomer DMC and introduced a large amount of C-N and C = O. The results of XPS analysis also proved again that after cross-linking-grafting modification, a considerable number of grafted chains with quaternary ammonium groups were introduced into the starch macromolecules, the result is in accordance with FTIR and 1³C-NMR analysis.

Table 1
Samples	C-C/C-H(%)	C-O(%)	C = O-C(%)	C-N(%)
St	41.04	58.96	0	0
CGSt	24.3	31.21	12.94	31.55

3.6 Gel Permeation Chromatography ( GPC )

Gel permeation chromatography is used to characterize the molecular weight of polymer compounds. Polymers with similar chemical properties and different molecular volumes can be separated on the column according to their hydrodynamic dimensions. Components with higher molecular weights and larger molecular sizes have shorter retention times, while components with lower molecular weights and smaller sizes have longer retention times.

The GPC chromatogram of CGSt prepared with different MBA addition is shown in Fig. 10. Since MBA is a cross-linking monomer, its a addition has a effect on the molecular weight and macro-molecular structure to CGSt, and in turn effect its flocculation capacity. It can be seen from Fig. 10, The GPC chromatogram of natural corn starch macromolecules has two major peaks, which attribute to its two major components, including linear macro-molecule amylose AM (fraction of lower molecular weight) and branched macro-molecule amylopectin AP (fraction of higher molecular weight). In St chromatogram, the peak intensity of AP is higher than that of AM. And for CGSt. with the increase in MBA addition, the peak value of AP tends to increase relative to that of AM, indicating that the degree of starch branching increases after crosslinking grafting co-polymerization. This is considered because: on one hand, the introduction of PDMC has introduced a certain amount of polymer branching chain segments to CGSt backbone, on the other hand, the MBA monomeric units can form abundant chemical crosslinking points among the starch backbones and the grafted side chains. AS a result, the branching degree of CGSt increased, leading to a formation of a more complex three-dimensional network structure of CGSt. It is beneficial for CGSt to play the role of bridge building and net catching in dyestuff removal. The retention time of CGSt did not change significantly, indicating that the molecular weight of CGSt did not change significantly compared with St. On the one hand, Fenton triggered the oxidation of hydrogen peroxide in the system, which had a tendency to degrade the main chain, but at the same time, the crosslinking effect of MBA can inhibited the degradation of CGSt backbone to a certain extent, as a result, the CGSt basically retained relatively high molecular weight, which was beneficial to keep a high flocculation capacity of CGSt.

3.7 X-ray diffraction characterization (XRD)

Figure 11 shows the X-ray diffraction patterns of St and CGSt prepared at different reaction temperatures. From the curve (St), it can be seen that there are obvious diffraction peaks of natural starch 15 ^o,17 ^o,18 ^o and 23 ^o, indicating that the starch is a type A gramineous starch. The starch granules are semi-crystalline in structure and their crystalline regions are mainly maintained by intermolecular hydrogen bonds of the starch macromolecules. Native starch has a large number of hydrogen bonds between macromolecules, which lead to a poor water solubility.

With the increase of reaction temperature, the peak intensity of the diffraction peak decreases gradually. Under higher temperature, part of the crystal structure of starch disintegrated, leading to an increases amorphous region. On one hand, with the increase of reaction temperature, the hydrogen bonds among starch macro-molecules were destroyed, leading to a degradation of the crystalline region. On the other hand, the introduced graft polymer segments would further decompose the crystalline region through the homo-charge repulsion and steric effect effect among the CGSt backbones. As a result, the proportion of crystalline regions decreased with the increase of reaction temperature. It can be seen from Table 2 that the crystallinity decreased from 21.86 to 16.83, which was not significant. This may be due to the low reaction temperature within the scope of this study.

Table 2
Samples	St	25 ℃	35 ℃	45 ℃
Crystallinity	21.86	19.76	17.20	16.83

3.8 Scanning electron microscopy analysis(SEM)

Figure 12 is the scanning electron microscope image of St and CGSt. Figure 12a shows that the particles of St are smooth, mostly round and polygonal irregular shapes. In Fig. 12b the CGSt particles are find to have a certain degrees of adhesion, this is considered to because under the cross-linking effect of MBA, the interaction among the granules of CGSt is enhanced. But since crosslinking is a molecular level reaction, St and CGSt have no significant change in the morphology of starch granules, and the granules maintain a complete structure. The Fenton initiation system adapted in this study can reduce the reaction temperature, and lead less damage to the starch granules, which can effectively avoid the product loss caused by high water solubility of starch in the preparation process, and reduce the difficulty of product separation.

3.9 Flocculation effect test

3.9.1 Effect of different flocculant addition on flocculation effect

The influence of flocculant dosage on RR plays a decisive factor. Figure 13 reflects the influence of flocculant dosage on RR. It can be seen from the Fig. 13 that the removal rate of three dyes presents a trend of "first increasing and then stabilizing" with the increase of flocculant dosage, which indicates that charge neutralization plays an important role in the flocculation process. CGSt is a cationic polymer electrolyte. The textile dyes always exist in exist in the form of anions and colloidal negatively charged particles, as a cationic polyelectrolyte, the CGSt has the electrical neutralization to dyes, making the dye destabilized to form microfloc. Then the high molecular backbones and grafted side chains of CGSt can diffuse in water and absorb multiple dye floc particles, thus the microfloc particles can be further aggregated through a bridging effect to form a larger flocs, and then settles under gravity. Generally speaking, the bridging effect is related to the concentration of flocculant. When the concentration of flocculant is low, it can promote the generation of flocs, and when the concentration of flocculant is too high, the surface of floc particles is covered by flocculant polymer, which plays a protective role, and the flocs are re-stabilized under the repulsive effect of opposite charges, and flocculation will not occur.

The flocculation window reflects the concentration range of flocculating agent that can effectively play a flocculation role. In the concentration range of flocculants studied in this paper, the measured RR of the three dyes tends to be stable with the increase of the de-flocculant addition, and no decreasing trend is found, indicating that this starch flocculant has a wide flocculation window. This is beneficial for the treatment of this flocculant in industrial wastewater, as well as to improve the synergy with other types of flocculants, such as inorganic polymer flocculants.

3.9.2 Effect of different pH on flocculation

Figure 14 reflects the effect of CGSt on the RR of three dyes at different pH. It can be seen from the figure that the starch flocculant has high removal performance for three dyes in a wide pH range. As mentioned above, the removal mechanism of the flocculant for dye molecules in water includes charge neutralization and bridging effects. In general, the former depends on the charge properties and density of the flocculant surface, and the latter depends on the morphology and conformation of the flocculant macromolecules in water. The DMC grafted side chain contains a large number of quaternary amine cationic groups, making CGSt has sufficient positive charge in a wide pH range, which increases the cationic strength of CGSt and enhances the attraction to anionic dyes[44, 45]. Therefore, the adsorption and electrical neutralization of dye ions in water can be fully exerted to form microflocs, and then form flocs and settle under bridging action. When the pH increased to more than 12, the flocculation effect of starch flocculant decreased significantly, which may be based on two reasons: ① the deprotonation of hydroxyl groups in starch flocculant, that cause electrostatic repulsion with dye anions in water. ② The collapse of the three-dimensional network structure of starch flocculant macromolecules, which weakened its diffusion ability in water and decreased its bridging ability. Nevertheless, in this study, the starch flocculant showed stable flocculation performance in a wide pH range, which was beneficial to its application in the treatment of printing and dyeing wastewater with complex and variable water quality.

The following conclusions can be made:

A starch-based natural modified polymer flocculant was prepared, corn starch (St) was used as raw material, methacryloyloxyethyl trimethyl ammonium chloride (DMC) and N.N'-methylenebisacrylamide (MBA) were used as cationization grafting monomer and crosslinking monomer, respectively, and an environmentally friendly Fenton initiation system was adopted. The optimal synthesis condition is: the molar ratio of St to DMC and MBA is 24:2:1, the molar ratio of FeCl₂•4H₂O to H₂O₂ is :1:7, and the reaction temperature is 35°C. The removal effect of the flocculant prepared under this condition is optimal.

The results of FTIR, ¹³C-NMR and XPS showed positively charged graft side chains have been introduced on CGSt backbone The results of XRD and SEM showed that compared with St, the cross-linking-grafting reaction of CGSt had less damage to the starch structure. The Zate-potential test showed that the positive charge density and isoelectric point of CGSt increased with the DMC addition. The results of GPC showed that the molecular structure of starch was changed after grafting-crosslinking, the branching degree of CGSt increase, which was beneficial to enhance the bridging capacity of CGSt.

The dosage of flocculant and pH have important effects on the flocculation effect. It is found that CGSt has a wide flocculation window, from 5 g/L to 12 g/L, and maintains good flocculation performance over a wide pH range of 4–9. Under these conditions, the removal rate of reactive brilliant blue KE-GN can reach 96.3%, and the removal rate of acid light yellow G and direct lake blue 5B can reach 97.2%.

Acknowledgments

Funding: This work was supported by the National Key R&D Program of China (2023YFE0101000), Key R&D Program of Shandong Province (2022CXGC020416).

Competing Interests

No, I declare that the authors have no competing interests as defined by Springer, or other interests that might be perceived to influence the results and/or discussion reported in this paper.

Author contribution

Hao zhang: Reviewing and Editing. Jiaqian Li: Conceptualization, Writing-Original draft preparation and Methodology. Shuchen Cao: Auxiliary experiments. Yang Ding: Auxiliary experiments. Na Chang, Haitao Wang : Supervision and Funding.

Data availability statements

All data generated or analysed during this study are included in this published article

Verma AK, Dash RR, Bhunia P (2012) J Environ Manage 93:154–168
Prus S, Kulpinski P, Matyjas-Zgondek E, Wojciechowski K (2022) Cellulose 29:4167–4182
Vuckovic N, Nikodijevic M, Djordjevic D (2021) Chem Ind Chem Eng Q 27:255–263
Akhtar Z, Ali SI, Ali SR, Khan S, Alam F, Abbas N, Khan MY (2019) J Chem Soc Pak 41:633–639
Crini G (2008) Dyes Pigm 77:415–426
Liu NN, Wu YH, Sha HT (2018) J Colloid Interface Sci 516:98–109
Soto D, Leon O, Munoz-Bonilla A, Fernandez-Garcia M (2021) Starch-Starke, 73
Mohapatra DP, Kirpalani DM (2019) Water Sci Technol 79:842–849
Sharma A, Ahmad J, Flora SJS (2018) Environ Res 167:223–233
Sivagami K, Sakthivel KP, Nambi IM (2018) J Environ Chem Eng 6:3656–3663
Ni HC, Arslan M, Wei J, Dai J, Luo ZJ, Cai RQ, Zhao S, El-Din MG, Wu ZR (2021) Sci Total Environ, 785
Patel D, Bapodra SL, Madamwar D, Desai C (2021) Bioresour Technol, 332
Cheng H, Liu YL, Li X (2021) J Hazard Mater, 415
Song JZ, Li Y, Wang Y, Zhong L, Liu Y, Sun XY, He B, Li YC, Cao S (2021) Materials, 14
Wang KX, Liu HF, Wang YT, Zhao DS, Zhai JH (2022) Starch-Starke, 74
Lapointe M, Barbeau B (2020) Sep Purif Technol, 231
Liu ZG, Lu X, Xie JK, Feng B, Han QN (2019) Sep Purif Technol 210:355–363
Peng SL, Jiang GC, Li XL, Yang LL, Liu F, He YB (2018) J Chem Technol Biotechnol 93:968–974
Salehizadeh H, Yan N, Farnood R (2018) Biotechnol Adv 36:92–119
Zhang WX, Wang XJ, Xu Q, Peng J, Lou T (2020) J Appl Polym Sci, 137
Liu YL, Li C, Lou ZM, Zhou CC, Yang KL, Xu XH (2021) Sep Purif Technol, 275
Vergili I, Gencdal S (2017) Water Environ Res 89:641–651
Gu SG, Lian F, Yan KJ, Zhang W (2019) Water Sci Technol 80:1562–1570
Lu HY, Qian CY, Luo SG, Zhu YG, Liu RQ, Wu MR (2023) Miner Eng, 191
Luo XG, Li XB, Wei C, Shi XG, Zheng SQ, Deng ZG (2021) Sep Purif Technol, 267
Qi GX, Wang XB, Shen Y, Liu XC, Alam MA, Liu BY, Chen YC (2022) J Environ Chem Eng, 10
Abdollahi Z, Frounchi M, Dadbin S (2011) J Ind Eng Chem 17:580–586
Chen XD, Wang DF, Wang S, Song HY, Gu Q, Zhang YM (2021) J Polym Environ 29:565–575
Nasim T, Bandyopadhyay A (2012) Sep Purif Technol 88:87–94
Nasim T, Pal A, Bandyopadhyay A (2018) Appl Clay Sci 152:83–92
Koshani R, Tavakolian M, de Ven T (2020) J Mater Chem B 8:10502–10526
Song YF, Hu QH, Li TM, Li JQ, Jiang K, Gao CJ (2020) J Clean Prod, 268
Asharuddin SM, Othman N, Altowayti WAH, Abu Bakar N, Hassan A (2021) Environmental Technology & Innovation, 23
Liu W, Ma JJ, Pang HJ, Wang ZW, Yao XD (2021) Iran Polym J 30:675–683
Hu P, Shen SH, Yang H (2021) Sci Rep, 11
Luo YL, Lin JL, Wang XT, Yeerken A, Ma HY (2023) Starch-Starke, 75
Wu YY, Jiang JY, Sun Q, An YY, Zhao R, Zheng HL, Li H (2022) Sep Purif Technol, 282
Jiang YX, Ju BZ, Zhang SF, Yang JZ (2010) Carbohydr Polym 80:467–473
Chen Y, Tian GW, Zhai BY, Zhang HL, Liang YN, Liang HB (2019) Compos Part B-Engineering, 177
Zhou L, Zhou HJ, Yang XY (2019) Sep Purif Technol 210:93–99
Zhou HJ, Zhou L, Yang XY (2018) Int J Biol Macromol 118:1431–1437
Hu P, Xi ZH, Li Y, Li AM, Yang H (2020) Chemosphere, 240
Lou T, Cui GP, Xun JJ, Wang XJ, Feng NY, Zhang J (2018) Colloids and Surfaces a-Physicochemical and Engineering Aspects 537:149–154
Kumar N, Mittal H, Alhassan SM, Ray SS (2018) ACS Sustain Chem Eng 6:17011–17025
Hernandez-Martinez AR, Lujan-Montelongo JA, Silva-Cuevas C, Mota-Morales JD, Cortez-Valadez M, Ruiz-Baltazar AD, Cruz M, Herrera-Ordonez J (2018) React Funct Polym 122:75–84

No competing interests reported.

Download PDF

Journal Publication

published 23 Jan, 2024

Read the published version in Journal of Polymers and the Environment →

Editorial decision: Major revision
07 Sep, 2023
Reviews received at journal
28 Aug, 2023
Reviewers agreed at journal
24 Aug, 2023
Reviewers invited by journal
07 Aug, 2023
Editor assigned by journal
01 Aug, 2023
Submission checks completed at journal
01 Aug, 2023
First submitted to journal
31 Jul, 2023

You are reading this latest preprint version

Preparation of crosslinking-grafting cationic starch flocculant and its study on textile dyes removal

Status:

Journal Publication

Version 1

Abstract

Figures

1. Introduction

2. Experiment

2.1 Materials and reagents

2.2 Preparation of CGSt

2.3 Flocculation performance test

3. Results and Discussion

3.1 Effect of synthesis process on flocculation effect

3.1.1 Effect of temperature

3.1.2 Influence of initiator dosage on flocculation effect

3.1.3 The effect of the amount of crosslinking agent on flocculation effect

3.1.4 Effect of different monomer addition on flocculation effect

3.2 Zate-potential analysis

3.3 Fourier infrared spectroscopy characterization (FT-IR)

3.4 Nuclear Magnetic resonance spectroscopy Characterization (¹³C NMR)

3.5 X-ray photoelectron spectroscopy characterization (XPS)

3.6 Gel Permeation Chromatography ( GPC )

3.7 X-ray diffraction characterization (XRD)

3.8 Scanning electron microscopy analysis(SEM)

3.9 Flocculation effect test

3.9.1 Effect of different flocculant addition on flocculation effect

3.9.2 Effect of different pH on flocculation

4. Conclusion

Declarations

References

Additional Declarations

Status:

Journal Publication

Version 1

Preparation of crosslinking-grafting cationic starch flocculant and its study on textile dyes removal

Status:

Journal Publication

Version 1

Abstract

Figures

1. Introduction

2. Experiment

2.1 Materials and reagents

2.2 Preparation of CGSt

2.3 Flocculation performance test

3. Results and Discussion

3.1 Effect of synthesis process on flocculation effect

3.1.1 Effect of temperature

3.1.2 Influence of initiator dosage on flocculation effect

3.1.3 The effect of the amount of crosslinking agent on flocculation effect

3.1.4 Effect of different monomer addition on flocculation effect

3.2 Zate-potential analysis

3.3 Fourier infrared spectroscopy characterization (FT-IR)

3.4 Nuclear Magnetic resonance spectroscopy Characterization (13C NMR)

3.5 X-ray photoelectron spectroscopy characterization (XPS)

3.6 Gel Permeation Chromatography ( GPC )

3.7 X-ray diffraction characterization (XRD)

3.8 Scanning electron microscopy analysis(SEM)

3.9 Flocculation effect test

3.9.1 Effect of different flocculant addition on flocculation effect

3.9.2 Effect of different pH on flocculation

4. Conclusion

Declarations

References

Additional Declarations

Status:

Journal Publication

Version 1

3.4 Nuclear Magnetic resonance spectroscopy Characterization (¹³C NMR)