Enhanced coagulation by two-stage alum addition: the role of solution pH, floc breakage and assistant of non-ionic polyacrylamide

Du, Peng; Li, Xing; Yang, Yunxia; Fan, Xiao-Yan; Fang, Xiaobo; Zhou, Zhiwei

doi:10.1080/09593330.2020.1762757

Cited by 8 publications

(3 citation statements)

References 38 publications

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“…The optimum dose and pH were found at 100 mg L -1 and 5 units for aluminum sulfate (Figure 2a) and 180 mg L -1 and 4 units for chitosan (Figure 2b). pH value for aluminum sulfate concurs with those reported by Du et al (2021). Due to the protonation of amine groups below pH 5 chitosan in acidic solutions behaves like a cationic coagulant, enhancing the ef ficiency of coagulation (Desbrières and Guibal, 2018).…”

Section: Ef Fect Of the Operation Conditionssupporting

confidence: 86%

Evaluation of Wastewater Coagulation/Flocculation with Chitosan from Shrimp Exoskeletons Waste and Aluminum Sulfate

Labastida-Núñez,

Velasco-Pérez,

Pablo-Reyes

et al. 2023

Terra Latinoam

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Intensive use of water, growing cities, and lack of wastewater treatment are some factors increasing hydric stress worldwide. Coagulation/flocculation is one of the preferred treatments for wastewater. However, aluminum salts are traditionally used in this process. This coagulant has a high environmental footprint and residual aluminum in wastewater is a public health concern. The preparation and use of chitosan as a coagulant aid in coagulation/flocculation with aluminum sulfate were investigated. The ef fect of the order of addition of coagulants (aluminum sulfate followed by chitosan, or chitosan followed by aluminum sulfate), dose of the coagulants, pH, and slow mixing velocity for flocculation were studied. It was found that the removal of total suspended solids (TSS) with aluminum sulfate was relatively unaf fected by pH (aluminum sulfate dose of 100 mg L-1 at pH of 5 units achieved 94% removal of TSS and at pH of 8.2 units 89% removal of TSS), whereas with chitosan was highly af fected (chitosan dose of 180 mg L-1 at pH of 4 units achieved 96% removal of TSS and at pH of 8.2 units 25% removal of TSS). In the coagulation/flocculation experiments where both coagulants were used, it was found that the order of coagulant addition and pH of wastewater have a statistically significant ef fect (P-value < 0.05) on the removal of TSS. Higher removal of TSS was achieved when aluminum sulfate was added followed by chitosan at a wastewater pH of 5 units. Chitosan can be ef fectively used to reduce the use of aluminum salts in wastewater treatment. However, it is necessary to optimize the preparation of this coagulant and investigate other factors, such as variation in the wastewater quality, that can af fect the robustness of the process.

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Section: Ef Fect Of the Operation Conditionssupporting

confidence: 86%

Evaluation of Wastewater Coagulation/Flocculation with Chitosan from Shrimp Exoskeletons Waste and Aluminum Sulfate

Labastida-Núñez,

Velasco-Pérez,

Pablo-Reyes

et al. 2023

Terra Latinoam

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“…It was moreover confirmed that the constant durability of the iron-organic complex increases along with an increase in pH, which is most likely caused by the growing dissociation of functional groups -COOH and -OH [9]. One of the recommended methods to remove iron-organic complexes from water is the use of a coagulation process [14][15][16][17][18][19][20]. When added to water, aluminum and iron coagulants yield hydrolysis products that destabilise the organic material present in the raw water.…”

Section: Introductionmentioning

confidence: 92%

The Influence of the Presence of Iron in Highly Alkaline Polyaluminium Chlorides on the Effectiveness of Precursors of Disinfection by-Products Removal

KRUPIŃSKA

2023

Civil and Environmental Engineering Reports

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The mechanism of coagulation with highly alkaline polyaluminum chlorides is well understood, but there is a lack of information on the effect of the presence of iron in these coagulants on the efficiency of purifying water with increased contents of natural organic matters among which humic substances are precursors of disinfection by-products. The dissolved forms of organic substances are the most problematic with regard to water treatment because major concern is the formation of disinfection by products resulting from reactions between dissolved organic matter fractions and disinfectants. The aim of this study was to evaluate the effectiveness of precursors of disinfection by-products removal using highly alkaline polyaluminium chlorides that had different alkalinity and iron content. In the water after the coagulation process a value of SUVA254 was calculated because this indicator correlates well with dissolved organic matter reactivity and disinfection by-products. The analysis of the obtained results showed that the effectiveness of dissolved organic matter removal was determined by the formation of colored iron-organic complexes.

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“…The so-called poloxamer is a new type of polymer nonionic polyol with low toxicity, low irritation, and good biocompatibility, which can be used in biological fields such as pharmaceutical excipients, gene therapy, and the inhibition of postoperative intestinal adhesions [22][23][24]. First, multiple models were established to simulate the interaction between poloxamers and three common polyacrylamides, which were anionic polyacrylamide (APAM) [25], cationic polyacrylamide (CPAM) [26], and nonionic polyacrylamide (NPAM) [27]. The results predicted strong hydrogen bonds between the amide groups on the polymer chain and the poloxamers.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics-Assisted Design of High Temperature-Resistant Polyacrylamide/Poloxamer Interpenetrating Network Hydrogels

Song

Lü²,

Wang

et al. 2022

Molecules

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Polyacrylamide has promising applications in a wide variety of fields. However, conventional polyacrylamide is prone to hydrolysis and thermal degradation under high temperature conditions, resulting in a decrease in solution viscosity with increasing temperature, which limits its practical effect. Herein, combining molecular dynamics and practical experiments, we explored a facile and fast mixing strategy to enhance the thermal stability of polyacrylamide by adding common poloxamers to form the interpenetrating network hydrogel. The blending model of three synthetic polyacrylamides (cationic, anionic, and nonionic) and poloxamers was first established, and then the interaction process between them was simulated by all-atom molecular dynamics. In the results, it was found that the hydrogen bonding between the amide groups on all polymers and the oxygen-containing groups (ether and hydroxyl groups) on poloxamers is very strong, which may be the key to improve the high temperature resistance of the hydrogel. Subsequent rheological tests also showed that poloxamers can indeed significantly improve the stability and viscosity of nonionic polyacrylamide containing only amide groups at high temperatures and can maintain a high viscosity of 3550 mPa·S at 80 °C. Transmission electron microscopy further showed that the nonionic polyacrylamide/poloxamer mixture further formed an interpenetrating network structure. In addition, the Fourier transform infrared test also proved the existence of strong hydrogen bonding between the two polymers. This work provides a useful idea for improving the properties of polyacrylamide, especially for the design of high temperature materials for physical blending.

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Enhanced coagulation by two-stage alum addition: the role of solution pH, floc breakage and assistant of non-ionic polyacrylamide

Cited by 8 publications

References 38 publications

Evaluation of Wastewater Coagulation/Flocculation with Chitosan from Shrimp Exoskeletons Waste and Aluminum Sulfate

Evaluation of Wastewater Coagulation/Flocculation with Chitosan from Shrimp Exoskeletons Waste and Aluminum Sulfate

The Influence of the Presence of Iron in Highly Alkaline Polyaluminium Chlorides on the Effectiveness of Precursors of Disinfection by-Products Removal

Molecular Dynamics-Assisted Design of High Temperature-Resistant Polyacrylamide/Poloxamer Interpenetrating Network Hydrogels

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