JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Gefei Ma,Hui Xu,Xiaofang Yang,Guangyu An,Qinxue Yang,Xi Wang,Dongsheng Wang
Natural organic matter (NOM) can tremendously influence the purification efficiency of the drinking water treatment process. Coagulation was the first and primary process of NOM removal in the drinking water treatment process. The interaction between coagulants and NOM molecules remains unclear. Three typical coagulants (Al 13 , FeCl 3, and AlCl 3 ) were used to investigate the effects on NOM removal. The measurement of NOM was conducted using 15 T Electrospray Ionization coupled Fourier-Transform-Ion Cyclotron Resonance Mass Spectrometry (ESI-FT-ICR MS). The coagulation process altered the mass peak numbers as well as relative intensity of the peaks which were positively correlated with TOC value. The lignin-like compound was the most abundant moiety in raw water. Al-based coagulants remove more unsaturated larger compounds (lower KMD and higher carbon number). Al 13 remove the unsaturated hydrocarbons preferably. FeCl 3 is more reactive with NOM molecules and removes more fully saturated compounds. These findings revealed the coagulation removal mechanism of NOM with different structural characteristics and advise the practical use of coagulants for various raw water with different NOM characteristics.
研究领域:
环境科学
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分析化学
✓ 已验证
DOI
高影响因子
RSC Advances
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2017
·Vol. 7
·期 67
·42329-42338
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IF 3.108
Zhaoyang Su,Xing Li,Yanling Yang,Yiran Fan
Much attention has been paid to coagulation as a pretreatment for controlling membrane fouling. Until now, however, there has been no literature available on the application of Zr-based coagulants in the coagulation–ultrafiltration process. The aim of this work is therefore to investigate the coagulation behavior of ZrOCl2 and its influence on membrane fouling, in comparison with that of the commonly used Al-based coagulants, Al2(SO4)3 and PACl. Floc formation kinetics were studied via ‘a turbidity fluctuation technique’ (PDA measurement). A variation in the pH and temperature of raw water was also considered in order to test the performance of the three targeted coagulants. The results indicated that the best coagulation efficiency was achieved with the Zr coagulant, under neutral pH conditions and at a room temperature of 25 °C. This coagulant resulted in minimum turbidity (0.72 NTU) and the lowest concentration of the supernatant at UV254 (0.005 cm−1); the corresponding values for Al2(SO4)3 were 2.79 NTU and 0.011 cm−1, respectively, while those for PACl being 6.78 NTU and 0.015 cm−1. The flocs obtained by the addition of this Zr coagulant were larger in size and had superior strength, recovery potential and settleability. In addition, membrane fouling was apparently alleviated through use of the Zr coagulant, especially in terms of the irreversible fouling, followed by PACl and Al2(SO4)3. The superior removal efficiency of low-medium MW HA may be a plausible explanation for this phenomenon. Particularly, this work describes a novel Zr coagulant as an important potential candidate for application to the coagulation–ultrafiltration process in the future.
研究领域:
环境工程
·
水处理技术
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产品关联
DOI
高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Yunong Tang,Xinyu Hu,Jun Cai,Zhonghua Xi,Hu Yang
In this work, a simple and environmentally-friendly enhanced coagulation, by using a cationic starch-based coagulant (starch-3-chloro-2-hydroxypropyl trimethyl ammonium chloride , St-CTA) coupled with an optimized polysilicic acid (PSA), has been tried to coagulate the kaolin suspensions and humic acid (HA) aqueous solutions, which are used as the simulated sources of inorganic colloidal particles and organic pollutant , respectively, in micro-polluted turbid surface water. Dosing of St-CTA and PSA at the same time is more efficient and more convenient than other two separated feeding methods in this enhanced coagulation process. The synergic coagulation process and mechanism were studied and discussed in detail based on the apparent coagulation performance, floc properties, and zeta potentials of supernatants. St-CTA caused an efficient charge neutralization, i.e. compression of electric double layer of kaolin particles and electrostatic adsorption of HA, followed by an effective netting-bridging effect of PSA, resulting in an improved purification performance. St-CTA with a higher charge density showed better purification performance due to enhanced charge neutralization effect. In addition to simulated water, the validation of this enhanced coagulation process was further confirmed by comparison with a conventional coagulant, polyaluminium chloride, in treating a real surface water. This work thus provides a simple and environmentally-friendly strategy to efficiently purify micro-polluted turbid surface water and further improve the water safety.
研究领域:
环境科学
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水处理技术
✓ 已验证
DOI
高影响因子
Journal of Cleaner Production
·
2024
·
IF 9.7
Panpan Li,Jianguo Zhang,Yongfa Yu,Wenlin Jia,Shuang Zhao
A collaborative coagulation strategy was proposed in this paper for algae-laden and dye-containing water treatment to realize the efficient, low-carbon, low-cost, fast, and synchronous removal of algal organic matters (AOMS) and dyes. Chemical conditions were optimized to achieve a higher collaborative coagulation efficiency, and the contributions of AOMS with different components and molecular weights (MW) were systematically analyzed to elucidate the mechanism of collaborative coagulation. Results showed that dye removal was enhanced with an increase in the proportion of AOMS (<50%). Collaborative coagulation efficiency showed a considerable dependence on the components of AOMS with high MW. 37.50% polysaccharides, 11.89% proteins, and 41.16% humic acid (HA) with WM higher than 100 kDa contributed 47.83–64.44% of the dye removal. The cross-linking reactions between the alum coagulant, AOMS, and dye active groups generated flocs with larger sizes and better settling abilities. Under alkaline conditions, alum hydrolysates produce efficient Lewis binding sites and lower steric hindrance, whereas AOMS deprotonation auxiliaries the formation of conjugated coordination and hydrogen bonds. These synergistic adsorption bridging effects were generated and the coagulation efficiency increased. Overall, the collaborative coagulation strategy realized the reutilization of algae-laden water from a new perspective, and achieved higher dye removal with a shorter hydraulic retention time, which are of great significance for the development of water treatment technology, energy savings, and emission reduction.
研究领域:
环境科学
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水处理技术
✓ 已验证
产品关联
DOI
高影响因子
Chemical Engineering Journal Advances
·
2022
·
IF 0
Jiangya Ma,Bangtao Jia,Sha Li,Yanli Kong,Yong Nie,Huiwen Zhang,Meng Xiao,Tian Gao
The enhanced coagulation performance for algae and extracellular organic matter (EOM) removal by using novel Al/Fe-based covalently bonded composite coagulants (CAFM) coupled with potassium permanganate oxidation was evaluated in the current study. For the CAFM coagulation and potassium permanganate oxidation combination process, two dosage sequences of oxidant and coagulant, the potassium permanganate pre-oxidation method, and the simultaneous oxidation method, was compared for algae and EOM removal. Polyaluminum chloride (PAC) and polyacrylamide (PAM) were selected as common used coagulants to compare with CAFM. The results show that 21.1% UV 254 , 99.6% OD 686, and 98.2% turbidity were removed from EOM algae laden water at CAFM dosage of 5.4 mg/L and KMnO 4 dosage of 1 mg/L. UV 254 removal rate was increased by 10% in potassium permanganate oxidation treatment compared with CAFM coagulation. In addition, pre-oxidation method exhibited better extracellular organic matter removal efficiency compared with simultaneous oxidation method. Furthermore, SEM, FTIR, XRD and XPS were employed to study the physical and chemical structure of flocs, whereas ICP-MS, EEM, GCMS– and GPC were used to analyze water quality before and after treatment for coagulation and oxidation in mechanism exploration. This study proposes a new process for algal bloom control, organic pollution reduction and ensure water quality of water plant effluent to provide research basis.
研究领域:
环境科学
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水处理工程
✓ 已验证
DOI
WATER ENVIRONMENT RESEARCH
·
2025
·Vol. 97
·期 2
·e70023
·
IF 1.9
Zihan Wang,Jingqian Ma,Kun Wu,Wenquan Sun,Yongjun Sun
In this study, a titanium-based coagulant, (i.e., PTFS), with a three-dimensional spatial mesh structure was prepared for the coagulation removal of polystyrene (PS) and titanium dioxide (TiO 2 ) nanoparticles in water. The results of scanning electron microscopy, TGA-DSC, Fourier infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy characterization showed that the PTFS was not a simple mixture of raw materials and a chemical reaction occurred, thereby generating new chemically connected bonds. The optimum removal of PS could reach 92.5% at the dosage of 0.6 mg/L, initial concentration of 70 mg/L, pH of 7, stirring intensity of 350 rpm, settling time of 60 min, and kaolin concentration of 70 mg/L. The best removal rate of TiO 2 could reach 95.3% when the dosage was 0.8 mg/L, the initial concentration was 70 mg/L, the pH was 7, the stirring intensity was 350 rpm, the settling time was 60 min, and the kaolin concentration was 50 mg/L. The flocs produced by PTFS were large and dense. In the early stage of coagulation, the flocculation mechanism was dominated by electroneutralization, and in the middle and late stages of coagulation, adsorption, bridging, and netting were dominated. This study aims to provide a reference for the removal of nanopollutants by coagulation in the actual water treatment process. Practitioner Points A titanium-based coagulant PTFS with a three-dimensional spatial mesh structure was prepared. PTFS effectively removes nano-PS and nano-TiO 2 from water. The flocs produced by PTFS were large and dense flocs. Removal of PS and TiO 2 by PFTS has been a combination of multiple coagulation mechanisms. Graphical The titanium-based coagulant PTFS was prepared to remove PS and TiO 2 nanoparticles from water. The removal of PS and TiO 2 by coagulation was a combination of compression bilayer, adsorption and electroneutralization, net trapping and sweeping, and adsorption and bridging mechanisms.
研究领域:
环境科学
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水处理技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Dachao Lin,Zhongsen Yan,Xiaobin Tang,Jinlong Wang,Heng Liang,Guibai Li
Nanofiltration is routinely applied as an advanced water treatment technology after conventional water treatment. However, the residual coagulant after coagulation process may affect the nanofiltration process and to our best of knowledge, few studies focused on this phenomenon. To address such issues, ferric and aluminum ions were adopted as the model coagulant, and the influences of coagulant concentrations, coagulant conditioning time and fouling strategies on gypsum scaling were systematically investigated. The results indicated that coagulant conditioned on the membrane surface could improve membrane flux, enhance scaling, and increase the conductivity of permeate. The contents of coagulant accumulated on the membrane surface gradually increased with its increasing concentration in feed solution and extending conditioning time, resulting in severer scaling and flux decline. Interestingly, the formation of heterogeneous scaling layer will contribute to membrane fouling alleviation and prevent the further flux decline regardless of the ongoing increase of coagulant concentrations in the feed water as well as on the membrane surface. As a result, a critical value of coagulant concentrations in the feed water was obtained in present conditions. Furthermore, it's found that successive fouling strategy could lead to less gypsum scaling but severer flux decline, compared to simultaneous fouling strategy. Both the scaling quantity and scaling morphologies conferred significant influence on the flux decline. It is suggested that the concentrations of coagulant should be strictly controlled prior to nanofiltration process, especially with practical relevance for the applications of it in treating the water rich in calcium ions and sulfate anions.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMOSPHERE
·
2016
·
IF 3.698
Fan Bu,Baoyu Gao,Ruihua Li,Shenglei Sun,Qinyan Yue
Two kinds of aluminum-based coagulants and epichlorohydrin-dimethylamine (DAM-ECH) were used in the treatment of humic acid-kaolin simulated water by coagulation-ultrafiltration (C-UF) hybrid process. Coagulation performance, floc characteristics, including floc size, compact degree, and strength were investigated in this study. Ultrafiltration experiments were conducted by a dead-end batch unit to implement the resistance analyses to explore the membrane fouling mechanisms. Results showed that DAM-ECH aid significantly increased the UV 254 and DOC removal efficiencies and contributed to the formation of larger and stronger flocs with a looser structure. Aluminum chloride (Al) gave rise to better coagulation performance with DAM-ECH compared with poly aluminum chloride (PACl). The consequences of ultrafiltration experiments showed that DAM-ECH aid could reduce the membrane fouling mainly by decreasing the cake layer resistance. The flux reductions for PACl, Al/DAM-ECH (dosing both Al and DAM-ECH) and PACl/DAM-ECH (dosing both PACl and DAM-ECH) were 62%, 56% and 44%, respectively. Results of this study would be beneficial for the application of PACl/DAM–ECH and Al/DAM–ECH composite coagulants in water treatment processes.
研究领域:
环境工程
·
水处理技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Yonghai Gan,Zhihao Hang,Bingdang Wu,Haojie Li,Wentao Zhang,Yeyang Sun,Runsheng Li,Shujuan Zhang
Basicity is an intrinsic factor of coagulants that plays important roles in turbidity removal. However, the effects of basicity on the coagulation performance of titanium (Ti) coagulants remain unclear. This knowledge gap is mainly due to the lack of highly polymerized Ti coagulants. In this study, we fabricated a series of Ti-based coagulants with basicity values in the range of 0–93% and evaluated their coagulation performance with simulated and real waters of low-turbidity. A positive correlation was observed between the basicity of the Ti coagulants and the coagulation performance, i.e., higher basicity led to higher turbidity removal, larger floc size, and faster settling rate. For the two titanium xerogel coagulants (TXC) of similar chemical structures, the one with a higher basicity (TXC-93%) worked better than the one of a lower basicity (TXC-78%). The advantage brought from the difference in basicity is of great significance in the purification of low-turbidity water. For the treatment of a surface river water, the required dosage of TXC-93% was about 1/2 to 1/3 of those of titanium tetrachloride (TiCl 4 ) and polytitanium tetrachloride (PTC-21%), and was comparable to that of a high-quality commercialized polyaluminum chloride (PAC-72%). The results here provide a useful technical guidance for the mass production and application of Ti coagulants.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Beibei Liu,Baoyu Gao,Kangying Guo,Jingwen Pan,Qinyan Yue
Safe and effective coagulants are necessary for surface water treatment. The polyaluminum-titanium chloride (PATC) composite coagulant has promise but its application is limited due to the lack of fundamental theoretical research. We prepared a series of novel PATCs and investigated the effects of the interaction between Al (III) and Ti (IV) on the chemical species distribution, physicochemical properties and coagulation efficiencies. The Al-O-Ti bonds observed in the PATC infrared spectra were predicted by density functional theory computation to appear in 4-atom rings in the structure. The differences in Al species distribution of PATC and PAC illustrated that the introduction of Ti retarded the hydrolysis of monomeric Al species (Al a ) and medium polymerized Al species (Al b ) to colloidal Al species (Al c ) at low B levels, but the transformation was promoted at high basicities (B). PATCs exhibited higher charge densities and larger molecular weights than PAC at the same B levels, which contributed to their excellent coagulation efficiencies. PATC with low B values but high Al/Ti molar ratios mainly provided charge neutralization in removal of humic acid kaolin, while the dominant coagulation mechanism converted from charge neutralization to sweeping and bridging effects at high B values or low Al/Ti molar ratios.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
PETROLEUM SCIENCE AND TECHNOLOGY
·
2022
·
IF 1.695
Huili Zhang,Min Li,Jinjun Deng,Hailin Yu,Yanbin Tong,Lingmin Wu,Liqun Sun,Hongsheng Liu
Whether the oilfield sewage index can reach the reinjection specification is a crucial issue that is urgently need to be solved in polymer flooding systems. Thus the coagulability and floc morphology development of dual coagulants was systematically studied in different pH oily wastewaters. Acidification improved the deprotonation ability of coagulant. Hydrophobic associative polyaluminum silicate-poly dimethyl diallyl ammonium chloride (PASSC-PD) resolved the problem of excessive acid addition. The dual coagulants prepared not only preserved the high charge density of polyaluminum silicate (PASS) itself but also made it have the hydrophobic association and strong bridging ability. Besides, PASSC-PD was compared with hydrophobic associative polyaluminum silicate (PASS-C), PASS, and poly dimethyl diallyl ammonium chloride (PDMDAAC) pertaining to the polymer flooding oily sewage of Daqing Oilfield. The coagulation result demonstrated that PASSC-PD exhibited more advantageous turbidity and oil removal efficiencies than PASS-C, PASS, and PDMDAAC. The floc morphology result showed that adding dual coagulant made the petal-like floc of oily sewage larger at the pH value of 6. Furthermore relevant results evidenced that the coagulant had more successful fruits of turbidity removal of 96.5% and oil removal of 96.3% under weak acid conditions. These can satisfy the reinjection condition of oily sewage.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
Journal of Environmental Sciences
·
2019
·
IF 3.556
Yuxiang Xue,Zhouzhou Liu,Aimin Li,Hu Yang
The applications of natural polymeric flocculants due to their green feature has been recently received much more attention. In this work, the combined usages of a cationic starch-based coagulant and polyaluminum chloride (PACl) were extensively evaluated for various addition sequences in the coagulation of both raw (surface water from the Jiuxiang River) and synthetic turbid water (two kaolin suspensions with different initial turbidities). Two typical cationic starch-based coagulants with different structures (St-G and St-E) were tried. In comparison to St-G, St-E and PACl used individually as well as St-G and St-E dosed after PACl, the combination of the starch-based coagulants fed before PACl showed higher turbidity removal efficiency, which featured not only less optimal doses of both inorganic and organic coagulants but also lower residual turbidity. On the basis of a detailed analysis of the particle size and its distribution in solution supernatants before and after coagulation by two starch-based coagulants and PACl, polymeric coagulants preferentially coagulate the small-sized colloids due to their distinct long-chain structures, but PACl preferentially coagulates the medium-sized ones. Thus, the medium-sized particles that were previously formed by the starch-based coagulants would be collectively and effectively removed by the subsequent addition of PACl. The addition sequence of the inorganic and organic coagulants in their combined usage is an important factor for improvement of the turbidity removal efficiency in practice.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）