International Journal of Coal Preparation and Utilization
·
2022
·
IF 2.791
Qiming Zhuo,Wenli Liu,Xiaomiao Jiao,Hongxiang Xu,Xiaopeng Sun
A dynamic floc measurement system was developed to analyze flocs during sedimentation and automatically extract floc characteristics without damaging them. An optimized algorithm was proposed to remove fuzzy flocs, and visual inspection verified that this algorithm achieved satisfactory separation performance between well-defined and fuzzy flocs. This program was used to study the development of coal flocs and showed that the flocs grew rapidly at the beginning of flocculation. The floc size at equilibrium at low stirring velocities was larger than those at high stirring velocities. A high stirring velocity can cause irreversible damage to the flocs, and those flocs cannot be restored to their original size by decreasing the stirring velocity. In addition, the fractal dimension decreased with increasing time, indicating that there is an optimal stirring velocity which can be selected to enhance the size and structure of flocs. This research provided an effective way to study the characteristics of flocs, and the change process of the flocs under different stirring velocities was investigated in detail to understand the growth, breakage, and regrowth process.
研究领域:
化学工程
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Scientific Reports
·
2016
·Vol. 6
·期 1
·1-11
·
IF 5.228
Yu Lei,Tang Qing-wen,Zhang Yu-jia,Chen Rong-ping,Liu Xin,Qiao Wei-chuan,Li Wen-wei,Ruan Hong-hua,Song Xin
In this work, the effect of cultivation factors on the flocculation efficiency (FE) of bioflocculant P-GS408 from Klebsiella oxytoca was optimized by the response surface methodology. The most significant factor, i.e . culture time, was determined by gray relational analysis. A total of 240 mg of purified P-GS408 was prepared from 1 liter of culture solution under the optimal conditions. GC-MS analysis results indicated that the polysaccharide of P-GS408 mainly contains Rhamnose and Galactose, and the existence of abundant hydroxyl, carboxyl and amino groups was evidenced by FTIR and XPS analyses. With the aid of Fe 3+ , the FE of kaolin solution by P-GS408 could achieve 99.48% in ten minutes. Functional groups of polysaccharide were involved in the first adsorption step and the zeta potential of kaolin solution changed from −39.0 mV to 43.4 mV in the presence of Fe 3+ and P-GS408. Three-dimensional excitation-emission (EEM) fluorescence spectra demonstrates that the trivalent Fe 3+ and Al 3+ can bind efficiently with P-GS408, while those univalent and divalent cations cannot. With the help of SEM images, FTIR, zeta potential and EEM spectra, we proposed the P-GS408 flocculation mechanism, which consists of coordination bond combination, charge neutrality, adsorption and bridging, and net catching.
研究领域:
微生物学
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环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
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2017
·
IF 1.591
Shuang Zhang,Ting Lü,Dongming Qi,Hongting Zhao
Chitosan (CS)-based flocculants, denoted as CS-g-PAM and CS-g-PDBC, were successfully prepared via graft copolymerization of CS with acrylamide (AM) or dimethyl acryloyloxyethyl benzyl ammonium chloride (DBC). The grafting was confirmed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The flocculation performance of CS-g-PAM and CS-g-PDBC, as well as flocculants such as cationic polyacrylamide (CPAM), polyaluminum chloride (PAC), and CS, was evaluated and compared for treating emulsified oil wastewater. It was found that CS-g-PDBC exhibited excellent flocculation performance under both acidic and neutral conditions, while CS showed better flocculation ability under alkaline condition. The flocculation mechanism of CS and CS-g-PDBC was investigated via zeta potential measurements. Results showed that different flocculation mechanisms were involved at various pH levels. As regarding CS, the flocculation mechanism is mainly charge neutralization, patching, and sweep floc under acidic, neutral, and alkaline conditions, respectively, while for CS-g-PDBC, patching was the dominant mechanism under both acidic and neutral conditions.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN
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2018
·Vol. 91
·期 6
·998-1007
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IF 3.526
Zhang Xuezhi,Jia Shaoyi,Song Jia,Wu Songhai,Han Xu
Flocculation using Fe(II) instead of Fe(III) has been considered more efficient in the removal of As. However, excess Fe(II) used in the process always leaves substantial TFe [Fe(II)+Fe(III)] unutilized. We therefore developed three methods [the one-staged process (OS), the one-staged process with H2O2 (OSH) and the two-staged process (TS)] to remove As(III)/As(V) by Fe(II) (Fe:As = 2.0). Our results indicate that pH is an important factor that determines the utilization efficiency of TFe and the removal efficiency of As. In OS, the initial pH was adjusted before the reaction. At the optimal pHs of 10.0 and 11.0, the removal efficiencies of As(V) and TAs [As(III)+As(V)] could reach 84.0% and 66.7%, with only 61.9% and 80.2% TFe being utilized, respectively. In OSH, H2O2 was added after pH adjustment. After OS, pH was re-adjusted to the optimal values before the next 30 min reaction (TS). Compared with OS, the removal efficiencies of As could increase by more than 9% in OSH and TS at the optimal pHs. Besides, there is more than 10% improvement in the utilization efficiencies of TFe except at 12.0. Accelerating oxidation of Fe(II) or re-adjusting pH is therefore highly efficient for a more efficient removal of As from Fe(II)-rich groundwater.
研究领域:
环境科学
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水处理工程
✓ 已验证
DOI
高影响因子
Journal of Environmental Sciences
·
2021
·
IF 5.565
Xuefeng Xiao,Yuanyuan Yu,Yongjun Sun,Xing Zheng,Aowen Chen
In this study, three magnetic flocculants with different chelating groups, namely, carboxymethyl chitosan-modified Fe 3 O 4 flocculant (MC), acrylamide-grafted magnetic carboxymethyl chitosan flocculant (MCM), and 2-acrylamide-2-methylpropanesulfonic acid copolyacrylamide-grafted magnetic carboxymethyl chitosan flocculant (MCAA) were prepared, synthesized, and characterized by photopolymerization technology. They were applied to the flocculation removal of Cr(III), Co(II), and Pb(II). The effect of flocculation condition on the removal performance of Cr(III), Co(II), and Pb(II) was studied. Characterization results show that the three magnetic carboxymethyl chitosan-based flocculants have been successfully prepared with good magnetic induction properties. Flocculation results show that the removal rates of MC, MCM, and MCAA on Cr(III) are 51.79%, 82.33%, and 91.42%, respectively, under the conditions of 80 mg/L flocculant, pH value of 6, reaction time of 1.5 hr, G value of 200 s −1 , and precipitation magnetic field strength of 120 mT. The removal rates of Co(II) by MC, MCM, and MCAA are 54.33%, 84.99%, and 90.49%, respectively. The removal rates of Pb(II) by MC, MCM, and MCAA are 61.54%, 91.32%, and 95.74%, respectively. MCAA shows good flocculation performance in composite heavy metal-simulated wastewater. The magnetic carboxymethyl chitosan-based flocculant shows excellent flocculation performance in removing soluble heavy metals. This research provides guidance and ideas for the development of efficient and low-cost flocculation technology to remove heavy metals in wastewater.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2017
·
IF 2.714
Lijun You,Lidao Song,Ao Wang,Feifei Lu,Qiqing Zhang
A cationic polysaccharide (CDCS) derived from dextran and chitosan was fabricated by crosslinking method as an eco-friendly flocculant. The flocculant was characterized by thermogravimetric analysis and Fourier transform infrared spectroscopy. Influences of temperature, pH and flocculant dosage on flocculation efficiency were examined. The CDCS presented enhanced high flocculation properties in a wide pH range conditions. In kaolin suspension, when pH was in the rang of 3–7, the flocculation efficiency was over 96.9% with dosage below 5 mg/L. In alkaline condition, it also presented a high flocculation efficiency of 98.2% (pH = 9) and 93.7% (pH = 11) with a low dosage of 7 and 17 mg/L, respectively. The flocculation efficiency decreased as the temperature rose from 10 to 40 ∘ C. For actual wastewater treatment, the CDCS flocculant performed much better than commercial polyacrylamide and ferric sulfate. It removed 97.7% of the solid suspended particles in the wastewater. The flocculant mechanism study suggested charge neutralization, adsorption bridging and sweeping flocculant mechanisms were included in the flocculation process. The flocculant CDCS exhibited a broad prospects for wastewater treatment.
研究领域:
环境科学
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生物化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2021
·
IF 7.312
Xuefeng Xiao,Yongjun Sun,Jianwen Liu,Huaili Zheng
Two bioflocculants of starch-graft-P[acrylamide-acrylic acid] (SAA) and starch-graft-P[acrylamide-2-acacrylamido-2-methyl-1-propanesulfonic acid] (SAS) are designed for the flocculation–chelation of heavy metals. The successful polymer synthesis is confirmed through physicochemical characterization. SAA and SAS are used to remove Cu(II), Zn(II), and Ni(II) from simulated wastewater and Ni(II) from actual electroplating wastewater. The removal efficiencies for Cu(II), Zn(II), and Ni(II) in the simulated wastewater by SAA and SAS are more than 80.00%, whereas those for Ni(II) are more than 90.0% in the Ni-containing electroplating wastewater at the optimal condition. Flocculation experiments reveal that the sulfonate structure of SAS is highly conducive to improve flocculation efficiency. SAA and SAS have high selectivities for Cu(II) in the simulated water sample with mixed heavy metal. Finally, the 3E (i.e., environmental impact, economic benefit, and energy consumption) triangular evaluation model is established to evaluate the flocculation experiments for the removal of heavy metal ions using SAA and SAS.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Na Li,Yuping Fan,Xianshu Dong,Qingxia Liu,Xiaomin Ma,Ruxia Chen
In this study, in order to improve the flocculation efficiency of natural organic flocculant in coal mine wastewater, guar gum (GG) and [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride (DMC)were used to synthesize a type of graft copolymer of GG with DMC (GG-g-DMC) with flocculating function by free radical polymerization under ultraviolet (UV) light initiation conditions. Performance testing and structural characterization of the composites including FTIR, NMR, XRD, SEM, TG, and XPS were conducted to verify the synthesis of the graft polymer. The GG-g-DMC was applied to treat coal mine wastewater, according to the sedimentation index and the optimal flocculation solution was determined, and the flocculation settling mechanism was studied using focused beam reflectance measurement (FBRM), Zeta potentiometer and adhesion force meter. The results indicated that GG-g-DMC synthesis by UV-initiated polymerization was feasible and the settling effect increased significantly; 0.5 mg/g (s) GG-g-DMC 4 was excellent in all aspects, its sedimentation speed reached 20.64 cm/min, the light transmittance was 95.00%, and the compression layer thickness was 1.89 cm; the mechanism is mainly the synergy of charge neutralization, bridging, and improve hydrophobicity.
研究领域:
环境科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2018
·
IF 5.158
Yongjun Sun,Wenquan Sun,Kinjal J. Shah,Pen-Chi Chiang,Huaili Zheng
In this work, carboxylated chitosan modified flocculant (CC-g-PCD) was prepared by graft copolymerization technique to enhance the charge-attracting and adhesion of bridges and net-sweeping capacity of flocculants. The dimethyldiallylammonium chloride (DMDAAC), carboxylated chitosan (CMCS), and 3-chloro-2-chloropropyltrimethylammonium chloride (CTA) were utilized for synthesis of CC-g-PCD via photopolymerization techniques. The synthesized CC-g-PCD was characterized by 1 H NMR, SEM, XRD, and FTIR, and the characteristic groups on the main chain and surface morphological structure of CC-g-PCD were investigated. The obtained results indicated that CTA and DMDAAC were successfully grafted into the CPCTS. In ordered to evaluate the flocculation performance of CC-g-PCD at various dosages, stirring intensity (G value), and pH value by detecting Chl a, COD, and turbidity, the actual lake water that contains algae was used for flocculation assessment tests. The experimental results of the water sample with flocculation showed that the maximum flocculation efficiency of turbidity (91.1%), Chl a (97.2%), and COD (97.0%) can be achieved by CC-g-PCD at pH 7, G value 200 s −1 , and 4.0 mg/L. The comparison results demonstrated that CC-g-PCD had better flocculation efficiency than commercial flocculants. Finally, based on the analysis of algae removal in combination with Zeta potential measurements, the flocculation mechanisms in actual lake water at various dosages and pH values were adsorption bridging and electrical neutralization.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Wei Wu,Junjie Qi,Jing Fang,Gaojin Lyu,Ze Yuan,Yifan Wang,Hao Li
Lignin shows good potential as a flocculant material, but more complex reaction processes are often required to obtain products with high flocculation performance. In this work, kraft lignin, acrylamide, and 3-chloro-2-hydroxypropyltrimethylammonium chloride were used as materials to prepare lignin-based flocculants (CPKL) using a one-pot method. The flocculation performance was significantly improved by the optimization of the synthesis conditions. Congo Red, an anionic azo dye , was used as a simulated contaminant to test the flocculation performance. Influencing factors such as flocculant dose, pH, and initial dye concentration were evaluated. The jar test results showed that CPKL has the advantages of a wide flocculation window, strong pH adaptability and the ability to maintain a high decolorization rate at different dye concentrations. Charge neutralization was the main flocculation mechanism, and adsorption bridging showed significant effects only at higher dye concentrations. In addition, lignin-based flocculants (CPKL-s) were prepared by gradient acid fractionation of kraft lignin (APKL-s), and their flocculation performance were further investigated. Among them, the product (CPKL-4) obtained by modifying the grade precipitated at pH 4 (APKL-4) exhibited good flocculation performance with a low dose and high decolorization rate. This method is environmentally friendly, technically feasible and has attractive application prospects in water treatment .
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2014
·
IF 4.331
Zhen Yang,Haijiang Li,Han Yan,Hu Wu,Hu Yang,Qian Wu,Haibo Li,Aimin Li,Rongshi Cheng
In this work, a novel chitosan-based flocculant, carboxymethyl chitosan- graft -poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] (CMC- g -PDMC), was designed and prepared successfully. Flocculation performance of CMC- g -PDMC was systematically evaluated using kaolin suspension, humic acid (HA) solution and kaolin-HA mixed suspension as synthetic wastewater under acidic, neutral and alkaline conditions, respectively. The experimental results demonstrated that CMC- g -PDMC exhibited lower optimal dosage, higher contaminant removal efficiency, wider applicable pH range, lower effluent toxicity and better floc properties for handling and disposal, in comparison with polyaluminum chloride. The high flocculation performance of CMC- g -PDMC was ascribed to two structural advantages of improved both positive charges and molecular weight. In addition, flocs characteristics including flocs formation, breakage, regrowth and fractal structure, were studied by an in-situ light scattering system during the flocculation process. Detailed analysis clearly illuminated the differences and relationship among floc size, fractal dimension and floc strength. Based on analysis of floc properties in combination with zeta potential measurements, flocculation mechanisms in different synthetic wastewater at various pHs were deeply discussed: charge neutralization or patching played the key role under different conditions, and the relationship between flocculation mechanisms and floc properties has been built. The effective and environment-friendly flocculant bear significant application potentials in water treatment fields.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
WATER RESEARCH
·
2016
·
IF 5.991
Hu Wu,Zhouzhou Liu,Hu Yang,Aimin Li
Three different starch-based flocculants with various chain architectures and charge properties have been prepared through etherification, graft copolymerization , or their combination. Two of the flocculants (starch- graft -poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] and starch-3-chloro-2-hydroxypropyl triethyl ammonium chloride , denoted as STC- g -PDMC and STC-CTA respectively) are cationic, and another one (carboxymethyl starch- graft -poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride], denoted as CMS- g -PDMC) is amphoteric. Those three flocculants have shown far different flocculation efficiency and floc properties for the removal of humic acid (HA) from water due to their distinct structural features. The effects of pH, flocculant dose, and initial HA concentration have been studied systematically. Accordingly, STC- g -PDMC and CMS- g -PDMC with strongly cationic branch chains have much better flocculation performance than polyaluminum chloride (PAC) and STC-CTA, the latter of which features linear chain architecture and strongly cationic pieces lying on its chain backbone. It indicates that the architecture of cationic branch chains plays an important role in HA flocculation due to their significantly enhanced bridging effects. Moreover, STC- g -PDMC has higher HA removal efficiency and better floc properties than CMS- g -PDMC, suggesting that charge neutralization effects make notable contributions to HA removal and that the additional anionic pieces on CMS- g -PDMC can weaken its flocculation performance. In addition, STC- g -PDMC used as coagulant aid for PAC has also been tried, which observably reduces the optimal dose of the inorganic coagulant.
研究领域:
环境科学
·
高分子化学
✓ 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）