COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Wenjie Zou,Bo Rao,Ruijing Xu,Ting Xiao,Wei Zhao,Zhijun Zhang,Jun Huang
In this work, the adsorption performance of a novel chitosan-based flocculant (Chi-g-CPAM) and a cationic flocculant (CPAM) onto the kaolinite surface as well as the interaction mechanisms have been investigated by settling tests, atomic force microscopy (AFM) and quartz crystal microbalance with dissipation (QCM-D). When the KCl concentration of the solution altered from 1 mM to 100 mM, the settling rate of kaolinite suspension using CPAM deteriorated from 2.73 m/h to 1.97 m/h. However, the Chi-g-CPAM exhibited salt resistance as the settling rate changed slightly from 2.34 m/h to 2.44 m/h. From the QCM-D results, the Δ f of CPAM onto silica sensor changed from − 3.6 Hz to − 33.6 Hz and -Δ D /Δ f × 10 6 increased from 0.167 to 0.223, confirming that the CPAM layer adsorbed on the silica surface was thicker and more dissipative in 100 mM KCl solution. Meanwhile, the Δ f of Chi-g-CPAM onto silica sensor changed from − 14.3 Hz to − 33.9 Hz. The conformation of Chi-g-CPAM layer changed slightly as the -Δ D /Δ f × 10 6 increased from 0.174 to 0.186. From the AFM measurements in 1 mM and 100 mM KCl solution, the distance of adhesion forces between the silica probe and CPAM expanded from approximately 20 nm to around 50 nm, and the adhesion force changed from 1.9 nN± 0.1 nN to 21.3 nN± 0.1 nN. The interaction forces with a long range (∼100 nm) maintained at about 3 nN between the silica probe and Chi-g-CPAM. Such difference was mainly attributed to the steric hindrance effect originating from the shorter molecular chain of Chi-g-CPAM. In 100 mM KCl solution, the CPAM molecules with long chains had a more coiled conformation than Chi-g-CPAM, which resulted a train-like flat adsorption conformation and larger adhesion, and formed a loose and thick polymer layer of CPAM in high salinity. The insights into the flocculating performance in varying salinity solutions of CPAM and Chi-g-CPAM will contribute to the molecular design of chitosan-based flocculants for efficient wastewater treatment .
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
WATER SCIENCE AND TECHNOLOGY
·
2021
·Vol. 84
·期 2
·484-498
·
IF 1.915
You Zhaoyang,Zhao Changrong,Sun Yongjun,Zhuang Chang
To cope with the increasingly severe challenges of zinc oxide nanoparticles (ZnO-NPs) in the field of the aquatic environment, this paper uses poly-aluminum ferric chloride (PAFC) and cationic polyacrylamide (CPAM) as coagulants to enhance the removal of ZnO-NPs from water. In two environments (pure-water environment and kaolin environment) that simulate suspended solids, we studied the dosage, pH, precipitation time, and hydraulic power of ZnO-NPs at three different initial concentrations (1, 2, and 30 mg/L). The effects of various conditions on the performance of PAFC, CPAM, and PAFC/CPAM to remove ZnO-NPs were examined. Results showed that the overall removal rate of ZnO-NPs in the kaolin environment was slightly higher than that in the pure-water environment. In contrast the removal rate of ZnO-NPs in the PAFC/CPAM was significantly higher than that of PAFC or CPAM alone. The coagulation removal conditions of ZnO-NPs were optimized using a response-surface model. Under the best conditions, the removal rate of ZnO-NPs with an initial mass concentration of 30 mg/L in the PAFC/CPAM combination in pure-water and kaolin environments was 98.54% and 99.17%, respectively. Finally, by studying the changes in floc size during coagulation, enhanced coagulation was an efficient method of removing ZnO-NPs from water. The combination of PAFC and CPAM can efficiently remove ZnO-NPs. Kaolin can promote the removal efficiency of ZnO-NPs. The RSM model can reflect the optimal removal conditions for coagulation to remove ZnO-NPs. CPAM can further increase the particle size and compactness of ZnO-NPs flocs after coagulation.
研究领域:
环境科学
·
水处理
·
材料科学
✓ 已验证
DOI
高影响因子
International Journal of Minerals Metallurgy and Materials
·
2023
·Vol. 30
·期 5
·813-823
·
IF 4.8
Xu Ruijing,Zou Wenjie,Rao Bo,Zhao Wei,Wang Ting,Zhang Zhijun
This study presents a comparative study of the flocculation behavior of kaolinite induced by chitosan-graft-poly(acrylamide-dimethyl diallyl ammonium chloride) (Chi-g-CPAM) and a commercial cationic polyacrylamide (CPAM). The flocculation behaviour was characterised in terms of both flocculation kinetics and the corresponding morphology changes during flocculation. Both Chi-g-CPAM and CPAM were grafted from silica wafers by means of atom transfer radical polymerization (ATRP). The quartz crystal microbalance with dissipation (QCM-D) tests were conducted. The equilibrium time flocculated by Chi-g-CPAM was found to be 0.46 times as that of CPAM, together with a larger total mass of kaolinite layer. The flocculation behaviour by Chi-g-CPAM can be well captured by a pseudo-first-order model. In contrast, the presence of CPAM leads to a more complex kinetics. A relatively larger fitting slope (0.4663) was obtained at the initial stage but the fitting slope droped to 0.2026 after 800 min, indicating a densification process caused by CPAM. The flocculation kinetics of CPAM can be captured by the Elovich model for the inital stage but the combination of pseudo-first-order and pseudo-second-order models for the latter stages, which can be attributed to the long chain of CPAM. With a dosage of 75 g/t, the settling test with Chi-g-CPAM exhibits the same turbidity in the supernatant but a smaller layer thickness of the settlement compared to CPAM. The study enables a better understanding of the flocculation behavior and contributes to the development of efficient flocculants in mineral processing and tailings treatment.
研究领域:
矿物加工
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2024
·
IF 3.7
Nana Sun,Huina Sun,Jianbo Hu,Shiqi Xu,Lisha Shen,Yuli Ma
In this study, cationic polyacrylamide (CPAM)-coated magnetic nanoparticles (MNPs) Fe3O4@CPAM were synthesized for treating heavy O/W emulsions. This Fe3O4@CPAM was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM) techniques, and its synergistic performances with microwaves were evaluated in detail with respect to the microwave radiation power, radiation time, and magnetic nanoparticle concentration. On this basis, the distribution of oil droplets and the wettability and chargeability of magnetic nanoparticles were measured without or with microwave radiation using biomicroscopy, contact angle measurement instrument, and a ζ-potential analyzer, thus revealing the synergistic demulsification mechanism between microwave and magnetic nanoparticles. The results showed that excessively high or low microwave radiation parameters had an inhibitory effect on the magnetic nanoparticle demulsification, and microwave promoted the magnetic nanoparticle demulsification only when the radiation parameters were in the optimal range. In addition, the water separation rate showed an increasing and then decreasing trend with the increase of magnetic nanoparticles concentration, with or without microwave action. As an example, the water separation rate of the emulsion for 1 h was 21.34% when the Fe3O4 concentration was 175 mg/L without microwave action, while it increased to 55.56% with microwave action. In contrast, when the concentration of Fe3O4@CPAM was 175 mg/L, the water separation rate was 42.86% without microwave radiation, while it was further increased to 77.38% under microwave radiation. These results indicate that magnetic nanoparticles and their complexes significantly affect the water separation process under different conditions. There is a more obvious coupling synergistic effect between Fe3O4@CPAM and microwave. This was due to the lower absolute potential of Fe3O4@CPAM and its higher hydrophobicity.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Yu Xie,Wanzhong Yin,Jin Yao,Feijia Xue,Jiayi Liu,Xiaoqi Ban
Chlorite is often associated with hematite and tends to form microfine particles during grinding, making it challenging to recover and separate from hematite through flotation . This study innovatively applies an ester-based cationic polyacrylamide (CPAM) as a flocculant in a reverse flotation system using dodecylamine (DDA) as a collector, to flocculate and recover microfine-grained chlorite. The method achieves efficient separation between microfine chlorite and hematite. Laser particle size testing and optical microscopy show that CPAM significantly increases the apparent particle size of microfine chlorite, causing it to aggregate into flocs, while having a extremely weak effect on hematite flocculation . Further analysis using techniques like Zeta potential , contact angle measurement, Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) reveals CPAM's stronger adsorption affinity for chlorite compared to hematite. The ester groups in CPAM selectively form hydrogen bonds with chlorite's surface H atoms, enhancing its hydrophobicity. Particle-bubble attachment angle testing confirms that the flocculated chlorite flocs exhibit better floatability and higher efficiency in collision and adhesion with bubbles. Thus, CPAM serves as an efficient flocculant for reverse flotation separation of microfine chlorite and hematite.
研究领域:
矿物加工工程
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2025
·Vol. 16
·期 1
·1-12
·
IF 15.7
Chen Ronghua,Li Chaozheng,Zhao Di,Yang Guili,Zeng Lingda,Lin Fei,Xu Hanhong
Controlling weeds before their emergence is crucial for minimizing their impacts on crop yield and quality. Bipyridyl herbicides (BPyHs), a class of highly effective and broad-spectrum herbicides, cannot be used as pre-emergence herbicides because they can be absorbed and inactivated by negatively charged soil after application. Here, we design and fabricate an adsorbed-but-active supramolecular pre-emergence herbicide consisting of cationic polyacrylamide and bipyridyl herbicides (CPAM-BPyHs). CPAM is a positively charged polymer. It can preferentially bind to soil particles and shift their electric potential to a more positive value. Thus, it prevents not only runoff but also inactivation of BPyHs. We also develop a BPyHs-resistant rice line by mutation of the gene encoding L-type amino acid transporter 5 ( OsLAT5 ). Field trial results show that the weed control efficiency of CPAM-diquat for direct-seeded herbicide-resistant rice line exceeds 90%. The herbicidal activity can maintain up to one month with only one application. This work offers a method for rice weed control and provides insights into the design of pesticides to prevent soil inactivation and runoff.
研究领域:
植物保护
·
遗传学
·
农业科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Desalination and Water Treatment
·
2024
·
IF 1
Jiangya Ma,Liyan Jiang,Xue Fu,Lei Ding,Shun Zhou,Qiongjie Wang,Kun Fu,Jun Shi,Houcheng Ding,Yi Liao
In this paper, we investigate the flocculation performance of composite coagulants polyaluminium chloride (PAC) and cationic polyacrylamide (CPAM) for landscape water treatment. The flocculant CPAM was synthesized through low-pressure UV initiation in our laboratory. This method was an environment-friendly and efficient approach. The flocculation mechanism of the combined flocculant was further analyzed by Fourier-transform infrared spectroscopy, three-dimensional fluorescence analysis, zeta potential and microscopic observation. Results indicated that turbidity, UV 254 , phosphorus, and algae were effectively removed using PAC/CPAM flocculants. Humus and protein were easily removed from landscape water through flocculation. Moreover, electrical neutralization of PAC and the adsorption bridging effect of CPAM were found to be dominant in flocculation. The flocs from using PAC/CPAM were more compacted and stabilized than those from using PAC or CPAM alone. In addition, the appropriate divided addition of PAC was favorable for flocculation.
研究领域:
环境工程
·
水处理技术
·
高分子化学
·
环境化学
·
给排水科学与工程
✓ 已验证
DOI
高影响因子
Science of Advanced Materials
·
2019
·Vol. 11
·期 6
·842-853
·
IF 1.158
Xu Qiyao,Liu Hongxia,Zheng Huaili,Liang Jianjun
In this study, a new cationic polyacrylamide (CPAM) was successfully synthesized through UV-H2O2-initiated polymerization technique using acryloyloxyethyl trimethyl ammonium chloride (DAC) and acrylamide (AM) as monomers, and applied to sludge dewatering experiments.
Parameters affecting the molecular weight and conversion of the polymers, including total monomer concentration, monomer concentration of DAC, H2O2 concentration, pH and illumination time were examined. Fourier transform infrared spectroscopy (FT-IR), 1H nuclear
magnetic resonance spectroscopy (1H NMR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were employed to characterize the properties of the polymers. The results showed that CPAM was successfully synthesized and possessed a coarse and porous surface morphology
and inferior thermal stabilities. When the dosage of polymer was 40 mg L–1 and the initial sludge pH value was 7.0, PAD-3 (cationic degree: 40%, molecular weight: 6.89 × 106 Da) showed a more excellent sludge dewatering performance (FCMC: 70.6% SRF: 2.8 ×
1012 m · kg –1; d
50: 436.802 μm, Df
: 1.59). During the sludge flocculation process, three mechanisms containing charge neutralization, patching and bridging co-contributed to a prominent flocculation performance.
研究领域:
环境科学
·
高分子化学
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2016
·Vol. 133
·期 40
·
IF 1.866
Yongjun Sun,Chengyu Zhu,Yanhua Xu,Huaili Zheng,Xuefeng Xiao,Guocheng Zhu,Mengjiao Ren
Cationic polyacrylamides (CPAMs) synthesized by thermal, ultrasonic, microwave, and UV initiation were characterized through magnetic resonance hydrogen spectroscopy ( 1 H NMR), Fourier transform infrared spectra, scanning electron microscopy, and thermal gravimetric analysis. The CPAMs for flocculation and dewatering of alum sludge produced through drinking water treatment were evaluated based on the residual turbidity of the supernatant, dry solid content, mean volume diameter and floc size distribution, fractal dimension of the flocs, and zeta potential as a function of flocculant dosage. Comparisons of the characteristics and performance of CPAMs synthesized through different initiation methods were systematically conducted. Flocculation and dewatering test results demonstrated that CPAMs synthesized through microwave and UV initiation had better flocculation performance and dewatering capability than those synthesized through thermal and ultrasonic initiation. All four CPAMs exhibited a similar final floc size distribution but different mean volume diameters and floc structures. The fractal dimension of the flocs and the zeta potential were in the following order: CPAM3 (microwave initiation) > CPAM4 (UV initiation) > CPAM1 (thermal initiation) > CPAM2 (ultrasonic initiation). Discussions on fractal dimension and zeta potential indicated that the electrostatic patches model and adsorption/bridging effect mechanisms played the main role in the formation of sludge flocs. Lastly, microwave and UV initiation were found to be alternative and recommendable initiation methods for the synthesis of CPAMs with improved flocculation performance and sludge dewatering capability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 44071.
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
Polymers
·
2024
·Vol. 16
·期 12
·1678
·
IF 4.7
Yueyue Wang,Pu Ma,Jun Huang,Lifang Guo,Yu Wang,Huamin Zhai,Hao Ren
As increasing fiber hydrophobicity can significantly improve the paper dewatering process, we found that replacing SBKP and HBKP with 0.5% superhydrophobic CPGMA can significantly improve the dewatering of paper sheets. Therefore, it can be concluded that if CPGMA has little effect on paper properties, it will have potential industrial value in the papermaking industry. Consequently, it is necessary to further study the effect of the CPGMAs@CPAM/SiO2/APAM system on paper properties. To evaluate the application potential of the system in the papermaking industry, we investigated the effects of CPGMAs, which replaced the fibers in the stocks, on the paper properties in the CPAM/SiO2/APAM system. The findings demonstrate that as the CPGMA replacement increased, the paper’s tensile strength, bursting strength, tear resistance, and folding endurance all declined. The trend can be segmented into two phases: a rapid decrease for substitution amounts below 0.5% and a gradual decline for substitution amounts exceeding 0.5%. When replaced with a small amount of CPGMAs, there was a negligible effect on these properties. Second, the paper air permeability increased with the CPGMA substitution amount in the stock. Furthermore, the trend of paper air permeability can be divided into two stages—a rapid stage with a substitution amount of <0.5% and a slow stage with a substitution amount of >0.5%. A small amount of CPGMAs could distinctly improve the paper’s air permeability. Third, CPGMAs, which replaced fibers in the stock, minutely affected the paper formation. A small amount of CPGMAs substantially boosted the efficacy of the process of paper manufacture and certain characteristics of the paper, and it had a negligible impact on the strength of paper. The CPGMAs@CPAM/SiO2/APAM technology has the potential to improve the retention and filtration performance of CPAM/SiO2/APAM.
研究领域:
材料科学
·
造纸工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
IRANIAN POLYMER JOURNAL
·
2021
·Vol. 30
·期 7
·675-683
·
IF 1.899
Wei Liu,Jinju Ma,Hongjian Pang,Zongwu Wang,Xinding Yao
A degradable flocculant was prepared by natural renewable products (starch) and a cationic polymer. A cationic polyamine polymer was prepared by reaction of bis(hexamethylene)triamine with epichlorohydrin. The influence of substrate ratio and molecular weight of cationic polymer on flocculation was investigated and the optimum molecular weight was about 4000. Polyamine-modified starch flocculant was prepared by etherification reaction of cationic polyamine polymer and corn starch. The influence of substitution degree (DS) of starch on flocculation was investigated and the maximum DS was 0.18. The structure of starch-modified flocculant was characterized by XRD and the results confirmed that the plasticized samples contained some crystalline structures that were not destroyed by the etherification reaction process and some newly formed V-type crystalline structures were mainly induced by processing. Flocculation performance was evaluated in simulated kaolin suspension and was compared with that of commercial cationic polyacrylamide (CPAM) and polyaluminium chloride (PAC) flocculants. The flocculation effects of polyamine-modified starch flocculants and commercial flocculants under different dosages and pH values were compared. The results showed that the starch-modified flocculant had the best effect and the cationic starch derivatives flocculation performance increased with increasing DS, and exhibited steady flocculation performance to kaolin suspension in the broad pH range from 4 to 10. The preparation method of starch-modified flocculant is simple in preparation process, low in production cost and pollution-free, and facilitates industrial production.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2024
·
IF 3.7
Liqin Tang,Xiang Jin,Bing Gao,Xuechao Gao,Xuehong Gu
Due to the low transport resistance, mullite hollow fiber (HF) could be regarded as a promising support for preparation of NaA zeolite membranes. However, insufficient coverage and undesired seed penetration often occur in the seeding step of the mullite support due to the rough surfaces with ultra-large macropores (2–4 μm). This leads to poor intergrowth of the membrane layer. To solve this issue, cationic polyacrylamide (CPAM) was employed to modify the chemical and electrostatic properties of the mullite HF surface, where the electrostatic attraction between the surface and seed crystals could significantly promote the coating effect. In the seeding, the original seeds (3.2 μm) were mixed with the ball-milled seeds (0.3 μm) to improve the seed coverage, i.e., the original seed was used to block the macropores on the support surface to prevent the penetration of small seeds, while the decked ball-milled seed was used to provide sufficient active sites to induce the intergrowth of the zeolite crystals. The effects of the concentration of CPAM, mixed mass ratio of seeds, and seed concentration on the preparation of NaA zeolite membranes were systematically examined, where the separation performances were characterized by pervaporation (PV) dehydration of 90% (mass) ethanol/water mixtures at 75 °C. The results indicated that under a CPAM concentration of 0.7% (mass), an equivalent mass ratio of mixed seeds in a seed concentration of 1.0% (mass), the prepared mullite HF supported NaA zeolite membrane yielded the best PV performance, where the permeation flux and separation factor corresponded to 5.45 kg·m −2 ·h −1 and 10000, respectively, being sufficient for industrial applications.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）