FUEL
·
2021
·
IF 6.609
Bao Ren,Kai Lv,Fanfei Min,Jun Chen,Chunfu Liu
The adsorption behavior and bridging mechanism of NPAM and kaolinite in aqueous solution were investigated using MD simulation and experiment. Turbidity, Zeta potential, and floc size were involved in the analysis of the settlement test; microscopic interaction mechanisms were further discovered via interaction energy, number and water density distribution, and self-diffusion coefficient. It emerged that too little NPAM has a high diffusivity in bulk water, NPAM cannot be directly adsorbed to kaolinite surfaces and the bridging mechanism is difficult to appear; experiment results in the high turbidity of the supernatant and inability to form flocs. As the number of chains increases, the adsorption probability and the adsorption capacity of NPAM on kaolinite surfaces are improved, the range of NPAM diffusion in bulk water expands and the bridging performance is enhanced; the turbidity decreases and the floc formation. When the number of NPAM chains is excessive, the interaction energy of NPAM in surface water with kaolinite surfaces is slightly weakened, NPAM in bulk water may weaken the combined affinity, but the bridging effect is further enhanced; which increases the turbidity and floc size. The adsorption of NPAM in surface water and kaolinite surfaces is the prerequisite for the formation of bridging mechanism, NPAM in bulk water is the crux to enhancing bridging performance. A large number of water molecules and NPAM have strong competitive adsorption on kaolinite surfaces. The interaction energy between NPAM and kaolinite surfaces in aqueous solution is mainly contributed by van der Waals interaction.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
OPTICS AND LASER TECHNOLOGY
·
2023
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IF 5
Yuanli Xu,Wenlin Feng
A transmission fiber-optic surface plasmon resonance (SPR) sensor based on three-core optical fiber (TCF) coated with mercaptoundecanoic acid (MUA)/ nonionic polyacrylamide (NPAM)/zinc oxide (ZnO) composite film for the detection of chromium ions (Cr 3+ ) in water was proposed and fabricated. Multi-mode fiber (MMF) was spliced with both ends of TCF to form the MMF1-TCF-MMF2 sensing structure. The silver (Ag) film was deposited on the surface of TCF cladding, and then a uniform MUA/NPAM/ZnO composite film was coated on the outer surface of the Ag film to adsorb Cr 3+ , resulting in the wavelength shift of the SPR resonance peak. After adsorption of Cr 3+ , the refractive index of the sensing film changed and the resonance wavelength shifted about 62 nm. The detection limit of the sensor is about 0.029 μΜ (1.5 ppb), and the minimum detection concentration of Cr 3+ is about 0.2 µM (10 ppb), which is far lower than that of the World Health Organization standard (50 ppb). The sensor shows excellent selectivity, high sensitivity and good stability for the trace Cr 3+ , and has potential application for monitoring Cr 3+ in water.
研究领域:
环境科学
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光学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2023
·Vol. 58
·期 13
·5808-5821
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IF 4.5
Wu Wei,Wang Yueming,Sun Jiyu
Color changing can immediately activate system of vision, which bring corresponding monitoring function without delay. Traditional color-changing sensor is not competent for the detection of large area, low-cost and easy preparing. Inspired by adaptive coloring strategies of beetle elytra, angle dependent and humidity responsive color-changing films are achieved with large area through convenient and low-cost technics of spin-coating and self-leveling. When observed at different angles, L 2B , L 2P and L 3G acquired with NPAM and HEMA-co-MMA layers can bring color-changing expect L 3P . And L 3G also conducts humidity responsive color-changing with stability from green to purple in variation from 46%rh to 84%rh and reversibly changing from purple to green while from high to low humidity, which ascribed to transformation between dehydration and hydration of NPAM layer with hydrophilic groups. To characterize the durability and stability in microscale, nano-indentation technology was used to reveal the nanomechanical properties of cross-link networks for NPAM and HEMA-co-MMA films. It was found out that the hydrophilic groups of networks can carry hydrogen bonds to enhance cross-link characteristic and low separation performance. This research provides insights into the simple and efficient technology for preparing functional material that displays potential applications in industrial, agricultural and military fields. Graphical Abstract
研究领域:
材料科学
·
仿生学
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产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Yongjoon Choe,Sungjun Cho,Chaemin Kim,Jongmuk Won,Susan E. Burns
Nonionic polyacrylamide (NPAM) is a water-soluble flocculant frequently used to immobilize toxic contaminants and for contaminant treatment. This study examines the influence of NPAM concentration (0–10 mg/L), cationic valence (NaCl or CaCl 2 solution), and clay mineralogy (kaolinitic and illitic clay) on the flocculation and post-settling behavior under water content ( w ) = 500–4000 %, using sedimentation and rheology experiments. The significant increase in settling velocity by NPAM treatment was observed, with a maximum of 92 % reduction in settling velocity. In addition, kaolinitic clay formed larger and faster-settling flocs than illitic clay, and CaCl 2 solution showed a stronger shear-thinning response than NaCl solution. The zero shear viscosity of NPAM-treated kaolinitic clay increased approximately 3-fold compared to untreated conditions, indicating strong intra-floc bonding of NPAM-treated kaolinitic clay. The high separation distance (up to 2.2 µm for kaolinitic clay) of stacked clay flocs at high NPAM concentration suggests that NPAM concentrations below 5 mg/L can be recommended for obtaining mechanical stability of settled clay after settling. Overall, these findings provide a comprehensive understanding of NPAM-clay interactions at varied cationic valence, clay type, and NPAM concentration under saline conditions.
研究领域:
环境科学
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胶体与界面科学
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土壤科学
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高分子科学
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化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2025
·
IF 4.3
Yunxiao Ban,Zhijie Wan,Cong Ma,Yuzhen Wu,Haoran Chen
This study proposes a magnetic levitation fixed bed flocculation reactor as an effective method for the removal of Cr (VI). The research examines the effects of both single and dual polymer flocculants on the efficiency of the flocculation process. Initially, a magnetic levitation layer was established using a radial magnetic field in conjunction with stainless steel balls. Subsequently, polyaluminum chloride (PAC) and a non-ionic coagulant, polyacrylamide (NPAM), were introduced into the water to create a magnetic levitation fixed bed flocculation reactor. This reactor with the objective of purifying water contaminated with simulated Cr (VI). The results indicate that the incorporation of a reducing agent, specifically FeSO 4 , in conjunction with PAC and NPAM respectively, can achieve Cr (VI) removal rates exceeding 97% and turbidity removal rates exceeding 96%. The interaction between the cross-flow influent and the flocculating particles promotes the formation of micro-vortex flocculation.
研究领域:
环境科学
·
水处理工程
✓ 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）