This review describes the mechanisms of natural coagulants.It provides a good understanding of the two key processes of coagulation-flocculation:adsorption and charge neutralization,as well as adsorption and bridging....This review describes the mechanisms of natural coagulants.It provides a good understanding of the two key processes of coagulation-flocculation:adsorption and charge neutralization,as well as adsorption and bridging.Various factors have influence the coagulation/flocculation process,including the effect of pH,coagulant dosage,coagulant type,temperature,initial turbidity,coagulation speed,flocculation speed,coagulation and flocculation time,settling time,colloidal particles,zeta potential,the effects of humic acids,and extraction density are explained.The bio-coagulants derived from plants are outlined.The impact of organic coagulants on water quality,focusing on their effects on the physicochemical parameters of water,heavy metals removal,and bacteriological water quality,is examined.The methods of extraction and purification of plant-based coagulants,highlighting techniques such as solvent extraction and ultrasonic extraction,are discussed.It also examines the parameters that influence these processes.The methods and principles of purification of coagulating agents,including dialysis,freeze-drying,ion exchange,electrophoresis,filtration,and centrifugation,are listed.Finally,it evaluates the sustainability of natural coagulants,focusing on the environmental,technical,and economic aspects of their use.At the end of this review,the readers should have a comprehensive understanding of the mechanisms,selection,extraction,purification,and sustainability of plant-based natural coagulants in water treatment.展开更多
Graft copolymers of MMA （methyl methacrylate） with NRL （natural rubber latex） referred to as NR-g-PMMA have been prepared using CHP （cumene hydroperoxide）/TEPA （tetraetbylenepentamine） redox initiator. 1H NMR ...Graft copolymers of MMA （methyl methacrylate） with NRL （natural rubber latex） referred to as NR-g-PMMA have been prepared using CHP （cumene hydroperoxide）/TEPA （tetraetbylenepentamine） redox initiator. 1H NMR （proton nuclear magnetic resonance） and FTIR （Fourier transform infrared） analysis have confirmed the occurrence of graft copolymerisations of MMA onto NR that containing 30% and 50% of MMA monomer. The influence of coagulating agents such as formic acid, sulfuric acid and boiling water on the coagulation of NR-g-PMMA latices were investigated. These types of coagulating agent formed compact coagulum and the effect of NR-g-PMMA compounds on cure characteristics, physical properties and appearances were reported.展开更多
Soil contaminated with typical heavy metals (Pb,Cd,Cu,and Zn) was remedied by using the polymeric aluminum salt coagulants including polyaluminum chloride (PAC) and polyaluminum sulfate (PAS).The remediation efficienc...Soil contaminated with typical heavy metals (Pb,Cd,Cu,and Zn) was remedied by using the polymeric aluminum salt coagulants including polyaluminum chloride (PAC) and polyaluminum sulfate (PAS).The remediation efficiencies are influenced by reaction time,water amount,and dosage of remediation agent.The optimal remediation conditions are as follows:6 h of reaction time,1 kg/kg of water addition amount,and 0.25 kg/kg of remediation agent dosage.After PAC addition,the remediation efficiencies of diethylenetriamine-pentaacetic acid (DTPA)-extractable Pb,Cd,Cu,and Zn reach 88.3%,85.1%,85.4%,and 73.7%,respectively;and those for PAS are 89.7%,88.7%,83.5%,and 72.6%,respectively.The main remediation mechanism of the polymeric aluminum salt may contribute to the ionization and hydrolysis of PAC and PAS.H + released from ionization of polymeric aluminum salt can cause the leaching of heavy metals,while the multinuclear complex produced from hydrolysis may result in the immobilization of heavy metals.For PAC,the immobilization of heavy metals is the main remediation process.For PAS,both leaching and immobilization are involved in the remediation process of heavy metals.展开更多
文摘This review describes the mechanisms of natural coagulants.It provides a good understanding of the two key processes of coagulation-flocculation:adsorption and charge neutralization,as well as adsorption and bridging.Various factors have influence the coagulation/flocculation process,including the effect of pH,coagulant dosage,coagulant type,temperature,initial turbidity,coagulation speed,flocculation speed,coagulation and flocculation time,settling time,colloidal particles,zeta potential,the effects of humic acids,and extraction density are explained.The bio-coagulants derived from plants are outlined.The impact of organic coagulants on water quality,focusing on their effects on the physicochemical parameters of water,heavy metals removal,and bacteriological water quality,is examined.The methods of extraction and purification of plant-based coagulants,highlighting techniques such as solvent extraction and ultrasonic extraction,are discussed.It also examines the parameters that influence these processes.The methods and principles of purification of coagulating agents,including dialysis,freeze-drying,ion exchange,electrophoresis,filtration,and centrifugation,are listed.Finally,it evaluates the sustainability of natural coagulants,focusing on the environmental,technical,and economic aspects of their use.At the end of this review,the readers should have a comprehensive understanding of the mechanisms,selection,extraction,purification,and sustainability of plant-based natural coagulants in water treatment.
文摘Graft copolymers of MMA （methyl methacrylate） with NRL （natural rubber latex） referred to as NR-g-PMMA have been prepared using CHP （cumene hydroperoxide）/TEPA （tetraetbylenepentamine） redox initiator. 1H NMR （proton nuclear magnetic resonance） and FTIR （Fourier transform infrared） analysis have confirmed the occurrence of graft copolymerisations of MMA onto NR that containing 30% and 50% of MMA monomer. The influence of coagulating agents such as formic acid, sulfuric acid and boiling water on the coagulation of NR-g-PMMA latices were investigated. These types of coagulating agent formed compact coagulum and the effect of NR-g-PMMA compounds on cure characteristics, physical properties and appearances were reported.
基金Project(K1201010-61)supported by the Science and Technology Program of Changsha,ChinaProject(51074191)supported by the National Natural Science Foundation of ChinaProject(2012BAC09B04)supported by National Key Technology Research and Development Program,China
文摘Soil contaminated with typical heavy metals (Pb,Cd,Cu,and Zn) was remedied by using the polymeric aluminum salt coagulants including polyaluminum chloride (PAC) and polyaluminum sulfate (PAS).The remediation efficiencies are influenced by reaction time,water amount,and dosage of remediation agent.The optimal remediation conditions are as follows:6 h of reaction time,1 kg/kg of water addition amount,and 0.25 kg/kg of remediation agent dosage.After PAC addition,the remediation efficiencies of diethylenetriamine-pentaacetic acid (DTPA)-extractable Pb,Cd,Cu,and Zn reach 88.3%,85.1%,85.4%,and 73.7%,respectively;and those for PAS are 89.7%,88.7%,83.5%,and 72.6%,respectively.The main remediation mechanism of the polymeric aluminum salt may contribute to the ionization and hydrolysis of PAC and PAS.H + released from ionization of polymeric aluminum salt can cause the leaching of heavy metals,while the multinuclear complex produced from hydrolysis may result in the immobilization of heavy metals.For PAC,the immobilization of heavy metals is the main remediation process.For PAS,both leaching and immobilization are involved in the remediation process of heavy metals.
