The Modification Of Anions Clay Materials And Application In Environment

Hydrotalcite-like compounds(LDH) is a sort of anionic clays with double-layer structure.It is layered mixed hydroxides containing exchangeable anions.This material has memory effect and adjustable aperture.The anionic clays were found application in agriculture,industry,medicine and other field.Because of surface basicity and memory effect,calcined layered double hydroxide(LDO) can be used in treatment of wastewater as adsorbent of heavy metal cations.The cations on the layers could be changed in wide range.The anionic surfactant SDS can be introduced into the interlayer of LDH in order to a significant organic solubilization.Many metallo-phthalocyanine compounds with potential catalytic activity can be introduced into the brucite layer in order to get supported catalyst.Metallo-phthalocyanine molecule was assembled on LDH,through electromagnetic force and Intermolecular force.Mg₃Al-CO₃^2--LDHs and Mg₃Al-NO₃^--LDHs were synthysized by the constant co-precipitation method.The LDHs and synthesized compounds were characterized by XRD,SEM,NMR,FT-IR,BET and TOC.Calcined Mg/Al-layered double hydroxides were tested for removal of nickel and lead from simulated wastewater. Data from batch experiments were obtained as a function of pH,calcination temperature and contact time.The physical and structural properties of the material before and after nickel and lead adsorption were investigated to determine the uptake mechanism.The adsorbability of the hydrotalcite surface modified by SDS was evaluated by its adsorption of p-Nitrotoluene in aqueous solution. Metallo-phthalocyanine molecule was assembled on LDH,through the method of exchanging anions or calcined-reconstrcution.The catalytic activity of the materials was evaluated by catalytic oxidation of H₂O₂.The study of Nickel and Lead removal by calcined Mg/Al-layered double hydroxides indicates:A "memory effect" material was provided by calcined Mg/Al-layered double hydroxides(LDO) and more than 95%adsorption of Ni²⁺ and Pb²⁺ could be achieved.The experimental equilibrium data can be described by Langmuir,Freundlich and linear models,although the Langmuir isotherm gave a better fit to the experimental data.The pH had basically no influence on the removal of Ni²⁺ and Pb²⁺ by LDO.The uptake of Ni²⁺ and Pb²⁺ attained equilibrium in 20 min and 2 h,respectively.The difference contact time of absorbing Pb²⁺ and Ni²⁺ relate to basic adsorption sediment,the process of the recovery,of LDH structure and the stability of the precipitates.LDO is a highly efficient adsorption agent for heavy metals and consequently may have wide applicability in treatment of wastewater.The adsorption of p- Nitrotoluene on LDH surface modified by SDS showed that, three samples prepared by different modification methods had the typical layered double hydroxides structure,and the sample synthesized by rehydration of the calcined hydrotalcite had the highest content of SDS.Anion surfactant SDS formed organic phase in SDS-HT,and the organic phase affected the ration of adsorption of p-Nitrotoluene between the surface adsorption and partition.All samples adsorbed p-Nitrotoluene effectively,and the effect of adsorption mainly resulted from surface adsorption,the maximum adsorption was 44.5mg/g at 162mg/L p-Nitrotoluene aqueous solution on the sample of rehydration of the calcined hydrotalcite.The results showed that it can be achieved by surface modification to increase the saturation adsorption capacity of organic compounds.The application of catalytic oxidation for the treatment of H₂O₂ simulated water showed that,metallo-phthalocyanine compounds had high catalyze ability,and could be assembled on surface or interlayer of LDH with electromagnetic force and Intermolecular force,through the method of exchanging anions and calcined-reconstrcution.But metallo-phthalocyanine molecules were assembled in the interlayer of LDH difficultly,many were on surface of LDH.The catalyze ability of assembled samples was good,evaluated by catalytic oxidation of H₂O₂.