摘要
选择Mg2+为掺杂离子,通过溶胶-凝胶法制备了不同比例的镁-钙羟基磷灰石吸附剂,研究其对水溶液中Pb^2+的去除特性和过程机制.结果表明,吸附剂表面以羟基磷铅矿化合物[Pb10(PO4)6(OH)2]为主,其晶体结构由短棒状转变为针状结构;在温度25℃,pH为5时,镁-钙羟基磷灰石吸附Pb^2+在720min内达到平衡,吸附剂的最佳投加量为0.6g·L^-1,最大吸附量为813.17mg·g^-1;热力学实验结果:ΔGθ<0、ΔSθ>0和ΔHθ>0,表明镁-钙羟基磷灰石吸附Pb^2+的过程是自发的吸热、熵增的过程,升温有利于吸附;吸附过程符合伪二级动力学方程,Langmuir吸附模型能更好地描述等温吸附行为;材料表征与吸附实验分析表明,表面络合与溶解-沉淀是镁-钙羟基磷灰石去除Pb^2+的主要机制.
A novel magnesium-calcium hydroxyapatite adsorbent was prepared by the Sol-gel method with different proportions of Mg/(Ca + Mg) using Mg^2+ as doped ions,and the removal characteristics and process mechanism of Pb^2+ on the magnesium-calcium hydroxyapatite in an aqueous solutions were studied.The results show that the surface of the adsorbent is composed mainly of a hydroxyphosphonite compound [Pb10(PO4)6(OH)2],The morphological characteristics of the magnesium-calcium hydroxyapatite adsorbent surface was investigated as crystal structure changes from short rods to needle structures according to scanning electron microscopy (SEM).Testing at a temperature of 25℃ and pH of 5 showed that the adsorption of Pb^2+ by magnesium-calcium hydroxyapatite reached equilibrium within 720 min.The adsorption capacity was determined to be 813.17 mg·g^-1 at a dosage of 0.6 g·L^-1.The thermodynamic test results of ΔGθ< 0,ΔSθ> 0,and ΔHθ> 0 indicated that the adsorption process of Pb^2+ by magnesiumcalcium hydroxyapatite is a spontaneous process with endothermic reaction and entropy increments,and higher temperatures were considered be favorable for adsorption at a range of 25-45℃.The adsorption could be effectively described by a pseudo-second-order kinetic equation.The equilibrium data were found to follow the Langmuir adsorption model.Material characterization and adsorption tests showed that surface complexation and dissolution-precipitation were the main mechanisms for the removal of Pb^2+ by magnesiumcalcium hydroxyapatite in an aqueous solution.
作者
何豪
朱宗强
刘杰
朱义年
阎起明
刘阳
莫南
玄惠灵
魏婉莹
HE Hao;ZHU Zong-qiang;LIU Jie;ZHU Yi-nian;YAN Qi-ming;LIU Yang;MO Nan;XUAN Hui-ling;WEI Wan-ying(Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology,Guilin University of Technology,Guilin 541004,China;Shenzhen General Institute of Architectural Design and Research Co.,Ltd.,Shenzhen 518000,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2019年第9期4081-4090,共10页
Environmental Science
基金
国家自然科学基金项目(21707024,41763012,51638006)
广西自然科学基金项目(2018GXNSFAA050044)
广西科技计划项目(桂科AD18126018)
广西创新驱动发展专项(桂科AA17204047)
广西高等学校高水平创新团队及卓越学者计划项目(桂财教函[2018]319号)
