新型除镉吸附剂MPWS制备条件的优化与机理  

Optimization of Preparation Conditions and Mechanism of MPWS Novel Adsorbent for Cd(Ⅱ)Removal

作　　者：孙永鹏 王刚[1] 高微微 徐敏[1] 蒋煜峰[1] SUN Yongpeng;WANG Gang;GAO Weiwei;XU Min;JIANG Yufeng(College of Environmental and Municipal Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学环境与市政工程学院,甘肃兰州730070

出　　处：《环境科学研究》2023年第3期546-556,共11页Research of Environmental Sciences

基　　金：甘肃省科技计划资助项目(No.20JR10RA243);兰州交通大学天佑创新团队项目(No.TY202005)。

摘　　要：为了提高小麦秸秆(WS)对废水中Cd(Ⅱ)的吸附性能,采用氢氧化钠(NaOH)、L-半胱氨酸(L-Cys)、碳二亚胺盐酸盐(EDC·HCl)、N-羟基琥珀酰亚胺(NHS)对WS进行化学改性,制备出新型吸附剂巯基丙酰化小麦秸秆(MPWS).以含Cd(Ⅱ)水样为考察对象,利用Plackett-Burman试验、最陡爬坡试验和响应面法的中心复合设计(CCD)对MPWS的制备条件进行优化,借助表征方法探讨了MPWS的制备机理,考察了WS、化学预处理小麦秸秆(CWS)、MPWS对Cd(Ⅱ)的吸附性能.结果表明:(1)由响应面法建立的二次项回归方程P值为0.0002,表明模型非常显著.(2)当WS粒径为30目(0.60 mm)、化学预处理试剂NaOH溶液浓度为0.07 mol/L、n(EDC·HCl)∶n(L-Cys)为0.099∶1、m(NHS)∶m(EDC·HCl)为0.5∶1、m(L-Cys)∶m(CWS)为4∶1、反应介质pH为11、反应温度为40℃、反应时间为2.39 h时,该条件下制备的MPWS对水样中Cd(Ⅱ)去除性能最优,MPWS投加量为10 g/L对应Cd(Ⅱ)的去除率为84.55%,与模型预测值(84.80%)的相对偏差仅为-0.29%.(3)MPWS制备机理为巯基丙酰基被接枝到WS结构中,发挥了其对Cd(Ⅱ)螯合吸附作用.(4)秸秆对Cd(Ⅱ)的吸附性能表现为MPWS>CWS>WS,表明WS经化学预处理、接枝改性可提升吸附Cd(Ⅱ)的性能,当MPWS投加量为20 g/L时,Cd(Ⅱ)的去除率可达95.56%.研究显示,通过响应面法优化MPWS制备条件的试验方法可行,经巯基丙酰基改性后可有效提升小麦秸秆对Cd(Ⅱ)的吸附性能.In order to improve the adsorption capacity of wheat straw(WS)for Cd(Ⅱ)in water,a novel adsorbent,named mercaptopropionyl wheat straw(MPWS),was prepared by chemically modifying WS by sodium hydroxide(NaOH),L-cysteine(L-Cys),carbondiimide hydrochloride(EDC·HCl)and N-hydroxysuccinimide(NHS).The optimal preparation conditions of MPWS were determined by Plackett-Burman experiment,steepest ascent experiment,and central composite design(CCD)of response surface method.The synthesis mechanism of MPWS was characterized,and the adsorption properties of WS,CWS(chemically pretreated wheat straw)and MPWS for Cd(Ⅱ)were also investigated.The results showed that:(1)The P value of the quadratic regression equation established by response surface method was 0.0002,indicating that the model was highly significant.(2)When the particle size of WS was 30 mesh(0.60 mm),the concentration of NaOH solution was 0.07 mol/L,the n(EDC·HCl)∶n(L-Cys)was 0.099∶1,the m(NHS)∶m(EDC·HCl)was0.5∶1,the m(L-Cys)∶m(CWS)was 4∶1,the pH of the reaction medium was 11,the reaction temperature was at 40℃,and the reaction time was 2.39 h,the MPWS prepared under these conditions had the best removal performance on Cd(Ⅱ)in water samples.Furthermore,at 10 g/L of MPWS,the experimental value of the Cd(Ⅱ)removal rate was 84.55%,which was close to predicted value of 84.80%,with a relative deviation of-0.29%.(3)The mercaptopropionyl groups was introduced into the structure of WS,and the chelation and adsorption of MPWS for Cd(Ⅱ)were good.(4)The order of adsorption capacity for Cd(Ⅱ)was MPWS>CWS>WS,suggesting that the adsorption capacity for Cd(Ⅱ)was enhanced by modifying WS with chemical pretreatment and graft modification.When the dosage of MPWS was20 g/L,the removal rate of Cd(Ⅱ)by MPWS could reach 95.56%.These results show that response surface method can be used to optimize the preparation conditions of MPWS,and the adsorption performance for Cd(Ⅱ)can be effectively improved by modifying WS with the mercaptopropionyl groups.

关 键 词：Plackett-Burman试验 最陡爬坡试验 响应面法 交互作用 镉污染 吸附 

分 类 号：X703[环境科学与工程—环境工程]