改性泡桐树叶吸附剂对水中铅和镉的吸附特性  

Adsorption Characteristics of Pb^(2+) and Cd^(2+) by Modified Paulownia Leaf Powder from Aqueous Solution

作　　者：刘文霞[1] 李佳昕[1] 王俊丽[1] 陈学斌[1] 孟祥远[1] 

机构地区：[1]河南农业大学林学院环境系,郑州450002

出　　处：《农业环境科学学报》2014年第6期1226-1232,共7页Journal of Agro-Environment Science

基　　金：国家自然科学基金(51008118);国家重点实验室开放基金(KF-2012-10)

摘　　要：分别采用酸、碱、巯基乙酸3种化学方法对泡桐树叶粉末进行改性,利用扫描电镜(SEM)和傅立叶变换红外光谱(FTIR)对泡桐树叶吸附剂结构特性进行表征,研究了其对水中Pb2+和Cd2+的吸附行为。结果表明:吸附剂用量为3 g·L-1,温度25℃,溶液pH为5时,3种改性方法制得的泡桐树叶吸附剂4h内都能达到吸附平衡,吸附过程可以用准二级吸附动力学模型描述。NaOH-乙醇改性的泡桐树叶(MPPA No.1)较未改性的泡桐树叶(UMPPA)对Pb2+和Cd2+的吸附能力得到明显提高,Pb2+、Cd2+平衡吸附量分别为15.38 mg·g-1和14.71mg·g-1,对Cd2+的吸附速率较Pb2+快。UMPPA表面平展光滑,改性MPPANo.1表面粗糙呈蜂窝状,MPPANo.1比表面积为3.124 m2·g-1,较UMPPA增大150%。泡桐树叶主要含有羟基、羧基、酰胺等活性基团,有利于对Pb2+和Cd2+的吸附,经NaOH-乙醇改性的泡桐树叶对水中Pb2+和Cd2+有更好的吸附性能。Tree leaves are waste litter and can be used as an adsorbent to remove heavy metals from water. In this study, paulownia leaf powder was modified with three chemicals, sulfuric acid, sodium hydroxide and thioglycolic acid, and was then examined its adsorption of Pb2＋and Cd2＋from aqueous solution. The surface and structure of modified paulownia leaf powder were characterized using Fourier transform infrared spectroscopy（FTIR）and scanning electron microscope（SEM）. Adsorption of Pb2＋and Cd2＋by three modified paulownia leaf pow-der was fast and reached an equilibrium within 4 h. At pH5, temperature of 25℃and adsorbent dose of 3 g·L-1 in solution, adsorption ki-netics of Pb2＋ and Cd2＋ could be expressed by pseudo-second-order kinetics model. Compared with unmodified paulownia leaf powder （UMPPA）, adsorption ability of NaOH-ethanol modified paulownia leaf powder（MPPA No.1）was improved significantly, and the equilibri-um adsorption capacity of Pb2＋and Cd2＋was 15.38 mg·g-1 and 14.71 mg·g-1, respectively. In addition, the adsorption speed was faster for Cd2＋than for Pb2＋. UMPPA revealed flat and smooth surface, while MPPA No.1 exhibited rough and honeycomb-patterned surface. The spe-cific surface area of MPPA No.1 was 3.124 m2·g-1, 50%greater than that of UMPPA. Paulownia leaves contain active functional groups such as hydroxyl, carboxyl and amides, facilitating adsorption of Pb2＋and Cd2＋. In conclusion, NaOH-ethanol modified paulownia leaves exhibited excellent adsorption for Pb2＋and Cd2＋in wastewater.

关 键 词：泡桐树叶 改性 PB2+ Cd2+ 吸附动力学 傅立叶变换红外光谱(FTIR) 

分 类 号：X705[环境科学与工程—环境工程]