title: Fast adsorption of Cd²⁺ and Pb²⁺ by EGTA dianhydride (EGTAD) modified ramie fiber.
abstract: In this study, the removal of Cd(2+) and Pb(2+) from aqueous solutions was investigated using a novel chelating material. The first part described the synthesis of ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid dianhydride (EGTAD), mercerization treatment of ramie fiber (MRF), and the MRF was then reacted with EGTAD to prepare the new material (ERF). The obtained material was characterized by weight gain, SEM, FTIR, and elemental analysis. The results of FTIR and elemental analysis confirmed that ester bond, carboxyl and amine groups were introduced onto ERF. The adsorption capacity of metals on ERF was evaluated at different contact times, pH values, initial metal concentrations, and temperatures in the second part. The adsorption equilibrium was reached within 5 min for Cd(2+) and Pb(2+). Adsorption isotherm could be well fitted by the Langmuir model, and the maximum adsorption capacities were 159.11 and 273.78 mg g(-1) for Cd(2+) and Pb(2+) at 298 K, respectively. Thermodynamic analysis showed that the adsorption process was spontaneous and endothermic. The molar ratio of adsorbed cation to grafted EGTA is close to 1.8:1, which confirmed that the adsorption was chemical process involving both surface chelation reaction and ion exchange. In addition, the absorbent was successfully regenerated using HCl and ultrasonic treatment.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Sun
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China. Electronic address: liuyunguo@hnu.edu.cn.
authors.forename: Yunguo
authors.initials: Y
authors.lastname: Liu
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
authors.forename: Yuanqing
authors.initials: Y
authors.lastname: Huang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Tan
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
authors.forename: Xinjiang
authors.initials: X
authors.lastname: Hu
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
authors.forename: Zhongzhu
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000327:Adsorption; D032402:Boehmeria / Q000737:chemistry*; D002104:Cadmium / Q000302:isolation & purification*; D002614:Chelating Agents / Q000737:chemistry*; D004533:Egtazic Acid / Q000031:analogs & derivatives*; D007854:Lead / Q000302:isolation & purification*; D008958:Models, Molecular; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods
chemical_list: D002614:Chelating Agents; D014874:Water Pollutants, Chemical; D002104:Cadmium; D007854:Lead; D004533:Egtazic Acid
keywords: Adsorption; Adsorption isotherm; EGTA dianhydride; Heavy metals; Mercerization; Modified ramie fiber; Regeneration