title: Efficiency and mechanisms of Cd removal from aqueous solution by biochar derived from water hyacinth (Eichornia crassipes).
abstract: This study investigated the efficiency and mechanisms of Cd removal by biochar pyrolyzed from water hyacinth (BC) at 250-550 °C. BC450 out-performed the other BCs at varying Cd concentrations and can remove nearly 100% Cd from aqueous solution within 1 h at initial Cd ≤ 50 mg l(-1). The process of Cd sorption by BC450 followed the pseudo-second order kinetics with the equilibrium being achieved after 24 h with initial Cd ranging from 100 to 500 mg l(-1). The maximum Cd sorption capacity of BC450 was estimated to be 70.3 mg g(-1) based on Langmuir model, which is prominent among a range of low-cost sorbents. Based on the balance analysis between cations released and Cd sorbed onto BC450 in combination with SEM-EDX and XPS data, ion-exchange followed by surface complexation is proposed as the dominant mechanism responsible for Cd immobilization by BC450. In parallel, XRD analysis also suggested the formation of insoluble Cd minerals (CdCO3, Cd3P2, Cd3(PO4)2 and K4CdCl6) from either (co)-precipitation or ion exchange. Results from this study highlighted that the conversion of water hyacinth into biochar is a promising method to achieve effective Cd immobilization and improved management of this highly problematic invasive species.
authors: College of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan 410081, China.
authors: Feng
authors: F
authors: Zhang
authors: College of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan 410081, China. Electronic address: hdhuanjing@163.com.
authors: Xin
authors: X
authors: Wang
authors: College of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan 410081, China.
authors: Daixia
authors: D
authors: Yin
authors: College of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan 410081, China.
authors: Bo
authors: B
authors: Peng
authors: College of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan 410081, China.
authors: Changyin
authors: C
authors: Tan
authors: College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082, China.
authors: Yunguo
authors: Y
authors: Liu
authors: College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082, China.
authors: Xiaofei
authors: X
authors: Tan
authors: College of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan 410081, China.
authors: Shixue
authors: S
authors: Wu
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D031806:Eichhornia / Q000737:chemistry*; D007474:Ion Exchange; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; C540010:biochar; D002104:Cadmium; D002606:Charcoal
keywords: Biochar; Cadmium; Invasive plants; Sorption; Water hyacinth