title: Immobilization of Cu2+and Cd2+by earthworm manure derived biochar in acidic circumstance.
abstract: Earthworm manure, the by-product obtained from the disposing of biowastes by earthworm breeding, is largely produced and employed as a feedstock for biochar preparation through pyrolysis. For repairing acidic soil or acidic electroplating effluent, biochar physicochemical properties would suffer from some changes like an acidic washing process, which hence affected its application functions. Pristine biochar (UBC) from pyrolysis of earthworm manure at 700°C and biochar treated by HCl (WBC) were comparatively investigated regarding their physicochemical properties, adsorption capability and adsorption mechanism of Cu2+and Cd2+from aqueous solution to explore the immobilization characteristics of biochar in acidic environment. After HCl treatment, the soluble ash content and phenolic-OH in the WBC sample was notably decreased against the increase of the carboxyl CO, aromatic CC and Si-O-Si, compared to that of UBC. All adsorption processes can be well described by Langmuir isotherm model. The calculated maximum adsorption capacity of Cu2+and Cd2+adsorption on UBC were 36.56 and 29.31mg/g, respectively, which were higher than that of WBC (8.64 and 12.81mg/g, respectively), indicating that HCl treatment significantly decreased biochar adsorption ability. Mechanism analysis revealed that alkali and alkaline earth metallic, salts (carbonates, phosphates and silicates), and surface functional groups were responsible for UBC adsorption, corresponding to ion exchange, precipitation and complexation, respectively. However, ion exchange made little contributions to WBC adsorption due to the great loss of soluble ash content. WBC adsorption was mainly attributed to the abundant exposure of silicates and surface functional groups (carboxyl CO and aromatic CC).
authors.affiliation: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096, China; Institute of Ecological and Environmental Science, Sichuan Agricultural University, Sichuan 611130, China. Electronic address: wangzh_fighting@163.com.
authors.forename: Zhanghong
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Institute of Ecological and Environmental Science, Sichuan Agricultural University, Sichuan 611130, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Shen
authors.affiliation: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096, China. Electronic address: 101011398@seu.edu.cn.
authors.forename: Dekui
authors.initials: D
authors.lastname: Shen
authors.affiliation: Institute of Ecological and Environmental Science, Sichuan Agricultural University, Sichuan 611130, China; College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China.
authors.forename: Yahui
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Xiao
mesh_terms: D002104:Cadmium / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical
chemical_list: C540010:biochar; D002104:Cadmium; D002606:Charcoal; D003300:Copper
keywords: Adsorption; Biochar; Earthworm manure; HCl