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| Adsorption performance and mechanism of biochar modified by humic acid and thiol for Cd2+ removal in water |
| Received:February 21, 2023 Revised:April 28, 2023 |
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| KeyWord:modified biochar;Cd2+;adsorption mechanism;DFT calculation |
| Author Name | Affiliation | | LAI Zhanghui | Long Hua Drainage, Shenzhen 518110, China | | ZHANG Xiaolong | Shenzhen Ecological Environment Monitoring Center Station, Shenzhen 523950, China
Bixing IoT Technology(Shenzhen) Co Ltd, Shenzhen 523950, China | | HE Muyu | Long Hua Drainage, Shenzhen 518110, China | | FANG Ruochao | School of Resources Environmental & Chemical Engineering, Nanchang University, Nanchang 330038, China | | SUN Shengjin | Long Hua Drainage, Shenzhen 518110, China |
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| Abstract: |
| This study presents the preparation of biochar(BC300)using rice straw as raw material, and the modification of its surface with humic acid and 3-mercaptopropyltrimethoxysilane, providing two modified biochars:HBC300 and SBC300, respectively. Herein, the ability of the modified biochars to adsorb Cd2+ was analyzed, and the physicochemical properties of the modified biochars and the effects of functional groups on the adsorption of Cd2+ were explored using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Boehm titration, and density functional theory(DFT)calculations. The results showed that the modification process changed the physicochemical properties of biochar. The HBC300 surface presented an increased number of COOH and OH functional groups, while in the SBC300 surface, the number of COC, CO, and SH functional groups increased. By enriching the surface functional groups of biochar, the adsorption reaction rate and adsorption performance of biochar for Cd2+ were improved, showing the potential of modified biochar to remove Cd2+ from water. Among them, SBC300 showed the best adsorption performance on Cd2+, with a maximum equilibrium adsorption capacity of 49.5 mg·g-1, but an adsorption reaction rate lower than that of HBC300. SBC300 conformed to the Pseudo-second-order kinetic equation and Langmuir isothermal adsorption model. The adsorption process consisted of a monolayer adsorption controlled by chemical adsorption. The characterization and DFT calculation fitting data results showed that the functional groups of surface-modified biochar accelerated the adsorption reaction rate of Cd2+; however, COC and CO functional groups limited the adsorption reaction rate of SBC300 to Cd2+. |
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