Cadmium removal by MgCl2 modified biochar derived from crayfish shell waste: Batch adsorption, response surface analysis and fixed bed filtration

• Published in: Journal of hazardous materials 2021-04, Vol.408, p.124860, Article 124860
• Main Authors: Zhang, Dawei, Zhang, Kejing, Hu, Xiaolan, He, Qianqian, Yan, Jinpeng, Xue, Yingwen
• Format: Article
• Language: English
• Subjects: Cd(II) adsorption; Fixed bed filtration; MgCl2 modified biochar; Response surface methodology; The BJP model
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.124860

Cadmium (Cd) pollution is regarded as a disturbing environmental problem due to its serious risks to the water body and human health. The removal of cadmium from wastewater is thus crucial to avoid its harmful effects on the ecosystem. This study comprehensively investigated Cd(II) adsorption onto MgCl2 modified biochar (MgC600) and results showed that the adsorption capacity of MgC600 was more than twice of that of pristine biochar due to its enhanced ion exchange ability. Response surface analysis revealed that reaction time played a crucial role in the Cd(II) adsorption, followed by initial concentration and solution pH. Moreover, the optimal adsorption conditions and capacity were precisely given by the quadratic regression model and thus proved that the model can be applied to predict the operation conditions of Cd(II) adsorption. Finally, a new model defined as BJP model (CtC0=11+(KJ⋅t)P) was proposed and proved to be more suitable for the fixed bed filtration process. Overall, our findings provide a promising material in treatment of Cd(II)-rich wastewater and give a clear picture of its application. More importantly, the newly developed BJP model can accurately describe the fixed bed filtration process and further promote its application in wastewater treatment. [Display omitted] •Cd(II) adsorption capacity of MgC600 (72.1 mg/g) was twice more than that of C600 (32.0 mg/g).•The order of importance of factors affecting the Cd(II) adsorption were: t > C0 > pH.•The quadratic regression model could accurately predict the optimal conditions of Cd(Ⅱ) adsorption.•A more accurate and simple model (CtC0=11+(KJ⋅t)P) for fixed bed filtration was proposed.