Continuous biosorption of nickel from aqueous solution using Chrysanthemum indicum derived biochar in a fixed-bed column.

The biosorption capability of Chrysanthemum indicum to remove nickel ions from aqueous solution in a fixed-bed column was examined in this study. Native C. indicum flower waste was improved for its biosorptive potential by pyrolysis to obtain its biochar form and, thereby, both raw (CIF-R) and biochar (CIF-BC) forms of the flower were used for Ni(II) removal. Fixed bed column studies were conducted to examine the influence of bed height (1.0-3.0 cm), flow rate (1.0-5.0 mL min-1) and initial metal ion concentration (25-75 mg L-1). The breakthrough curves (Cout/Cin vs time) were modelled using different dynamic adsorption models, viz. Adams-Bohart, Thomas and Yoon-Nelson model. Interpretation of the data revealed a favorable correlation with the Thomas model with higher R2 values and closer model-predicted and experimental biosorption capacity values. The equilibrium uptake capacity of CIF-R and CIF-BC for Ni(II) were found to be 14.02 and 29.44 mg g-1, respectively. Further, the column was regenerated using HCl as eluent, to desorb the adsorbed Ni(II) ions. The experimental results implied and affirmed the suitability of the biosorbents for nickel ion biosorption with its nature being favorable, efficient, and environmentally friendly.