Multifunctional eco-friendly sorbent based on marine brown algae and bivalve shells for subsequent uptake of Congo red dye and copper(II) ions

Herein, a novel eco-friendly urea calcium alginate xerogel beads chemically functionalized with Congo red dye (U-CAB-CR1.43) was fabricated on the basis of commercial valorization of two copious waste biomass; Padina boergesenii brown alga and Anadara uropigimelana bivalve shells. The synthesized sorbent was characterized via FT-TR, BET surface area, TGA, SEM and EDX analyses. Sequential sorption capability of as-prepared biosorbent was investigated by appraising its efficiency to capture Cu(II) metal ion under variable operational parameters. Varying of sorbent doses form 0.5 g L-1 to 5 g L-1 was studied. Sorption isotherms, uptake kinetics and thermodynamic studies as prerequisite tools for plausible apprehension of sorption mechanism were also analyzed under optimized pH value (i.e. pH = 6.5). The results revealed that the isotherm profile of U-CAB-CR1.43 fits Langmuir equation with maximum sorption capacity of 6.94 mmol g(-1) (441 mg g(-1)). Kinetic profile was accurately conformed to pseudo-second order rate equation. Thermodynamic function parameters emphasized the endothermic nature of sorption process. Successful desorption scenario using 0.5 mol L-1 of HCl has considerably promoted the spent sorbent to be further used up to four consequent sorption/desorption cycles. Feasibility of productive sorbent to expel Cu(II) from miscellaneous wastewater was successfully researched. To sum up, this study presents an efficient strategy for capturing Cu(II) from miscellaneous wastewater.