Remediation of lead by pretreated red algae: adsorption isotherm, kinetic, column modeling and simulation studies

Batch and column biosorption experiments were carried on for lead uptake using ecofriendly biosorbents (raw and calcium chloride [CaCl2] or formaldehyde pretreated form of red marine algae Jania ruben [Linnaeus]). The best-fit (linear and nonlinear) isotherms, kinetics, and column adsorption models were identified using statistical analysis. Freundlich, Langmuir, Temkin, Redlich-Peterson, and Elovich adsorption isotherm models were tested. Highest adsorption capacity (774 mg/g) has been observed with Jania algae pretreated with formaldehyde. Pseudo-first-and second-order adsorption kinetics were applicable. The column capacity for lead removal with Jania pretreated with CaCl2 was found to be 1089.6 (mg/g) from the breakthrough curve area method. Thomas, Yoon-Nelson, Yan, and Clark column models were tested with regression analysis. Thomas model is the best column model with capacity q(Th) = 1092.4 mg/g. Overall, 98.5% regeneration of column was achieved, indicating the suitability of using algae materials in multioperational cycles. Adsorbed lead present in algae material was confirmed by thermal analysis.