Use of central composite design in optimizing zinc removal by an ecofriendly biosorbent pithophora cleveana wittrock: Application of isotherms

The ultimate aim of research worldwide is to make the environment a pollution free environment with clean as well as safe air and water. Our subject is too closely related to the on the ongoing research, i.e., removal of toxic constituents from the aqueous solutions for dependable and clean water for several uses. Pithophora Cleveana Wittrock was used as an biosorbent for the removal of zinc metal ions from aqueous solutions. Batch experiments were taken out over an agitation time of 0.5-30 min, using 0.1 g of Pithophora Cleveana Wittrock, 30 mL of 20 mg/L of individual metal concentration at pH 5, temperature 303 K and 180 rpm shaking speed. The removal percentage of zinc at the end of 20 min of contact time was then measured. The Central Composite Design (CCD) software was used to design the experiments and determine the optimum conditions. The equilibrium isotherm models Langmuir, Freundlich, Temkin, Redlich-Peterson and Dubinin–Radushkevich (D–R) were employed to analyze the fitness of the equilibrium data. Langmuir isotherm for Zinc with an average higher correlation coefficient of 0.996, followed by D–R, Freundlich, Temkin, and Redlich-Peterson with a correlation coefficient of 0.9484, 0.925, 0.903 and 0.2177 respectively. Confirmatory experiments conducted at the suggested optimized conditions showed experimental findings within 5% of the projected values. From the CCD, the suggested optimum values for metal ion concentration, pH, biosorbent dosage and Zinc removal efficiency were 37.6 mg/L, 5.09, 0.3 g and 78.97%, respectively.