An evidence of bio-adsorption of acid blue dye using neem cake powder: A natural approach for water treatment

Abstract

Normally, the coagulation process is used to remove organic and inorganic pollutants, colloids, and microorganisms present in the domestic and industrial effluents. In this study, a lab-scale experiment is conducted to treat the acid blue-114 textile dyeing effluent with the naturally available indigenous plant-based material such as Neem Cake Powder (NCP) as natural coagulant. The NCP was prepared and characterized by using XRD, UV–Vis spectrophotometer, FTIR, FESEM, EDX and Zeta potential analysis methods. The initial and final characteristics of dyeing effluent like pH, turbidity, total solids (TS), Chemical Oxygen Demand (COD), and colour are tested and compared. For NCP dosage, the maximum removal efficiency of turbidity, COD, TS, and colour at dosage of 2.9g is found to be 96.8%, 79.9%, 89.2%, and 96.7% respectively. When lowering the pH slightly, it enhances the coagulation and sedimentation process with less time, but further reduction in the pH level increases the turbidity and TS than the normal pH condition. The equilibrium adsorption capacity of the coagulant material is studied and the results are fitted with Langmuir, Freundlich, Pseudo-first-order and Pseudo-second-order kinetic models. The experimental results were almost perfectly fitted with Langmuir Linear isotherm with maximum adsorption capacity of 43.48 mg.g−1 and R2 of 0.9993. In this study, it is found that the NCP, an indigenous plant-based coagulant that is locally available and cost effective material can be used as a coagulant for treating the industrial effluent.