Kinetics and equilibrium adsorption of iron (II), lead (II), and copper (II) onto activated carbon prepared from olive stone waste

Abstract

The adsorption of heavy metals Fe²⁺, Pb²⁺, and Cu²⁺ onto olive stone activated carbon (OSAC) was investigated in this study. The effects of different reaction parameters (i.e. adsorbent dosage, contact time, shaking speed, and initial pH) on the pollutant removal efficiency were determined. The adsorption processes of Fe²⁺, Pb²⁺, and Cu²⁺ were effectively explained using Langmuir and Freundlich isotherms. OSAC efficiently removed 99.39% Fe²⁺, 99.32% Pb²⁺, and 99.24% Cu²⁺ at pH 5 and with 200 rpm shaking speed. The adsorption equilibrium data were best represented by the Langmuir model, and the monolayer adsorption capacities were found to be 57.47, 22.37, and 17.83 mg/g for Fe²⁺, Pb²⁺, and Cu²⁺, respectively. A pseudo-second-order model sufficiently described the adsorption kinetics, which indicated that the adsorption process was controlled by chemisorption. The results revealed that OSAC can be used as a low-cost adsorbent for the treatment of wastewaters contaminated by heavy metals.