GRAPHENE-MAGNETITE AS EFFICIENT ADSORBENT FOR REMOVAL OF LEAD FROM INDUSTRIAL WASTEWATER

<strong>Abstract</strong>: Wastewater from industry can lead to water pollution if not treated, especially due to its high concentration of lead. Lead is considered extremely harmful because it can cause illnesses, disorder and diseases to human. Therefore; industrial wastewater containing lead should be treated before it is discharged to the water stream. There are several techniques to remove lead from wastewater such as biosorption, filtration and adsorption but there are some limitations such as long treatment time. In this study, the adsorption of lead from synthetic wastewater by RGO/Fe3O4 was investigated. The effect of different environmental conditions such as adsorbent dosage, initial lead ion concentration, contact time, shaking speed and pH on lead ions removal was studied by at a temperature of (25 ± 1 oC). Experimental results showed that maximum removal of lead ion by graphene-magnetite at optimum conditions (0.125 g adsorbent dose, 15 mg/L of initial Pb (II) concentration, 60 min contact time, 200 rpm shaking speed and pH 6), was 99.72 %. These experimental studies on adsorbents can be quite useful in developing an appropriate technology for the removal of toxic metals from contaminated industrial effluents. The adsorption data of lead ions at a temperature of 25 ± 1 °C have been described by the Langmuir and Freundlich isotherm models. The sorption process conformed to both Langmuir and Freundlich isotherms with correlation coefficient (R2) of 0.999 and 0.9499, respectively. Sorption kinetics was determined using pseudo-first-order and pseudo-second-order with maximum sorption capacity of 10.9896 and, hence adsorption rate constants were calculated to be (0.1154 and 0.04936 min-1), respectively. The results revealed that sorption kinetics of the metal followed pseudo-second-order with regression coefficients of 0.9991. The results showed, graphene magnetite reduced lead ions from its initial concentration of 15 mg/L to 0.042 mg/L and the removal efficiency was 99.72 %. In addition, the performance of graphene magnetite for removal of Pb from wastewater was found to be 99.65 %.