Methylene blue removal from aqueous solutions by activated carbon prepared from N. Microphyllum (AC-NM): RSM analysis, isotherms and kinetic studies

Abstract

This study was conducted to remove Methylene Blue (MB) from aqueous solution using activated carbon prepared from N. microphyllum (AC-NM) as a new, cheap, and nontoxic. Design of experiments based on Response Surface Methodology (RSM) conducted to investigate the effect of variables namely; initial dye concentration, pH, contact time and absorbent dosage. An empirical model was developed applying ANOVA analysis. The interaction effects of all factors and their optimization have been carried out using RSM. Dye removal efficiency increased to more than 90% with increasing pH and initial concentration of dye from 3 to 11 and 10 to 210 mg/L, respectively under 1.1 to 1.4 g/L of absorbent dosage. Among factors, initial concentration of MB known as an important factor with P-value <0.0001. The experimental data are fitted with Freundlich model based on multilayer adsorption states (R2=0.99). The adsorption kinetics well described by second order model with R2 = 0.98. This novel absorbent has different advantages such as low cost, high ability to absorb pollutants and easily available that can be suggested for water and wastewater treatment.