Process development for the removal of malachite Green dye from wastewater using sewage sludge (STP) as an adsorbent

In the present study, Sewage sludge (STP) was used to develop an effective adsorbent and investigations were carried out for removal of malachite green dye from wastewater. The developed adsorbent was characterized using various techniques such as XRF, FTIR and SEM. Batch studies were carried out for optimization of parameters like contact time, reaction temperature, pH, adsorbent dose and adsorbate concentration. Adsorption data were also correlated with Langmuir, Freundlich, Temkin and Dubinin isotherm models. The Pseudo-first-order, Pseudo-second-order, Intra-particle diffusion and Elovich models were used to describe the adsorption kinetics. The results of batch studies revealed that removal efficiency was 95.7% at optimum experimental conditions of pH 6.0, contact time 120 min, Malachite green dye concentration 10 mg/L and adsorbent dose 10g/L. The results also showed that adsorption increased with an increase in temperature thereby showing the process endothermic in nature. The Freundlich adsorption model and Pseudo-second order kinetics were found to have the highest regression value and hence the fitted well. The results indicated that the sewage sludge could be employed as a low-cost adsorbent for the removal of Malachite green dye from wastewater.