Background: The adsorption process is one of the most effective methods for removal of dyes from wastewater. The main aim of the present study was to investigate the efficiency of hydrated cement as an adsorbent for removal of Direct Yellow 12 dye from aqueous solutions.
Methods: This study was performed experimentally in laboratory scale and in a batch system. The effects of initial dye concentration, absorbent dosage, contact time and pH on efficiency of dye removal were investigated. SEM, XRD and FT-IR were used to characterize the hydrated cement powder particles. Langmuir and the Freundlich adsorption isotherms were selected to explicate the interaction between the dye and adsorbent. The pseudo-first and the pseudo-second-order kinetic models were used to calculate the adsorption rates.
Results: The results showed that by increasing the adsorbent dose from 0.05 to 2 g/l, dye removal efficiency increased from 31.1 to 97.43%. The highest dye removal efficiency (87.33%) was obtained at pH= 1. By decreasing initial dye concentration from 60 to 5 mg/l, dye removal efficiency increased from 50.79% to 68.94%. The appropriate time period to get maximum dye adsorption was 180 min. The results also showed that the adsorption of dye followed the Freundlich isotherm model (r2= 0.99) and adsorption kinetics of the dye followed a pseudo-second-order model (r2= 0.99).
Conclusion: Compared to other costly methods of dye removal, hydrated cement powder can be used as an efficient and low-cost adsorbent for the removal of dye from aqueous solutions
