Montmorillonite Nanoparticles in Removal of Textile Dyes from Aqueous Solutions: Study of Kinetics and Thermodynamics

Dyeing wastewaters are one of the most common pollutants that cause many problems for public health and environment due to dermatitis and skin rashes, cancer production, mutagenesis, etc. Thus, treatment of these wastewaters is necessary. The purpose of this study was to investigate the efficiency of montmorillonite nanoparticles as an adsorbent in adsorption process of Reactive Yellow 15 (RY15) and Reactive Yellow 42 (RY42) dyes from aqueous solutions. In this study, montmorillonite nanoparticles were used to remove RY15 and RY42 dyes. The effect of different variables such as pH, contact time, dye concentration and adsorbent dosage was studied. Finally, the effect of process temperature and thermodynamic was studied. Also, pseudo-first and second orders of kinetics were studied. The results showed that 3 is the best pH for the removal of both dyes. As contact time increases to 15 minutes, adsorption capacity increases and then reaches an approximately constant value. Adsorption capacity was also increased with increased dye concentration. By changing the adsorbent dosage from 0.2 to 0.6 g/L, adsorption capacity for RY15 and RY42 was reduced from 142and 166 to 63 and 59 mg/g, respectively. The results also showed that both dyes had the highest correlation with pseudo-second-order kinetics. The results of analyzing the process thermodynamics and temperature showed that values of DH, DS and DG are negative for both dyes.