Enhancement of adsorption capacity of clay through spray drying and surface modification process for wastewater treatment

Abstract Nowadays, removal of contaminants like dye from wastewater has become an uncompromising task. In view of this, enhancing the performance of adsorbents so as to facilitate the adsorption technique and reduce the overall cost of the purification process is of great interest to industrial sector. In this study, the adsorption capacity of clay was improved by spray drying a dispersed clay solution and also through its surface modification. Fourier transform infrared spectroscopy (FTIR) confirmed that the surface modification was successful; X-ray diffraction (XRD) analysis showed that surface modification did not affect the crystal structure of the clay, and BET specific surface area results attest that spray dried clay has the highest surface area of 102 m 2 /g. The adsorption tests were carried out using methylene blue and results showed that the adsorption capacity was influenced by solution pH, with maximum adsorption at pH 10 and 120 min contact time. Adsorption kinetics data were well fitted to pseudo-second order kinetics model. Langmuir and Freundlich adsorption isotherm models were used to investigate the mechanism of adsorption. Freundlich model is more applicable for this process. Spray dried clay performed better than the modified and raw clay with adsorption capacity of 168 mg/g (at 333 K). The calculated thermodynamics parameters revealed that the adsorption process is spontaneous at all the studied temperatures (303–333 K) for spray dried clay.