Kinetic, Thermodynamic, and Isothermal Studies on Methylene Blue Adsorption on Jordanian Desert Sand

One of the biggest sources of water pollution is dyestuff manufacturing waste. There are numerous techniques that have been used to clean up contaminated water. Currently, the simplest and most effective approach is adsorption using sand, a cheap, plentiful, and environmentally benign adsorbent. Under several experimental setups, the adsorption of Methylene blue on Wadi Rum desert sand was investigated. Investigations were conducted on the effects of Methylene blue concentration, Wadi Rum desert sand mass used as an adsorbent, contact time, temperature, and pH. The linear versions of the Langmuir, Temkin, and Freundlich isotherm models were used to examine the experimental data, which demonstrated a satisfactory fit with the Freundlich equation for MB adsorption. To evaluate the kinetics of the adsorption process, pseudo-first order, pseudo-second order, and intra-particle diffusion were used. According to the correlation coefficients for each kinetic equation, the pseudo-second order kinetic equation with a correlation coefficient of 0.9999 provided the best fit for the adsorption kinetics. Gibb's free energy (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees), three thermodynamic parameters, were calculated to be -6.345 kJ mol(-1), -23.860 kJ mol(-1), and -60.595 J mol(-1) K-1, respectively, for the adsorption process. These results demonstrate that the MB adsorption on the desert sand of Wadi Rum was exothermic and spontaneous in nature. Additionally, findings from the Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) revealed that methylene blue dye ions were deposited on the sand particles.