SORPTION KINETICS AND INTRAPARTICULATE DIFFUSIVITIES OF METHYLENE BLUE DYE ON WATER HYACINTH SHOOT..

The kinetics of methylene blue dye towards water hyacinth shoot adsorbent were investigated using three rate models: pseudofirst-order, pseudosecond-order, and Elovich equation. To explore the major sorption mechanism, intraparticle diffusion models such as fractional attainment to equilibrium (FATE), McKay and Poots, Weber and Morris were used. The rate constants (g/mg min) for the pseudofirst-order model were determined to be 1.3 x 10-3, 1.4 x 10-3, 9.0 x 10-4, and 1.0 x 10-3 for adsorbate concentrations of 100 mg/L, 200 mg/L, 300 mg/L, and 400 mg/L, respectively. Sorption capacities were reported to be 13.58 mg/g, 30.20 mg/g, 38.46 mg/g, and 49.35 mg/g at adsorbate concentrations of 100 mg/L, 200 mg/L, 300 mg/L, and 400 mg/L, respectively, using the pseudofirst-order model. For 100 mg/L, 200 mg/L, 300 mg/L, and 400 mg/L, the pseudosecond-order model rate constants were 5.78 x 10-2, 2.27 x 10-2, 2.76 x 10-2, and 1.84 x 10-2 g/mg min, respectively. Sorption capacities were 13.25, 24.21, 27.77, and 30.96 mg/g for adsorbate concentrations of 100 mg/L, 200 mg/L, 300 mg/L, and 400 mg/L, respectively, based on the pseudosecond-order model. The R2 values of the kinetic models utilised revealed that pseudosecond-order was the most highly correlated (at R2=1.000) for all adsorbate concentrations tested. For all concentrations considered, percent removal efficiency increased with time and declined with concentration increase for all timeframes considered. The use of sorption diffusion models revealed that intraparticle diffusion (percent adsorbed) was the most correlated (at R2 = 0.9624), indicating that penetrant or pore diffusion was the primary mechanism. The mass transfer coefficient D rose as the sorbate content increased. Please see the link :- https://www.ikprress.org/index.php/JACSI/article/view/3015