Optimization and modeling of reactive yellow adsorption by surface modified Delonix regia seed: Study of nonlinear isotherm and kinetic parameters

Surface modified activated carbon (Delonix regia seeds) as an adsorbent was prepared and utilized for quick and adequately removing reactive yellow dye from aqueous solution. The adsorbent material was described exploiting Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Batch adsorption study was done to consider the factor affecting parameters (initial reactive yellow dye concentration, solution pH, sorbent dose and temperature). Optimum values of each parameters were calculated as pH of 2.0, temperature of 303 K (30 degrees C), contact time of 60 mins and 2.5 g/L and 1 g/L of adsorbent dosage for RDRS and SMDRS respectively for the removal of reactive yellow dye 145. Adsorption results were displayed to characterize fundamental parameters, for example, the adsorption isotherm and kinetics. The evaluated results are studied with four isotherms models and based on higher R-2 values (0.9515) and lower errors values (SSE-0.46; RMSE-1.888), Freundlich isotherm models were observed to be best fitted. The kinetic model outcomes determined by fitted with contact time data, pseudo-second-order kinetic model shown best-fitted model. The maximum monolayer adsorption capacity (q(m)) value for the reactive yellow removal was found to 24.15 mg/g. Thermodynamic results reveals that the adsorption of reactive yellow 145 dye onto RDRS and SMDRS are spontaneous, exothermic in nature and randomness at the adsorbent-solution interface during sorption process based on its Delta G(o), Delta H-o and Delta S-o respectively. It was exhibited that the unaffectedly modest and good-natured surface modified Delonix regia seeds have a solid adsorption and removal capacity for dyes.