Efficient adsorbent derived from Haloxylon recurvum plant for the adsorption of acid brown dye: Kinetics, isotherm and thermodynamic optimization

The capacities, mechanisms, and potential of low-cost Haloxylon recurvum stem (HRS) biomass for sorption of acid brown 354 dye (AB354) from waters were studied. Fourier transformed infrared spectroscope (FTIR), scanning electron microscope (SEM), thermal analysis (TGA) and elemental analyzers were utilized for the characterization of biomass before and after sorption of dye. There was an enhancement in adsorption capacity with increasing the dye concentrations. With an increase in the initial dye concentration, the increase in the sorption capacity of the biomass was noticed (i.e. 2.846 mg/g – 10.011 mg/g). The extent of removal of dye decreased with the increase in temperature (i.e. 77.7% to 52.9%) and the particle size of the biomass (i.e. 81.3% to 36.6%). Ho's pseudo-second-order kinetic model (χ² = 0.0679361), as well as Langmuir (χ2 = 1.05637 × 10–12) and Temkin sorption isotherms (χ2 = 1.36752 × 10–12), were well in line with the sorption data and best represented the equilibrium sorption of the dye. Negative Gibb's free energy value ∆G (-3.616–-0.333) and enthalpy ∆H^o (-24.826) values were the indication of spontaneous, as well as feasible and exothermic nature of the sorption process. The investigations demonstrated that HRS biomass was an attractive and potential material for removal of acidic dye from dyed effluents than many others reported in the literature.