Kinetics and thermodynamic studies for removal of acid blue 129 from aqueous solution by almond shell

Efficiency and performance of almond shell (as) adsorbent for the removal and recovery of acid blue 129 (ab129)from wastewater is presented in this report. the influence of variables including ph, initial dye concentration,adsorbent dosage, particle size, contact time and temperature on the dye removal have been investigated in batchmethod by one at a time optimization method. the experimental equilibrium data were tested by four widely usedisotherm models namely, langmuir, freundlich, tempkin and dubinin-radushkevich (d–r). it was found that adsorptionof ab129 on as well with the langmuir isotherm model, implying monolayer coverage of dye molecules onto thesurface of the adsorbent. more than 98% removal efficiency was obtained within 14 min at adsorbent dose of 0.4 gfor initial dye concentration of 40 mg/l at ph 2. kinetics of the adsorption process was tested by pseudo-first-orderand pseudo-second-order kinetics, and intraparticle diffusion mechanism. pseudo-second-order kinetic model provideda better correlation for the experimental data studied in comparison to the pseudo-first-order model. calculation ofvarious thermodynamic parameters such as, gibb’s free energy, entropy and enthalpy of the on-going adsorptionprocess indicate feasibility and endothermic nature of ab129 adsorption on all adsorbents. this work can be used indesign of adsorption columns for dyes removal.