Decolourization of cationic and anionic dyes from aqueous solution by adsorption on NaOH treated eggshells: Batch and fixed bed column study using Response Surface Methodology

In this study,we investigated the adsorption of methylene blue (mb) and acid orange 7 (ao7) dyes on a natural adsorbent,we have selected a food derivative product (eggshells) treated with naoh (tes) as a new and potential biosorbent. different models of adsorption isotherms in batch study were applied to fit experimental equilibrium data at different solution temperatures; langmuir and temkin model fitted the adsorption data quite reasonably (r2 > 0.98). results have showed that the adsorption of mb on tes dye followed very well the second order kinetic model. the thermodynamic parameters were evaluated; the negative values of δh° and δg° indicated respectively that the adsorption of mb onto tes was exothermic and spontaneous process. the continuous method was modeled by response surface methodology (rsm) . the effect of operating parameters such as flow rate,initial dye concentration,and bed height were exploited in this study. the precision of the equation obtained by box-behnken design (bbd) utility for modeling and optimization by response surface methodology rsm was confirmed by the analysis of variance (anova). the optimum conditions proposed by box-behnken design (bbd) to reach the maximum dye removal through adsorption process. under the optimum conditions,the removal efficiency ofao7 was 89.89%. in summary,the results have established good potentiality for the waste eggshell particles to be used as a sorbent for the removal of mb from wastewater in batch study and were shown to be suitable adsorbent for adsorption of ao7 using fixed-bed adsorption column. © 2017,university of mohammed premier oujda morocco.