Biosorption of amaranth red in aqueous solution onto treated and untreated lignocellulosic materials (pineapple peelings and coconut shells)

The removal of amaranth red dye from aqueous solution by untreated and treated pineapple peelings and coconut shells with phosphoric acid was studied in batch mode at room temperature. the study highlighted several parameters such as the contact time,the mass of the adsorbent,the ph of the solution,and the initial concentration of the dye. the results showed that the removal of dyes by the bioadsorbents depended on the ph and the initial concentration of the adsorbate. the adsorption capacity increased with increasing amaranth red dye concentration and the mass of the bioadsorbent. it was also established that maximum adsorption took place at ph = 2 for different adsorbents. the treated raw materials have greater surface area than the untreated materials. in order to deduce the adsorption mechanism,four simplified kinetic models were investigated. the kinetic data were well represented by the pseudo second order kinetic model giving high correlation coefficients r2 values for all the biosorbents suggesting that chemisorption was the rate determining step. an equilibrium study of the adsorption process also showed that the langmuir model best described the adsorption on all the biosorbents. the values of energy obtained from the temkin isothermare also positive,this shows that the adsorption process isexothermic. these results indicate that pineapple peelings and coconut shells have a high potential as adsorbents for removing amaranth red dye from aqueous solution. © 2017,university of mohammed 1er oujda morocco.