Bio sorption of textile dyes from aqueous solution onto three different pine barks: kinetics and isotherm studies

The main objective of the present study is to evaluate the sorption capacities of some natural raw materials of vegetable origin for the treatment of the sewage coming from the textile industry. The selected barks are: maritime pine (MP), pine pinion (PP) and Aleppo pine (AP) bark. The effectiveness of these barks was evaluated in the removal of three dye; rhodamine B (RhB), Green Malachite (GM) and Methyl Orange (MO). Initially, the effects of some parameters such as the nature of the adsorbents, the nature of the dyes and the pH were studied. Obtained results reveals that the speed sorption is strongly influencing by the pH medium and the comparative study shows that the adsorption is favourable in the acidic medium with a sorbed amount of (Q=40mg/g) for rhodamine B. The results of the biosorption kinetics reveal that the GM molecules are better biosorbed (Q=48 mg/g) than those of RhB (Q=46 mg/g) and methyl orange (Q=18mg/g), with an equilibrium time of 6 hours. The results of the biosorption isotherms show clearly that the maritime pine bark is the most effective biosorbents with sorbed amount of (QRhB=200mg/g) and (QMO=88mg/g) followed by pignon pine (PP) with (QRhB=184mg/g) and (QMO=56mg/g) and finally Aleppo pine (AP) bark with (QRhB=131mg/g) and (Qmo=46mg/g). All obtained isotherms are modeled using the Langmuir and Freundlich models. According to the adjustment coefficient values R2, corresponding isotherms are well represented by Freundlich model.