Peach palm and cassava wastes as biosorbents of tartrazine yellow dye and their application in industrial effluent

Abstract

In this study, the wastes from cassava (CAW) and peach palm (PPW) agro-industries were investigated as potential low-cost biosorbents for removing the tartrazine yellow dye (TAR). The by-products were prepared by washing and drying steps and characterized into physicochemical parameters and microstructure. The effects of contact time, pH, dosage and dye concentration were analyzed for the biosorbents in comparison to commercial activated carbon (AC). The biosorbents were applied to the treatment of an effluent from a juice industry containing TAR. Cellulose was the main component of the biosorbents (31.47–51.20 g 100     g^-1), which was correlated to the functional groups identified by ATR-FTIR spectra and the materials had a porous surface. The zero point of charge was 3.75 for PPW and 4.60 for CAW. The pH parameter had a significant effect on the adsorption process, with the maximum values of adsorption being reached at pH 2.0, with removal of 94.7% for PPW, 74.4% for CAW and 97.7% for AC, at the dosage of 7.5 g L^-1 at 25.0 ºC. The adsorption of TAR was fast in the early stages, and at 120 min the three adsorbents reached the equilibrium. Isotherms of adsorption showed that Langmuir’s and Freundlich’s models fitted the best to the CAW and PPW experimental data, respectively. The wastes evaluated in this work can be an interesting alternative to TAR adsorption in the industrial effluent without being subjected to chemical treatments.