2 research outputs found
Removal of wood dyes from aqueous solutions by sorption on untreated pine (Pinus radiata) sawdust
In this work, the possibility of using un-treated pine (Pinus radiata) sawdust as biosorbent for the removal of three wood dyes (blue, red and black) from aqueous solutions was investigated. The BET surface area of the material was 1.55â±â0.81 m2 gâ1 using N2 at ââ196 °C and 17.83â±â0.032 m2 gâ1 using CO2 at 0 °C. The point of zero charge was 4.8. In addition, the material was characterized before and after adsorption by surface analytical techniques. Assays were performed to analize the stability of wood dyes with time and pH and also to estimate the pKa values. Batch adsorption experiments were performed and the influence of experimental parameters such as contact time (up to equilibrium), stirring rate (100 and 210 rpm), adsorbent dose (2â10 g Lâ1), pH (2â9) and initial dye concentration (5 and 300 mg Lâ1) were studied. The optimum conditions were pH 2 and adsorbent dose of 6 g Lâ1 and the highest adsorption percentages achieved at 5 mg Lâ1 were: 100.0% for the blue, 99.7% for the black and 92.4% for the red. For 300 mg Lâ1 adsorption efficiency decreased to 85.6, 57.0 and 63.8% for the blue, black and red ones, respectively. Kinetic data were best fitted to the pseudo-second order model, suggesting a chemisorption process. Freundlich and Dubidin-Radushkevich were the best isotherm models. Regeneration study showed that un-treated pine sawdust could be reused efficiently for red dye removal at least in up to four repeated adsorptionâdesorption cycles using NaOH as desorption agentOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was financial supported by Xunta de Galicia (ED431B 2020/039)S