Adsorptive removal of direct yellow 161dye from aqueous solution using bamboo charcoals activated with different chemicals

The adsorption of direct yellow 161 dye from aqueous solution on derived bamboo charcoals activated with orthophosphoric acid, nitric acid, potassium hydroxide and zinc chloride was investigated. Batch adsorption results showed that under optimal sorption condition including initial dye concentration 24.62 mg/L, pH 1.0, contact time 21 h, and temperature 298 k the maximum and the minimum adsorption capacities were 2.401 mg/g and 1.705 mg/g for bamboo charcoals activated with orthophosphoric acid and with potassium hydroxide, respectively. Avrami kinetic model provided the best fit to experimental data compared with Elovich, pseudo-first-order, pseudo-second-order and intra-particle diffusion models. Fitting of the equilibrium data using Langmuir, Freundlich, Jovanovic, Khan and Koble-Corrigan isotherm models indicated that Koble-Corrigan model was the best and three-parameter models gave better fitting than two-parameter models did. Thermodynamic parameters revealed that the adsorption process was spontaneous and endothermic with a physical nature. Compared with the other activated bamboo charcoals the bamboo charcoal activated with orthophosphoric acid was the best adsorbent for removal of direct yellow 161 dye.

Research highlights
► The bamboo charcoal activated with H3PO4 exhibited more effective removal of DY-161 than those with KOH, HNO3 and ZnCl2.
► The kinetic data were well described by Avrami model and intra-particle diffusion model.
► The Koble-Corrigan model was the best fitting for the isotherm results.
► The adsorption was a typical physical process, spontaneous and exothermic in nature.
► The OBC could be used as an economical adsorbent to remove DY-161 dye from aqueous solution.