Adsorption of anionic dye (Reactive black 5) using macadamia seed Husks: Kinetics and equilibrium studies

Adsorption of Reactive black 5 dye currently used in textile industries was investigated using Macadamia Seed Husks (MSH) from a local Macadamia nut processing industry. Adsorption increased with increase in contact time, adsorbent dose and dye concentration. Conversely, the percentage dye adsorbed decreased with increase of solution pH and size of MSH particles. Sorption increased with an increase in temperature signaling an endothermic process. Batch adsorption data best fitted to Freundlich adsorption isotherm model with Kf value of 4.20679 and n = 2.3375. The adsorption kinetics followed a pseudo-second-order kinetic model with high correlation coefficients (R2 > 0.98). These results demonstrated that MSH is an environmentally friendly, locally available, effective and economical adsorbent for the removal of RB5 dye from industrial wastewaters.