Adsorption of crystal violet dye from wastewater on <i>Phyllanthus emblica</i> fruit (PEF) powder: kinetic and thermodynamic
Hira Urooj, Tariq Javed, Muhammad Babar Taj, Muhammad Nouman Haider
Abstract
This research focused on removal of cationic crystal violet dye using Phyllanthus emblica fruit (PEF) powder (as an adsorbent) from wastewater. Operational parameters such as solution pH, adsorbent dose, contact time, dye concentration, as well as temperature were optimised. Results showed that maximum amount of dye, i.e. 84%, has been adsorbed at optimised condition employing particles of mesh sizes 510 µm, at 12 pH, adsorbent dose of 0.4 g, with contact time of 30 min, having dye concentration of 20 ppm at 20°C temperature. Characterisation of adsorbent was done by FTIR and SEM techniques which confirmed the involvement of carboxylic as well as hydroxyl functional groups in dye adsorption, and heterogeneous, highly porous surface (which were occupied after dye adsorption) of adsorbent which favours dye adsorption. Concentration and contact time data of study was applied to various isotherms and kinetic models respectively and investigation of the best fitted model of was carried out. It was found that Freundlich isotherm model (with R2 = 0.986) and pseudo-second-order kinetic model (with R2 = 0.986) was best fitted to experimental data. Thermodynamic study revealed value of ΔG varied from −29.495 to-33.610 kJmol−1 and ΔH was 6.175 kJmol−1 confirming that the process was spontaneous and endothermic in nature. Applicability of current procedure with tap water showed 74% results, and regeneration showed that nearly 79% of dye was desorbed, indicating the effectiveness of Phyllanthus emblica fruit (PEF) powder for adsorptive removal of crystal violet dye from wastewater.