Removal of Hazardous Crystal Violet from Aqueous Media by Coffee-Husk Biomass: Equilibrium Behavior, Adsorption Kinetics, and Thermodynamic Assessment

Crystal violet (CV) is a cationic triphenylmethane Water-soluble dye which has the ability to persist in aquatic systems and has also been linked to negative health and environmental effects.The paper is a waste coffee husk (WCH) biomass that is examined as a low-cost and renewable biosorbent to remove CV in aqueous media through the batch adsorption experiment carried out at the University of Baghdad.Contact time, initial dye concentration, dose of adsorbent systematically investigated, particle size, initial pH, and temperature were also investigated.The uptake of CV was fast at low contacts and high decolorization was seen in the presence of acid and at ambient temperature.Higher doses of the WCH increased the percentage removal and decreased mass-normalized capacity whereas smaller particle sizes increased the removal since they had more surface area and decreased diffusion length.The higher the temperature the lower adsorption became, which was in favor of an exothermic reaction.Kinetic modelling indicated that the pseudo-second-order model accounted experimentally for the experimental results significantly better than the pseudo-first-order model.Both Langmuir and Freundlich isotherms were in equilibrium over the concentration range studied.The thermodynamic parameters recorded feasibility and spontaneity (negative DG also known as negative DG ), exothermicity (negative DH also known as negative DH ) and increased interfacial randomness (positive DS ).The findings justify the use of WCH as a cheap and non-toxic biosorbent in the process of dye-bearing wastewater remediation.