Use of activated carbon from date seeds to treat textile effluent

Abstract

Treatment of wastewater is one of the major problems faced by textile manufacturers because of involvement of many complicated process and chemicals used throughout the production. The possible utilization of Date seeds activated carbon as an adsorbent for the removal of color and COD from aqueous solution has been investigated. In this study, activated carbon prepared from Date seeds has been activated using zinc chloride solution. Systematic batch mode studies of removal of color and COD on Date seeds activated carbon were carried out as a function of process parameters including initial concentration, dose of adsorbent, contact time, agitation speed, temperature, particle size and pH. Freundlich and Langmuir adsorption isotherm models were used to explain obtained data. Both the isotherms were found to be fitted well; but Freundlich isotherm fitted better. The linear regression coefficient R2 was used to reveal the best fitting of Freundlich isotherm model (R2≈ 0.999).The monolayer (maximum) adsorption capacity (qm) for color was found 500 Pt-Co (per gram of adsorbent per litre) and for Date seeds activated carbon. The dimensionless separation factor (RL) indicating favorability of adsorption that lies between 0.284 to 0.581 denotes a favorable adsorption for Date seeds activated carbon. Langergen pseudo first order and second order model were used to explain the kinetics of adsorption. Langergen pseudo second order model fitted better the kinetics of adsorption (R2 = 0.999, qe(theoretical) ≈ qe (exprimental)). Intra particle diffusion model showed both external film and intra-particle pore diffusion mechanism were involved in the adsorption of color onto Date seeds activated carbon; either of the two (i.e., film diffusion or pore diffusion) or both might be the rate controlling. Adsorption was found to be increased with increasing temperature, contact time, dosage of adsorbent, agitation speed, pH and decreasing particle sizes. Thermodynamic analysis showed negative value of ΔG indicating favorable and spontaneous adsorption, positive value of ΔH indicating endothermic physical adsorption and positive value of ΔS indicating increased disorder as randomness at the solid-liquid interface of adsorbate with Date seeds activated carbon adsorbent.