Adsorptive removal of doxycycline from aqueous solutions by unactivated carbon and acid activated carbon brewery waste grain

This study investigates the adsorptive characteristics of unactivated carbon (UC) and acid activated carbon (AAC) Brewery waste grain BSG for effective DOX removal from aqueous solutions. Batch adsorption experiments were carried out to investigate the sorption behaviour of DOX-adsorbent systems with varying adsorbent doses and initial DOX concentrations. The possibility of mass transfer resistance was examined to improve the diffusion rate, while kinetic aspects were investigated to produce thermodynamic equilibrium for the proposed adsorption process. The degree of ionization of the functional groups of the adsorbate was discovered to have a significant impact on adsorption efficiency. Under optimal reaction conditions, all DOX-adsorbent systems removed more than 90% of the DOX. Before and after adsorption, the shape and functional groups of the adsorbents were investigated. In a kinetic examination, the pseudo-second order kinetic model with normalized standard deviation Dqt (percent) 5% and regression coefficient R2 0.94 was demonstrated to be more capable of representing kinetic data than the pseudo-first order and elovich kinetic models. For the adsorbate-adsorbent interaction, the applicability of Langmuir and Freundlich isotherms for the proposed adsorption process was examined. DOX had the highest maximum adsorption capacity qm (0.8576 mgg^-1 and 0.8216 mgg^-1) when using UC and AAC, respectively. Based on the results of thermodynamic studies, the hypothesized process was demonstrated to be exothermic and spontaneous. This study can help better understand industrial waste management as well as an environmentally friendly technology for eliminating DOX from pharmaceutical waste water.