Removal of tetracycline from the aquatic environment using activated carbon: A comparative study of adsorption performance based on the activator agents

This research focus endeavour to compare the remediation of tetracycline (TC) through activated carbon (AC), crafted utilizing two distinct chemical activators: zinc chloride (ACZ), and potassium hydroxide (ACK), using pine cone biowaste as an effective carbon precursor, followed by microwave-assisted activation. The impact of TC removal by ACZ and ACK adsorbents was thoroughly examined. The influence of pH, adsorbent mass, adsorption isotherms, kinetics, and inclusive thermodynamics were studied. Our results revealed that the interaction between TC and ACZ or ACK adsorbents aligned well with the model of pseudo-second-order kinetics, whilst the Langmuir model fitted the adsorption isotherm data of ACZ and ACK. The ACZ have a maximum adsorption capacity of 327.87 mg/g compared to that of the ACK (283.29 mg/g). Adsorption of TC was facilitated by the suitable pore volume, abundant microporous, and mesoporous structure of these adsorbents. The ACZ adsorbent is abundant in oxygen-containing functional groups, compared to ACK with minimized reactive sites, in bonding with the TC molecules through hydrogen bonding, for faster removal of TC. Our finding from this work further highlights that the synthesized ACZ from pine cones evidenced significant environmental potentials in the elimination of antibiotics from aqueous solution, to promote clean application perspectives.