Adsorption of doxycycline hydrochloride onto powdered activated carbon synthesized from pumpkin seed shell by microwave-assisted pyrolysis

In the present study, pumpkin seed shell activated carbon (PSSAC) was efficiently synthesized via microwave-assisted pyrolysis technique, employing pumpkin seed shell as the precursor and H3PO4 activator. The adsorptive performance of PSSAC was quantified for decontamination of water from a doxycycline hydrochloride (DOX) antibiotic. Prepared PSSAC was characterized to determine its chemical and morphological characteristics employing FTIR, XRD, FESEM and zeta potential. Surface area and pore size distribution were evaluated with the help of BET and BJH characterization techniques respectively. The effect of relevant process parameters like solution pH, PSSAC dose, contact time and temperature were assessed to get the optimum experimental conditions. The kinetic and isotherm studies reveal that the adsorption process is performed via pseudo-second-order reaction and multilayer adsorption. The calculated thermodynamic parameters (Delta H-O,Delta S-O and Delta G(O)) represented that the adsorption of DOX onto PSSAC was endothermic, instinctive and practicable in the temperature extent of 288-318 K. Moreover, the investigation about adsorption mechanisms resulted that H-bonding and pi - pi electron-donor-acceptor (EDA) interactions heavily affected DOX adsorption over PSSAC. The maximum identified adsorption capacity value was 23.6 mg/g at 318 K. Good regeneration capability and high adsorption capacity of PSSAC represents its excellent potential to alleviate emerging contaminants from wastewater. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study successfully synthesized pumpkin seed shell activated carbon (PSSAC) using microwave-assisted pyrolysis technique for decontamination of water from antibiotic pollutants. The PSSAC showed excellent adsorption performance for DOX, with high adsorption capacity and good regeneration capability within a certain temperature range.