Upcycling of spent granular carbon into sustainable and recyclable biopolymeric hybrid hydrogel for highly efficient adsorptive removal of tetracycline pollutant from environmental waters and industrial effluents

Abstract

In this study, sustainable and recyclable biopolymeric composite hydrogel was prepared by incorporating activated carbon (AC) into the alginate matrix for the effective removal of emerging pollutants (pharmaceutical) in industrial wastewater and environmental water samples. The activated carbon was prepared from upcycling of spent granular carbon of reverse osmosis (RO) plant via simple physicochemical methods. The surface morphology of prepared composite hydrogel (AC-SGC@SA-HHB) was examined by Scanning Electron Microscope (SEM) while examination of surface area and porosity were characterized through BET (Brunauer-Emmette-Teller). The FTIR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) were done to know the surface functionality and existence of elements in materials respectively. The crystalline nature of the designed hydrogel was studied by XRD (X-ray diffraction) and the adsorption capacity of pollutant tetracycline (TC) was analysed by UV–visible spectrophotometer with respect to adsorption capacity and percentage removal. The maximum adsorption capacity of TC was calculated by the Langmuir adsorption isotherm model is 166.66 mg. g-1. The effect on adsorption capacity of AC-SGC@SA-HHB was studied by several experimental variables including concentration of pollutant, adsorbent dose, pH and contact time of pollutant with adsorbent. The recyclability of AC-SGC@SA-HHB was studied with various aqueous reagents and warm water was found to be one of the greener solvents and last long up to ten cycles (50% removal of TC). Furthermore, versatility of the AC-SGC@SA-HHB for diverse organic (dyes) and inorganic pollutants (ions) were evaluated under identical experimental conditions. Practicability of AC-SGC@SA-HHB for removal of TC from real water sources (River, Pond and Tap) and industrial effluents was also checked by standard addition method.