Synthesis of nanosorbents from coal fly ash for the uptake of Fe(III) in acid mine drainage and the reuse of the spent nanosorbent in the photocatalytic degradation of ciprofloxacin

Abstract: This study’s main aim was focused on the removal Fe(III) using a nanorsorbent and degradation of ciprofloxacin using the Fe-laden in wastewater. The treatment of acid mine drainage which primarily targeted the removal of Fe(III), which is a problematic element in acid mine drainage as it causes a yellow /orange like slimy substance also referred to as yellow boy. With regards to treatment of ciprofloxacin the spent adsorbent will be used as a reuse application to photocatalytic degradation ciprofloxacin as a precaution to prevent exposure of bacteria to the ciprofloxacin which can cause bacterial resistant to the antibiotic. The treatment method employed in this study was adsorption which utilized a low-cost adsorbent synthesized from coal fly ash that is obtained from power plants. The waste coal fly ash was chemically modified using zinc hexahydrate and physically modified into a zinc-oxide nanosorbent using hydrothermal techniques. The synthesized zinc-oxide nanosorbent and the unmodified coal fly ash were characterized using BET (Brunauer–Emmett–Teller Theory), UV–VIS DRS (diffuse reflectance spectroscopy), SEM (Scanning Electron Microscopy), TGA (Thermal Gravimetric Analysis), TEM (Transmission Electron Microscopy), XRD (X-Ray Diffraction), XRF (X-Ray Florescence), EDS (Energy Dispersive Spectroscopy) and FT-IR (Fourier-Transform Infrared Spectroscopy). The SEM and TEM analysis of the zinc-oxide nanosorbent (ZnO/CFA) indicated light grey spherical-like clustered particles with pores on the surface. The thermal (TGA) and surface (BET) analysis of the zinc-oxide nanosorbent indicated high stability at high temperature and an increased surface area and pore volume of 22.8476m²/g and 0.081598cm³/g respectively. This modification improved adsorption, which produced a 10.6 % adsorption difference as compared to untreated coal fly ash. Furthermore the batch adsorption studies indicated that the zinc-oxide nanosorbent has an adsorption percentage removal optimum of 95.6 %. The effective pH studies revealed that at pH 4 the zinc-oxide nanosorbent was the most effective. Therefor since precipitation can occur at pH 4 the removal of Fe(III) is a combination of precipitation and adsorption. The adsorption kinetics and adsorption isotherms indicated that zinc-oxide nanosorbent followed a pseudo second-order kinetic relationship and a Langmuir relationship respectively...M.Sc. (Chemistry