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In this work, significant interest has been focused on removing pharmaceutical pollutants, i.e., oxytetracycline (OTC), which was studied through adsorption onto activated carbon (ACT) produced from households or agricultural wastes under various experimental conditions. The physicochemical properties of the produced carbon were investigated using multiple techniques. The characterization analysis highlighted an essential concentration of surface functional groups and a very developed porous structure. The adsorption process onto activated carbon occurs with a high yield at a large range of pH values varying between 4 and 8 at an optimum contact time of 2 h. It was established that the pseudo-second-order kinetic model fitted well OTC adsorption onto ACT. Moreover, the adsorption isotherm data showed that the pollutant removal process followed the Langmuir model with high regression coefficients ($R^2$) values and important adsorption efficiency of 80% for $100~\text{mg}{\cdot }\text{L}^{-1}$ of OTC. The displayed results consequently, the use of ACT as an adsorbent could be considered an efficient, sustainable, and low-cost alternative for pharmaceuticals-loaded wastewater treatment.

Sillenite catalysts have shown efficient photocatalytic activity for the removal of various pollutants from water in previous studies, thus enhancing their activity by combining them with other materials will be very promising for environmental applications. In this context, an interesting hybrid system containing Polyaniline (PANI) as an adsorbent and Bi12TiO20 (BTO) sillenite as a catalyst was proposed in this work. Cefixime (CFX) has been selected as a pollutant for this study, and its removal was evaluated using PANI (adsorption), PANI and BTO (combined system) and the hybrid system Bi12TiO20/Polyaniline (BTO/PANI). First, the impact of PANI adsorption was investigated on its own; after that, the solution was filtered to separate the adsorbent from the liquid in order to re-treat the solution using photocatalysis (combining adsorption with photocatalysis). At the same time, a similar technique was used involving the hybrid system BTO/PANI. The results show that the hybrid system can remove a very high Cefixime concentration of 30 mg/L, almost 100%, within only 2 h, and this is better than previous investigations. These results indicate that it is possible to combine photocatalysis and adsorption processes to control water pollution. [ABSTRACT FROM AUTHOR]

This research attempted to synthesize a photocatalyst with a narrow bandgap and to investigate the possibility of using it to remove dyes from wastewater. The spinel CuCr2O4 (CCO) was selected as a topical catalyst as it showed interesting proprieties in previous studies. The catalyst CCO has been synthesized using the sol–gel method and used to degrade Sunset Yellow (SY) in a stirred reactor. Before starting, the phase was identified by X-ray diffraction (XRD) and Fourier transform infrared (FTIR). Rietveld structure refinement (RSR) and the maximum entropy method (MEM) were used to derive accurate electron-density distributions of CCO from X-ray diffraction results, as well as to study the crystal and electronic structures. An orthorhombic structural phase with space group Fddd was observed for CCO. The morphology of this spinel was investigated using a scanning electron micrograph (SEM) and transmission electron microscope (TEM). The optical properties were measured using Diffusion reflectance spectroscopy (DRS) and an optical gap band of 0.9 eV was determined. After characterization, the photocatalytic activity of CCO was investigated for SY degradation. The effect of pH, catalyst dose and initial concentration (Co) on photocatalytic degradation was investigated. A degradation efficiency of 97% was achieved for 4 h under optimal conditions (pH 4, catalyst dose 0.8 g/L, Co 10 ppm). Highlights: The spinel CuCr2O4 spinel has been synthesized by the sol–gel method. An orthorhombic structural phase with space group Fddd was observed for CuCr2O4. An optical bandgap of 0.9 eV was found for this semiconductor. Efficient degradation of sunset yellow dye around 97% has been recorded using this catalyst. [ABSTRACT FROM AUTHOR]