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Photocatalytic degradation using TiO2 is one of the most effective techniques for treating residual emerging compounds present in water. However, practical applications are limited since it only absorbs ultraviolet irradiation. Nitrogen and sulfur (N, S) co-doped TiO2 nanomaterials (N,S-TiO2) were prepared by a controlled sol–gel method; the characterization and photocatalytic activity have been studied for the removal of ciprofloxacin antibiotic under UV–Visible light. The interstitial doping of nitrogen and sulfur substitute oxygen and titanium into the TiO2 lattice, which increases the valence band and decreases the conduction band, respectively. The lowest value band-gap of 2.5 eV and the crystallite size of 5.13 nm compared to other available synthesis methods was observed on N,S-TiO2 which allowed to broaden the light absorption to the visible region. The low level electron and hole recombination was related by the N, S doping. The optimal ciprofloxacin removal was obtained at pH 5.5, a dosage of 0.05 g, initial concentration of 30 mg L−1 with a removal efficiency of 78.7%. A comparison of the effectiveness of antibiotic treatment of N,S-TiO2 with synthetic TiO2 and commercial TiO2 was also made, taking the potential for regeneration into account. The photocatalytic degradation of ciprofloxacin catalyzed by N,S-TiO2 was described by pseudo-first-order kinetics. [ABSTRACT FROM AUTHOR]

N,S-TiO2 deposited on three kinds of pre-treated sugarcane bagasse was synthesized via a sol–gel method. The obtained composites were characterized by various techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and photoluminescence spectroscopy (PL). UV-visible induced degradation of ciprofloxacin was investigated. The influence of some experimental parameters such as contact time, pH, dosage, and initial concentration on the efficiency of ciprofloxacin elimination was also evaluated. The highest efficiency was observed for the alkaline pre-treated sugarcane bagasse combined with N,S-TiO2, about 86% under optimal conditions (contact time 150-min irradiation, pH 5.5–6, dosage 0.5 g L−1, and the initial concentration CIP 30 ppm). There may be a rapid ciprofloxacin transition from the adsorption site to the photocatalytic site, and the alkaline pre-treated sugarcane bagasse/N,S-TiO2 prevented the recombining of holes and electrons of the photocatalyst. Furthermore, the alkaline pretreatment sugarcane bagasse/N,S-TiO2 composite material was sustainable, with only a 10% reduction after reusing the material three times. The presence of sugarcane bagasse made the material easy to recover from the liquid phase. [ABSTRACT FROM AUTHOR]

This study investigated the effect of 3 biochar application rates (1%, 5%, and 10%) on the pH, surface charge, and bioavailability of Cu, Pb, Zn on a degraded Acrisols soil and their accumulation in water spinach (Ipomoea aquatica). After an incubation period of 28 days, a titration experiment confirmed that increasing the biochar application rates enhanced the negative charge along with an increased pH. In an experiment spiked with metals, the 0.01 M CaCl2-extractability of the metals after incubation significantly decreased with the increasing rate of biochar additions. This is mostly attributed to a rise in the soil pH and an increase in the negative charge as result of the biochar additions. Metal extractability continued to decrease over the next 1,344 h, most probably due to the aging effect. Immobilization speeds exhibited in the order Pb>Cu>Zn, can be partially attributed to the bigger ionic radius of Pb compared to those of Cu and Zn. By the end of incubation period, extractable Cu, Pb and Zn was significantly reduced, irrespective rates of biochar application 1%, 5% or 10%. In a greenhouse experiment, water spinach was unable to grow in the 10%biochar addition because of a high alkaline pH of 9.2. The Cu, Pb, and Zn concentrations and bioaccumulation factor in the grown water spinach decreased along with the increasing biochar application rates in the order 5%>1%>0%, showing a good agreement with the 0.01 M CaCl2-extractable concentrations. The bioaccumulation factors of Pb were far less than those of Cu and Zn, reflecting the immobilization speeds as concluded in the incubation tests. Therefore, biochar amendment into degraded soil for metal immobilization is feasible, provided the appropriate rate for crop growth is applied. [ABSTRACT FROM AUTHOR]