Sol-Gel Synthesis of New TiO2 Ball/Activated Carbon Photocatalyst and Its Application for Degradation of Three Hormones: 17α-EthinylEstradiol, Estrone, and ß-Estradiol.

Many approaches have been investigated to eliminate pharmaceuticals in wastewater treatment plants during the last decades. However, a lack of sustainable and efficient solutions exists for the removal of hormones by advanced oxidation processes. The aim of this study was to synthesize and test new photoactive bio composites for the elimination of these molecules in wastewater effluents. The new materials were obtained from the activated carbon (AC) of Arganian spinosa tree nutshells and titanium tetrachloride by the sol gel method. SEM analysis allowed one to confirm the formation of TiO2 particles homogeneously dispersed at the surface of AC with a controlled titanium dioxide mass ratio, a specific TiO2 anatase structure, and a highly specific surface area, evidenced by ATG, XRD, and BET analysis, respectively. The obtained composites were revealed to quantitatively absorb carbamazepine (CBZ), which is used as a referred pharmaceutical, and leading to its total elimination after 40 min under irradiation with the most effective material. TiO2 high content disfavors CBZ adsorption but improves its degradation. In the presence of the composite, three hormones (17α-ethinylestradiol, estrone, and ß-estradiol) are partially adsorbed onto the composite and totally degraded after 60 min under UV light exposure. This study constitutes a promising solution for the efficient treatment of wastewater contaminated by hormones.

Enhanced photocatalytic activity of hydrozincite-TiO2 nanocomposite by copper for removal of pharmaceutical pollutant mefenamic acid in aqueous solution.

Nanocomposites based on hydrozincite-TiO2 and copper-doped HZ-xCu-TiO2 (x = 0.1; 0.25; 0.35) were synthesized in a single step using the urea method. The samples were characterized by XRD, FTIR, SEM/TEM, and DRS. The study of adsorption capacity and photocatalytic efficiency of these nanocomposites have been tested on a pharmaceutical pollutant, mefenamic acid (MFA). Kinetic study of removal of MFA indicates that this pollutant was adsorbed on the surface of the synthesized phases, according to Langmuir's model. Such adsorption proved to be well adapted in a kinetic pseudo-second-order model with capacity of 13.08 mg/g for HZ-0.25Cu-TiO2. Subsequently, the kinetics of photocatalytic degradation under UV-visible irradiation was studied according to several parameters, which allowed us to optimize our experimental conditions. The nanocomposite HZ-0.25Cu-TiO2 showed significant removal efficiency of MFA. Elimination rate reached 100% after 20 min under UV-vis irradiation, and 77% after 7 h under visible light irradiation. Repeatability tests have shown that this nanocomposite is extremely stable after six photocatalytic cycles. By-products of MFA were detected by LC/MS. These photoproducts was produced by three types of reactions of hydroxylation: cyclization and cleavage of the aromatic ring. MFA underwent complete mineralization after 22 h of irradiation in the presence of the HZ-0.25Cu-TiO2.

Determination of dissolved nickel in natural waters using a rapid microplate fluorescence assay method.

A new microplate analytical procedure is described for the determination of nickel (Ni2+) ions in natural water samples. A lophine analogue fluorescent sensor was synthesized and a spectral study showed a selective fluorescence quenching effect of chemical sensor by Ni2+ under optimized conditions. Density functional theory (DFT) calculations confirmed the formation of a Ni(II)L3 complex obtained by the Job plot. The calculations showed that the fluorescence emission peak of L collapses due to the distortion of L in the complex. The simple and fast microplate procedure allowed us to quantify Ni2+ with a linear response from 1.6 to 40 µg L-1 and a quantification limit of 5.4 µg L-1 without the need of a preconcentration step. The optimized procedure using high-throughput microplate assay has been applied for the determination of Ni2+ in natural water samples with good analytical performances.

Nanocomposite material from TiO2 and activated carbon for the removal of pharmaceutical product sulfamethazine by combined adsorption/photocatalysis in aqueous media.

This work was dedicated to the elaboration of new composite materials based on activated carbon and titanium oxide as an ecological solution for the cleaning of water contaminated with pharmaceutical pollutants. Such new composite materials allowed the combining of adsorption and photocatalytic process, which allows a cleaning process that is low cost making them promising materials. The functionalization of the surface of activated carbon (AC) by TiO2 nanoparticles forms the core of the nanocomposite material. This was accomplished using sol-gel process with molar ratios Rn (nTi/nAC) in the range of 1/10 to 7/10 followed by a calcination step (400 °C, N2, 2 h). Using various characterization techniques, AC surface functionalization was confirmed and the formation of a TiO2 coating on the AC was noticed with TiO2 under its unique anatase crystallographic form. The study of adsorption and photocatalytic degradation of the sulfamethazine antibiotic demonstrated that the most photoactive nanocomposite corresponds to the one with Rn = 0.5. Freundlich model was proved to be a perfect fit with the experimental results stating that the adsorption is of multilayer nature on the surface of the adsorbent and with interactions between the pollutants adsorbed on its surface. The photocatalytic degradation of the remaining pharmaceutical pollutant in the solution was evidenced and essentially occurred through the involvement of hydroxyl radicals formed by the excitation of the photocatalyst. The formation of the photoproducts analyzed by the LC/MS technique implies the splitting of the sulfonamide bridge, and by the hydroxylation of the aromatic ring and the pyrimidine group.

Zebrafish toxicity assessment of the photocatalysis-biodegradation of diclofenac using composites of TiO2 and activated carbon from Argania spinosa tree nutshells and Pseudomonas aeruginosa.

The occurrence and persistence of pharmaceutical products (PPs) in the environment have recently been well-documented and are a major concern for public health. Their incidence in aquatic ecosystems is the result of their direct release without any prior treatment or insufficient wastewater treatment. Therefore, an efficient and safe posttreatment process for removing PPs must be developed. In this study, we focused on the ability of photocatalysis or combined photocatalysis and biodegradation to effectively and safely remove diclofenac (DCF) and its by-products from water. The heterogeneous photocatalysis system was based on bio-sourced activated carbon obtained from Argania spinosa tree nutshells and Degussa P25 titanium dioxide (ACP-TiO2), and biodegradation involved Pseudomonas aeruginosa. Toxicity tests were conducted with zebrafish embryos to evaluate the applicability of the treatment processes. The results showed that photocatalytic treatment with 0.1 mg/L of ACP-TiO2 9% for 7.5 h is sufficient to eliminate DCF (50 mg L-1) and its by-products from water. Low levels of malformation (< 20%) were detected in zebrafish embryos treated with photocatalyzed DCF solutions at 1, 5, and 7 mg L-1 after 4 days of exposure. After 3 h of incubation, P. aeruginosa was found to reduce the toxicity of DCF (10 mg L-1) photocatalyzed for 2 and 4 h. Additional studies should be conducted to elucidate the biodegradation mechanism.

Sustainable Construction of Heterocyclic 1,2,3-Triazoles by Strict Click [3+2] Cycloaddition Reactions Between Azides and Alkynes on Copper/Carbon in Water.

1,4-Disubstituted-1,2,3-triazoles, considered as an important and useful class of heterocycles with potential applications in material science and biology, have been prepared in an efficient and selective manner by copper on carbon-catalyzed [3+2] cycloaddition reactions of azides and alkynes (CuAAC) in water under strict click chemistry conditions. Copper(I) catalysts heterogenized onto commercially activated carbon materials (Cu-CC) and on another carbon material produced from vegetable biomass using Argan nut shells (Cu-CANS) were found to be versatile catalytic sources for sustainable CuAAC. These copper on carbon supports were prepared and fully characterized by using two types of activated carbons that exhibit different porosity and specific surface. The delineation of the nature of the catalytic copper species and the role of the carbon support in the CuAAC were addressed. These heterogeneous copper on carbon catalysts were recovered and reused until ten catalytic runs without any noticeable loss of activity.