In this work, CoTiO 3 /TiO 2 (CTO/Ti) heterostructures were prepared by a hydrothermal procedure in a neutral medium using perovskite CoTiO 3 and tetraisopropyl titanate. Characteristics of the synthesized catalysts were analyzed by various techniques including X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, UV−vis diffuse reflectance spectroscopy, Brunauer−Emmett−Teller adsorption−desorption, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and point of zero charges. The activity in the photodegradation of cinnamic acid (CA) under UV-A irradiation of the CTO/Ti heterostructure was investigated and compared with individual materials TiO 2 (Ti-w) and CoTiO 3 (CTO). The investigation showed that the heterostructured CoTiO 3 /TiO 2 catalyst with optimal composition (5% CTO) exhibited much higher photocatalytic activity for degradation of cinnamic acid than individual CoTiO 3 and TiO 2 . Under the optimal conditions (C cat = 0.75 g/L, Q air = 0.3 L/min, and pH = 3.8) the 90 min conversion of cinnamic acid reached 80.9% on 5CTO/Ti, much higher than those of CTO (4.6%) and Ti-w (75.2%). It was found that the enhancement in activity for the CA removal of the CTO/Ti heterostructure was due to the construction of a heterojunction structure between TiO 2 (Ti-w) and CoTiO 3 that resulted in an increase in the specific surface area and porosity, reduction of the band gap energy, and higher efficient separation of charge carriers on the surface to prevent recombination. Alternatively, a comparison of the recyclability of 5CTO/Ti and Ti-w was made for CA degradation. The results showed a decrease in the CA conversion by 38% on 5CTO/Ti and 48% on Ti-w after six reaction cycles.

In the current study, using Cleistocalyx operculatus bud extracts to synthesize silver nanoparticles is considered a novel, eco-friendly, and low-priced process that advances chemical and physical methods. Cleistocalyx operculatus bud extracts played a dual part in reducing and stabilizing silver nanoparticles. The formation of silver nanoparticles was recognized on UV-Vis spectra at an absorption maximum of 432 nm. Transmission electron microscopy images detected the quasi-spherical nanoparticle shape with an average size of 26.2 nm corresponding with water extract and 27.5 nm synthesized by ethanol-water extract. The obtained silver nanoparticles had moderate stability with zeta potential ranging from −15.4 to −38.4 mV. The phase purity of the bio-synthesized materials was confirmed by an X-ray diffraction pattern. The Fourier-transform infrared analysis demonstrated hydroxyl groups acting as stabilizing agents in the extract. Silver nanoparticles synthesized from ethanol-water extract exhibited higher antibacterial and anticancer activity than nanomaterials prepared with water extract. Positive-gram bacteria (Bacillus subtilis, Lactobacillus fermentum, and Staphylococcus aureus, negative-gram bacteria (Escherichia coli, Pseudomonas aeruginosa, and Salmonella enterica), and cancer cell lines (lung cancer A549, hepatic cancer Hep-G2, epidermal carcinoma KB, and breast cancer MCF-7) were both inhibited by the nanoparticles synthesized with ethanol-water extract.

The adsorption of Co(II) from the simulated solution was investigated using zeolite NaX derived from rice husk ash as an alternative adsorbent. The adsorption behavior of Co(II) depended strongly on the equilibrium pH, Co (II) concentration, zeolite NaX dosage, and reaction time. The high adsorption efficiency of Co(II) by zeolite NaX was obtained under the conditions: pH 3.0, 100 mg/L of Co(II), 5 g/L of zeolite NaX, and a reaction time of 75 min. The loading behavior of Co(II) onto the zeolite NaX was well-fitted to the Freundlich adsorption isotherm and the Co(II) loading capacity by zeolite NaX was around 38 mg/g. The obtained results indicate that synthesized zeolite NaX from rice husk ash is a potential adsorbent to remove cobalt from waste solutions due to its high adsorption.

In this work, silver nanoparticles (AgNPs) were synthesized by the extract of Citrus maxima (C. maxima) peel with the presence of pectin as a principal reductant and stabilizer. Parameters such as concentration of C. maxima powder, extraction temperature, and extraction time for AgNPs synthesis have been studied. The synthesized AgNPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and transmission electron microscopy instrument (TEM). The synthesized AgNPs were quasi-spheres with an average particle size of 17 nm and high purity of silver phases. In addition, synthesized AgNPs exhibited good antibacterial activity against Gram-positive bacteria: Salmonella enterica (S. enterica) and Pseudomonas aeruginosa (P. aeruginosa) while no activity inhibited against Gram-negative bacteria: Staphylococcus aureus (S. aureus) and Lactobacillus fermentum (L. fermentum).