Hydrothermally synthesized titanium/hydroxyapatite as photoactive and antibacterial biomaterial.

The present work investigated hydrothermal synthesis of titanium/hydroxyapatite (Ti/HA) nanocomposite at varied Ti content. The synthesis was performed by coprecipitation method using CaO, ammonium dihydrogen phosphate and titanium oxide chloride precursor with the additional cetyl trimethyl ammonium chloride as templating agent, followed by hydrothermal treatment at 150 °C. The derived materials were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy analyses. The photocatalytic properties of materials were tested on methyl violet (MV) photocatalytic oxidation, meanwhile the antibacterial testing was performed against Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia, and Streptococcus pyogenes. In addition, cytotoxicity evaluation of the materials as potential biomaterial was also conducted. The results showed that physicochemical character of Ti/HA exhibits exhibit the excellent properties to be photocatalyst along with antibacterial activity. From the detail study of effect of varied titanium content ranging from 5 to 10 %wt., the increasing crystallite size of anatase phase of about 25.81 nm and 38.22 nm for Ti content of 5 and 10 % wt., respectively. In other side, the band gap energy value increases as the increasing Ti content, i.e. the values are 3.08; 3.18; and 3.20 eV for Ti content of 5, 10, 20 % wt., respectively. The band gap energy is correlated with the photocatalytic activity which the highest MV degradation was 96.46% over Ti/HA with 20% wt. of Ti (Ti20/HA). The nanocomposites also express the antibacterial activity with comparable minimum inhibitory concentration (MIC) with other similar Ti/HA nanocomposites. The MIC values of Ti20/HA against E. coli, S. aureus, K. pneumonia, and S. pyogenes are 25; 25; 50 and 50 µg/mL, respectively. In addition, the cytotoxicity test revealed the potency to be a biomimetic material as shown by severe toxicity.

Nanocomposite of Nickel Nanoparticles-Impregnated Biochar from Palm Leaves as Highly Active and Magnetic Photocatalyst for Methyl Violet Photocatalytic Oxidation.

Photocatalysis has been recognized as a feasible method in water and wastewater treatment. Compared to other methods such as adsorption and chemical oxidation, the use of photocatalyst in the advanced oxidation processes gives benefits such as a longer lifetime of the catalyst and less consumable chemicals. Currently, explorations into low-cost, effective photocatalysts for organic contaminated water are being developed. Within this scheme, an easily separated photocatalyst with other functionality, such as high adsorption, is important. In this research, preparation of a magnetic nanocomposite photocatalyst based on agricultural waste, palm leaves biochar impregnated nickel nanoparticles (Ni/BC), was investigated. The nanocomposite was prepared by direct pyrolysis of palm leaves impregnated with nickel (II) chloride precursor. Furthermore, the physicochemical characterization of the material was performed by using an X-ray diffractometer (XRD), scanning electron microscopy-energy dispersive X-ray fluorescence (SEM-EDX), transmission electron microscopy (TEM), gas sorption analysis, X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The photocatalytic activity of Ni/BC was evaluated for methyl violet (MV) photocatalytic oxidation. The results from XRD, XPS and TEM analyses identified single nickel nanoparticles dispersed on the biochar structure ranging from 30-50 nm in size. The dispersed nickel nanoparticles increased the BET specific surface area of biochar from 3.92 m2/g to 74.12 m2/g oxidation. High photocatalytic activity of the Ni/BC was exhibited by complete MV removal in 30 min for the concentration ranging from 10-80 mg/L. In addition, the Ni/BC showed stability in the pH range of 4-10 and reusability without any activity change until fifth usage. The separable photocatalyst is related to magnetism of about 13.7 emu/g. The results highlighted the role of biochar as effective support for Ni as photoactive material.

Enhanced Photocatalytic Activity of Zn-Al Layered Double Hydroxides for Methyl Violet and Peat Water Photooxidation.

Zn-Al Layered Double Hydroxides (Zn-Al LDHs) and its calcined form were successfully prepared and utilized for the removal of methyl violet (MV) and treatment of peat water by photocatalytic oxidation. The research was aimed to evaluate the effect of calcination to Zn-Al LDHs for the effect on the physicochemical character and the capability as a photocatalyst. The characterization of the samples was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmet-Teller specific surface area (BET), and X-ray photoelectron spectroscopy (XPS). The results showed that the increased BET specific surface area along with the enhanced porous structure was achieved by the calcination procedure, which is associated with the enhanced interlayer space of d003 identified by XRD analysis. Thermal conversion showed an influence to the increased band gap energy from 3.10 eV in the uncalcined Zn-Al LDHs into 3.16 eV for the calcined material. These character changes contributed to the enhanced photocatalytic activity of the Zn-AL LDHs by calcination, which was proposed and verified by experiments. It was observed that photocatalytic activity of the material for MV gave about a 45.57% removal of MV and a 68% removal for the natural organic material of the peat water.