Magnetic cobalt ferrite composite as an efficient catalyst for photocatalytic oxidation of carbamazepine

Fabrication of an in situ-grown TiO2 nanowire thin film and its enhanced photocatalytic activity

TiO2 is a promising photocatalyst used in practical environmental remediation. TiO2 photocatalysts are usually implemented in two forms: suspended powder and immobilized thin films. A simple technique for fabricating TiO2 thin film photocatalyst was developed in this work. The fabricated TiO2 thin film photocatalyst featured a homogeneous nanowire layer grown in situ on the parent Ti plate. The optimized fabrication protocol was to soak the ultrasonically cleaned and acid-washed Ti plate in 30% H2O2 solution containing 3.2 mM melamine and 0.29 M HNO3 at 80 °C for 72 h and then anneal at 450 °C for 1 h. TiO2 nanowires with uniform diameters were homogeneously arrayed on the Ti plate surface. The thickness of the TiO2 nanowire array layer was 1.5 μm. The pore properties of the TiO2 thin film were close to those of P25. The band gap of the fabricated photocatalyst was 3.14 eV. The photocatalytic activity of the fabricated photocatalyst toward 10 mg/L RhB and 1 mg/L CBZ demonstrated greater than 60% degradation under 2 h UVC irradiation. The RhB and CBZ degradation efficiencies remained at a good level after 5 consecutive cycles. Mechanical wearing, such as 2 min sonication, will not lead to significant suppression of the photocatalytic activity. Photocatalytic RhB and CBZ degradation using the fabricated photocatalyst favored an acidic > alkaline > neutral environment. The presence of Cl- slightly suppressed the photocatalytic degradation kinetics. However, RhB and CBZ photocatalytic degradation kinetics were promoted in the copresence of SO42- or NO3-.

Microwave Sol-Gel Synthesis of Co, Ni, Cu, Mn Ferrites and İnvestigation of Their Activity in the Oxidation Reaction of Carbon Monoxide

Background:

The study effect of microwave radiation on the catalytic properties of transition metal ferrites synthesized by ceramic and sol-gel methods, in the oxidation reaction of carbon monoxide into dioxide.

Objective:

The aim of this work is to study the effect of microwave radiation on the production of cobalt, copper, nickel and manganese ferrites by sol-gel combustion technology using various organic reagents and to study their catalytic activity in the oxidative conversion of carbon monoxide into dioxide.

Methods:

Microwave treatment was carried out on a setup based on an EM-G5593V microwave oven (Panasonic) with a magnetron power varying from 300 to 800 W with an operating frequency of 2450 MHz. X-ray phase analysis of the products was carried out on a Bruker D 2Phazer automatic diffractometer. The measurement of the specific surface area of the samples was determined by low-temperature nitrogen adsorption by the multipoint BET method on a SORBI-MS instrument (ZAO META, Russia). IR spectra were recorded using FT-IR LUMOS Bruker spectrometers. The micrographs of samples were analyzed on the Sigma VP (Carl Zeiss Jena) equipment.

Results:

It was determined that the most active catalysts for the oxidation of carbon monoxide to dioxide are ferrites obtained by the sol-gel combustion method using microwave radiation to "ignite" the gel.

Conclusion:

The use of microwave radiation in the preparation of ferrites by the sol-gel method with combustion can, in a very short time, measured in seconds, initiate a self-propagating exothermic combustion reaction in the entire volume of the sample. The catalytic activity in the oxidative conversion of carbon monoxide obtained by this method of ferrites comparable to the activity of ferrites obtained by the sol-gel method with traditional combustion.

Magnetite-based catalysts for wastewater treatment

The increasing number and concentration of organic pollutants in water stream could become a serious threat in the near future. Magnetite has the potential to degrade pollutants via photocatalysis with a convenient separation process. This study discusses in detail the control size and morphology of magnetite nanoparticles, and their composites with co-precipitation, hydrothermal, sol-gel, and electrochemical route. Further photocatalytic enhancement with the addition of metal and porous support was proposed. This paper also discussed the technology to extend the lifetime of recombination through an in-depth explanation of charge transfer. The possibility to use waste materials as catalyst support was also elucidated. However, magnetite-based photocatalysts still require many improvements to meet commercialization criteria.

Pharmaceutically active compounds in aqueous environment: A status, toxicity and insights of remediation

Pharmaceutically active compounds (PhACs) have pernicious effects on all kinds of life forms because of their toxicological effects and are found profoundly in various wastewater treatment plant influents, hospital effluents, and surface waters. The concentrations of different pharmaceuticals were found in alarmingly high concentrations in various parts of the globe, and it was also observed that the concentration of PhACs present in the water could be eventually related to the socio-economic conditions and climate of the region. Drinking water equivalent limit for each PhAC has been calculated and compared with the occurrence data from various continents. Since these compounds are recalcitrant towards conventional treatment methods, while advanced oxidation processes (AOPs) have shown better efficiency in degrading these PhACs. The performance of the AOPs have been evaluated based on percentage removal, time, and electrical energy consumed to degrade different classes of PhACs. Ozone based AOPs were found to be favorable because of their low treatment time, low cost, and high efficiency. However, complete degradation cannot be achieved by these processes, and various transformation products are formed, which may be more toxic than the parent compounds. The various transformation products formed from various PhACs during treatment have been highlighted. Significant stress has been given on the role of various process parameters, water matrix, oxidizing radicals, and the mechanism of degradation. Presence of organic compounds, nitrate, and phosphate usually hinders the degradation process, while chlorine and sulfate showed a positive effect. The role of individual oxidizing radicals, interfering ions, and pH demonstrated dissimilar effects on different groups of PhACs.