Green approach for polyphenol extraction from waste tea biomass: Single and hybrid application of conventional and ultrasound-assisted extraction.

Based on a green approach, the potential use of waste tea biomass (fiber and second sieving) with rich polyphenol content was investigated as an alternative source of polyphenol to achieve an economic added value. In addition, this study demonstrated a comparative approach to explore the most sustainable green extraction method by the assessment of single ultrasound-assisted extraction (UAE) at various frequencies (20, 35, and 200 kHz) and the hybrid operations of ultrasound (US) and thermal extraction (50 °C and 80 °C). As a result, it has been determined that waste tea biomass, with a polyphenol extraction rate of more than 80%, provides a higher recovery capacity than tea leaf (the highest polyphenol recovery rate of 72.

Oxidative decomposition and mineralization of caffeine by advanced oxidation processes: The effect of hybridization.

The study consists of a detailed investigation of the degradability of the emerging water contaminant-caffeine by homogeneous and heterogeneous Advanced Oxidation Processes (AOP's), estimation of a synergy index for each hybrid operation thereof, and proposing the most plausible reaction mechanisms that are consistent with the experimental data. It also encompasses evaluation of the effect of the water matrix represented by carbonate species and humic acids, as strong scavengers of hydroxyl radicals. The results showed that single AOP's such as sonolysis (577 kHz) and photolysis with HO provided complete caffeine elimination, but they were insufficient for the mineralization of the compound.

Hydroxyl radical-mediated degradation of diclofenac revisited: a computational approach to assessment of reaction mechanisms and by-products.

Advanced oxidation processes (AOPs) are based on the in situ production of hydroxyl radicals (•OH) and reactive oxygen species (ROS) in water upon irradiation of the sample by UV light, ultrasound, electromagnetic radiation, and/or the addition of ozone or a semiconductor. Diclofenac (DCF), one of the emerging organic contaminants (EOC), is of environmental concern due to its abundancy in water and is known to be subjected to AOPs. The current study uses density functional theory (DFT) to elucidate the mechanisms of the reactions between •OH and DCF leading to degradation by-products, P1-P9.

Catalytic ozonation of paracetamol using commercial and Pt-supported nanocomposites of AlO: The impact of ultrasound.

The study is the assessment of commercial γ-AlO and its sonolytically modified nanocomposite in catalytic ozonation of paracetamol (PCT), which is an emerging water contaminant and a highly reactive compound with ozone. The results showed that commercial alumina was ineffective regardless of the solution pH, due to the low affinity of the catalyst surface for PCT and the high reactivity of the solute with molecular ozone. The modified catalyst, which was synthesized by decoration of the original surface with nanoparticles of platinum provided considerable improvement in the performance of the catalyst, particularly in mineralization of the target compound.

Single, simultaneous and sequential applications of ultrasonic frequencies for the elimination of ibuprofen in water.

The study is about the assessment of single and multi-frequency operations for the overall degradation of a widely consumed analgesic pharmaceutical-ibuprofen (IBP). The selected frequencies were in the range of 20-1130kHz emissions coming from probes, baths and piezo-electric transducers attached to plate-type devices. Multi-frequency operations were applied either simultaneously as "duals", or sequentially at fixed time intervals; and the total reaction time in all operations was 30-min.

Enhanced photo-degradation of paracetamol on n-platinum-loaded TiO2: The effect of ultrasound and OH/hole scavengers.

Elimination/mineralization of paracetamol (PCT) was investigated by catalytic oxidation under ultrasound, UV and both. The catalyst was synthesized by immobilization of nPt on TiO2 to benefit from the ability of Pt to facilitate charge transfer processes and to separate e(-)/h(+) pairs. It was found that increasing the Pt-loading enhanced the rate of sonochemical reactions, but retarded that of photolytic reactions, due to reduced UV absorption on the surface.