Paracetamol Degradation by Catalyst Enhanced Non-Thermal Plasma Process for a Drastic Increase in the Mineralization Rate

Effects of solution chemistry on dielectric barrier atmospheric non-thermal plasma for operative degradation of antiretroviral drug nevirapine

The global prevalence of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) has been an environmental menace. Tons of drug wastes from antiretroviral therapy are released into the environment annually. We, for the first time, employed the novel dielectric barrier atmospheric non-thermal plasma (DBANP) discharge, to mitigate the inadvertent pollution arising from the antiretroviral therapy. A 40-min treatment of nevirapine achieved >94 % (0.075 min-1) removal efficiency at discharge power of 63.5 W and plasma working gas of atmospheric air. Chemical probes confirmed •OH, ONOO- and eaq- as the dominant reactive species whilst further revealing the reaction acceleration role of NaNO3 and CCl4 which are known reaction terminators. The commonly coexisting inorganic anions potentiated nevirapine removal with over 98 % efficiency, achieving the highest rate constant of 0.148 min-1 in this study. Moreover, the initial solution pH (1.5-11.1) was no limiting factor either. The insensitivity of the DBANP discharge to actual water matrices was an eminent inference of its potential applicability in practical conditions. With reference to data obtained from the liquid chromatography-mass spectrometer analysis, nevirapine degradation pathway was proposed. A nucleophilic attack by ONOO- at the cyclopropyl group and •OH attack at the carbonyl carbon of the amide group, respectively, initiated nevirapine degradation process. It is anticipated that the findings herein, will provide new insights into antiretroviral drug waste management in environmental waters using the innovative and green non-thermal plasma process.

Degradation and transformation of carbamazepine in aqueous medium under non-thermal plasma oxidation process

Carbamazepine (CBZ) is a pharmaceutical compound detected in various water resources. With a view to removing this contaminant, the applicability of non-thermal plasma (NTP) oxidation process has been widely tested in recent years. This study utilized NTP from a dielectric barrier discharge reactor in the treatment of CBZ. NTP on the surface of a water sample containing 25 mg.L-1 of CBZ resulted in a removal efficiency of over 90% with an energy yield of 0.19 g. (kWh)-1. On the other hand, a rapid reduction in pH and an increase of conductivity and nitrate/nitrite ions concentration were observed during the degradation. The applied voltage amplitude significantly affected the removal efficiency and the energy yield as the degradation efficiency was 55%, 70%, and 72% respectively with an applied voltage of 8, 10, and 12 kV. The water matrices containing inorganic anions such as chloride and carbonate ions reduced the removal efficiency by scavenging the reactive species. Accordingly, a reduction in the removal efficiency was observed in tap water. The high-resolution mass spectrometry (HRMS) results revealed that both reactive oxygen and nitrogen species take part in the reaction process which yields many intermediate products including aromatic nitro-products. This study concluded that NTP can effectively degrade CBZ in both pure and tap water, but special attention must be paid to changes in the water quality parameters (pH, conductivity, and nitrate/nitrite ions) and the fate of nitro products.

A comprehensive insight on plasma-catalytic degradation of organic pollutants in water: Comparison between ZnO and TiO2

A novel system combining underwater plasma bubbles and high voltage nanopulses was combined for the first time with ZnO and TiO2 for the degradation of organic pollutants in water. The effect of catalyst loading, discharge power and plasma gas on pollutant degradation was investigated whereas the plasma-catalytic mechanism was explored through the quantification of plasma species, COD/TOC measurements and scavenging experiments in the presence and absence of catalysts. The increased efficiency in the presence of either ZnO or TiO2, especially under plasma gases (air and oxygen) able to produce UV radiation in the range of wavelengths absorbed by both catalysts, lies on the increased concentration of the critical reactive species (e.g. ·O2-, ·ΟΗ, H2O2). Compared to plasma alone process, H2O2 was significantly enhanced in the presence of TiO2 and decreased in the presence of ZnO, whereas ·OH concentration was higher in the plasma-ZnO but lower in the plasma-TiO2 system which supports the overall superior performance of ZnO compared to TiO2. The synergy of plasma-ZnO process compared to that of plasma-TiO2 was ∼2.4 and ∼1.5 times higher for Orange II (OII) and Methylene Blue (MB), respectively, exhibiting a very low electrical energy per order (1.4 kWh m-3 for OII and 0.31 kWh m-3 or MB). The present effort contributes on providing fundamental insights and further expand of plasma-catalysis for water treatment.

A review on the degradation of acetaminophen by advanced oxidation process: pathway, by-products, biotoxicity, and density functional theory calculation

Water scarcity and the accumulation of recalcitrance compounds into the environment are the main reasons behind the attraction of researchers to use advanced oxidation processes (AOPs). Many AOP systems have been used to treat acetaminophen (ACT) from an aqueous medium, which leads to generating different kinetics, mechanisms, and by-products. In this work, state-of-the-art studies on ACT by-products and their biotoxicity, as well as proposed degradation pathways, have been collected, organized, and summarized. In addition, the Fukui function was used for predicting the most reactive sites in the ACT molecule. The most frequently detected by-products in this review were hydroquinone, 1,4-benzoquinone, 4-aminophenol, acetamide, oxalic acid, formic acid, acetic acid, 1,2,4-trihydroxy benzene, and maleic acid. Both the experimental and prediction tests revealed that N-(3,4-dihydroxy phenyl) acetamide was mutagenic. Meanwhile, N-(2,4-dihydroxy phenyl) acetamide and malonic acid were only found to be mutagenic in the prediction test. The findings of the LC50 (96 h) test revealed that benzaldehyde is the most toxic ACT by-products and hydroquinone, N-(3,4-dihydroxyphenyl)formamide, 4-methylbenzene-1,2-diol, benzoquinone, 4-aminophenol, benzoic acid, 1,2,4-trihydroxybenzene, 4-nitrophenol, and 4-aminobenzene-1,2-diol considered harmful. The release of them into the environment without treatment may threaten the ecosystem. The degradation pathway based on the computational method was matched with the majority of ACT proposed pathways and with the most frequent ACT by-products. This study may contribute to enhance the degradation of ACT by AOP systems.

Recent Advances of Emerging Organic Pollutants Degradation in Environment by Non-Thermal Plasma Technology: A Review

Emerging organic pollutants (EOPs), including endocrine disrupting compounds (EDCs), pharmaceuticals and personal care products (PPCPs), and persistent organic pollutants (POPs), constitute a problem in the environmental field as they are difficult to completely degrade by conventional treatment methods. Non-thermal plasma technology is a novel advanced oxidation process, which combines the effects of free radical oxidation, ozone oxidation, ultraviolet radiation, shockwave, etc. This paper summarized and discussed the research progress of non-thermal plasma remediation of EOPs-contaminated water and soil. In addition, the reactive species in the process of non-thermal plasma degradation of EOPs were summarized, and the degradation pathways and degradation mechanisms of EOPs were evaluated of selected EOPs for different study cases. At the same time, the effect of non-thermal plasma in synergy with other techniques on the degradation of EOPs in the environment was evaluated. Finally, the bottleneck problems of non-thermal plasma technology are summarized, and some suggestions for the future development of non-thermal plasma technology in the environmental remediation were presented. This review contributes to our better understanding of non-thermal plasma technology for remediation of EOPs-contaminated water and soil, hoping to provide reference for relevant practitioners.

Recent Progress and Prospects in Catalytic Water Treatment

Presently, conventional technologies in water treatment are not efficient enough to completely mineralize refractory water contaminants. In this context, the implementation of catalytic processes could be an alternative. Despite the advantages provided in terms of kinetics of transformation, selectivity, and energy saving, numerous attempts have not yet led to implementation at an industrial scale. This review examines investigations at different scales for which controversies and limitations must be solved to bridge the gap between fundamentals and practical developments. Particular attention has been paid to the development of solar-driven catalytic technologies and some other emerging processes, such as microwave assisted catalysis, plasma-catalytic processes, or biocatalytic remediation, taking into account their specific advantages and the drawbacks. Challenges for which a better understanding related to the complexity of the systems and the coexistence of various solid-liquid-gas interfaces have been identified.

Catalysts: Special Issue on Plasma-Catalysis for Environmental and Energy-Related Applications

Plasma-catalysis has been a topic of research for many years due to its potential for applications in a wide range of chemical, environmental, and energy-related processes [...]

A review on non-thermal plasma treatment of water contaminated with antibiotics

Large amounts of antibiotics are produced and consumed worldwide, while wastewater treatment is still rather inefficient, leading to considerable water contamination. Concentrations of antibiotics in the environment are often sufficiently high to exert a selective pressure on bacteria of clinical importance that increases the prevalence of resistance. Since the drastic reduction in the use of antibiotics is not envisaged, efforts to reduce their input into the environment by improving treatment of contaminated wastewater is essential to limit uncontrollable spread of antibiotic resistance. This paper reviews recent progress on the use of non-thermal plasma for the degradation of antibiotics in water. The target compounds removal, the energy efficiency and the mineralization are analyzed as a function of discharge configuration and the most important experimental parameters. Various ways to improve the plasma process efficiency are addressed. Based on the identified reaction intermediates, degradation pathways are proposed for various classes of antibiotics and the degradation mechanisms of these chemicals under plasma conditions are discussed.

Effective removal of paracetamol in compound parabolic collectors and fixed bed reactors under natural sunlight

Removal of persistent organic pollutants from water is quite challenging using biological treatment processes in waste water treatment plants. In order to improve the wastewater treatment quality for water reuse, many techniques are developed and the most commonly used is heterogeneous photocatalysis. This work studies the degradation of paracetamol (PAR), which is one of the most persistent pharmaceutical drugs in water, and widely used as an analgesic and antipyretic drug in Algeria. The paracetamol degradation has been carried out via heterogeneous photocatalysis, in a suspended solution of catalyst using a Compound Parabolic Collectors (CPC) reactor and in a fixed bed with immobilized catalyst under natural solar radiation. The degradation performance has been studied under various parameters such as substrate concentration and pH of solution. The degradation efficiency decreased when the initial paracetamol concentration increased from 2.5 mg/L to 20 mg/L. In addition, the selected reactors were found to be competent for the paracetamol degradation with an almost 98-99% removal of PAR. For the CPC reactor with suspended TiO₂, the paracetamol elimination reached 98% after 300 min; however, for the fixed-bed reactor, TiO₂ immobilized on cellulose-based paper was utilized, which yielded an almost 99% reduction in the PAR concentration after 90 min only of solar irradiation.