Degradation of aqueous 3,4-dichloroaniline by a novel dielectric barrier discharge plasma reactor

Health status assessment of people adjacent to temporary waste disposal sites in Khulna city, Bangladesh

Despite rapid population growth, urbanization, and economic development in Bangladesh, there is a lack of evidence to measure the impact of dumpsites on human health and the environment. This study sought to assess the health impact of temporary disposal sites in Khulna city on residents living nearby. Data was collected through self-administered questionnaire surveys surrounding the dumpsite areas. Altogether 180 households were surveyed by random sampling approach from >50 m (close to the dumpsites, CD) and 50-300 m radius (away from the dumpsites, AD) of the dumpsite. The participants were mostly employed with low income ( Collapse

Key Words

• Environmental problem
• Health impact
• Proximities
• Waste disposal site

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Affiliation(s)

Afra Tanjim Shammi Environmental Science Discipline, Khulna University, Khulna-9208, Bangladesh
Nazia Hassan Environmental Science Discipline, Khulna University, Khulna-9208, Bangladesh
Md Rony Golder Fisheries and Marine Resource Technology Discipline, Khulna University, Khulna-9208, Bangladesh
Hriday Molla Urban and Rural Planning Discipline, Khulna University, Khulna-9208, Bangladesh
Shikder Saiful Islam Fisheries and Marine Resource Technology Discipline, Khulna University, Khulna-9208, Bangladesh

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Drug Delivery Strategies for Avobenzone: A Case Study of Photostabilization

Several developments and research methods are ongoing in drug technology and chemistry research to elicit effectiveness regarding the therapeutic activity of drugs along with photoprotection for their molecular integrity. The detrimental effect of UV light induces damaged cells and DNA, which leads to skin cancer and other phototoxic effects. The application of sunscreen shields to the skin is important, along with recommended UV filters. Avobenzone is widely used as a UVA filter for skin photoprotection in sunscreen formulations. However, keto-enol tautomerism propagates photodegradation into it, which further channelizes the phototoxic and photoirradiation effects, further limiting its use. Several approaches have been used to counter these issues, including encapsulation, antioxidants, photostabilizers, and quenchers. To seek the gold standard approach for photoprotection in photosensitive drugs, combinations of strategies have been implemented to identify effective and safe sunscreen agents. The stringent regulatory guidelines for sunscreen formulations, along with the availability of limited FDA-approved UV filters, have led many researchers to develop perfect photostabilization strategies for available photostable UV filters, such as avobenzone. From this perspective, the objective of the current review is to summarize the recent literature on drug delivery strategies implemented for the photostabilization of avobenzone that could be useful to frame industrially oriented potential strategies on a large scale to circumvent all possible photounstable issues of avobenzone.

Degradation of carbamazepine by high-voltage direct current gas-liquid plasma with the addition of H2O2 and Fe2

Carbamazepine (CBZ) is a typical psychotropic pharmaceutical which is one of the most commonly detected persistent pharmaceuticals in the environment. The degradation of CBZ in the aqueous solution was studied by a direct current (DC) gas-liquid phase discharge plasma combined with different catalysts (H₂O₂ or Fe²⁺) in this study. The concentrations of reactive species (H₂O₂, O₃, and NO₃^-) and •OH radical yield in the liquid were measured during the discharge process. The various parameters that affect the degradation of CBZ, such as discharge powers, initial concentrations, initial pH values, and addition of catalysts, were investigated. The energy efficiency was 25.2 mg·kW^-1·h^-1 at 35.7 W, and the discharge power at 35.7 W was selected to achieve the optimal balance on the degradation effect and energy efficiency. Both acidic and alkaline solution conditions were conducive to promoting the degradation of CBZ. Both H₂O₂ and Fe²⁺ at low concentration (10-100 mg/L of Fe²⁺, 0.05-2.0 mmol/L of H₂O₂) were observed contributing to the improvement of the CBZ degradation rate, while the promotional effect of CBZ degradation was weakened even inhibition would occur at high concentrations (100-200 mg/L of Fe²⁺, 2.0-5.0 mmol/L of H₂O₂). The degradation rate of CBZ was up to 99.1%, and the total organic carbon (TOC) removal efficiency of CBZ was up to 67.1% in the plasma/Fe²⁺ (100 mg/L) system at 48 min, which suggested that high degradation rate and mineralization efficiency on CBZ could be achieved by employing Fe²⁺ as a catalyst. Based on the intermediate products identified by Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS), the possible degradation pathways were proposed. Finally, the growth inhibition assay with Escherichia coli (E. coli) showed that the toxicity of plasma/Fe²⁺-treated CBZ solution decreased and a relatively low solution toxicity could be achieved. Thus, the plasma/catalyst could be an effective technology for the degradation of pharmaceuticals in aqueous solutions.

Physiological Effects of Neonicotinoid Insecticides on Non-Target Aquatic Animals-An Updated Review

In this paper, we review the effects of large-scale neonicotinoid contaminations in the aquatic environment on non-target aquatic invertebrate and vertebrate species. These aquatic species are the fauna widely exposed to environmental changes and chemical accumulation in bodies of water. Neonicotinoids are insecticides that target the nicotinic type acetylcholine receptors (nAChRs) in the central nervous systems (CNS) and are considered selective neurotoxins for insects. However, studies on their physiologic impacts and interactions with non-target species are limited. In researches dedicated to exploring physiologic and toxic outcomes of neonicotinoids, studies relating to the effects on vertebrate species represent a minority case compared to invertebrate species. For aquatic species, the known effects of neonicotinoids are described in the level of organismal, behavioral, genetic and physiologic toxicities. Toxicological studies were reported based on the environment of bodies of water, temperature, salinity and several other factors. There exists a knowledge gap on the relationship between toxicity outcomes to regulatory risk valuation. It has been a general observation among studies that neonicotinoid insecticides demonstrate significant toxicity to an extensive variety of invertebrates. Comprehensive analysis of data points to a generalization that field-realistic and laboratory exposures could result in different or non-comparable results in some cases. Aquatic invertebrates perform important roles in balancing a healthy ecosystem, thus rapid screening strategies are necessary to verify physiologic and toxicological impacts. So far, much of the studies describing field tests on non-target species are inadequate and in many cases, obsolete. Considering the current literature, this review addresses important information gaps relating to the impacts of neonicotinoids on the environment and spring forward policies, avoiding adverse biological and ecological effects on a range of non-target aquatic species which might further impair the whole of the aquatic ecological web.

Rapid photochemical decomposition of perfluorooctanoic acid mediated by a comprehensive effect of nitrogen dioxide radicals and Fe3+/Fe2+ redox cycle

Developing efficient methods to degrade perfluorochemicals (PFCs), an emerging class of highly recalcitrant contaminants, are urgently needed in recent years, due to their persistence, high toxicity, and resistance to most regular treatment procedures. Here, a UV-photolysis system is reported for efficient mineralization of perfluorooctanoic acid (PFOA) via irradiation of ferric nitrate aqueous solution, where in-situ generating •NO₂ and the effective Fe³⁺/Fe²⁺ redox cycle synergistically play great roles on rapidly mediating the mineralization of PFOA. A fast PFOA removal kinetics with first-order kinetic constants of 2.262 h^-1 is observed at initial PFOA concentration of 5 ppm (50 mL volume), reaching ∼ 92 % removal efficiency within only 0.5-h irradiation. Near-stoichiometric fluoride ions liberation and high total organic carbon (TOC) removal efficiency (∼100 %) further validated the capability for completely destructive removal of PFOA. A tentative pathway for PFOA destruction is proposed. This work, by UV photolysis of abundant existing iron/nitrate-based systems in natural environment, provides an economical, sustainable and highly efficient approach for complete mineralization of perfluorinated chemicals.

"Self-cleaning" electrochemical regeneration of dye-loaded activated carbon

A low maintenance, "self-cleaning" electrochemical approach is evaluated for regeneration of dye-loaded granular activated carbon (GAC). To do so, batch experiments were conducted using a low-cost granular activated carbon/stainless steel mesh (GACSS) composite cathode and a stable Ti/mixed metal oxides (Ti/MMO) anode without the addition of oxidants or iron catalysts. The GACSS cathode supports simultaneous H2O2 electrogeneration via the in situ supplied O2 from Ti/MMO anode and the subsequent H2O2 activation for ·OH generation, thus enabling the cracking of dye molecules adsorbed on GAC and regenerating the GAC's sorption capacity. Results show that a prolonged electrochemical processing for 12h will achieve up to 88.7% regeneration efficiency (RE). While RE decreases with multi-cycle application, up to 52.3% could still be achieved after 10 adsorption-regeneration cycles. To identify the mechanism, experiments were conducted to measure H2O2 electrogeneration, H2O2 activation, and ·OH generation by various GAC samples. The dye-loaded GAC and GAC treated after 10 adsorption-regeneration cycles were still capable of ·OH generation, which contributes to effective "self-cleaning" and regeneration over multi-cycles.

State of the art of the environmental behaviour and removal techniques of the endocrine disruptor 3,4-dichloroaniline

In recent years, the presence of Endocrine Disrupting Chemicals (EDCs) in wastewater discharges from agricultural and industrial sources, ^[1] fresh- and estuarine-waters, as well as soils, has been reported in the literature. ^[2] Studies of adverse changes in wildlife, linked to environmental exposure to these substances, and the suggestion that humans could also be at similar risk of adverse health effects, ^[3-5] have raised concern for urgent action to understand and reduce such risks. 3,4-Dichloroaniline (3,4-DCA) has been recognized as an EDC, with regards to endocrine disruption data for both wildlife populations and human health. ^[5] 3,4-DCA is present in the environment as a product of the biodegradation of phenylurea and phenylcarbamate pesticides ^[6,7] ; furthermore, it can be introduced from industrial and municipal wastewater that is insufficiently purified, or via accidental spills. ^[8-10] Increasing concentrations of 3,4-DCA in soil and water are the result of its high persistence and accumulation, as well as its low biodegradability. ^[11,12] Hence, remediation techniques require in-depth study, especially when considering the low removal achieved by traditional activated sludge treatments, and the generation of carcinogenic trihalomethanes as a consequence of the chlorine oxidation methods frequently used in drinking water plants. ^[13] Fe⁰/H₂O₂ systems, photodegradation using doped TiO₂, and the use of dielectric barrier discharge reactors, seem to be the most promising techniques for the removal of 3,4-DCA from water.

Simultaneous removal of Cr(VI) and acid orange 7 from water solution by dielectric barrier discharge plasma

A feasibility study was conducted for simultaneous removal of hexavalent chromium (Cr(VI)) and azo dye acid orange 7 (AO7) by the dielectric barrier discharge (DBD) plasma. The results showed that there was a synergistic effect between Cr(VI) reduction and AO7 degradation. The presence of Cr(VI) enhanced the degradation efficiency of AO7. Meanwhile, the removal efficiency of Cr(VI) also increased in the presence of AO7. Under acidic conditions (pH = 3.0), the reduction efficiency of Cr(VI) was higher (approximately 94%). However, the presence of Cr(VI) diminished the effect of pH on the AO7 degradation efficiency. By increasing the input voltage from 80 to 120 V, the removal efficiencies of Cr(VI) and AO7 were observably increased from 54% to 88% and 62% to 89%, respectively. Adding organic matters inhibited the degradation of AO7 and promoted the reduction of Cr(VI). The addition of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) could inhibit the Cr(VI) reduction, but not significantly affect the degradation of AO7. The degradation intermediates of AO7 were identified by LC-MS/MS system and a possible degradation pathway was proposed. This study showed that the DBD plasma can simultaneously remove Cr(VI) and AO7, which provided a new idea for the actual wastewater treatment.

Dielectric barrier discharge plasma induced degradation of aqueous atrazine

Degradation of herbicide atrazine in aqueous solution was investigated using a plate type dielectric barrier discharge (DBD) plasma reactor. DBD plasma was generated at the gas-liquid interface of the formed water film. At discharge time of 14 min, atrazine was degradated effectively with a degradation rate of 99 % at the discharge power of 200 W. The experimental data fitted well with first-order kinetics and the energy efficiency for 90 % degradation of atrazine (G value) was calculated, obtaining a rate constant of 0.35 min(-1) and a G value of 1.27 × 10(-10) mol J(-1) (98.76 mg kW(-1) h(-1)) at a discharge power of 200 W, respectively. The addition of Fe(2+) increased the rate constant and G value dramatically, and a significant decrease of the rate constant and G value was observed with the addition of radical scavengers (tert-butyl alcohol, isopropyl alcohol, or Na2CO3). The generated aqueous O3 and H2O2 were determined, which promoted the degradation of herbicide atrazine. Dechlorination was observed and the experimentally detected Cl(-) was 1.52 mg L(-1) at a discharge time of 14 min. The degradation intermediates of atrazine were detected by means of liquid chromatography-mass spectrometry; dechlorination, hydroxylation, dealkylation, and alkyl oxidation processes were involved in the degradation pathways of atrazine.

Degradation Characteristics of Aniline with Ozonation and Subsequent Treatment Analysis

Owing to the toxicity and low biodegradability of aniline in water, its removal usually needs high cost processes such as adsorption and advanced oxidation. The degradation characteristics of aniline during ozonation were studied. The influence of operation parameters such as contact time, initial concentration, ozone dosage, temperature, and pH was also investigated. With ozone dosage of 22 mg/L, neutral pH, and room temperature, the ozonation removed aniline efficiently. After two hours’ ozonation, aniline removal reached 93.57%, and the corresponding COD removal was 31.03%, which indicated most of aniline was transformed into intermediates. At alkaline conditions, the aniline was more susceptible to being removed by ozonation owing to more hydroxyl radicals’ production. The results of GC-MS indicated many intermediates appeared during the process of ozonation such as butane diacid, oxalic acid, and formic acid. The intermediates produced during ozonation were more biodegradable than aniline; thus the ozonation of such organic compounds as aniline could be integrated with biological processes for further removal.