Presence Of Organic Pollutants Research Articles

Zooplankton Bio-indicators Against Changing Hydrological Parameters at Bidyadhari River of Indian Sundarbans

Sundarban Estuarine System is influenced by periodic tidal input and fresh water inflow. It is surrounded by world’s largest mangrove ecosystem and harbour naturally grown fishery. The total system is intersected by a network of many rivers and creeks. Bidyadhari is one of the major rivers of Sundarbans that is surrounded by human habitation on both banks. The dynamic condition of the river due to tidal inflow and fresh water input which is further increased many folds due to human interventions. In the present study, 26 zooplankton taxa have been recorded where 16 taxa were found perennial in all three seasons. 19 species showed its highest density in the monsoon season, 4 in post-monsoon and 3 in pre-monsoon season. Considering all seasons, Pseudodiaptomus serricaudatus was found to be the most abundant species in monsoon when there was a marked increase in temperature, nitrate, phosphate, silicate and a decrease in salinity, DO, TDS, EC and chlorophyll-a concentration. On the other hand, Acrocalanus longicornis was most abundant during the post-monsoon season when pH, EC, DO, chlorophyll-a were found to be highest and temperature was lowest of all seasons. Only 3 of the 26 taxa were found in highest concentration during pre-monsoon season when salinity was found in highest concentration. The Shannon-Weiner Diversity Index, Simpson 1_D Index and Margalef Richness Index of zooplankton diversity were found highest in station 3 (nearest to the sea) during all the three seasons. Pearson Correlation Analysis showed some significant correlation between different hydrological parameters and zooplankton diversity indices. The result of the study indicates the presence of organic pollutants and eutrophication in Bidyadhari river that demands regular monitoring of water quality for maintenance of long-term sustainability of one the largest naturally grown fisheries in the world.

Understanding of interfacial molecular interactions and inner-sphere reaction mechanism in heterogeneous Fenton-like catalysis on Mn-N4 site

This study investigated interface molecular interactions between atomically-dispersed active sites and reactants in Fenton-like catalysis for deep understanding catalytic mechanism and dynamics. N-doped carbon nanotubes (NCNTs), atomically-dispersed Mn onto NCNTs (Mnsa-NCNT) and peroxymonosulfate (PMS) were applied as the research platforms. PMS adsorption on atomically-dispersed Mn sites was found to perform an inner-sphere interaction rather than an outer-sphere interaction on NCNT. The inner-sphere interaction leads to efficient electron transfer and robust PMS adsorption in the presence of organic pollutants, therefore high decontamination efficiency in Fenton-like catalysis. Theoretical calculation, X-ray electron spectrum, X-ray absorption spectrum indicated chemical bonds, specifically ionic bonds, were formed between Mn-N4 moieties and PMS. In contrast, the N-doped surface adsorbed PMS via van der Waals interactions. These findings provide a deep understanding of solid/liquid interface processes and additionally gives a new perspective on the superiority of single atom catalysts.

Metagenomic analysis reveals the distribution, function, and bacterial hosts of degradation genes in activated sludge from industrial wastewater treatment plants

For comprehensive insights into the bacterial community and its functions during industrial wastewater treatment, with a particular emphasis on its pivotal role in the bioremediation of organic pollutants, this study utilized municipal samples as a control group for metagenomic analysis. This approach allowed us to investigate the distribution, function, and bacterial hosts of biodegradation genes (BDGs) and organic degradation genes (ODGs), as well as the dynamics of bacterial communities during the industrial wastewater bioprocess. The results revealed that BDGs and ODGs associated with the degradation of benzoates, biphenyls, triazines, nitrotoluenes, and chlorinated aromatics were notably more abundant in the industrial samples. Specially, genes like clcD, linC, catE, pcaD, hbaB, hcrC, and badK, involved in the peripheral pathways for the catabolism of aromatic compounds, benzoate transport, and central aromatic intermediates, showed a significantly higher abundance of industrial activated sludge (AS) than municipal AS. Additionally, the BDG/ODG co-occurrence contigs in industrial samples exhibited a higher diversity in terms of degradation gene carrying capacity. Functional analysis of Clusters of Orthologous Groups (COGs) indicated that the primary function of bacterial communities in industrial AS was associated with the category of “metabolism”. Furthermore, the presence of organic pollutants in industrial wastewater induced alterations in the bacterial community, particularly impacting the abundance of key hosts harboring BDGs and ODGs (e.g. Bradyrhizobium, Hydrogenophaga, and Mesorhizobium). The specific hosts of BDG/ODG could explain the distribution characteristics of degradation genes. For example, the prevalence of the Adh1 gene, primarily associated with Mesorhizobium, was notably more prevalent in the industrial AS. Overall, this study provides valuable insights into the development of more effective strategies for the industrial wastewater treatment and the mitigation of organic pollutant contamination.

Adsorption of Phenols from Aqueous Solution with A pH-Sensitive Surfactant-Modified Bentonite

The presence of organic pollutants in wastewater remains a prominent environmental concern due to the related ecological and health hazards. In response, this study employs an adsorptive methodology to address the removal of phenol and catechol, utilizing an organo-bentonite material modified with a pH-responsive switchable surfactant, dodecyldimethylamine oxide (C12DAO). The synthesized organo-bentonite (C12DAO-Bt) manifests commendable thermostability resulting from thermogravimetric analyses. The adsorption capacities of C12DAO-Bt concerning phenol and catechol intensify with the augmentation of the C12DAO/bentonite mass ratio. The utmost adsorption capacities of 150C12DAO-Bt, deduced through a pseudo-second-order kinetic model, stand at 5.72 mg·g−1 for phenol and 5.55 mg·g−1 for catechol, respectively. Subject to modification by a pH-responsive surfactant, conditions leaning towards weakly acidic and neutral conditions (pH = 6~7) are conducive to the adsorption of phenolic compounds. Conversely, alkaline conditions (pH = 8~9) facilitate the dissociation of adsorbates from adsorbents. The augmentation of cationic strength within the examined scope incites the adsorption procedure while impeding the desorption efficacy. In the case of cationic species with comparable ionic strengths, Na+ exhibited a superior effect on the adsorption–desorption dynamics of phenol, while Ca2+ exerts a more pronounced effect on those of catechol. Moreover, even following five consecutive acid–base regulation cycles, C12DAO-Bt retains a relatively high adsorption capacity and desorption efficacy, which underscores its exceptional regenerative capacity for removing phenolic compounds from wastewater.

Fabrication of sputter coated Cu impregnated TaO[sbnd]NbO composite: A synchronized scavenging photocatalyst for water purification

Synchronized scavenging photocatalysts are needed for water purification due to the increasing demand for clean and safe water resources. The presence of organic pollutants and microorganisms in water sources can pose a significant risk to human health and the environment. This study compared the photocatalytic activity of the sputter-coated TaONbO and Cu-impregnated TaONbO/Cu nanocomposite with TiO2 (Degusa P-25) under solar radiation. The TaONbO/Cu and TaONbO nanocomposites crystallinity, structure and defects of composite, surface morphology, elemental composition and chemical state of material were evaluated by XRD, HRTEM, SEM, and XPS, respectively. Photoluminescence (PL) studies were employed to analyze the optical properties of the photocatalyst. The photocatalytic activity of TiO2, TaONbO/Cu and TaONbO was evaluated under solar radiation using P-Rosaniline Hydrochloride (PRH-Dye) as a model contaminant. IC and GC–MS were used to track the mineralized byproducts and intermediates produced during PRH-Dye degradation. The sputter-coated TaONbO/Cu photocatalyst was reused for up to 5 cycles, and no change in reaction kinetics was observed. This clearly indicates that TaONbO/Cu can be reused for several cycles. Using sputter-coated TaONbO/Cu photocatalysts enhanced performance compared to TiO2 and TaONbO. Using sputter-coated TaONbO/Cu photocatalysts to remove organic contamination from drinking water under solar radiation is a promising technology that can be a game-changer in the field of water treatment.

Synthesis and investigation of catalytic HER/OER performances of Al2SSe in alkaline/acidic media and water detoxification behavior

The increasing demand for renewable energy sources and the presence of organic pollutants in water are pressing issues that require sustainable and environmentally friendly solutions. Electrocatalytic water splitting, and water detoxification offer promising approaches to address these challenges, but current electrocatalysts often suffer from low efficiency and pH-specificity, which limits their practical application. In this study, we synthesized low-cost, effective aluminum sulfoselenide (Al2SSe) nanorods as electro- and photocatalysts for water splitting that works in wide range of pH and water detoxification. Characterization of the Al2SSe nanorods using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques confirmed their shape and crystallinity. Subsequent testing of the Al2SSe catalyst in three different electrolytes revealed excellent performance in both light and dark conditions for both the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). In particular, the Al2SSe catalyst displayed low overpotentials and small tafel slopes of 32 mV/dec, 42 mV/dec, 49 mV/dec, and 91 mV/dec for the OER and 31.4 mV/dec, 34 mV/dec, 45 mV/dec and 56 mV/dec for the HER in 1 M potassium hydroxide (KOH), 0.1 M sulfuric acid (H2SO4), 0.1 M perchloric acid (HClO4) and 1 M phosphate buffer solution (PBS) electrolytes, respectively, under light conditions. The Al2SSe photocatalyst was also found to be highly effective at degrading 89% of Congo Red. These findings suggest that post-transition metal chalcogenides such as Al2SSe may have significant potential for use in electro- and photocatalytic applications.

The g-C3N4 decorated carbon aerogel with integrated solar steam generation and photocatalysis for effective desalination and water purification

Although solar steam generation (SSG) technology has shown promising advantages in the desalination of seawater, the treatment of organic pollutants in wastewater using SSG technology remains a challenge. Furthermore, the efficacy of evaporation materials is often hindered by the presence of organic pollutants, thereby limiting their practical application in the desalination of high-salinity wastewater. To address this issue, a synergistic approach combining photoevaporation and photocatalysis has been proposed as a potential solution. In this study, a novel rGO/MWCNTs aerogel (GMA) modified by photocatalyst g-C3N4 was fabricated by hydrothermal synthesis in the integrated treatment of unconventional waters. At one solar radiation (1 kW·m−2), GMA achieved an evaporation rate of 2.07 kg·m−2·h−1 and a remarkable solar evaporation efficiency of 92.7 %. In addition, GMA demonstrated excellent desalination performance with over 98 % removal of waste metal ions from seawater and brackish water after desalination. First applied aerogel to the lithium chloride wastewater evaporation and concentration, achieving the concentration of lithium chloride wastewater from 700 mg/L to 5.18 g/L. Additionally, the coordinated photocatalysis of g-C3N4 and rGO resulted in catalytic degradation rates of RhB and TB up to 91.6 % and 87.9 %, respectively. This study provides a new idea for SSG technology in high-salinity wastewater treatment.

Application of Hydrogen-Based Denitrification: Simultaneous Removal of Nitrate and Reactive Black 5 Dye from Textile Wastewater Containing Organic Matter

In this study, a hydrogen-based denitrification (HD) reactor was used to investigate the simultaneous treatment of nitrogen and decolorization in textile wastewater contaminated with organic matter. The reactor operated in two phases: without and with organic matter. Despite the short hydraulic retention time, the HD system successfully removed all pollutants, including nitrate, nitrite, reactive black-5 dye and chemical oxygen demand. The unhindered treatment efficiency for nitrogen and decolorization in the presence of organic pollutants was observed. With the addition of organic matter, the nitrogen removal efficiency increased slightly from 85% to 90–100%, and the decolorization rate doubled from 25% to 50–60%. Organic matter played a crucial role in stimulating heterotrophic bacteria during biological denitrification and acted as a carbon source facilitating biological denitrification and azo bond cleavage during dye degradation. Despite the generation of toxic byproducts and changes in the dominant microbial community, the treatment efficiency remained stable and improved. This approach offers a promising solution for enhancing treatment efficiency in textile wastewater, providing a cost-effective and environmentally friendly option for developing countries to treat wastewater before discharge.

Assessment of Water Quality Using Organic Pollution Index in Some Marshes North of Basra Province

The organic pollution index (OPI) was applied to assess the state of the organic pollution in the southern part of Eastern Hammar marsh, Al-Chebiyesh marsh, and the Euphrates and explain the role of submerged aquatic plants in reducing the level of water pollution. Water samples were collected monthly from two stations for each part (i.e., with and without submerged plants). The OPI depended on three parameters, namely, NO3, PO4, and BOD5. Results show that the highest NO3 was 6.4 mg/L in February in Al Burka, whereas the lowest value was 2.3 mg/L in August in the Euphrates station, which contains submerged plants. The highest PO4 was 0.76 mg/L in February in Al Burka, whereas the lowest value was 0.24 mg/L in August in Saleh River’s station, which contains submerged plants. The highest BOD5 was 3.63 mg/L in August in the Al Burka station, whereas the lowest value was 0.91 mg/L in February in the Euphrates station, which contains submerged plants. The index values indicate the presence of organic pollution in all stations, with discounts varying between (65.9 and 36.2), (49.9 and 35), and (40.1 and 22) in Eastern Hammar, Al-Chebiyesh, and the Euphrates, respectively. The vital role of submerged plants in the consumption of nutrients reduced the OPI annual values to (44.4, 37.8, and 25.3) compared with the values in stations without plants (54.9, 44.6, 36). The annual values varied between the Deteriorated category in the East Hammar marsh, a Poor category in Al-Chebiyesh, and the Medium category in the Euphrates, with yearly values of 49.7, 41.2, and 30.7, respectively.

Synthesis of Ce and Sm Co-Doped TiO2 Nanoparticles with Enhanced Photocatalytic Activity for Rhodamine B Dye Degradation

One of the major concerns that receive global attention is the presence of organic pollutants (dyes, pharmaceuticals, pesticides, phenolic compounds, heavy metals, and so on), originating from various industries, in wastewater and water resources. Rhodamine B is widely used in the dyeing of paints, plastics, textiles, and other fabrics, as well as biological products. It is highly persistent, toxic, and carcinogenic to organisms and humans when directly released into the water supply. To avoid this hazard, several studies have been conducted in an attempt to remove Rhodamine B from wastewater. Metal oxide semiconducting materials have gained great interest because of their ability to decompose organic pollutants from wastewater. TiO2 is one of the most effective photocatalysts with a broad range of applications. Several attempts have been made to improve its photocatalytic activity. Accordingly, we have prepared in this work a series of cerium (Ce) and samarium (Sm) co-doped TiO2 nanoparticles (x = 0.00, 0.25, 0.50, 1.00, and 2.00%) using a sol–gel auto-combustion approach. The influence of Ce–Sm concentrations on the structural, morphology, electronic, and optical properties, as well as the photocatalytic activity, was investigated. Structure and elemental mapping analyses proved the presence of Ce and Sm in the compositions as well as the development of the TiO2 anatase phase with a tetragonal structure and crystallite size of 15.1–17.8 nm. Morphological observations confirmed the creation of spherical nanoparticles (NPs). The examination of the electronic structure properties using density functional theory (DFT) calculations and of the optical properties using a UV/Vis diffuse spectrophotometer showed a reduction in the bandgap energy upon Ce–Sm co-doping. The photocatalytic activity of the synthesized products was assessed on the degradation of Rhodamine B dye, and it was found that all Ce–Sm co-doped TiO2 nanoparticles have better photocatalytic activities than pristine TiO2 nanoparticles. Among all of the prepared nanoparticles, the sample with x = 0.50% demonstrated the best photocatalytic activity, with a degradation efficiency of 98% within 30 min and a reaction rate constant of about 0.0616 min−1. h+ and •O2− were determined to be the most important active species in the photocatalytic degradation process. Besides the high photocatalytic degradation efficiency, these photocatalysts are highly stable and could be easily recovered and reused, which indicates their potential for practical applications in the future.

Прямое и комбинированное действие озона на биоплёнку Pseudomonas aeruginosa

In modern medicine, the issue of combating biofilms, including various surfaces in medical facilities, is acute. Ozonation is an environmentally friendly and effective technology in the fight against microbial pollution, including biofilms. The article presents studies of the disinfecting properties of ozone and its combination with various disinfectants on planktonic and adhered (in the biofilm form) Pseudomonas aeruginosa cells. As a result, it was found that ozone is highly effective against various forms of bacterial life, and also requires longer exposure in the presence of organic pollution. When combined with hydrogen peroxide, it shows the greatest bactericidal effect not only on the destruction of the biofilm, but also on the viability of the cells themselves. Keywords: biofilm, ozone disinfection, destruction of biofilm.

Sol-gel combined mechano-thermal synthesis of Y2O3, CeO2, and PdO partially coated ZnO for sulfamethazine and basic yellow 28 photodegradation under UV and visible light

The presence of organic pollutants in marine systems has made wastewater treatment extremely complicated, due to the release of a series of harmful contaminants into the ocean and causing direct damage to humans and the aquatic ecosystem. The present research aims to examine the impact of ZnO partial coating with different nonmetric layers based on CeO2, Y2O3, or PdO for water-charged organic contaminants treatment, using a photocatalysis process. In this vision, the photodegradation of two organic pollutants, sulfamethazine (SMZ) and basic yellow 28 (BY28), using ZnO and ZnO partially coated with cerium, yttrium or palladium oxides was studied. These materials have been successfully synthesized by the combination of both sol-gel and mechano-thermal methods. The prepared catalysts were characterized using X-ray diffraction, scanning electron microscopy SEM-EDX, UV diffuse reflectance spectra (DRS), and X-ray photoelectron spectroscopy analysis (XPS). The XRD measurements discovered that all the synthesized photocatalysts have the hexagonal crystal system of ZnO, and the crystallite size value is calculated to be 36 nm. EDX results affirmed the existence of yttrium, cerium and palladium elements in the prepared ZnO/Y2O3, ZnO/CeO2, and ZnO/PdO materials, respectively, with good dispersion and homogeneity. The XPS spectra of ZnO/Y2O3, ZnO/CeO2, and ZnO/PdO, confirmed the presence of Zn, O, Y, Ce, and Pd elements, where they are, excited as Zn2+, Y3+, Ce4+, and Pd2+ oxidation state, respectively. The photoactivity tests demonstrate that the partial coating increases the degradation efficiency of ZnO, with a total photodegradation of BY28 and SMZ under UV irradiation. Moreover, ZnO/PdO under visible light degrades 94% of BY28 in 120 min and 60% of SMZ in 180 min due to the effective separation of photo-induced charge carriers between PdO and ZnO.

Tumoral and normal brain tissue extraction protocol for wide-scope screening of organic pollutants

Little is known about the presence of organic pollutants in human brain (and even less in brain tumors). In this regard, it is necessary to develop new analytical protocols capable of identifying a wide range of exogenous chemicals in this type of samples (by combining target, suspect and non-target strategies). These methodologies should be robust and simple. This is particularly challenging for solid samples, as reliable extraction and clean-up techniques should be combined to obtain an optimal result. Hence, the present study focuses on the development of an analytical methodology that allows the screening of a wide range of organic chemicals in brain and brain tumor samples. This protocol was based on a solid-liquid extraction based on bead beating, solid-phase extraction clean-up with multi-layer mixed-mode cartridges, reconstitution and LCHRMS analysis. To evaluate the performance of the extraction methodology, a set of 66 chemicals (e.g., pharmaceuticals, biocides, or plasticizers, among others) with a wide range of physicochemical properties was employed. Quality control parameters (i.e., linear range, sensitivity, matrix effect (ME%), and recoveries (R%)) were calculated and satisfactory results were obtained for them (e.g., R% within 60–120% for 32 chemicals, or ME% higher than 50% (signal suppression) for 79% of the chemicals).

Adequacy of Water Use Resources for Drinking and Irrigation, Study Case of Sarh City, Capital of Moyen-Chari Province, CHAD

Our objective is to evaluate adequacy of water for consumption and irrigation. We collected nineteen water samples from 21 to 26, May 2017. Twenty-two physico-chemical and bacteriological parameters were taken into account, electrical conductivity, pH, total hardness, bicarbonate, nitrates, sulfates, chlorides, calcium, sodium, magnesium, potassium, dissolved oxygen and biochemical oxygen demand, chemical oxygen demand, total coliforms, Escherichia Coli, and fecal coliforms. To evaluate water intended for consumption, average values measured parameters were compared to [1] for quality water drinking and we evaluated overall quality of water by means of simplified SEQ-Water grid. Concerning irrigation water, evaluation is based on interpretation of quality parameters of irrigation water that we have calculated; among these parameters we can mention the percentage of sodium, rate of sodium absorption, ratio of magnesium adsorption, residual sodium carbonate. Kelly ratio, Corrosivity ratio and Permeability Index. Results show that surface water is weakly mineralized compared to groundwater and presents a good chemical quality; however, it is slightly altered by presence of organic pollutants. The overall assessment of groundwater quality shows that about 47% of water sampled varies between average quality and very poor quality for consumption. This poor quality is mainly due to presence of nitrates in water, whose content sometimes exceeds the limit authorized by [1]. From a bacteriological point of view, germs of faecal origin such as Total Coliforms, Escherichia Coli and Faecal Coliforms contaminate all groundwater points sampled. They are of poor quality and unfit for human consumption without prior treatment. We also evaluated the quality of water used for irrigation using 6 parameters. The results show that all of our water points are suitable for irrigation, according to the values of CSR and Kelly ratio. The same is true for the permeability index, which shows that all samples fall into class I and II type to indicate their suitability for irrigation purposes. According to [2] all waters are excellent quality for agriculture; and for Richard diagram, 89.5% of waters are generally suitable for irrigation and 10% are generally not suitable for irrigation without prior dilution with low salinity water.

A Multiplex Gene Expression Assay for Direct Measurement of RNA Transcripts in Crude Lysates of the Nematode Caenorhabditis elegans Used as a Bioanalytical Tool.

Gene expression profiling in Caenorhabditis elegans has been demonstrated to be a potential bioanalytical tool to detect the toxic potency of environmental contaminants. The RNA transcripts of genes responding to toxic exposure can be used as biomarkers for detecting these toxins. For routine application in environmental quality monitoring, an easy-to-use multiplex assay is required to reliably quantify expression levels of these biomarkers. In the present study, a bead-based assay was developed to fingerprint gene expression in C. elegans by quantitating messenger RNAs (mRNAs) of multiple target genes directly from crude nematode lysates, circumventing RNA extraction and purification steps. The assay uses signal amplification rather than target amplification for direct measurement of toxin-induced RNA transcripts. Using a 50-gene panel, the expression changes of four candidate reference genes and 46 target mRNAs for various contaminants and wastewaters were successfully measured, and the expression profiles indicated the type of toxin present. Moreover, the multiplex assay response was in line with previous results obtained with more time-consuming reverse-transcription quantitative polymerase chain reaction and microarray analyses. In addition, the transcriptomic profiles of nematodes exposed to wastewater samples and extracts prepared from tissues of swimming crabs were evaluated. The profiles indicated the presence of organic pollutants. The present study illustrates the successful development of a multiplex fluorescent bead-based approach using nematode C. elegans crude lysates for gene expression profiling of target RNAs. This method can be used to routinely fingerprint the presence of toxic contaminants in environmental samples and to identify the most biologically active fraction of the contaminant mixture in a toxicity identification and evaluation approach. Environ Toxicol Chem 2023;42:130-142. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

2D/2D heterojunction of graphitic carbon nitride and hexagonal boron nitride nanosheets mediated electrochemical detection of hazardous hydroquinone with high selectivity and sensitivity

The presence of organic pollutants in our environment is often unnoticed and they silently create serious health hazards. Monitoring and control of these harmful chemicals in both land and water is very much necessary. Graphitic carbon nitride/boron nitride (g-C3N4/BN) nanocomposites were successfully synthesized through a solvothermal process and characterized via XRD, FTIR, UV-Visible, SEM, TEM, and XPS techniques. The electrochemical behavior of g-C3N4/BN nanocomposites was studied using Cyclic Voltammetry (CV), impedance potential, and A.C – impedance experiments. In this work, g-C3N4/BN, 2D‐2D nanocomposite-based electrochemical sensor was developed to detect hazardous hydroquinone (HydQ). CV, Differential Pulse Voltammetry (DPV), and amperometric detection techniques were employed for the detection of HydQ and achieved a good limit of detection of 8.2 nM. g-C3N4/BN(1:1)@GCE exhibits a lower flat band potential of −2.15 V and charge transfer resistance (Rct) of 375.0 Ω than other ratios of g-C3N4/BN nanocomposites based electrodes, making it most suitable for sensor application. The practicality of the prepared electrochemical sensor was validated by performing real sample analysis using industrial wastewater and tap water as analytes.

Assessment of Phytotoxicity of Landfilled Waste and Foundry Dust Based on The Direct Test

The article presents the results of phytotoxicity tests on foundry dust and landfilled waste. Currently, all this waste is being reused. The research has focused on phytotoxicity tests performed directly on the waste. Garden cress (Lepidium sativum L.) was used as the test plant. The germination test (GI) and the accumulation test were used to assess phytotoxicity. All dust types were highly phytotoxic to L. sativum L. in the direct test. The reason for this effect could be the low pH, the high level of heavy metals (HM), and probably the presence of organic pollutants (phenol, formaldehyde). The most phytotoxic was electric arc furnace dust (EAFD), classified as hazardous waste due to the high content of HM. The landfilled foundry waste (LFW) was characterised by moderate phytotoxicity in the direct test. The study confirmed the usefulness of the direct test in the phytotoxicity assessment of foundry waste with L. sativum L.

Distribution Pattern and Influencing Factors of Heavy Metal Resistance Genes in the Yellow River Sediments of Henan Section.

The transformation of heavy metal resistance genes (MRGs) in the environment has attracted increasing attention in recent years. However, few studies have reported the MRG content in the Yellow River, one of the main irrigation water sources in the North China Plain. In this study, we quantified MRG abundance by a metagenomic approach, and assessed the influence on MRGs of both bioavailable and total heavy metal (HM) content. The results indicate that Cu-resistant genes are the most common genes, and the prevalence of arsM needs more attention. Comamonadaceae is the dominant family in the Yellow River, and the presence of organic pollutants may contribute to the prevalence of Vicinamibacteraceae, Nocardioidaceae, and Flavobacteriacea. The results of the Mantel test and Spearman analysis indicate that both the bioavailable fractions and total content of HMs could have little influence on MRGs. Network analysis results indicate that some dominant bacteria could be the potential hosts of some prevalent MRGs, which may exert an adverse impact on human health.

Micromotor-in-Sponge Platform for Multicycle Large-Volume Degradation of Organic Pollutants.

The presence of organic pollutants in the environment is a global threat to human health and ecosystems due to their bioaccumulation and long-term persistence. Hereby a micromotor-in-sponge concept is presented that aims not only at pollutant removal, but towards an efficient in situ degradation by exploiting the synergy between the sponge hydrophobic nature and the rapid pollutant degradation promoted by the cobalt-ferrite (CFO) micromotors embedded at the sponge's core. Such a platform allows the use of extremely low fuel concentration (0.13% H2 O2 ), as well as its reusability and easy recovery. Moreover, the authors demonstrate an efficient multicycle pollutant degradation and treatment of large volumes (1 L in 15 min)byusing multiple sponges. Such a fast degradation process is due to the CFO bubble-propulsion motion mechanism, which induces both an enhanced fluid mixing within the sponge and an outward flow that allows a rapid fluid exchange. Also, the magnetic control of the system is demonstrated, guiding the sponge position during the degradation process. The micromotor-in-sponge configuration can be extrapolated to other catalytic micromotors, establishing an alternative platform for an easier implementation and recovery of micromotors in real environmental applications.

A designed miniature sensor for the trace level detection and degradation studies of the toxic dye Rhodamine B.

The presence of organic pollutants in water and food samples is a risk for the environment. To avoid this hazard a variety of analytical tools are used for the detection of toxic organic contaminants. Herein we present a selective and sensitive electrochemical sensor based on amino group functionalized multi walled carbon nanotubes and carboxylic group functionalized multi walled carbon nanotubes (HOOC-fMWCNTs/NH2-fMWCNTs) as modifiers of the glassy carbon electrode for the detection of a toxic dye, Rhodamine B. The sensing ability of the designed sensor was examined by electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry. The synergistic effect of HOOC-fMWCNTs and NH2-fMWCNTs (layer by layer) led to enhanced electrocatalytic activity of the modified electrode surface for Rhodamine B detection. Under optimized conditions, the graph between concentration and peak current followed a linear trend in the concentration range of 0.1 nM to 0.05 μM. The limits of detection and quantification were found to be 57.4 pM and 191.3 pM respectively. The designed sensor was also used for probing the degradation of Rhodamine B. Sodium borohydride was found to degrade Rhodamine B in neutral media under ambient conditions. The kinetics of degradation followed first order kinetics. Rhodamine B degraded to the extent of more than 80% as revealed by electrochemical and spectrophotometric techniques. The developed method is promising for the treatment of dye contaminated wastewater. Moreover, it uses only a microliter volume of the sample for analysis.