Contamination Of Water Resources Research Articles

A single-step method as a green approach to fabricate magnetite nanocomposite for removal of moxifloxacin and cadmium from aqueous solutions

The increasing pace of water resource contamination by heavy metal and pharmaceutical pollutants necessitates the use of advanced methods. Nanomaterials with unique properties are widely employed as adsorbents to address this issue. In this research, a single-step method was developed to coat the magnetite nanoparticles (MNPs) on the sand to produce sand coated with MNPs (S-MNPs), then to use this nanocomposite for the removal of moxifloxacin (MFX) and cadmium (Cd(II)) from aqueous solutions. This method is intended to solve the problem of aggregation and difficulty in the separation of MNPs. The coating method was based on the green synthesis approach by coprecipitation of Fe2+ and Fe3+ ions using green (polyphenolic) extract. The extract of cucumber (Cucumis sativus) peels was selected among six other types of vegetal peels. A trial and error procedure was performed to obtain the suitable amount of the extract to produce MNPs with higher stability and the desired surface functionality. It was found that 5 mL per 100 mL (extract/solution) is the best ratio. The synthesized MNPs were categorized by a set of tests. Then, the synthesized S-MNPs were used in a set of batch experiments with varying conditions to remove the contaminants, moreover, isotherm, kinetics, and thermodynamic study were applied to study the ability of the manufactured nanocomposite to remove contaminants from aqueous solutions and to optimize its utilization. The experimental results proved that the synthesized S-MNPs have a good ability to remove the selected contaminants, with a removal capacity of 94 % and 80 % for MFX and Cd(II), respectively.

Natural Juncus effusus fiber-based separator with 3D porous structure for oil/water emulsion separation

The leakage of oil and organic solvents has emerged as the primary factor of water resources contamination and environmental degradation, causing an urgent and desirable quest for widely exploring and developing eco-friendly materials with hydrophobicity and lipophilicity. Herein, we presented a biomass-based separator composed of poly(vinyl butyral) (PVB) and natural Juncus effusus (JE) which effectively separated oil-water mixtures, to address the aforementioned issue. The as-prepared PVB/JE-based separator, benefiting from the microporous, inner three-dimensional (3D) structure, and natural wettability of JE fiber, exhibits satisfied oil absorption and separation capabilities. The hydrophobic porous in PVB/JE can effectively block the water within the oil, while providing saturated oil absorption capacity. Furthermore, the separator can also efficient separate water in multiple types of water-in-oil surfactant-stabilized emulsion (separation efficiency > 93%). After repeated use (10 cycles) or continuous filtration (20 min), the separator maintained good separation efficiency ( > 83%) and flux ( > 2000 L m−2 h−1). The PVB/JE-based separator exhibited satisfied potential for the rational utilization of biomass materials and application in oil/water separation, owing to its convenient manufacturing process, high separation efficiency, and eco-friendly raw material.

Семей полигоны: тарихы, ядролық сынақтар және оның зардаптары

Семей ядролық полигоны — бұл әлемдегі ядролық қаруды сынаудың ең ірі полигондарының бірі. Семей полигонының 40 жылдай уақыт аралығындағы қызметі Кеңес Одағының қару жарақ жарысы тарихының бір кезеңі саналады. Өкінішке орай, Семей полигонының тарихы отандық тарихнамада тарихи тұрғыдан жан-жақты қарастырылмаған, ғылыми жұмыстар жоқтың қасы. Мұның негізгі себептерінің бірі — архив құжаттарына деген қолжетімділіктің болмауы және олардың қатаң құпия түрінде сақталуы. Сондықтан, қазіргі уақытта Семей ядролық полигонына қатысты жаңа архивқұжаттарын қолдану арқылы ғылыми жұмыстарды басып шығарудың қажеттілігі туындап отыр. Екінші жағынан, Семейдегі ядролық сынақтар су және жер ресурстарының зақымдануына алып келді, экономика масштабының қысқаруына, әлеуметтік құрылымдардың әлсіреуіне ықпал еткені белгілі. Сондықтан, қазіргі уақытта халықтық өмірлік қуатын және аймақтың өмірлік кеңістігін сауықтыру үшін әлеуметтік қорғау жүйесін құру өзекті саналады. Осы себептен, мақалада Семей полигонының құрылу тарихы және 1949–1989 жылдар аралығындағы ядролық қаруды сынаудың салдарықарастырылған.

The Nitrate Fate Tool: A Decision Support System for the Assessment of the Groundwater Vulnerability to Nitrate in Support of Sustainable Development Goals

This article introduces a new web-based and freely accessible tool, the Nitrate Fate tool (NFt), for the assessment of groundwater vulnerability to nitrate pollution in a variety of pedoclimatic conditions. The contamination of water resources by nitrate, in fact, represents a growing and persistent global environmental problem, and the utilization of practical tools to assist personnel working in the agricultural sector is key for mitigating the impact on land use, while maintaining farmers’ incomes. The (NFt) has been developed and integrated into the geospatial decision support system, LandSupport, as a way to support multiple stakeholders in conducting the so-called what-if scenario analysis (e.g., what would happen to the crop production if I substitute a quote of inorganic fertilizer with the same quote of an organic one?). The tool couples a state-of-art crop-growth model—which simulates crop growth dynamics, the nitrogen and carbon cycles—with a novel transfer function model in order to assess the transport of nitrate through the unsaturated zone to the groundwater table. Within the LandSupport platform, the results are shown both as coloured maps and as cumulative charts representing the travel times and the concentrations of root leachate to groundwater table depths. This work details the tool’s rationale, the coupling of the models, and their implementation. Moreover, this article shows examples of applications supporting several public authorities and end-users, underlining that, by combining all of the information on soils, groundwater table depths, management and climates, it is possible to obtain a comprehensive understanding of nitrogen transport dynamics. Two case studies are presented: the Piana del Sele and the eastern plain of Naples, both located in the Campania region of Italy. The results of the tool’s applications reveal significant groundwater vulnerability in both plains, mainly due to the shallow groundwater table depths, resulting in remarkably fast mean nitrate travel times ranging from 0 to 6 years. Finally, the tool provides a reproducible and replicable solution, and future implementation is foreseen for additional case studies all over the world.

Dual crosslinking of low-methoxyl pectin by calcium and europium for the simultaneous removal of pharmaceuticals and divalent heavy metals

The contamination of water resources by heavy metals and pharmaceuticals is a significant threat to human health and the environment. Pectin is a promising material for removing heavy metals from water. However, its removal efficacy for other types of pollutants is limited. In this study, we developed a novel approach to enhance the remediation capacity of pectin (with a low degree of methylation) by crosslinking it with different agents: calcium, europium, and their combination. We performed scanning electron microscopy, infrared spectroscopy, and X-ray diffraction experiments to understand the molecular structure of pectin after gelation with the three agents. Our results showed that calcium, europium, and their combination all induce the gelation of pectin. However, the reticulated pectin structures exhibited significant structural differences depending on the type of crosslinking agent used, which affected the adsorption capacity. Specifically, calcium cations partially formed a crystalline “egg-box” structure, whereas europium cations produced a more homogeneous network without crystalline regions. The dual-crosslinking system comprising calcium and europium cations resulted in an intermediate network with both crystalline and amorphous regions. Our findings suggest that dual-cross-linked pectin is a highly effective adsorbent for the simultaneous removal of both heavy metals and pharmaceutical products. This novel approach of crosslinking pectin with multiple agents has the potential to significantly enhance its remediation capacity, offering a promising solution for the simultaneous removal of multiple pollutants from water.

Selection of the best nitrogen fertilizer management scenario in wheat based on Palmer drought severity index with an environmental perspective

In arid and semi-arid regions, where winter wheat relies partially on precipitation for its water requirements, the timing and amount of precipitation play a pivotal role in nitrogen (N) losses. Given the extensive cultivation of wheat in these areas, farmers' oversight of N rates, N splitting, and the impact of precipitation patterns on N losses have led to water resources contamination. Therefore, tailoring N management to drought condition fluctuations can reduce N losses. The goal was to boost wheat yield while minimizing N losses. The CERES-Wheat model was meticulously calibrated and evaluated over three years, involving an experimental field and five farmer fields. The calibrated model simulated twenty-five N fertilizer scenarios, spanning various N levels (50–250 kg ha−1) and split patterns. This conesidered soil textures and meteorological data from 1992 to 2020. The model's outcomes, encompassing various yield indices and performance metrics such as water productivity (WP), irrigation water productivity (IWP), N residual in soil (NR), N leaching (NL), available N use efficiency (ANUE), N absorption efficiency (NAE), and N utilization efficiency (NUE), were categorized into four distinct groups based on the Palmer's Drought Severity Index (PDSI): Group A: Positive PDSI all season, Group B: Negative PDSI all season, Group C: Positive early, negative later, and Group D: Negative early, positive later. Indices underwent thorough Principal Component Analysis (PCA) to identify the optimal scenario. Model evaluation represented key parameters comprehensively. Simulated total biomass matched real-world conditions (NRMSE 12.44–26.08%, d-index 0.86–0.97). Soil moisture and N fell within specific ranges (NRMSE 18.79–25.60%, RMSE 1.98–4.95 mg kg−1). Comparing different drought and soil conditions, significant performance metric differences emerged. Specifically, in Groups A and D, WP, IWP, ANUE, and NAE increased by 3.38%, 11.53%, 5.86%, and 5.76% compared to C and B. Group B had an 8.55-fold NL increase over A, while Group A saw a substantial 50.64% NR surge compared to B. In overall assessment, the study has identified that the optimal N application rate for the study area is 150 kg ha−1. However, determining the most appropriate N split pattern hinges on the dynamic interplay between PDSI and soil available water content (AWC).

EFFECT OF PIG FARMING EFFLUENTS ON LIMNOLOGICAL PARAMETERS AND PHYTOPLANKTON COMPOSITION

Pig farming plays an important role in the Brazilian economy, but it may trigger environmental issues, especially regarding the contamination of water resources. In this study, we evaluated the effects of the deposition of effluents from a pig farm on the phytoplankton assemblage composition and limnological parameters at different spots of the Divisa River - Fazenda São Luís, Aparecida de Minas/MG, Brazil. Over six months, we analyzed several variables at three different sampling sites on the surface of a coastal zone. We registered seventy-four phytoplankton genera, with Chlorophyceae and Cyanophyceae representing the most abundant classes, and Cryptophyceae and Cyanophyceae displaying the highest densities. The PERMANOVA analysis revealed dissimilarity between sampling sites P1 x P3 and P2 x P3, and the SIMPER analysis showed that Cryptophyceae and Cyanophyceae contributed to the observed dissimilarity. The correspondence canonical analysis (CCA) allowed the organization of sampled sites in three groups, in which the phytoplankton composition was distinguished according to trophic gradients. We concluded that pig farming effluents discharged without previous treatment into water bodies exert influences in both the phytoplankton community and the dynamics of its assemblage, by increasing total phosphorus and contributing for increased abundances of Cryptophyceae and Cyanophyceae in the last evaluated site (P3).

Elucidating the Potential of Biochar-Bentonite Composite and Kaolinite-Based Seed Balls for the Remediation of Coal Mining Impacted Heavy Metals Contaminated Soil

Globally, open-pit coal mining is associated with severe land use impact and the contamination of soil and water resources with heavy metals. Thus, in growing economies like India, where coal is a significant energy source, the heavy metals contamination of soil and water become ubiquitous. This study uses a unique remediation approach by developing biochar-bentonite-based seed balls encapsulating Shorgham grass seeds at their core for application in the contaminated soil. The seed ball was developed by using the bentonite biochar composite in varying weight fractions of 0.5–5% with respect to the kaolinite, whose fractions in the seed ball also varied at one, three, and five parts. The seed balls were applied to the pots containing 3 kg of heavy-metals-contaminated soil for a pot-culture study in a polyhouse for a period of four months. Initial soil analysis results indicated that the mine soil samples showed poor nutrient and organic matter content and were contaminated with heavy metals such as Ni, Zn, Cr, and Cd. Post-pot-culture soil analysis results indicated that the application of seed balls containing five fractions of biochar composite with its combination with three and five-weight fractions of kaolinite showed substantial improvement in the pH, available nutrients, organic matter content, soil enzymes, and overall soil fertility index compared to the controlled study and other cases. The same combination of seed balls also significantly reduced the plant-available fractions of Ni, Zn, Cr, and Cd in the soil, indicating the stabilization of heavy metals within the soil matrix. Also, the application of seed balls substantially improved the plant physiology and reduced the release of stress hormones within the plant cells, indicating improvement in the plant’s biotic and abiotic stress factors. Thus, the application of seed balls in heavy metals contaminated soils, particularly over a large stretch of land, could be a low-cost and viable remediation technique.

Ag Nanoparticles-decorated p-type CuO/n-type ZnO heterojunction nanofibers with enhanced photocatalytic activities for dye degradation and disinfection

With the rapid development of industry, organic pollutants and bacterial contamination in water resources are becoming increasingly severe. Photocatalysis is an effective approach to address this problem. ZnO, as a traditional n-type semiconductor photocatalyst, has a relatively wide bandgap, which results in a narrow range of light absorption and quick recombination of photogenerated charge carriers, thus limiting its development. In this work, we constructed p-type CuO/n-type ZnO heterojunction nanofibers (HNFs) to extend the light harvesting range and improve the migration and separation of the photoinduced electrons and holes across the hetero-interface through. Afterwards, Ag nanoparticles were introduced into above HNF matrix to reinforce the photocatalytic activity. Results showed that, upon simulated sunlight irradiation, the Ag NPs-decorated p-type CuO/n-type ZnO HNFs exhibited enhanced photocatalytic activities. After 20 min of simulated sunlight irradiation, approximately 98.5% of MB was degraded by 1.0 at% Ag NPs-decorated p-type CuO/n-type ZnO HNFs. Additionally, after 10 min of irradiation, the disinfection efficiency of HNFs for Escherichia coli was > 99.99%. It is worth noting that this study has opened up a new pathway for the rational design of p-n junction photocatalysts with superior charge transfer properties, to achieve remarkable photocatalytic disinfection and degradation activities.

Green synthesis of a mesoporous hyper-cross-linked polyamide/polyamine 3D network through Michael addition for the treatment of heavy metals and organic dyes contaminated wastewater

Environmental pollution is the greatest challenge of the modern age due to unprecedented industrialization and urbanization that has led to the contamination of water resources with a wide range of pollutants. The release of untreated industrial and municipal wastewater to water bodies further intensifies the problem. The presence of heavy metals and organic contaminants in water poses significant threats to humans, aquatic life, and the environment. Adsorption is one of the famous water treatment technologies due to its simplicity, low cost, efficiency, and minimal secondary pollution. The selection or synthesis of an effective adsorbent is key to the success of the adsorptive removal of pollutants. In this work, we synthesized an adsorbent consisting of a mesoporous hyper-cross-linked polyamide/polyamine 3D network through a single-step Michael addition reaction. The adsorbent was characterized by FTIR, PXRD, TGA, SEM, and TEM to investigate its functional moieties, material nature, thermal, morphological, and internal structural features, respectively. Due to its mesoporous structure, presence of functional groups, and 3D hyper-cross-linked network, it efficiently removed heavy metals (Cd, Cr, and Pb) from aqueous media. The effect of various parameters such as sample pH, adsorbent dosage, contact time, and adsorbate concentrations was thoroughly investigated. The experimental data were analyzed by a variety of isotherm models wherein Langmuir was found to be the best fit for explaining the adsorption of all the metals. The adsorption kinetics was best explained by the pseudo-second-order model. The maximum adsorption capacities for Cd, Cr, and Pb were 60.98 mg g−1, 119 mg g−1, and 9.302 mg g−1, respectively. The synthesized adsorbent was also tested for removal of organic dyes, and it showed selective and fast removal of Eriochrome Black T. Polymeric resins can be promising materials for adsorptive remediation of pollutants in aqueous media.

A Breakthrough in Photocatalytic Wastewater Treatment: The Incredible Potential of g-C3N4/Titanate Perovskite-Based Nanocomposites.

Water pollution has emerged as a major global environmental crisis due to the massive contamination of water resources by the textile dyeing industry, organic waste, and agricultural residue. Since water is fundamental to life, this grave disregard puts lives at risk, making the protection of water resources a serious issue today. Recent research has shown great interest in improving the photocatalytic performance of graphitic carbon nitride (g-C3N4) for wastewater treatment. However, the photocatalytic removal activity of pure g-C3N4 is poor, owing to its minimal surface area, fast recombination of photo-generated electron-hole pairs, and poor light absorption. Recently, titanate perovskites (TNPs) have attracted significant attention in both environmental remediation and energy conversion due to their exceptional structural, optical, physiochemical, electrical, and thermal properties. Accordingly, TNPs can initiate a variety of surface catalytic reactions and are regarded as an emerging category of photocatalysts for sustainability and energy-related industries when exposed to illumination. Therefore, in this review article, we critically discuss the recent developments of extensively developed g-C3N4/TNPs that demonstrate photocatalytic applications for wastewater treatment. The different synthetic approaches and the chemical composition of g-C3N4/TNP composites are presented. Additionally, this review highlights the global research trends related to these materials. Furthermore, this review provides insight into the various photocatalytic mechanisms, including their potential impact and significance. Also, the challenges faced by such materials and their future scope are discussed.

Examining the microbial composition of natural springs in Bhaderwah, Jammu and Kashmir, India.

Natural springs are the main source of water supply for domestic and agricultural use for humans living in the mountainous regions of Asia. Increasing anthropogenic activities with associated waste load, coupled with inadequate sanitation, and contamination of natural water resources and the environment are emerging as important public health issues. We performed a prospective microbiological and physicochemical investigation of water samples from seven distinct natural springs situated at an altitude of 1615m in the Bhaderwah region of Jammu and Kashmir, India. Bacterial groups belonging to opportunistic pathogens such as members of Moraxellaceae (Acinetobacter), Arcobacteraceae (Pseudoarcobacter), Pseudomonadaceae (Pseudomonas), Oxalobacteraceae (Massilia), and Flavobacteriaceae (Flavobacterium) were observed. The total coliform test indicated an intermediate level of risk of fecal contamination of the springs, except for one site. Through a questionnaire-based survey of the local population, we discovered that around 40% of participants had suffered from waterborne diseases including typhoid (~14%) and diarrhea (~11%). Our data suggests that increased surveillance of fecal contamination and heterotrophic opportunistic pathogens is needed to enhance water quality and reduce health risks for people living in mountainous regions.

Insights into Recent Advances of Biomaterials Based on Microbial Biomass and Natural Polymers for Sustainable Removal of Pharmaceuticals Residues.

Pharmaceuticals are acknowledged as emerging contaminants in water resources. The concentration of pharmaceutical compounds in the environment has increased due to the rapid development of the pharmaceutical industry, the increasing use of human and veterinary drugs, and the ineffectiveness of conventional technologies to remove pharmaceutical compounds from water. The application of biomaterials derived from renewable resources in emerging pollutant removal techniques constitutes a new research direction in the field. In this context, the article reviews the literature on pharmaceutical removal from water sources using microbial biomass and natural polymers in biosorption or biodegradation processes. Microorganisms, in their active or inactive form, natural polymers and biocomposites based on inorganic materials, as well as microbial biomass immobilized or encapsulated in polymer matrix, were analyzed in this work. The review examines the benefits, limitations, and drawbacks of employing these biomaterials, as well as the prospects for future research and industrial implementation. From these points of view, current trends in the field are clearly reviewed. Finally, this study demonstrated how biocomposites made of natural polymers and microbial biomass suggest a viable adsorbent biomaterial for reducing environmental pollution that is also efficient, inexpensive, and sustainable.

The photocatalytic and antibacterial potential of highly efficient S-scheme binary S-gC3N4@Co-zinc ferrite nanocomposite

Dye contamination of water resources is a global issue threatening aquatic life and humans due to its persistence, toxicity, and carcinogenic potential; it must be resolved immediately. This paper reports the hydrothermally synthesized S-gC3N4/cobalt-zinc ferrite (S-GCN/Co-ZF) binary s-scheme heterojunction and its remarkable characteristics, including the lowest rate of charge carrier recombination and the highest absorption of solar energy with excellent photocatalytic and antibacterial potential. The photocatalytic performance of Co-ZF nanoparticles (0.5–12.5 wt%) was tested in the first phase to determine the ideal Co-doping into the ZF. The highest methylene blue photocatalytic degradation was shown by the as-synthesized 6.5% Co-ZF nanoparticles, which were then disseminated on sulphur-doped graphitic carbon nitride (S-GCN) nanosheets as an active constituent to create a series of 25–70 wt % S-GCN@6.5% Co-ZF nanocomposites in the subsequent stage. The optimized composite (55% S-GCN@6.5% CO-ZF) performed excellent photocatalytic performance and accomplished about 93% degradation of methylene blue within 120 min. The antibacterial potential of ZF, S-GCN, 6.5% Co-ZF, 55% S-GCN@6.5 %Co-ZF was examined against Escherichia coli and Bacillus subtilis bacteria. Among these samples, the 55% S-GCN@6.5%CO-ZF nanocomposite demonstrates excellent antibacterial potential. All the synthesized photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-disperse X-ray (EDX), Fourier transform infrared (FTIR) and ultraviolet–visible (UV–Visible) spectroscopic techniques.

Solid Waste Audit and Characterization Study at Tuensang Town Nagaland

Today scenario improper waste management causes serious pollution and health risk, which is the main concerning environmental management in developing countries. In most cities, the use of open dumps is common for the disposal of wastes, resulting in soil and water resource contamination. The study carried from March to May 2023.A Total of 30 households were studied for data collection (210 samples) from three types of family, low income, medium income and high income family using the random sample, out of 15 wards,8 wards were used for the sample selection. The study shows that the majority of the residents are very much concerned about the poor condition of the environment due to the inappropriate and improper SWM in Tuensang town. The residents are not much satisfied with the service of the town council in regard with SWM dumping in the hearts of Tuensang. There is no scientific engineered solid waste disposal site in the Tuensang town and the results can be a starting point in planning for such. This paper give the total waste generation in the household level, weekly and yearly per capita per day and and also give the types of solid waste generation in the town. Based on the findings of the study, researcher proposes that district and town needs to provide proper solid waste segregation awareness to the general citizen to every household. It may also encouraged citizens not to dispose of their household wastes randomly.

Arsenic in groundwater in the Grand Canyon region and an evaluation of potential pathways for arsenic contamination of groundwater from breccia pipe uranium mining

The Grand Canyon in northern Arizona is an international tourist destination, a home or sacred place to many Native Americans, and hosts some of the highest-grade uranium deposits in the United States. Although potential contamination of water resources by uranium from mining activities is a concern, other elements commonly associated with these uranium deposits may pose a greater risk to human populations in the area. This study presents an assessment of arsenic in groundwater in the Grand Canyon area. First, sampling results for arsenic are presented and areas with elevated arsenic concentrations are discussed. Potential pathways of groundwater contamination by arsenic from uranium mines are then discussed to elucidate situations and conditions under which elevated concentrations of arsenic might be expected to become mobilized from breccia-pipe uranium mining activities. Results for arsenic in groundwater in the study area were available for 652 samples collected from 230 sites. Arsenic concentrations in groundwater ranged from less than reporting limits in 60 samples to a maximum concentration of 875 μg/L at Pumpkin Spring. About 88% (202) of the sites sampled had a maximum arsenic concentration below the drinking water standard of 10 μg/L. Available data from near former or current breccia-pipe uranium mines in the area indicate limited evidence to-date of mining effects on elevated arsenic in groundwater, although slow groundwater flow paths in the region may result in extended times of decades or more for groundwater to reach discharge locations. Post-mining entry of groundwater into the shaft and underground mine workings, with subsequent transport of metal-enriched groundwater offsite, may be a potential pathway of groundwater arsenic contamination from mining, although concentrations would likely be attenuated by contact with sedimentary rock units and dilution with native groundwater along flow paths. Monitoring of perched groundwater at reclaimed mine sites post-reclamation could provide data on the effectiveness of clean-closure practices on protecting groundwater quality in the area.

Green Approaches in Rubber Recycling Technologies: Present Status and Future Perspective

As a consequence of massive production and consumption of rubbers, rubber blends, and rubber composites for myriad applications, elastomeric products have enormously accumulated and become an environmental threat. The disposal and burning of rubber wastes have been banned because of environmental and economic reasons. By contrast, a great deal of attention has been directed toward strategies enabling recycling and reuse of rubbers. Basically, conventional recycling methods suffer from several drawbacks such as the formation of dust, fumes, and toxic gases in the air, as well as contamination of underground water resources. Thus, green and sustainable formulations and processing methods nowadays are of priority and importance. Taking advantage of sustainable development horizons, scientific and technological aspects of waste rubber management such as processing techniques, properties of the resulting products, industrial applications, and compatibilization with other materials such as thermoplastics, thermosets, and rubbers are herein reviewed and discussed. A particular emphasis is placed on reactive extrusion as a highly flexible in situ compounding method enabling innovations and taking care of sustainability concerns. Finally, the current status of green rubber recycling and future opening doors ahead of this technology are highlighted.

Efficient removal of Mn2+ ions from aqueous solutions using apple pomace biochar

The increasing contamination of water resources is a severe environmental problem. Manganese is highly soluble in water, has adverse effects on the environment and human health during excessive exposure, and is difficult to remove. Biosorbents have been suggested to remove metals from aqueous solutions, therefore, apple pomace was utilized to prepare activated biochar (activated charcoal from apple pomace, ACAP). The biochar sample was characterized by X-ray fluorescence spectrometry, scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller analysis. The aim of this study was to use ACAP as an adsorbent to remove Mn2+ ions from aqueous solutions. Adsorption experiments were performed in the pH range 3.2–6.5, with various masses of ACAP biochar and Mn2+ ion concentrations. The results were evaluated using the pseudo-first order, pseudo-second order, general order, Elovich, and Webber and Morris kinetics models. All the models fitted the experimental results, the equilibrium time was 15 min, and the pseudo-second order model presented the highest constant (k2), indicating that chemosorption is an important mechanism in adsorption. The adsorption isotherm results were adjusted using different models, wherein the Langmuir and Temkin models exhibited the best fit to the experimental results. Adsorption experiments yielded a 97.5% removal rate of Mn2+ ions at pH 6.5 and <5% at pH 3.2, and the desorption of manganese in nitric acid (0.1 M) was 97.5%. Overall, apple pomace biochar is an efficient adsorbent for removing Mn2+ ions in aqueous media, and is applicable for treating water for human consumption.

Effective nanomembranes from chitosan/PVA blend decorated graphene oxide with gum rosin and silver nanoparticles for removal of heavy metals and microbes from water resources

Fabricating an effective bio-adsorbent based on functional spots can surely be able to eliminate numerous of heavy metals and pathogens from contaminated water resources. Thus, this study aimed to fabricate depollution bionanomembranes based on amalgamated the decorated graphene oxide (GO) with antibacterial natural rosin and silver (Ag) NPs inside chitosan (CS)/polyvinyl alcohol (PVA) blend by the solvent-casting route. The nanostructure of prepared GO nanoplatelets and its decoration are investigated by X-ray diffraction (XRD). Various ratios from decorated GO (i.e., 1, 2 and 3 wt.%) are utilized to prepare CS/PVA nanomembranes. The structure and surface topography of casted nanomembranes are analyzed by XRD and SEM. The obtained outcomes revealed that the use of decorated GO, especially at 2 wt.%, increased the tensile strength to ∼ 48 MPa compared to the unfilled blend (33 MPa). Other investigations such as thermal stability and antibacterial properties are also conducted on the casted CS/PVA nanomembranes. Moreover, depollution of heavy metals is explored through adsorption into the polymeric membranes at ambient temperature and pH 4–6. The gotten results supported that CS/PVA-3% NPs membrane possessed higher adsorption property towards the selective metal ions (i.e., 85–99.7% depending on the metal ion type) compared to other nanomembranes. However, the tensile strength achieved for the nanomembrane containing 2 wt.% nanoplatelets. The impact of pH, temperature, contacting time, and bacterial colony counting on CS/PVA-3% NPs is also studied, in addition to the recovery and reusability of adsorbent. Furthermore, kinetic and isothermal models are suggested to depict the adsorption efficacy of CS/PVA-3% NPs membrane. The obtained data showed that CS/PVA-3% membrane is a promising candidate to be utilized for removal of heavy metals and biological species from water resources for irrigation and agricultural applications.

Integrated LIBS-Raman spectroscopy: A comprehensive approach to monitor microplastics and heavy metal contamination in water resources

The increased use of plastic products and global industrial conditions have contaminated natural resources, especially water, with pollutants such as microplastics and trace elements, including heavy metals. Hence, continuous monitoring of water samples is an urgent requirement. However, the existing microplastic-heavy metal monitoring methodologies require discrete and sophisticated sampling approaches. The article proposes a multi-modal LIBS-Raman spectroscopy system for detecting microplastics and heavy metals from water resources with unified sampling and pre-processing approaches. The accomplishment of the detection process is using a single instrument by exploiting the trace element affinity of microplastics, which operates in an integrated methodology to monitor water samples for microplastic-heavy metal contamination. The polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) plastic types dominate the identified microplastics from different sampling spots: in an estuary formed by the Swarna River near Kalmadi (Malpe) in Udupi district, and from River Netravathi in Mangalore, Dakshina Kannada District, Karnataka, India. The detected trace elements from microplastic surfaces include heavy metals such as Al, Zn, Cu, Ni, Mn, and Cr and other elements counting Na, Mg, Ca, and Li. The system could record concentrations of trace elements down to 10 ppm, and comparing results with the conventional technique of Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) confirms the ability of the system to detect trace elements from microplastic surfaces. In addition, comparing results with direct LIBS analysis of water from the sampling site shows better results in microplastic-based trace element detection.