Search Results (63)

Water scarcity is an increasingly critical global issue, particularly in arid regions like Morocco. Innovative approaches, such as the use of alternative water sources like landfill leachate, offer promising solutions. In this study, phosphate washing sludge was used to treat landfill leachate with the aim of producing irrigation-quality water and recovering nitrogen from the resulting sediment. A total of 40 L of raw leachate was treated with three concentrations of phosphate washing sludge (25%, 37%, and 50%). This volume was processed at the laboratory scale as a proof of concept for potential larger-scale applications. After 24 to 36 h of mixing and agitation, the mixture underwent sedimentation, yielding clear supernatants and nitrogen-rich sludge pellets. These pellets showed a significant increase in organic matter content, from 6.4% to 13.5%, representing an enhancement of 110.9%, thus demonstrating partial leachate depollution and organic matter enrichment. Microbiological analyses revealed a 98.9% reduction in fecal streptococci. The supernatants met irrigation water standards in terms of pH and electrical conductivity, and phytotoxicity tests on maize seeds confirmed their suitability for irrigation. Additionally, the recovered nitrogen-rich sediment presents a valuable input for composting and soil amendment. Full article

The photoinitiation properties of two porphyrins were evaluated for the free-radical photopolymerization (FRP) of a bio-based acrylated monomer, i.e., soybean oil acrylate (SOA). Their combination with various co-initiators, such as a tertiary amine as electron donor (MDEA), an iodonium salt as electron acceptor (Iod), as well as two biosourced co-initiators used as H-donors (cysteamine and N-acetylcysteine), makes them highly efficient photoinitiating systems for FRP under visible light irradiation. Electron paramagnetic resonance spin trapping (EPR ST) demonstrated the formation of highly reactive radical species, and fluorescence and laser flash photolysis highlighted the chemical pathways followed by the porphyrin-based systems under light irradiation. High acrylate conversions up to 96% were obtained with these different systems at different irradiation wavelengths (LEDs@385 nm, 405 nm, 455 nm, and 530 nm), in laminate or under air. The final crosslinked and bio-based porphyrin-based materials were used for the full photo-oxidation in water of an azo-dye (acid red 14) and under UV irradiation. These materials have been involved in three successive depollution cycles without any reduction in their efficiency. Full article

Soil pollution by petroleum hydrocarbons is a problem of concern to researchers in various domains. Many depollution methods exist for these situations, but not in all cases can the pollutant be recovered. Soil, an important environmental factor, has to be kept clean and often has to be returned to agricultural use. A common situation of accidental soil pollution is the transportation of petroleum products through pipelines. In this paper, a study is presented that highlights a fast-acting option for significant pollutant recovery, thus limiting major soil pollution. A study on the use of electrodes to help achieve these objectives is proposed. Three working variants have been established, with different electrodes (stainless steel and copper). The degrees of depollution achieved during one week with a working voltage of 12 V were determined. The highest degree of depollution (52.94%) was obtained for copper electrodes. Although electrokinetic depollution is mainly applied to polluted waters and for the removal of metals, the method proved to be efficient also for an agricultural soil polluted with 7% diesel oil. Nutrients (NPKs) and wash water were analyzed before and after depollution to verify if secondary pollution was present. Full article

Water scarcity is a global crisis and of particular concern in arid regions like Morocco. One creative solution is mining unusual water sources, such as landfill leachate. The presence of nitrogen in the sediment was studied as part of the use of sugar lime sludge in treating landfill leachate for irrigation purposes. A volume of 40 L of landfill leachate was treated with three different concentrations of sugar lime sludge (25%, 35%, and 50%). After homogenization and agitation of the mixture for 24 to 36 h, it was permitted to settle through the concrete decantate and supernatant. Nitrogen was efficiently decanted into the sediment during the composting process with green waste, enhancing the quality of the finished compost. The supernatants underwent physicochemical and microbiological analyses to ascertain their suitability for irrigation. The findings showed that the number of fecal streptococci was decreased by 99.13% at a 25% concentration of sugar lime sludge. The percentage of organic matter in the sediment rose from 10% to 40%, suggesting that the leachate had partially depolluted. The pH and electrical conductivity of the supernatants were within irrigation guidelines. The safety of diluted supernatants for plant germination was verified by phytotoxicity experiments conducted on maize seeds. The compost made from the decantate and green waste showed acceptable physical and chemical properties. Statistical analysis was conducted using JAMOVI software version 2.6.26. One-way ANOVA was used to assess the significance of treatment effects on microbiological and physicochemical parameters. The results confirmed statistically significant differences (p < 0.05) between the sludge concentrations, supporting the effectiveness of the treatment process. This study demonstrates how sugar lime sludge can be used to turn landfill leachate into a sustainable and safe irrigation water source, resolving environmental issues and promoting creative water management techniques. Full article

The need for sustainable and efficient water decontamination methods has led to the increasing use of redox enzymes such as glucose oxidase (GOx). GOx immobilization on textile supports provides a promising alternative for catalyzing pollutant degradation in bio-Fenton (BF) and bio-electro-Fenton (BEF) systems. However, challenges related to enzyme stability, reusability, and environmental impact remain a concern. This communication paper outlines innovative strategies developed to address these challenges, notably the use of ecotechnologies to achieve efficient GOx immobilization while maintaining biocatalytic activity. Plasma ecoprocesses, amino-bearing biopolymer-chitosan, as well as a bio-crosslinker genipin have been used efficiently on conductive carbon and non-conductive polyester-PET nonwovens. In certain cases, immobilized GOx can retain high catalytic activity after multiple cycles, making them an effective biocatalyst for organic dye degradation (Crystal Violet and Remazol Blue) via bio-Fenton reactions, including total heterogeneous bio-Fention system. Moreover, the conductive carbon felt-based bioelectrodes successfully supported simultaneous pollutant degradation and energy generation in a BEF system. This work highlights the potential of textile-based enzyme immobilization for sustainable wastewater treatment, bio-electrochemical energy conversion, and also for bacterial deactivation. Future research will focus on optimizing enzyme stability and enhancing BEF efficiency for large-scale applications. Full article

In this study, the applicability of an integrated-hybrid process was performed in a divided electrochemical cell for removing organic matter from a polluted effluent with simultaneous production of green H₂. After that, the depolluted water was reused, for the first time, in the cathodic compartment once again, in the same cell to be a viable environmental alternative for converting water into energy (green H₂) with higher efficiency and reasonable cost requirements. The production of green H₂ in the cathodic compartment (Ni-Fe-based steel stainless (SS) mesh as cathode), in concomitance with the electrochemical oxidation (EO) of wastewater in the anodic compartment (boron-doped diamond (BDD) supported in Nb as anode), was studied (by applying different current densities (j = 30, 60 and 90 mA cm⁻²) at 25 °C) in a divided-membrane type electrochemical cell driven by a photovoltaic (PV) energy source. The results clearly showed that, in the first step, the water anodically treated by applying 90 mA cm⁻² for 180 min reached high-quality water parameters. Meanwhile, green H₂ production was greater than 1.3 L, with a Faradaic efficiency of 100%. Then, in a second step, the water anodically treated was reused in the cathodic compartment again for a new integrated-hybrid process with the same electrodes under the same experimental conditions. The results showed that the reuse of water in the cathodic compartment is a sustainable strategy to produce green H₂ when compared to the electrolysis using clean water. Finally, two implied benefits of the proposed process are the production of green H₂ and wastewater cleanup, both of which are equally significant and sustainable. The possible use of H₂ as an energetic carrier in developing nations is a final point about sustainability improvements. This is a win-win solution. Full article

Heavy metal pollution is a worldwide and stringent concern following many decades of industrialization and intensive mining without (in some cases) consideration for environmental protection. This review aims to identify the existing and emerging techniques for heavy metals (HM) removal/recycling from water and wastewater, with an emphasis on cobalt. Unlike many other heavy metals, cobalt has not been considered a detrimental element for the environment and human beings until recently. Thus, several methods and applicable techniques were evaluated to identify the best treatment approaches applicable to cobalt-polluted water and wastewater. The most feasible depollution methods adapted to the source, environment, and economic conditions were investigated and concluded. The operations and processes presented in this paper are conventional and innovative as well, including precipitation, membrane separation, with emphasis on ultrafiltration (UF) and nanofiltration (NF), but also reverse osmosis/forward osmosis (RO/FO), sorption/chemisorption processes, flotation/mechanical separation operations combined with coagulation/flocculation, photocatalysis, and electrochemical processes. For each one, depending on the frequency of use, physicochemical mechanisms and optimal operational conditions were identified to carry out successful cobalt removal and recovery from aqueous environments. Full article

This study investigated the adsorption properties of graphene oxide in a magnetic-assisted adsorber for the depollution of water containing heavy metals. Two samples of graphene oxide with different surface chemistry were synthetized and assessed using the magnetic-assisted adsorption systems. One graphene oxide sample exhibited a dual magnetic behavior presenting both diamagnetic and ferromagnetic phases, while the other graphene oxide was diamagnetic. The adsorption properties of these graphene oxide samples for removing Pb²⁺ and Cu²⁺ were tested and compared with and without a magnetic field exposure. The results showed that the Pb²⁺ removal increased using both graphene oxide samples in the magnetic-assisted configuration, while Cu²⁺ adsorption was less sensitive to the application of the magnetic field. A monolayer model was used to simulate all the heavy metal adsorption isotherms quantified experimentally. It was concluded that the adsorption mechanism designed to remove Pb²⁺ and Cu²⁺ using tested graphene oxide samples was mainly multi-ionic where two metallic cations could interact with one active site (i.e., oxygenated functional groups) from the adsorbent surface. The oxygenated surface functionalities of graphene oxide samples played a relevant role in determining the impact of magnetic field exposure on the heavy metal removal efficacy. Magnetic-assisted adsorption using graphene oxide is an interesting alternative to reduce the concentration of Pb²⁺ in polluted effluents, and it can also be applied to improve the performance of adsorbents with a limited concentration of oxygenated functional groups, which usually show poor removal of challenging water pollutants such as toxic heavy metals. Full article

Activated carbons are commonly used for adsorption/depollution applications, but only a few studies are related to their lubricating properties. In order to investigate a new family of friction reducers, the tribological properties of biochars and derived activated carbons obtained from sugar cane bagasse are investigated. Activated carbons are obtained from either a physical (steam water) or chemical (with phosphoric acid) activation process. The tribological tests show that the activated carbons present very low friction coefficients, close to 0.08. The correlation of textural and tribological investigations shows that the specific surface area of the compounds as well as the microporous and mesoporous domain extensions are key parameters to optimize the friction reduction properties of activated carbons. The friction properties of the compounds are improved if the mesoporous domain extension is above 40% of the total porous volume. This study shows that local biomass waste valorization is possible and that sugar cane bagasse-derived activated carbons appear as interesting new friction reduction additives for lubricants. Full article

In the context of waters polluted with different high-risk contaminants, the development of efficient materials able to efficiently clean them is necessary. In the first part, the present review focuses on the ability of various types of magnetic layered double hydroxide materials to act as adsorbents for water contaminated mainly with heavy metals and dyes. Also, this paper reviews the ability of different magnetic layered double hydroxide materials to act as potential adsorbents for the treatment of wastewater contaminated with other types of pollutants, such as pharmaceutical products, phenolic compounds, phytohormones, and fungicides. In the second part, the applicability of the catalytic method for water depollution is explored. Thus, the use of simple or composite materials based on Fe₃O₄ is reviewed for the purpose of the catalytic degradation of organic compounds (dyes/phenols/pharmaceuticals). At the end, a review of multifunctional materials able to simultaneously neutralize different types of pollutants from wastewater is provided. Full article

Petroleum hydrocarbons like diesel, crude oil, and bitumen are persistent soil contaminants, necessitating urgent remediation due to their harmful effects on the soil and living organisms. Plasma remediation is a thermochemical method that is gaining attention as an alternative to soil de-pollution. Accordingly, the purpose of this experimental research is to investigate the feasibility of thermal air and water vapour plasmas to de-pollute bituminous soil. Pre-/post-remediation of soil and generated products, an analysis was carried out using SEM, EDX, TGA, and elemental and gas analysers. Despite the plasma type, the research showed that the bituminous soil’s surface morphology changed and resembled clean soil after the remediation. The EDX analysis revealed that the carbon content in the soil reduced from 70.14 wt.% to 7.70 wt.% and 5.74 wt.% and the sulphur concentration decreased from 2.64 wt.% to 0.70 wt.% and 0.74 wt.% after treatment in the environment of water vapour and air plasmas, respectively. The gas analysis revealed that bitumen was mainly decomposed into a synthesis gas (H₂ + CO) and CO₂, with concentrations ranging from 8.67% to 13.66% and 10.89% to 12.82% when air and water vapour plasma were used. Thus, both thermal plasmas effectively remediated soil, with the bitumen concentration not being detected or below the laboratory’s finding limit (<0.089 g/kg). Full article

Driven by concerns over polluted industrial wastewater, particularly heavy metals and dyes, this study explores biosorption using chemically cross-link chitosan derivatives as a sustainable and cost-effective depollution method. Chitosan cross-linking employs either water-soluble polymers and agents like glutaraldehyde or copolymerization of hydrophilic monomers with a cross-linker. Chemical cross-linking of polymers has emerged as a promising approach to enhance the wet-strength properties of materials. The chitosan thus extracted, as powder or gel, was used to adsorb heavy metals (lead (Pb²⁺) and copper (Cu²⁺)) and dyes (methylene blue (MB) and crystal violet (CV)). Extensive analysis of the physicochemical properties of both the powder and hydrogel adsorbents was conducted using a range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM), as well as ¹H and ¹³C nuclear magnetic resonance (NMR). To gain a comprehensive understanding of the sorption process, the effect of contact time, pH, concentration, and temperature was investigated. The adsorption capacity of chitosan powder for Cu(II), Pb(II), methylene blue (MB), and crystal violet (CV) was subsequently determined as follows: 99, 75, 98, and 80%, respectively. In addition, the adsorption capacity of chitosan hydrogel for Cu(II), Pb(II), MB, and CV was as follows: 85, 95, 85, and 98%, respectively. The experimental data obtained were analyzed using the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models. The isotherm study revealed that the adsorption equilibrium is well fitted to the Freundlich isotherm (R² = 0.998), and the sorption capacity of both chitosan powder and hydrogel was found to be exceptionally high (approximately 98%) with the adsorbent favoring multilayer adsorption. Besides, Dubinin has given an indication that the sorption process was dominated by Van der Waals physical forces at all studied temperatures. Full article

ZnO nanostructured materials have been widely utilized in several environmental depollution applications. In the current work, ZnO nanorods were grown using the electrodeposition method with different precursor concentrations. A variation in the dimensions of the nanorods grown with the different precursor concentrations was noticed, as expected. The ability of the fabricated nanorods to remove water pollutants under UV irradiation and their photocatalytic performance stability was also evaluated over a prolonged period of time. Interestingly, the samples grown in different conditions exhibited different capabilities to maintain their morphology and their photocatalytic performance after they were kept in contaminated water for a long time. Moreover, some samples also were found to remain photocatalytically active for approximately 47% longer than other samples. These findings indicate that the performance stability of ZnO nanorods for pollutants removal and their robustness can be greatly improved by controlling their growth parameters, which will favorably impact the use of ZnO nanorods for water-treatment applications and their economic aspects. Full article

Water is one of the fundamental resources for the existence of humans and the environment. Throughout time, due to urbanization, expanding population, increased agricultural production, and intense industrialization, significant pollution with persistent contaminants has been noted, placing the water quality in danger. As a consequence, different procedures and various technologies have been tested and used in order to ensure that water sources are safe for use. The adsorption process is often considered for wastewater treatment due to its straightforward design, low investment cost, availability, avoidance of additional chemicals, lack of undesirable byproducts, and demonstrated significant efficacious potential for treating and eliminating organic contaminants. To accomplish its application, the need to develop innovative materials has become an essential goal. In this context, an overview of recent advances in hydrogels based on chitosan and nanocomposites and their application for the depollution of wastewater contaminated with dyes is reported herein. The present review focuses on (i) the challenges raised by the synthesis process and characterization of the different hydrogels; (ii) the discussion of the impact of the main parameters affecting the adsorption process; (iii) the understanding of the adsorption isotherms, kinetics, and thermodynamic behavior; and (iv) the examination of the possibility of recycling and reusing the hydrogels. Full article

This study explores the depollution activity of a photocatalytic cementitious composite comprising various compositions of n-TiO₂ and CaCO₃. The photocatalytic activity of the CaCO₃–TiO₂ composite material is assessed for the aqueous photodegradation efficiency of MB dye solution and NO_x under UV light exposure. The catalyst CaCO₃–TiO₂ exhibits the importance of an optimal balance between CaCO₃ and n-TiO₂ for the highest NO_x removal of 60% and MB dye removal of 74.6%. The observed trends in the photodegradation of NO_x removal efficiencies suggest a complex interplay between CaCO₃ and TiO₂ content in the CaCO₃–n-TiO₂ composite catalysts. This pollutant removal efficiency is attributed to the synergistic effect between CaCO₃ and n-TiO_2, where a higher percentage of n-TiO₂ appeared to enhance the photocatalytic activity. It is recommended that CaCO₃–TiO₂ photocatalysts are effectiveness in water and air purification, as well as for being cost-effective construction materials. Full article