Efficient oxidation of sulfides into sulfoxides catalyzed by a chitosan–Schiff base complex of Cu(II) supported on supramagnetic Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles

Sulfoxides are versatile synthetic intermediates for the preparation of biological products. Therefore, there is a need for efficient methods to oxidize sulfides into sulfoxides. Such oxidation may be catalyzed by magnetic nanocatalysts due to their good stability, easy synthesis, high surface area, low toxicity and easy separation by magnetic forces. Here we prepared a nanocatalyst by immobilization of the chitosan–Schiff base complex on supramagnetic Fe₃O₄ nanoparticles. The chitosan–Schiff base complex has been previously prepared by functionalization of chitosan with 5-bromosalicylaldehyde and metalation with copper(II) acetate. The catalyst was characterized by Fourier transform infrared, powder X-ray diffraction, transmission electron microscope, scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermogravimetric analysis. Results show that the Fe₃O₄ nanoparticles and nanocatalyst were spherical in shape with an average size of 20 nm. Upon the covalently anchoring of chitosan–Schiff base Cu complex on the magnetic Fe₃O₄ nanoparticles, the average size increased to 60 nm. The prepared Fe₃O₄–chitosan–Schiff base Cu complex catalyzed very efficiently the oxidation of sulfides to sulfoxides with 100 % selectivity in all cases under green reaction conditions and excellent yields. Additionally, ease of recovery and reusability up to four cycles without noticeable loss of catalytic activity make the present protocol beneficial from industrial and environmental viewpoint.     

Bioleaching metal-bearing wastes and by-products for resource recovery: a review

The global transition to a circular economy calls for research and development on technologies facilitating sustainable resource recovery from wastes and by-products. Metal-bearing materials, including electronic wastes, tailings, and metallurgical by-products, are increasingly viewed as valuable resources, with some possessing comparable or superior quality to natural ores. Bioleaching, an eco-friendly and cost-effective alternative to conventional hydrometallurgical and pyrometallurgical methods, uses microorganisms and their metabolites to extract metals from unwanted metal-bearing materials. The performance of bioleaching is influenced by pH, solid concentration, energy source, agitation rate, irrigation rate, aeration rate, and inoculum concentration. Optimizing these parameters improves yields and encourages the wider application of bioleaching. Here, we review the microbial diversity and specific mechanisms of bioleaching for metal recovery. We describe the current operations and approaches of bioleaching at various scales and summarise the influence of a broad range of operational parameters. Finally, we address the primary challenges in scaling up bioleaching applications and propose an optimisation strategy for future bioleaching research.

     

Emerging electrochemical processes for materials recovery from wastewater: Mechanisms and prospects

• Mechanisms for selective recovery of materials in electrochemical processes are discussed. • Wastewaters that contain recoverable materials are reviewed. • Application prospects are discussed from both technical and non-technical aspects. Recovering valuable materials from waste streams is critical to the transition to a circular economy with reduced environmental damages caused by resource extraction activities. Municipal and industrial wastewaters contain a variety of materials, such as nutrients (nitrogen and phosphorus), lithium, and rare earth elements, which can be recovered as value-added products. Owing to their modularity, convenient operation and control, and the non-requirement of chemical dosage, electrochemical technologies offer a great promise for resource recovery in small-scale, decentralized systems. Here, we review three emerging electrochemical technologies for materials recovery applications: electrosorption based on carbonaceous and intercalation electrodes, electrochemical redox processes, and electrochemically induced precipitation. We highlight the mechanisms for achieving selective materials recovery in these processes. We also present an overview of the advantages and limitations of these technologies, as well as the key challenges that need to be overcome for their deployment in real-world systems to achieve cost-effective and sustainable materials recovery.     

Anaerobic digestion and recycling of kitchen waste: a review

About 1.6 billion tons of food are wasted worldwide annually, calling for advanced methods to recycle food waste into energy and materials. Anaerobic digestion of kitchen waste allows the efficient recovery of energy, and induces low-carbon emissions. Nonetheless, digestion stability and biogas production are variables, due to dietary habits and seasonal diet variations that modify the components of kitchen waste. Another challenge is the recycling of the digestate, which could be partly solved by more efficient reactors of anaerobic digestion. Here, we review the bottlenecks of anaerobic digestion treatment of kitchen waste, with focus on components inhibition, and energy recovery from biogas slurry and residue. We provide rules for the optimal treatment of the organic fraction of kitchen waste, and guidelines to upgrade the anaerobic digestion processes. We propose a strategy using an anaerobic dynamic membrane bioreactor to improve anaerobic digestion of kitchen waste, and a model for the complete transformation and recycling of kitchen waste, based on component properties.

     

Antimutagenic and bacteriostatic activities of Schiff‐base compounds derived from aminoguanidine,semicarbazone and thiosemicarbazone and a copper(II)‐coordination complex

The Schiff‐base aminoguanidine compounds including a resorcylidene aminoguanidine copper(II) complex that were synthesized at our laboratory posses non‐mutagenic properties when tested with Ames test using Salmonella typhimurium TA97, TA100 and TA102 bacterial strains. These compounds were tested as possible pharmacological agents in preventing a wide array of illnesses. Additionally, some of these compounds exhibit strong antimutagenic and bacteriostatic activity. Nitrovin, a known mutagen, was used in the antimutagenicity tests as the inducer. A three‐dimensional projection of the copper(II) complex was derived by the semi‐empirical method ZINDO/1 to obtain additional information about its structure, and to help elucidate a possible mechanism of action.     

Green technology for sustainable surface protection of steel from corrosion: a review

Plants contain substances that inhibit corrosion. Here we review biomass-based corrosion inhibitors from plant leaves, nuts, and fruit peels, after treatment with acids, bases or saline solutions. The mechanism of corrosion inhibition involves a monolayer coverage, according to isotherm and Langmuir models. Plant extract-based corrosion inhibitors contain heteroatoms whose electrons pair in the p-electron level in multiple bonds and the vacant d-orbitals of iron. Corrosion inhibition under marine conditions involves various chemical interactions between metals and dissolved ionic components.

     

Variations in the elemental compositions of plants,and computer‐aided sampling in ecosystems∗

To obtain comparable results of multi‐element analysis of plant materials by different laboratories, a harmonized sampling procedure for terrestrial and marine ecosystems is essential. The heterogeneous distribution of chemical elements in living organisms is influenced by different biological parameters. These parameters are mainly characterized by genetic predetermination, seasonal changes, edaphic and climatic conditions, and delocalization processes of chemical substances by metabolic activities.

The biological variations of the element content in plants were divided into 5 systematic levels, which are: 1. the plant species; 2. the population; 3. the stand (within an ecosystem); 4. the individual; and 5. the plant compartment. Each of these systematic levels can be related to: 1. genetic variabilities; 2. different climatic, edaphic and anthropogenic influences; 3. microclimatic or microedaphic conditions; 4. age of plants (stage of development), exposure to environmental influences (light, wind, pollution etc.), seasonal changes; and 5. transport and deposition of substances within the different plant compartments (organs, tissues, cells, organelles).

An expert system for random and systematic sampling for multi‐element analysis of environmental materials, such as plants, soils and precipitation is presented. After statistical division of the research area, the program provides advice for contamination‐free collection of environmental samples.     

Effects of catalytic hydrogenation on coal liquids which exhibit microbial mutagenic activity

An interdisciplinary strategy is outlined for characterizing the disposition of bioactive (toxic, teratogenic, mutagenic, and/or carcinogenic) materials in coal‐derived hydrocarbon liquids during upgrading processing. Engineering input is required to select representative PDU and pilot‐scale samples and appropriate processing schemes and conditions for upgrading experiments to ensure reliable extrapolation of results to demonstration and commercial scale. Biology expertise is required to perform and interpret short‐term in vitro cellular assays and whole‐animal toxicity and carcinogenesis testing on raw and upgraded samples. Chemical separation and identification of active classes and components in the samples aid in interpreting bioactivity results and in quantifying effects of various upgrading processes and conditions. The end result will be a data base for reliably assessing and addressing potential occupational and environmental safety and health concerns associated with upgraded coal‐derived liquids.

An example of the value of this interdisciplinary approach is given by work performed on generically representative raw and hydrotreated SRC‐II gas oil samples. Biological and chemical characterization indicates significant loss of bioactivity during hydrotreatment, with one postulated mechanism being removal of primary amine groups from multi‐ring aromatic compounds.     

Biopolymer-supported TiO2 as a sustainable photocatalyst for wastewater treatment: a review

The rising water pollution by pesticides, pharmaceuticals and dyes is a major health issue calling for advanced remediation methods such as photocatalysis with titanium dioxide (TiO₂), yet the use of TiO₂ displays issues of aggregation, mass loss, recovery, and reusability. These issues have been recently solved by synthesizing biopolymer-supported photocatalysts using cheap, biodegradable and safe biopolymers such as chitosan, alginate, cellulose, cyclodextrin, guar gum and starch. Here we review biopolymer-supported TiO₂ photocatalysts for the removal of organic compounds, with focus on preparation methods, photo and chemical stability, reusability, and adsorptive capacity. We discuss applications of immobilized photocatalysts at the industrial scale.

     

Chemistry,abundance, detection and treatment of per- and polyfluoroalkyl substances in water: a review

Per- and polyfluoroalkyl substances (PFAS) encompass a wide range of compounds containing carbon–fluorine bonds. Due the strength of this bond and the high electronegativity of fluorine atoms, PFAS display stability, wettability and other characteristics that are unique for industrial applications and products. However, PFAS induce adverse effects on the environment and human health. Here we review the chemistry, synthesis, properties, analysis, occurrence in water, filtration, removal and oxydation of PFAS.  We highlight emerging hybrid treatments to remove PFAS from water.

     

Generation of new carbon–carbon and carbon–heteroatom bonds mediated by agro-waste extracts: a review

Agro-waste extracts are considered green solvents since they are easy to handle, readily accessible from natural waste feedstock, biodegradable and recyclable. Therefore, the employment of these extracts in reaction media has emerged as the most useful and eco-friendly alternative in modern organic chemistry. Here, we review recent developments for the generation of new carbon–carbon and carbon–heteroatom bonds mediated by agro-waste extracts. We show that these aqueous extracts have great applicability in several transformations, including condensations, oxidations, multicomponent and coupling reactions. The challenges and advantages on the use of water of agro-waste extracts in synthetic methodologies is also detail.

     

Thermochemical conversion of municipal solid waste into energy and hydrogen: a review

The rising global population is inducing a fast increase in the amount of municipal waste and, in turn, issues of rising cost and environmental pollution. Therefore, alternative treatments such as waste-to-energy should be developed in the context of the circular economy. Here, we review the conversion of municipal solid waste into energy using thermochemical methods such as gasification, combustion, pyrolysis and torrefaction. Energy yield depends on operating conditions and feedstock composition. For instance, torrefaction of municipal waste at 200 °C generates a heating value of 33.01 MJ/kg, while the co-pyrolysis of cereals and peanut waste yields a heating value of 31.44 MJ/kg at 540 °C. Gasification at 800 °C shows higher carbon conversion for plastics, of 94.48%, than for waste wood and grass pellets, of 70–75%. Integrating two or more thermochemical treatments is actually gaining high momentum due to higher energy yield. We also review reforming catalysts to enhance dihydrogen production, such as nickel on support materials such as CaTiO₃, SrTiO₃, BaTiO₃, Al₂O₃, TiO₃, MgO, ZrO₂. Techno-economic analysis, sensitivity analysis and life cycle assessment are discussed.

     

环境污染条件下生物体内DNA损伤的生物标记物研究进展

在正常条件下生物体内的基因组是稳定的;但在环境污染条件下,其DNA容易遭受伤害,主要损伤形式为:碱基改变、脱碱基位点、碱基错配、插入或缺失片段、嘧啶联合、DNA加合物、DNA链断裂、甲基化损伤、DNA链内和链间交联等. 这些受损的DNA对生物细胞产生遗传毒性或细胞毒性. 利用生物标记物进行DNA损伤的检测和定量分析是可行的方法. 本文重点介绍了一些典型的DNA损伤(如DNA加合物、断裂、DNA序列改变等)的生物标记物及其检测方法;认为这些生物标记物在环境污染物的早期诊断和评价方面具有广阔的应用前景. 参32     

The role of spatial scale in sustainable development

The role of spatial scale in sustainable development is assessed by dividing the world into multiple spatial units at different levels on a socio-political spatial scale. The basic patterns of sustainable development do not appear to be evident at all spatial levels, owing to the absence of some capital stocks and the conversion processes linking them, but environmental economics theory can be generalized to explain phenomena at various levels. Capital conversion processes influencing the sustainability of development of spatial units are constrained by processes at different levels, e.g. those imposing environmental conditions on development or affecting availability of investment capital. The autonomy of individual spatial units is also compromised by capital transfers to and from other units at the same level, so it is proposed that the sustainability of development of a particular unit should be estimated using net, rather than gross capital trends. Because of uneven development the same degree of sustainability should not be expected at the same time for all spatial units at the same spatial level.     

Towards the definition of budget models for the evolution of deltas

Global climatic change is likely to take place and could eventually affect Mediterranean deltas and other lowlying coastal regions. This would have serious implications for the natural resources of these deltaic areas, as well as for human settlements and related economic activities. To achieve sound decision making, to prevent damages and to avoid risky investments, it is necessary to understand the integral functioning of deltaic areas and to determine their vulnerability and response to large-scale change phenomena. Optimal use of the available knowledge will require that existing and new field measurements are combined and that integrated (physical/ecological) conceptual models of deltaic behaviour are developed with socio-economics scenarios as boundary conditions. This paper illustrates the methodological effort towards organizing a modeling framework to conduct budget computations at various scales with reference to the most significant ‘physiogrpahic units’ and to the most significant deltaic processes. The final objective is to handle the problem of evaluating possible changes under different scenarios.     

Environmental impact assessment for aquatic ecosystems of industrial effluents†

A system of environmental impact assessment of industrial effluents is presented and discussed. Environmental assessment consists of three phases, hazard assessment, risk determination, and societary evaluation. It is regarded an integrated study of natural sciences, i.e. ecochemicology (chemical fate), ecotoxicology (toxical effects), and ecoepidemiology (biological damages); and social sciences, e.g. geography, sociology, and economy. And the outcome should be the basis of political decision making. Hazard assessment may be divided into a subphase of hazard identification from a base set of scientific information on the industrial effluent, and a second subphase of hazard analysis at a more elevated level of scientific information akin to the procedures suggested elsewhere for single chemicals. Methods of hazard assessment are laboratory experiments, e.g. chemical analysis, degradation and bioaccumulation studies, acute and chronic toxicity assessments, physical modelling, etc. Risk determination may then be conducted by extrapolation of the obtained results from laboratory to field, i.e. by risk estimation to the receiving waters, using methods of hydraulic modelling, biological surveillance, etc. Risk‐benefit evaluation is conducted in the society evaluation phase by balancing environmental consequences against the society value of the production. The outcome is determined by the interaction between hazard‐makers (industry), risk‐takers (administrators), guardians (regulators), and assessors (scientists) in risk management, the crank of environmental assessment.     

Stimulation of soil microbial activity by essential oils

Summary. Although essential oils are well known antimicrobial agents, some microorganisms are activated by them and can use them as a carbon and energy source; this is the case for soil bacteria from Mediterranean ecosystems. We examined the assumption that soil microorganisms when offered with an essential oil, to which they had been previously exposed, would respond faster making immediate use of the newly added substrate. Origanum vulgare subsp. hirtum, Rosmarinus officinalis, Mentha spicata, and Coridothymus capitatus plants were collected and their essential oils isolated. Soil samples from the upper surface layer, beneath these aromatic plants, were also collected. All possible combinations of essential oils and soil samples were examined as well as the effect of the oil of R. officinalis and the non-indigenous, Lavandula angustifolia, on soil samples collected from cultivated fields. Soil respiration was used as a measure of the microbial activity. Oils (0.1 ml) were repeatedly added to the soil samples (150 g) and CO₂ release was measured every seven days. Essential oils differed in their chemical composition. In spite of that, they activated respiration of the different soil samples, even of those not previously exposed to essential oils, to a comparable degree. These results suggest that essential oils are used as a carbon and energy source by rather ubiquitously occurring soil microorganisms and provide evidence that they would not accumulate in the soil, if environmental conditions favour growth of these microorganisms.     

Methods for chemical conversion of plastic wastes into fuels and chemicals. A review

Plastics are utilized in various materials that are useful in everyday life. As the usage of plastics increases, the disposal of plastic materials has become a major issue, calling for recycling methods. Here, we review the different methods to recycle plastics, with focus on catalytic cracking. We present catalysts, cracking mechanisms, and we compare the various treatment methodologies. Several attempts were made by researchers to increase the efficiency of the cracking process using different catalysts and reactors. Many studies reveal high quality products are obtained by catalytic cracking, which consumes low energy and produces lesser residues when compared to other treatment technologies.