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The access to drinkable water is a critical challenge in the context of the rising urbanization and industrialization, calling for advanced technologies to clean contaminated waters and wastewater. Here we review the use of metal oxides biochar composites to treat pollution by hevay metals and dyes. We focus on the synthesis of metal oxide nanobiochar; the treatment of pollution by mercury, lead, methylene blue and methyl orange; life cycle analysis; and techno-economical assessment. Metal oxide nanoparticles can act as photocatalysts to allow for the complete mineralization of organic pollutants. For instance, the doping of tin oxide nanoparticles into biochar surface degraded 99.5% of methylene blue dye after 105 min. Ball-milled magnetic nanobiochar achieves 99% mercury removal in 720 min. The presence of biochar enhanced the uptake of contaminants on nanoparticles and facilitated the photocatalytic reaction [ABSTRACT FROM AUTHOR]

Antibiotic resistance is a major health issue partly caused by the diffusion of antibiotic pollution in the natural environment, thus calling for advanced methods to remove antibiotics such as tetracyclines, a major class of pharmaceuticals. Here we review the use of MXene and nano-zero-valent iron-based materials to treat tetracycline in wastewater. MXenes are a class of two-dimensional nanomaterials represented as Mn+1XnTx, where M is an early transition metal, X refers to carbon or nitrogen, and T denotes surface termination groups. Values of n ranges between 1 and 4, and x indicate the number of surface functional groups. MXene and nano-zero-valent iron-based materials can be used as adsorbents, photocatalysts, electrocatalysts and membranes for removing tetracyclines. We review the toxicology of tetracycline, the synthesis and recycling of materials, the removal of tetracyclines and underlying mechanisms, and the use of materials as sensors. Remarkably, a MXene derived from carbide nitride and bismuth oxobromide removed 99% of tetracycline in 30 min. Similarly, a nano-zero-valent iron doped with graphene oxide and copper allowed 100% degradation of tetracycline in 15 min. [ABSTRACT FROM AUTHOR]

Global warming is partly due to excessive carbon dioxide emissions, calling for methods to capture carbon dioxide for conversion into value-added materials and fuels. Here we review the microbial conversion of carbon dioxide into biomethane, bioethanol, polyhydroxybutyrate and succinic acid by bacteria, algae and yeast. We also present genetic engineering and machine learning to improve carbon dioxide capture and conversion. Photoautotrophic biosynthesis, dark fermentation and biodegradation are detailed. We observed that Chlorella vulgaris and Cyanobacteria are able to capture more than 90% of carbon dioxide in their cells and yield about 0.45 g/L.d of biomass in a typical photobioreactor. [ABSTRACT FROM AUTHOR]

Most dyes are pollutants that should be removed from waters due to their mutagenic and carcinogenic properties, requiring advanced adsorption methods. Here, we review polymeric nanocomposites with focus on their synthesis and functionalization, nanofillers, dispersion strategies, factors and mechanisms controlling dye adsorption, and applications. We detail composites including organic or inorganic complexes, carbon nanotubes, biowaste, polyaniline, polypyrrole, and magnetic materials. [ABSTRACT FROM AUTHOR]

Global warming and plastic pollution result from the massive use of fossil fuels, calling for the development of sustainable bioplastics derived from modern biomass. Bioplastic production is expected to increase to 2.43 million tons globally in 2024. In particular, the production of biopolymers from bioresources and organic waste should highly reduce waste accumulation. Biopolymers can be produced by employing microbes or by using monomers from agro-resources. Here we review the use of lignin and polylactic acid for polymer production using enzymes and microorganisms. Carnobacterium, Enterococcus and Aspergillus niger show high lactic acid productivity of about 0.4–1.4 g/L/h. Lignin and polylactic acid can also be transformed into value-added chemicals such as muconic acid, hydrouronic acid, adipic acid and terephthalic acid. [ABSTRACT FROM AUTHOR]

Dihydrogen, commonly named 'hydrogen', is a carbon–neutral and renewable fuel meeting environmental regulations in transportation and industrial production. Hydrogen is currently employed in fuel cells, hydrogen vehicles, and as an efficient energy carrier due to its high energy capacity of 121 kJ per g. Here we review hydrogen production by steam reforming of alcohols including methanol, ethanol, propanol, glycerol and butanol, with focus on catalysts, mechanisms, and analytical methods to characterize deposited carbon. In general, Ru- and Rh-based catalysts show efficient performance with almost 100% feedstock conversion and up to 89% of hydrogen yield, while Ni and Co catalysts exhibit lower ethanol conversion in the range of 40–100% depending on operating conditions. Nevertheless, Ni and Co catalysts have been mainly chosen as active metals for alcohols steam reforming due to their lower cost. [ABSTRACT FROM AUTHOR]

Endocrine disruptors are hazardous chemicals with chronic health effects for most living organisms, inducing homeostasis, hormonal imbalances, cancer, reproductive and neurological disorders, cardiovascular diseases, vulnerability to fetus and neonates. Over 1,000 chemicals display endocrine disrupting characteristics. Endocrine disruptors are found among industrial chemicals, pharmaceuticals, heavy metals, plastic materials, fertilizers, pesticides, herbicides and fungicides. Endocrine disruptors enter human organs via ingestion, inhalation and diffusion through the skin. Here, we review the detection, toxicity, hazard identification and remediation methods of three classes of endocrine disruptors: steroid hormones, pharmaceutical and personal care products, and pesticides. Remediation methods include biological, physical, chemical, electrochemical and radiative methods. Bisphenol A was removed of 99% by biodegradation and ultraviolet with hydrogen peroxide, 98.4% by electropolymerization, 97.5% by photoelectrolysis and 80% by sand filtration. We present advanced treatment chemicals and discuss the performance of remediation using the combination of 2–3 treatment methods. In silico methods and machine learning for predicting toxicity and remediation are discussed [ABSTRACT FROM AUTHOR]

Dihydrogen (H2), commonly named "hydrogen", is attracting research interest due to potential applications in fuel cells, vehicles, pharmaceuticals and gas processing. As a consequence, the recent discoveries of natural gas reservoirs have prompted the development of technologies for methane conversion to hydrogen. In particular, the catalytic decomposition of methane is a promising technology to generate COx-free hydrogen and multi-wall carbon materials. Carbon nanomaterial byproducts can be used in electronics, fuel cells, clothes, and for biological and environmental treatments. Recent research has investigated the performance of hydrogen production and the characteristic of carbon nanomaterials. Here, we review the decomposition of methane on Ni-based catalysts, with focus on the influence of reaction temperature, gas hourly space velocity, support, and promoter. Ni-based catalysts allow CH4 conversion higher than 70% with H2 yield of about 45% at more than 700 °C. We present catalyst regeneration by various techniques such as combustion. Reactors used for catalytic decomposition of methane include fluidized bed, fixed-bed and plasma reactors. [ABSTRACT FROM AUTHOR]

Some pharmaceutical and personal care products, including endocrine disruptors, are polluting ecosystems, thus requiring advanced materials and methods for detection and remediation. Here we review carbon nanotubes for detection and remediation of pharmaceutical and personal care products, with focus on green synthesis of hybrid carbon nanotubes, removal of pollutants, and deep learning networks to predicts adsorption. Pollutants include bisphenol, phthalates, tetracycline, and ciprofloxacin. We found that magnetic carbon nanotubes are easily recovered from water with a relatively low production cost. Functionalized carbon dots/carbon nanotube hybrids can detect ciprofloxacin contamination at 0.001 mg/L. Some studies report the adsorption of 95% or the photocatalytic degradation of 100% of pollutants using magnetic carbon nanotubes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Pharmaceutical waste generation in domestic and industrial discharges is a major challenge requiring adapted treatment solutions. Antibiotics, pain killers, lifesaving drugs, birth control pills, and tetracycline are released by human activities. Biochar has recently drawn attention as an adsorbents to remove pharmaceutical pollutants. Here we review biochar applications for the treatment of tetracycline, sulfonamides, quinolones and non-steroidal anti-inflammatory drugs. We discuss production methods, biochar properties, post-treatment methods and agents for biochar activation, adsorption mechanisms involved, performance of the biochar with respect to the sorbate, and operating conditions. Biochars from renewable materials show 100% recovery of pharmaceutical pollutants. Unlike other adsorbents, biochar can be recycled up to 8 times with a very low decline of efficiency. The highest recoveries of pharmaceutical pollutants using biochars is 1163 mg/g for tetracycline by biochar from Eucommia ulmoides; 400 mg/g for sulfamethoxazole with sugarcane bagasse biochar; 596 mg/g for naproxen by peanut shell biochar, and 698.6 mg/g for norfloxacin by corncob-derived biochar. [ABSTRACT FROM AUTHOR]