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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]

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]

• Biological sequestration techniques for CO 2 reduction are described. • Bioenergy with carbon capture and storage concept is reviewed. • The economic feasibility and environmental outlook are reviewed. • A novel illustration of the artificial photosynthesis process is addressed. Drastic changes in climatic conditions accelerate the need for the implementation of emission reduction techniques to restrict global warming. Conventional technologies do face severe drawbacks in reducing carbon emissions. Carbon neutrality is considered as the most essential concept as it can alleviate the issues of greenhouse gas emissions while deriving energy and fuels from fossil origin. Several reduction technologies are proposed in the recent past, in which the integration of renewable energy resources such as solar and wind power are signified. The review aims to provide an understanding of the technology transition to attain carbon neutrality through production of carbon-free energies such as hydrogen and bioenergy. Despite the chemical and physical sequestration methods, the biological sequestration technique is given special attention for the mitigation of CO 2 emissions by utilizing photosynthetic microalgae. Of numerous microalgae, Chlorella vulgaris , a common eukaryotic microalga found in freshwater showed a maximum CO 2 fixation rate of about 3.35 g/L/d with 10 % CO 2 input. Apart from capturing and storing carbon in the geological site, the concept of utilizing and converting carbon into valuable byproducts is described elaborately. The possibilities for utilizing renewable energy sources for carbon-free energy production through unique prototypes are reviewed and elaborated. It mainly aids to utilize renewable resources more than conventional, which significantly minimizes the carbon footprint. The integration of bioenergy, carbon capture and storage concepts with renewable energy sources extends opportunities to minimize emissions and transition towards carbon neutrality and indeed can aid in achieving carbon negativity. The aforementioned concept was reported to produce about 12.5 million tons ton of hydrogen with 133 million tons of CO 2 recovery. An innovative prototype to resolve emission issues other than CO 2 was also addressed. Illustrations of the artificial photosynthesis process, convective vortex system and integrated multi energy system are disc proposed innovative carbon reduction technologies' economic feasibility and environmental outlook technologies are reviewed and presented. [ABSTRACT FROM AUTHOR]

Treatment of recalcitrant and xenobiotic pharmaceutical compounds in polluted waters have gained significant attention of the environmental scientists. Antibiotics are diffused into the environment widely owing to their high usages, very particularly in the last two years due to over consumption during covid 19 pandemic worldwide. Quinolones are very effective antibiotics, but do not get completely metabolized due to which they pose severe health hazards if discharged without proper treatment. The commonly reported treatment methods for quinolones are adsorption and advanced oxidation methods. In both the treatment methods, metal organic frameworks (MOF) have been proved to be promising materials used as stand-alone or combined technique. Many composite MOF materials synthesized from renewable, natural, and harmless materials by eco-friendly techniques have been reported to be effective in the treatment of quinolones. In the present article, special focus is given on the abatement of norfloxacin and ofloxacin contaminated wastewater using MOFs by adsorption, oxidation/ozonation, photocatalytic degradation, electro-fenton methods, etc. However, integration of adsorption with any advanced oxidation methods was found to be best remediation technique. Of various MOFs reported by several researchers, the MIL-101(Cr)–SO 3 H composite was able to give 99% removal of norfloxacin by adsorption. The MIL – 88A(Fe) composite and Fe LDH carbon felt cathode were reported to yield 100% degradation of ofloxacin by photo-Fenton and electro-fenton methods respectively. The synthesis methods and mechanism of action of MOFs towards the treatment of norfloxacin and ofloxacin as reported by several investigation reports are also presented. [Display omitted] • Applications of metal organic framework for removal of pharmaceutical components are discussed. • Toxicological properties of norfloxacin and ofloxacin are presented. • Action mechanisms of MOFs in treatment of quinolones are explained. • Future scope and existing research gaps are identified. [ABSTRACT FROM AUTHOR]

Electro deionization using microbial communities has been proven as a competent method for desalination and abatement of water pollution by removing ionic chemicals from the target waters. Microbial Desalination Cell (MDC) facilitates microbial deionization which can either support or be a substitute for the conventional desalination methods. Generation of electricity is accomplished by the bio electrochemical oxidation of organic compounds present as contaminants in wastewater which in turn attribute to the migration of ions in MDC system. The present review aims to elucidate the theory, principles and the application of microbial desalination cell and microbial fuel cell (MFC) in treatment of saline and wastewaters. Air cathode MDC and stacked MDC for purification of saline water are found to give promising results. Air pump assisted microbial desalination cell reported 150.39 ppm h−1 of salt removal with an operational time period of 80 h and showed consistent results. Hence the air cathode assisted MDC showed dominant capacity of salt removal compared to stacked MDC. Also, three major types of microbial fuel cell, namely photosynthetic biofilm MFC, constructive wetland MFC and ceramic membrane supported MFC are reviewed for their potentials in wastewater treatment by deionization method and electricity generation. Complete (100%) removal of chemical oxygen demand was reported by photosynthetic microbial fuel cell operated for 16 days having 435.8 Ω of external resistance. When constructive wetland microbial fuel cell was operated for 10 days with 1000 ohms of external resistance, it exhibited complete (100%) removal of chemical oxygen demand from the wastewater. About 92% of chemical oxygen demand removal was demonstrated by ceramic membrane supported microbial fuel. Compared to ceramic membrane microbial fuel cell, photosynthetic and constructive wetland microbial fuel cell displayed better performance in terms of pollutant removal capacity and economical factor. Ability of the electrogenic species, namely Geobacter, Shewanella, Clostridium and Bacillus and the photosynthetic species, namely Chorella Vulgaris Rhodopsuedomonas, and Scenedesmus abundans in microbial deionization methods and their performance levels reported by several researchers are presented. [ABSTRACT FROM AUTHOR]

Graphene is a high surface area special carbon compound with exceptional biological, electronic and mechanical properties. Graphene-based materials are potential components used in water treatment on different modes and processes. Ibuprofen and ciprofloxacin are two commonly found pharmaceutical contaminants discharged into water bodies from industrial, domestic and hospital sources. Their concentration levels in water bodies are reported in the range of 1 μg/L to 6.5 mg/L and 0.050–100 μg/L respectively. Their toxic effects pose very high risk to the inhabiting organisms. Their ability to resist biodegradation and capacity to bioaccumulate makes the conventional methods less effective in removal. In the present article, treatment of these compounds via three methods, adsorption, photocatalytic degradation and electro–fenton reactions using graphene-based materials along with the methods adopted for synthesis and treatment are reviewed. The uptakes obtained by graphene-derived adsorbents are presented along with the optimal operating conditions. Studies reported complete removal of ibuprofen from wastewater was achieved at 7 pH for 60 min using graphene membrane as adsorbent and uptake of 99% of ciprofloxacin was exhibited for graphene nanoplates/boron nitrate aerogel at a pH of 7 and 60 min. The reduced graphene oxide surface exhibits higher affinity to light adsorption which leads to the formation of photo generated electrons. The future perspectives for improved applications of graphene-based materials and the research gap currently existing are highlighted. [Display omitted] • Applications of graphene based materials for removal of pharmaceutical components are reviewed. • Mechanism of ibuprofen and ciprofloxacin removal is described. • Toxicological properties are discussed. • Photocatalytic degradation of ibuprofen and ciprofloxacin is described. [ABSTRACT FROM AUTHOR]

The excessive and unorganised utilisation of pesticides have posed negative impacts on soil and water at higher levels. Pesticides are a major class of persistent organic compounds with high resistance to natural biodegradation and enhanced tendency to bio accumulate. The severe health hazards imposed on the living organisms hinder the ecosystem and lead to chronic and irreversible health issues. Photocatalytic method is reported as a potential alternative with a variety of techniques and materials that are safer, easier, durable, cost-effective and efficient. Nanomaterials play a key role in this domain due to their versatility. In particular, nanostructured materials of organized shapes and morphological properties have gained enormous attention in research and real-time applications. Specifically, nanomaterials like nanotubes, nanorods and nanowires have unique properties and anisotropic structure that make them more suitable for treating pesticide wastes with photocatalysis. Variety of tuning methods and materials are emerging to enhance the activity of titanium and zinc based nanocatalysts in remediation methods. In the present article, four pesticides, namely, atrazine, chlorpyrifos, paraquat and naphthalene are chosen due to their common occurrence and usage in agricultural applications. These pesticides are highly toxic and need special attention to explore appropriate remediation methods. The report also details the latest innovations reported by several research studies in exploring the potential of specially synthesised nanoparticles for photocatalytic removal of pesticide pollutants from environment. For zinc-based hybrid nanomaterials, the maximum disintegration reported were 99%, 98%, 73.3% and 92.3% for atrazine, chlorpyrifos, paraquat and naphthalene, respectively. [Display omitted] • Photocatalytic remediation technologies for pesticide pollutants are discussed. • Removal of atrazine, chlorpyrifos, paraquat and naphthalene are described. • Mechanism of photocatalytic degradation and the pathways are elaborated. • Existing research gaps and future perspectives are explained. [ABSTRACT FROM AUTHOR]

Membrane based filtration is one of the promising technologies for rehabilitation of wastewater streams for reuse and recycle. Many advancements have emerged with the use of novel materials and innovative integrated technologies. The present investigation focuses on the treatment methods based on submerged and stages systems of membranes for water purification. Ceramic, polymeric and mixed matrix type of membranes fabricated for specific type of effluents, their modification methods for accelerating the rejection efficiency, permeability, durability, stability and antifouling properties are detailed in this review. Graphene oxide is the most considered membrane material for adsorption purposes as it exhibits larger surface area, abundant functional groups contain oxygen and has good supply of ligands which is responsible in metal adsorption as it enhances electrostatic interaction by bonding metal ions with graphene oxide nanosheets. Energy derivation in terms of biogas production was also reported in some integrated methods. In many cases, embedded nanomaterial matrices yielded maximum efficiencies in both the submerged and staged operations. However, submerged type of membranes are reported more than the staged type due to simpler configuration with relatively lesser equipment, operational and maintenance issues. In treatment of a low strength wastewater, aluminum oxide based membrane in fluidized bed assembly was reported to yield promising results with reduced power requirement. [Display omitted] • Comprehensive review on novel membrane system application for removal of pollutants is presented. • Applications of submerged and staged membrane systems for wastewater treatment are discussed. • Removal performance using embedded nano materials is explained. • Bottlenecks and future perspectives on membrane research are presented. [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]

The contamination of ecosystems by pharmaceuticals and personal care products represents a significant threat to public health, necessitating innovative approaches to clean wastewater before release into aquatic environments. Here, we review the emerging strategies and methods for the remediation of gemfibrozil and carbamazepine, emphasizing toxicological impacts, advanced oxidation processes, membrane-based removal techniques, and the underlying mechanisms driving these removal processes. We found that engineered composites with strong electron transfer capabilities can enhance the removal efficiency as they boost the generation of highly oxidative radicals. For instance, a nano zero-valent ion incorporated carbon–nitrogen composite removes 100% of gemfibrozil within 60 min. Similarly, a ruthenium perovskite-based heterogeneous catalyst achieved 100% elimination of carbamazepine in 7.5 min. [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]

Polycyclic aromatic hydrocharbons (PAHs) are a class of highly toxic pollutants that are highly detrimental to the ecosystem. Landfill leechate emanated from municipal solid waste are reported to constitute significant PAHs. In the present investigation, three Fenton proceses, namely conventional Fenton, photo-fenton and electro-fenton methods have been employed to treat landfill leehcate for removing PAHs from a waste dumpig yard. Response surface methodology (RSM) and artificial neural network (ANN) methodologies were adopted to optimize and validate the conditions for optimum oxidative removal of COD and PAHs. The statistical analysis results showed that all independent variables chosen in the study are reported to have significant influence of the removal effects with P-values <0.05. Sensitivity analysis by the developed ANN model showed that the pH had the highest significance of 1.89 in PAH removal when compared to the other parameters. However for COD removal, H 2 O 2 had the highest relative importance of 1.15, followed by Fe2+ and pH. Under optimal treatment conditions, the photo-fenton and electro-fenton processes showed better removal of COD and PAH compared to the Fenton process. The photo-fenton and electro-fenton treatment processes removed 85.32% and 74.64% of COD and 93.25% and 81.65% of PAHs, respectively. Also the investigations revelaed the presence of 16 distinct PAH compunds and the removal percentage of each of these PAHs are also reported. The PAH treatment research studies are generally limited to the assay of removal of PAH and COD levels. In the present investigation, in addition to the treatment of landfill leachate, particle size distribution analysis and elemental characterization of the resultant iron sludge by FESEM and EDX are reported. It was revealed that elemental oxygen is present in highest percentage, followed by iron, sulphur, sodium, chlorine, carbon and potassium. However, iron percentage can be reduced by treating the Fenton-treated sample with NaOH. • Realtime landfill leachate treated using three distinct Fenton oxidation methods. • Photo-Fenton treatment removal attained 85.32% for COD and 93.25% for PAH. • Electro-Fenton treatment removal attained 74.64% for COD and 81.65% for PAH. • Degradation of 16 distinct PAHs, classified by USEPA, is reported. • Sludge characterization was accomplished using FESEM and EDX. [ABSTRACT FROM AUTHOR]

Biobutanol is gaining more interest as advanced biofuel owing to its characteristics such as higher energy content, density and lesser corrosiveness. Deriving butanol from biological sources is an approach to attain carbon neutrality by exploiting renewable and sustainable reserves for biorefineries. Lignocellulosic materials are regarded as the suitable resources for the manufacture of butanol and several value-added products. The yield and quality of biobutanol largely rely on three factors, namely, the pretreatment of lignocellulosic feedstock, bioconversion methods adopted and the downstream oil upgradation. In the present report, a critical review on six pretreatment methods, namely, radiative treatment, ultrasonication, hydrothermal methods, organic solvation, ionic liquids solvation and biological treatment of distinct lignocellulosic materials along with their performance levels are presented. The recent strategies devised in the utilization and modification of yeast and bacterial strains for the biorefinery approach in the synthesis of biobutanol are described. The optimal butanol yield of 13.3 g/L was reported using from rice straw and mixed culture of Saccharomyces cerevisiae and Pichia species by enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

Bioremediation of heavy metals has become a major environmental concern due to their bio resistant nature and tendency to accumulate. Application of various technologies, involving physical and chemical working principles are applied and passive uptake using sorption involving eco-friendly substrates gained significant attention. Biochar, a cheaper and efficient material, offers good potential due to the greater ease of production, treatment and disposal. This review focuses on the effective application of biochar to treat water contaminated by three specific heavy metals: chromium, lead and arsenic. The on-field applications like soil amendment, industrial wastewater treatment and groundwater treatment using biochar are highlighted. The review article describes the feedstock available for biochar production, various production processes and the importance of optimum conditions like pyrolysis temperature, rate and retention time for various feedstocks reported in literature. The energy requirement of the production process can be supplied by its own energy output. Various modifications that are suitable for the biochar from distinct feedstocks are also discussed. The removal performance of biochar at different working conditions like pH, initial concentration of pollutant and adsorbent dose are consolidated. The highest removal efficiencies reported were by coconut shell biochar (Cr – 99.9%), canola straw biochar (Pb – 100%) and perilla leaf biochar (As – 100%). The adsorption mechanism is explained with reference to kinetics, isotherms, and molecular dynamics. Adsorption mechanism of most of the biochars was found to fit either Freundlich or Langmuir isotherm. [Display omitted] • Comprehensive review on biochar application for removal of chromium, lead and arsenic is discussed. • Different methods used for biochar modification are discussed. • Removal performance of biochar at different working conditions are consolidated. • Kinetic, isotherm and molecular dynamic models are reviewed. [ABSTRACT FROM AUTHOR]