Nanotechnology in Wastewater Management: A New Paradigm Towards Wastewater Treatment

Bacterial transport mediated by micro-nanobubbles in porous media

Determining the role of micro-nanobubbles (MNBs) in controlling the risk posed by pathogens to soil and groundwater during reclaimed water irrigation requires clarification of the mechanism of how MNBs block pathogenic bacteria. In this study, real-time bioluminescence imaging was used to investigate the effects of MNBs on the transport and spatiotemporal distribution of bioluminescent Escherichia coli 652T7 strain in porous media. The presence of MNBs significantly increased the retention of bacteria in the porous media, decreasing the maximum relative effluent concentration (C/C0) by 78 % from 0.97 (without MNBs) to 0.21 (with MNBs). The results suggested that MNBs provided additional sites at the air-water interface (AWI) for bacterial attachment and acted as physical obstacles to reduce bacterial passage. These effects varied with environmental conditions such as solution ionic strength and pore water velocity. The results indicated that MNBs enhanced electrostatic attachment of bacteria at the AWI and their mechanical straining in pores. This study suggests that adding MNBs in pathogen-containing water is an effective measure for increasing filtration efficiency and reducing the risk of pathogenic contamination during agricultural irrigation.

Recent development of substrates for immobilization of bimetallic nanoparticles for wastewater treatment: a review

Bimetallic nanoparticles (BMNPs) have gained considerable attention due to their remarkable catalytic properties, making them invaluable in wastewater treatment applications. One of these challenges lies in the propensity of BMNPs to aggregate due to Van der Waals interactions, which can reduce their overall performance. Additionally, retrieving exhausted NPs from the treated solution for subsequent reuse remains a significant hurdle. Moreover, the leaching of NPs into the discharged wastewater can have harmful effects on humans as well as aquatic life. To overcome these issues, various substrates have been researched to maximize the efficiency and stability of the NPs. This review paper delves into the pivotal role of various substrates in immobilizing BMNPs, providing a comprehensive analysis of their performances, advantages, and drawbacks. The substrates encompass a diverse range of materials, including organic, inorganic, organic-inorganic, beads, fibers, and membranes. Each substrate type offers unique attributes, influencing the stability, efficiency, and recyclability of BMNPs. This review paper aims to provide an up-to-date and detailed analysis and comparison of the substrates used for the immobilization of BMNPs. This work further reviews the underlying mechanisms of the composites involved in treating pollutants from wastewater and how these mechanisms are enhanced by the synergistic effects produced by the substrate and BMNPs. Furthermore, the reusability and sustainability of these composites are discussed. Also, high-performing substrates are highlighted to give direction to future research focusing on the immobilization of BMNPs in the application of wastewater treatment.

Efficient removal of oxytetracycline antibiotic from aqueous media using UV/g-C3N4/Fe3O4 photocatalytic process

Residual pharmaceuticals in the environment are a class of emerging pollutants that endanger human health. Tetracycline's family, including oxytetracycline (OTC), are known as one of the most produced and consumed antibiotics worldwide. The g-C3N4/Fe3O4 nanocomposite with high level of catalytic efficiency features suitable performance in water/wastewater treatment. Therefore, in the present study, this nanocomposite was applied to remove the oxytetracycline from the aqueous environment. In this research study, g-C3N4/Fe3O4 nanocomposite (serving as catalyst) was initially synthesized by a simple hydrothermal method. The effect of key operating parameters such as initial solution pH, dose of catalyst, contact time and initial concentration of OTC in aqueous solutions was investigated under UV irradiation. In addition, COD and TOC tests, the kinetics and the effect of radical scavengers on the applied photocatalytic process were all evaluated. The maximum removal efficiency of OTC (99.8 %) was achieved under the following conditions: neutral solution pH 7; catalyst dose, 0.7 g/L; and an initial OTC concentration of 5 mg/L. The data showed that the kinetics of the reaction followed the first-order model with R2 of 0.9755. The respective COD and TOC efficiency values for the applied photocatalytic process were determined to be 87 and 59 %, respectively. In addition, the lowest removal efficiency of OTC was observed in the presence of tert-butanol radical scavengers, and OH radicals played a main role. The UV/g-C3N4/Fe3O4 photocatalytic process proved to be highly efficient for the removal of OTC antibiotic and could be potentially applied for the removal of other pollutants from aqueous solutions.

Exploring synthesis and applications of green nanoparticles and the role of nanotechnology in wastewater treatment

Current research endeavours are progressively focussing towards discovering sustainable methods for synthesising eco-friendly materials. In this environment, nanotechnology has emerged as a key frontier, especially in bioremediation and biotechnology. A few areas of nanotechnology including membrane technology, sophisticated oxidation processes, and biosensors. It is possible to create nanoparticles (NPs) via physical, chemical, or biological pathways in a variety of sizes and forms. These days, the investigation of plants as substitutes for NP synthesis methods has drawn a lot of interest. Toxic water contaminants such as methyl blue have been shown to be removed upto 70% by nanoparticles. In our article, we aimed at focussing the environmental sustainability and cost-effectiveness towards the green synthesis of nanoparticles. Furthermore it offers a comprehensive thorough summary of green NP synthesis methods which can be distinguished by their ease of use, financial sustainability, and environmentally favourable utilization of plant extracts. This study highlights how green synthesis methods have the potential to transform manufacturing of NPs while adhering to environmental stewardship principles and resource efficiency.

Potential of biosynthesized titanium dioxide nanoparticles towards wastewater treatment and antimicrobial activity

This study reports a green, sustainable, reliable, and cost-effective method for the biosynthesis of titanium dioxide nanoparticles (TiO2NPs) using the leaf and stem extracts of Carissa opaca. The newly synthesized biogenic TiO2NPs were confirmed and characterized using various analytical techniques, such as Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), zeta potential, X-ray diffraction (XRD), inductively coupled plasma analysis (ICP), and scanning electron microscopy (SEM). Both the electron microscopy, i.e., SEM and HRTEM confirmed the spherical/hexagonal crystalline structure of TiO2NPs with an average particle size range from 72.8 to 84.11 nm. These nanoparticles (NPs) exhibited aggregation and possessed a diverse array of functional groups on their surface. Biosynthesized TiO2NPs showed excellent photocatalytic activity against methylene blue (MB) with decolorizing efficiency of 87.8% and 91.95%, whereas in case of methyl violet (MV), the decolorizing efficiency of 82.1% and 71.9% was observed with nanoparticles synthesized using leaf and stem extract, respectively. The newly synthesized NPs have also shown good antibacterial potential against Klebsiella pneumoniae and Staphylococcus aureus. This new biomimetic approach offers an economical and environmentally benign alternative for the removal of hazardous dyes and may find a place for antimicrobial applications.

Sunlight mediated removal of toxic pollutants from Yamuna wastewater using efficient nano TeO2-ZnO nanocomposites

We have utilised our TeO2-ZnO nanocomposites for Yamuna wastewater treatment in natural sunlight wherein the sampling site was Nigam Bodh Ghat, Kashmere Gate, Delhi. In BET isotherm, TZ NCs exhibited type IV isotherm forming a H3 like hysteric loop sustaining mesoporous characteristic with an increase in surface area, pore volume and pore diameter of 56.76 m2/g, 0.257 cc/g and 17.18 nm respectively, when compared to pristine ZnO NPs. Yamuna wastewater treatment was carried out using various concentrations of TZ NCs (range 0.1-0.3 g/500 mL) under natural sunlight. Post-treatment, all the physicochemical parameters such as DO, BOD, COD, Nitrates, Ammonia and Phenolic contents were found to be reduced to 10 times bringing Yamuna water parameters within safe limits. Our TZ NCs have shown to have high selectivity for the removal of Chromium from water. Out of all the three concentrations 0.2 g/500 mL or 0.4 mg/mL is the most optimum concentration of TZ NCs for complete Yamuna wastewater treatment. Also, the bacterial culture present in Yamuna water was killed by 90% using TZ having MIC of 0.1 mg/mL. The antibiofilm activity of TZ against K.pneumoniae MTCC 109 was also checked using Congo Red Agar Assay. The presence of heavy metals, their corresponding degradation and leaching studies were analysed using ICP-OES. TZ NCs showed a very minimal leaching rate of Zinc into the water, proving no toxicity associated with these nanocomposites. Further, to observe the safe disposal of TZ NCs into the soil, TZ NCs were utilised for ecotoxicity studies.

Nanoparticles and nanofiltration for wastewater treatment: From polluted to fresh water

Water pollution poses significant threats to both ecosystems and human health. Mitigating this issue requires effective treatment of domestic wastewater to convert waste into bio-fertilizers and gas. Neglecting liquid waste treatment carries severe consequences for health and the environment. This review focuses on intelligent technologies for water and wastewater treatment, targeting waterborne diseases. It covers pollution prevention and purification methods, including hydrotherapy, membrane filtration, mechanical filters, reverse osmosis, ion exchange, and copper-zinc cleaning. The article also highlights domestic purification, field techniques, heavy metal removal, and emerging technologies like nanochips, graphene, nanofiltration, atmospheric water generation, and wastewater treatment plants (WWTPs)-based cleaning. Emphasizing water cleaning's significance for ecosystem protection and human health, the review discusses pollution challenges and explores the integration of wastewater treatment, coagulant processes, and nanoparticle utilization in management. It advocates collaborative efforts and innovative research for freshwater preservation and pollution mitigation. Innovative biological systems, combined with filtration, disinfection, and membranes, can elevate recovery rates by up to 90%, surpassing individual primary (<10%) or biological methods (≤50%). Advanced treatment methods can achieve up to 95% water recovery, exceeding UN goals for clean water and sanitation (Goal 6). This progress aligns with climate action objectives and safeguards vital water-rich habitats (Goal 13). The future holds promise with advanced purification techniques enhancing water quality and availability, underscoring the need for responsible water conservation and management for a sustainable future.

Nanotechnology-assisted treatment of pharmaceuticals contaminated water

The presence of pharmaceutical compounds in wastewater due to an increase in industrialization and urbanization is a serious health concern. The demand for diverse types of pharmaceutical compounds is expected to grow as there is continuous improvement in the global human health standards. Discharge of domestic pharmaceutical personal care products and hospital waste has aggravated the burden on wastewater management. Further, the pharmaceutical water is toxic not only to the aquatic organism but also to terrestrial animals coming in contact directly or indirectly. The pharmaceutical wastes can be removed by adsorption and/or degradation approach. Nanoparticles (NPs), such as 2D layers materials, metal-organic frameworks (MOFs), and carbonaceous nanomaterials are proven to be more efficient for adsorption and/or degradation of pharmaceutical waste. In addition, inclusion of NPs to form various composites leads to improvement in the waste treatment efficacy to a greater extent. Overall, carbonaceous nanocomposites have advantage in the form of being produced from renewable resources and the nanocomposite material is biodegradable either completely or to a great extent. A comprehensive literature survey on the recent advancement of pharmaceutical wastewater is the focus of the present article.

3D-Printed Materials for Wastewater Treatment

The increasing levels of water pollution pose an imminent threat to human health and the environment. Current modalities of wastewater treatment necessitate expensive instrumentation and generate large amounts of waste, thus failing to provide ecofriendly and sustainable solutions for water purification. Over the years, novel additive manufacturing technology, also known as three-dimensional (3D) printing, has propelled remarkable innovation in different disciplines owing to its capability to fabricate customized geometric objects rapidly and cost-effectively with minimal byproducts and hence undoubtedly emerged as a promising alternative for wastewater treatment. Especially in membrane technology, 3D printing enables the designing of ultrathin membranes and membrane modules layer-by-layer with different morphologies, complex hierarchical structures, and a wide variety of materials otherwise unmet using conventional fabrication strategies. Extensive research has been dedicated to preparing membrane spacers with excellent surface properties, potentially improving the membrane filtration performance for water remediation. The revolutionary developments in membrane module fabrication have driven the utilization of 3D printing approaches toward manufacturing advanced membrane components, including biocarriers, sorbents, catalysts, and even whole membranes. This perspective highlights recent advances and essential outcomes in 3D printing technologies for wastewater treatment. First, different 3D printing techniques, such as material extrusion, selective laser sintering (SLS), and vat photopolymerization, emphasizing membrane fabrication, are briefly discussed. Importantly, in this Perspective, we focus on the unique 3D-printed membrane modules, namely, feed spacers, biocarriers, sorbents, and so on. The unparalleled advantages of 3D printed membrane components in surface area, geometry, and thickness and their influence on antifouling, removal efficiency, and overall membrane performance are underlined. Moreover, the salient applications of 3D printing technologies for water desalination, oil-water separation, heavy metal and organic pollutant removal, and nuclear decontamination are also outlined. This Perspective summarizes the recent works, current limitations, and future outlook of 3D-printed membrane technologies for wastewater treatment.

Green synthesis of silver nanoparticles using Adhatoda vasica leaf extract and its application in photocatalytic degradation of dyes

The paper describes biogenic synthesis of silver nanoparticles (AgNPs) using Adhatoda vasica leaf extracts at room temperature. The prepared AgNPs were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction, Energy dispersive X-ray (EDX), High Resolution Transmission Electron Microscope, Scanning Electron Microscopy and Thermogravimetric analyser. The bio reduction method is devoid of any toxic chemicals, organic solvents, and external reducing, capping and stabilizing agent. The synthesized AgNPs had spherical shape with particle size ranging between 3.88 and 23.97 nm and had face centered cubic structure. UV-visible spectral analysis confirmed the formation of AgNPs with a characteristic surface plasmon resonance band at 419 nm. The EDX pattern revealed the presence of elemental Ag in AgNPs. The prepared AgNPs were used for degradation of Amaranth, Allura red and Fast green in aqueous medium, with ≥ 92.6% efficiency within 15 min using 5 mg of AgNPs. The optical bandgap, Eg value of 2.26 eV for AgNPs was found to be effective for rapid photocatalytic degradation of all the three dyes. The degradation process was observed to follow pseudo first order kinetics.

Yeast-driven valorization of agro-industrial wastewater: an overview

The intensive industrial and agricultural activities currently on-going worldwide to feed the growing human population have led to significant increase in the amount of wastewater produced. These effluents are high in phosphorus (P), nitrogen (N), chemical oxygen demand (COD), biochemical oxygen demand (BOD), and heavy metals. These compounds can provoke imbalance in the ecosystem with grievous consequences to both the environment and humans. Adequate treatment of these wastewaters is therefore of utmost importance to humanity. This can be achieved through valorization of these waste streams, which is based on biorefinery idea and concept of reduce, reuse, and recycle for sustainable circular economy. This concept uses innovative processes to produce value-added products from waste such as wastewater. Yeast-based wastewater treatment is currently on the rise given to the many characteristics of yeast cells. Yeasts are generally fast growing, and they are robust in terms of tolerance to stress and inhibitory compounds, in addition to their ability to metabolize a diverse range of substrates and create a diverse range of metabolites. Therefore, yeast cells possess the capacity to recover and transform agro-industrial wastewater nutrients into highly valuable metabolites. In addition to remediating the wastewater, numerous value-added products such as single cell oil (SCO), single cell proteins (SCPs), biofuels, organic acid, and aromatic compounds amongst others can be produced through fermentation of wastewater by yeast cells. This work thus brings to limelight the potential roles of yeast cells in reducing, reusing, and recycling of agro-industrial wastewaters while proffering solutions to some of the factors that limit yeast-mediated wastewater valorization.

Starch-Based Polymer Materials as Advanced Adsorbents for Sustainable Water Treatment: Current Status, Challenges, and Future Perspectives

Over the past three decades, chemical and biological water contamination has become a major concern, particularly in the industrialized world. Heavy metals, aromatic compounds, and dyes are among the harmful substances that contribute to water pollution, which jeopardies the human health. For this reason, it is of the utmost importance to locate methods for the cleanup of wastewater that are not genuinely effective. Owing to its non-toxicity, biodegradability, and biocompatibility, starch is a naturally occurring polysaccharide that scientists are looking into as a possible environmentally friendly material for sustainable water remediation. Starch could exhibit significant adsorption capabilities towards pollutants with the substitution of amide, amino, carboxyl, and other functional groups for hydroxyl groups. Starch derivatives may effectively remove contaminants such as oil, organic solvents, pesticides, heavy metals, dyes, and pharmaceutical pollutants by employing adsorption techniques at a rate greater than 90%. The maximal adsorption capacities of starch-based adsorbents for oil and organic solvents, pesticides, heavy metal ions, dyes, and pharmaceuticals are 13,000, 66, 2000, 25,000, and 782 mg/g, respectively. Although starch-based adsorbents have demonstrated a promising future for environmental wastewater treatment, additional research is required to optimize the technique before the starch-based adsorbent can be used in large-scale in situ wastewater treatment.

Isolation of Pseudomonas oleovorans Carrying Multidrug Resistance Proteins MdtA and MdtB from Wastewater

The pollution of industrial wastewater has become a global issue in terms of economic development and ecological protection. Pseudomonas oleovorans has been studied as a bacterium involved in the treatment of petroleum pollutants. Our study aimed to investigate the physicochemical properties and drug resistance of Pseudomonas oleovorans isolated from industrial wastewater with a high concentration of sulfate compounds. Firstly, Pseudomonas oleovorans was isolated and then identified using matrix-assisted flight mass spectrometry and 16S rDNA sequencing. Then, biochemical and antibiotic resistance analyses were performed on the Pseudomonas oleovorans, and a microbial high-throughput growth detector was used to assess the growth of the strain. Finally, PCR and proteomics analyses were conducted to determine drug-resistance-related genes/proteins. Based on the results of the spectrum diagram and sequencing, the isolated bacteria were identified as Pseudomonas oleovorans and were positive to reactions of ADH, MTE, CIT, MLT, ONPG, and ACE. Pseudomonas oleovorans was sensitive to most of the tested antibiotics, and its resistance to SXT and CHL and MIN and TIM was intermediate. The growth experiment showed that Pseudomonas oleovorans had a good growth rate in nutrient broth. Additionally, gyrB was the resistance gene, and mdtA2, mdtA3, mdtB2, mdaB, and emrK1 were the proteins that were closely associated with the drug resistance of Pseudomonas oleovorans. Our results show the biochemical properties of Pseudomonas oleovorans from industrial wastewater with a high concentration of sulfate compounds and provide a new perspective for Pseudomonas oleovorans to participate in biological removal of chemical pollutants in industrial wastewater.

Antimicrobial properties of promising Zn-Fe based layered double hydroxides for the disinfection of real dairy wastewater effluents

Bacterial resistance to conventional antibiotics is a serious challenge that requires novel antibacterial agents. Moreover, wastewater from dairy farms might contain countless number of pathogens, organic contaminants and heavy metals that consider a threat to the terrestrial and aquatic environment. Therefore, the development of cost-effective, highly operation-convenient, recyclable multifunctional antimicrobial agents became an urgent necessity. Layered double hydroxides (LDH) have shown promising results as antibacterial agents. However, more work is required to further investigate and improve the antimicrobial performance of LDH structures against pathogens. In this study three Zn-Fe based LDH were investigated for real dairy wastewater disinfection. The three LDH samples were cobalt substituted Zn-Fe LDH (CoZnFe), magnesium substituted Zn-Fe LDH (MgZnFe) and MgZnFe-Triazol LDH (MgZnFe-Tz) nanocomposite. Seventy-five wastewater samples were collected from a dairy farm sewage system. The sensitivity of isolated pathogens was tested against two commonly used disinfectants (Terminator and TH4) and was assessed against the three LDH samples at different concentrations. The overall prevalence of S. agalactiae, S. dysgalactiae and Staph. aureus was significantly at 80.0% (P-value = 0.008, X2 = 9.700). There was variable degree of resistance to the tested disinfectants, whereas the antimicrobial activity of CoZnFe LDH was increased significantly at a concentration of 0.005 mg/L followed by MgZnFe LDH while MgZnFe-Tz LDH showed minor antibacterial potency. It was concluded that CoZnFe LDH showed a better biocidal activity in killing the isolated resistant pathogens, making it a good choice tool in combating the zoonotic microbes in wastewater sources.

Study on the Adsorption Properties of Oxalic Acid-Modified Cordierite Honeycomb Ceramics for Neutral Red Dyes

Removal of organic dyes from water by monolithic adsorbents is considered as an efficient and no-secondary pollution method. Herein, for the first time cordierite honeycomb ceramics (COR) treated with oxalic acid (CORA) were synthesized. This CORA exhibits outstanding removal efficiency toward the azo neutral red dyes (NR) from water. After optimizing the reaction conditions, the highest adsorption capacity of 7.35 mg·g^-1 and a removal rate of 98.89% could be achieved within 300 min. Furthermore, investigation of the adsorption kinetics indicated this adsorption process could be described as a pseudo-second-order kinetic model with k ₂ and q _e of 0.0114 g·mg^-1·min^-1 and 6.94 mg·g^-1, respectively. According to the fitting calculation, the adsorption isotherm could also be described as the Freundlich isotherm model. The removal efficiency could be maintained above 50% after 4 cycles, negating the need for toxic organic solvent extraction, offering a method for bringing the technology one step closer to industrial application and giving CORA promising potential in practical water treatment.

A mini review on green nanotechnology and its development in biological effects

The utilization of living organisms for the creation of inorganic nanoscale particles is a potential new development in the realm of biotechnology. An essential milestone in the realm of nanotechnology is the process of creating dependable and environmentally acceptable metallic nanoparticles. Due to its increasing popularity and ease, use of ambient biological resources is quickly becoming more significant in this field of study. The phrase "green nanotechnology" has gained a lot of attention and refers to a variety of procedures that eliminate or do away with hazardous compounds to repair the environment. Green nanomaterials can be used in a variety of biotechnological sectors such as medicine and biology, as well as in the food and textile industries, wastewater treatment and agriculture field. The construction of an updated level of knowledge with utilization and a study of the ambient biological systems that might support and revolutionize the creation of nanoparticles (NPs) are presented in this article.

Recent innovation and impacts of nano-based technologies for wastewater treatment on humans: a review

Sustainable wastewater management requires environment-friendly, efficient, and cost-effective methods of water treatment. The ever-growing list of emerging contaminants in municipal wastewater requires advanced, efficient, and cost-effective techniques for its treatment to combat the increasing water demand. The nano-based technologies hold great potential in improving water treatment efficiency and augmenting the water supply. However, the environmental effects of these technologies are still questionable among the public and scientific community. The present review discusses risks to human health due to the use of nano-based technology for the removal of emerging contaminants in water. The discussion will be about the impacts of these technologies on humans. Recommendations about safe and environmentally friendly options for nano-based technology for water treatment have been included. Safest options of nano-based technologies for water treatment and steps to minimize the risk associated with them have also been incorporated in this article. Since all biological systems are different, separate risk analyses should be performed at the environmentally relevant concentration for different durations. There is little/no information on the quantitative impact on humans and requires more understanding. The quantitative measurement of the cellular uptake of nanoparticles is usually difficult. We hope this article will serve its purpose for water researchers, medical researchers, environmentalists, policymakers, and the government.

Recent advances in the design and use of Pickering emulsions for wastewater treatment applications

Pickering emulsions have recently emerged as versatile systems capable of targeting many applications of wastewater treatment. The unique properties, which include high emulsion stability, easy preparation, low toxicity, and stimuli-responsiveness, pave the way for advances in common pollutant control processes. This review aims to provide a comprehensive overview on different aspects in the Pickering emulsion design focusing on the key structural relations and their implications in specific applications. The first section is dedicated to the critical parameters governing the Pickering emulsion type, droplet size and stability. Furthermore, a section describing methods for demulsification and particle recovery is included, in which various stimuli have been explored. Finally, the most potent applications of Pickering emulsions such as photocatalytic degradation, adsorption, extraction, and separation of common wastewater pollutants are presented and discussed with a great deal of attention towards the efficacy, current limitations, and future potential. Recognizing the rise of innovative Pickering emulsion solutions is expected to induce profound effects facilitating the technology transfer to industrial processes.

Efficient and recyclable degradation of organic dye pollutants by CeO2@ZIF-8 nanozyme-based non-photocatalytic system

Advanced oxidation processes-based catalysis system as the most typical pollutant degradation technology always suffer from poor durability and photo-dependent. Inspired by the fact that some nanomaterials exhibit catalytic properties closer to natural enzymes, a high peroxidase-like activity and stability CeO₂@ZIF-8 nanozyme was synthesized in this study for non-photodegradation of dyes pollution. Multiple characterization techniques were applied to prove the successful synthesis of the nanozyme. The influence of different parameters on the catalytic degradation of organic dye by nanozyme was investigated. This nanozyme achieved a maximum degradation efficiency of 99.81% for methyl orange and maintained its catalytic performance in repeated experiments. Possible degradation intermediates and pathways for methyl orange were then proposed. In addition, the CeO₂@ZIF-8 loaded starch/agarose films were prepared for the portable and recyclable remediation of real dye wastewater, which maintained more than 80% degradation efficiency after 5 successive cycles. These results suggested that nanozyme based non-photocatalytic system is a potential catalyst for dye degradation and it opens a new avenue to develop high-performance and recyclable catalysts for pollutant remediation.

Development of MoS2-ZnO heterostructures: an efficient bifunctional catalyst for the detection of glucose and degradation of toxic organic dyes

The heterostructure catalyst MoS2-ZnO possesses binary properties and provides a novel platform for the remediation of environmental as well as health issues.

Influence of operation modes on gravity-driven membrane process in treating the secondary effluent: Flux improvement and biocake layer property

A low flux level of the gravity-driven membrane (GDM) process constrained its extensive application in treating the secondary effluent. In this study, different operation modes were introduced to the GDM process without aeration, backwashing, and chemical cleanings, hoping to develop simple and economic flux regulating strategies, and their influences on the filtration performances and biocake layer characteristics were systematically investigated. The results indicated that the stable fluxs in the intermittent GDM systems elevated by 40%-100% relative to the continuous GDM case, attributing to the synergetic effects of forming more permeable, mushroom-like structures and reducing the concentrations of EPS and SMP within biocake layers. The quantitative analysis of biocake layer properties suggested that the structural parameters of porosity and absolute roughness were closely related to the flux variation compared to the thickness and relative roughness. Besides, the intermittent GDM system generated an apparent detachment of the biocake layer from the membrane surface along with a persistent flux increase than in the continuous GDM case during long-term filtration, achieving its self-sustained operation in a higher flux level without any interferences. The periodical flux recovery and decline occurred daily in each intermittent GDM system since the biocake layer attached to the membrane surface was mainly reversible. Although there were no significant differences in removing dissolved organic pollutants under different operation modes, the manganese removals decreased by 0%-25% in the intermittent GDM filtrations compared to the continuous GDM scenario. The optimized daily operation mode was 16 h on / 8 h off (operation of 16 h, interruption of 8 h), considering the trade-off effects between membrane flux level and water production. These findings provide a new simply-feasible optimized GDM process operation strategy and benefit promoting the application of the GDM system in the reclamation of wastewater.

Wastewater treatment with nanomaterials for the future: A state-of-the-art review

Aquatic and terrestrial ecosystems are both threatened by toxic wastewater. The unique properties of nanomaterials are currently being studied thoroughly for treating sewage. Nanomaterials also have the advantage of being capable of removing organic matter, fungi, and viruses from wastewater. Advanced oxidation processes are used in nanomaterials to treat wastewater. Additionally, nanomaterials have a large effective area of contact due to their tiny dimensions. The adsorption and reactivity of nanomaterials are strong. Wastewater treatment would benefit from the development of nanomaterial technology. Second, the paper provides a comprehensive analysis of the unique characteristics of nanomaterials in wastewater treatment, their proper use, and their prospects. In addition to focusing on their economic feasibility, since limited forms of nanomaterials have been manufactured, it is also necessary to consider their feasibility in terms of their technical results. According to this study, the significant adsorption area, excellent chemical reaction, and electrical conductivity of nanoparticles (NPs) contribute to the successful treatment of wastewater.

Exploring Microbial-Based Green Nanobiotechnology for Wastewater Remediation: A Sustainable Strategy

Water scarcity due to contamination of water resources with different inorganic and organic contaminants is one of the foremost global concerns. It is due to rapid industrialization, fast urbanization, and the low efficiency of traditional wastewater treatment strategies. Conventional water treatment strategies, including chemical precipitation, membrane filtration, coagulation, ion exchange, solvent extraction, adsorption, and photolysis, are based on adopting various nanomaterials (NMs) with a high surface area, including carbon NMs, polymers, metals-based, and metal oxides. However, significant bottlenecks are toxicity, cost, secondary contamination, size and space constraints, energy efficiency, prolonged time consumption, output efficiency, and scalability. On the contrary, green NMs fabricated using microorganisms emerge as cost-effective, eco-friendly, sustainable, safe, and efficient substitutes for these traditional strategies. This review summarizes the state-of-the-art microbial-assisted green NMs and strategies including microbial cells, magnetotactic bacteria (MTB), bio-augmentation and integrated bioreactors for removing an extensive range of water contaminants addressing the challenges associated with traditional strategies. Furthermore, a comparative analysis of the efficacies of microbe-assisted green NM-based water remediation strategy with the traditional practices in light of crucial factors like reusability, regeneration, removal efficiency, and adsorption capacity has been presented. The associated challenges, their alternate solutions, and the cutting-edge prospects of microbial-assisted green nanobiotechnology with the integration of advanced tools including internet-of-nano-things, cloud computing, and artificial intelligence have been discussed. This review opens a new window to assist future research dedicated to sustainable and green nanobiotechnology-based strategies for environmental remediation applications.

Emerging applications of nanotechnology in context to immunology: A comprehensive review

Numerous benefits of nanotechnology are available in many scientific domains. In this sense, nanoparticles serve as the fundamental foundation of nanotechnology. Recent developments in nanotechnology have demonstrated that nanoparticles have enormous promise for use in almost every field of life sciences. Nanoscience and nanotechnology use the distinctive characteristics of tiny nanoparticles (NPs) for various purposes in electronics, fabrics, cosmetics, biopharmaceutical industries, and medicines. The exclusive physical, chemical, and biological characteristics of nanoparticles prompt different immune responses in the body. Nanoparticles are believed to have strong potential for the development of advanced adjuvants, cytokines, vaccines, drugs, immunotherapies, and theranostic applications for the treatment of targeted bacterial, fungal, viral, and allergic diseases and removal of the tumor with minimal toxicity as compared to macro and microstructures. This review highlights the medical and non-medical applications with a detailed discussion on enhanced and targeted natural and acquired immunity against pathogens provoked by nanoparticles. The immunological aspects of the nanotechnology field are beyond the scope of this Review. However, we provide updated data that will explore novel theragnostic immunological applications of nanotechnology for better and immediate treatment.

Nanomaterials as a sustainable choice for treating wastewater

Wastewater containing toxic substances is a major threat to the health of both aquatic and terrestrial ecosystems. In order to treat wastewater, nanomaterials are currently being studied intensively due to their unprecedented properties. The unique features of nanoparticles are prompting an increasing number of studies into their use in wastewater treatment. Although several studies have been undertaken in recent years, most of them did not focus on some of the nanomaterials that are now often utilized for wastewater treatment. It is essential to investigate the most recent advances in all the types of nanomaterials that are now frequently employed for wastewater treatment. The recent advancements in common nanomaterials used for sustainable wastewater treatment is comprehensively reviewed in this paper. This paper also thoroughly assesses unique features, proper utilization, future prospects, and current limitations of green nanotechnology in wastewater treatment. Zero-valent metal and metal oxide nanoparticles, especially iron oxides were shown to be more effective than traditional carbon nanotubes (CNTs) for recovering heavy metals in wastewater. Iron oxide achieved 75.9% COD (chemical oxygen demand) removal efficiency while titanium oxide (TiO₂) achieved 75.5% COD. Iron nanoparticles attained 72.1% methyl blue removal efficiency. However, since only a few types of nanomaterials have been commercialized, it is important to also focus on the economic feasibility of each nanomaterial. This study found that the large surface area, high reactivity, and strong mechanical properties of nanoparticles means they can be considered as a promising option for successful wastewater treatment.

Synthesis of two different zinc oxide nanoflowers and comparison of antioxidant and photocatalytic activity

Nanoflowers are a newly developed class of nanoparticles that show flower-like structures and attract much attention due to their simple preparation methods, high stability, and increased efficiency. The aim of the study is to investigate a strong alternative to reduce the severity of infection and increase the treatment of wastewater by exhibiting biofilm inhibition in medical and environmental applications of the ZnO-NFs with two different shapes. ZnO-NFs were synthesized by two different processes hydrothermal method (named ZnO-NF1) and the precipitation method (named ZnO-NF2). ZnO-NFs produced by two different synthesis methods were compared for the photocatalytic and antioxidant efficiency. The effects of Reactive Red 180 (RR180) and Basic Red 18 (BR18) dyes concentration, photocatalyst amount, and reaction time were investigated on dye removal efficiency for photocatalytic experiments. The color was completely removed for 25 mg/L BR18 and RR180 dyes for 75 min and 90 min, respectively, using 1.5 g/L photocatalyst amount using ZnO-NF1. However, 59.18% dye removal efficiency was obtained for 90 min by using a 1.5 g/L ZnO-NF2 photocatalyst for 25 mg/L BR18 dye removal, while a dye removal efficiency of 90.00% was detected for 90 min using 2 g/L ZnO-NF2 for 25 mg/L RR180 dye. Then, comparison of general properties such as antibacterial, antibiofilm, microbial cell viability, DNA fragmentation, antioxidant activities, and antimicrobial photodynamic therapy of ZnO-NFs were investigated. The antioxidant activity of ZnO-NF2 was found to be higher than ZnO-NF1 at each concentration (82.32% and 87.18% for ZnO-NF1 and ZnO-NF2, respectively, at 200 mg/mL).

A review on synthesis methods and recent applications of nanomaterial in wastewater treatment: Challenges and future perspectives

Freshwater has been incessantly polluted by various activities such as rapid industrialization, fast growth of population and agricultural activities. Water pollution is considered as one the major threatens to human health and aquatic bodies which causes various severe harmful diseases including gastrointestinal disorders, asthma, cancer, etc. The polluted wastewater could be treated by different conventional and advanced methodologies. Amongst them, adsorption is the most utilized low cost, efficient technique to treat and remove the harmful pollutants from the wastewater. The efficiency of adsorption mainly depends on the surface properties such as functional group availability and surface area of the adsorbents used. Since various waste-based carbon derivatives are utilized as adsorbents for harmful pollutants removal; nanomaterials are employed as effective adsorbents in recent times due to its excellent surface properties. This review presents an overview of the different types of nanomaterials such as nano-particles, nanotubes, nano-sheets, nano-rods, nano-spheres, quantum dots, etc. which have been synthesized by different chemical and green synthesis methodologies using plants, microorganisms, biomolecules and carbon derivatives, metals and metal oxides and polymers. By concentrating on potential research difficulties, this study offers a new viewpoint on fundamental field of nanotechnology for wastewater treatment applications. This review paper critically reviewed the synthesis of nanomaterials more importantly green synthesis and their applications in wastewater treatment to remove the harmful pollutants such as heavy metals, dyes, pesticides, polycyclic aromatic hydrocarbons, etc.

The impact of co-treatment with graphene oxide and metal mixture on Salmo trutta at early development stages: The sorption capacity and potential toxicity

Graphene oxide (GO) are novel nanomaterials with a wide range of applications due to their high absorption capacity. This study was undertaken with a view to assess the bioaccumulation and acute toxicity of GO used in combination with the heavy metal mixture (Cr, Cu, Ni and Zn) to fish embryos and larvae. For this purpose, Salmo trutta embryos and larvae were subjected to the 4-day long treatment with three different concentrations of GO, the metal mixture, which was prepared of four metals at the concentrations corresponding to the maximum-permissible-concentrations for EU inland waters (Cr-0.01, Cu-0.01, Ni-0.034, and Zn-0.1 mg/L), and with GO in combination with MIX (GO+MIX). When used in combination with the metal mixture, GO exhibited a high metal sorption capacity. The obtained confocal fluorescence microscopy results showed that GO located in the embryo chorion causing its damage; in larvae, however, GO were found only in the gill region. Results of these experiments confirmed the hypothesis that GO affects the accumulation of metals and mitigates their toxic effects on organism. In embryos, the acute toxicity of exposure to GO and co-exposure to MIX+GO was found to manifest itself through the decreased heart rate (HR) and malondialdehyde (MDA) level and through the increased metallothionein (MT) concentration. Meanwhile, in larvae, GO and MIX+GO were found to induce genotoxicity effects. However, changes in HR, MDA, MT, gill ventilation frequency, yolk sack absorption and cytotoxicity compared with those of the control group were not recorded in larvae. The obtained results confirmed our hypothesis: the combined effect of MIX and GO was less toxic to larvae (especially survival) than individual effects of MIX components. However, our results emphasize that fish exposure to GO alone and in combination with heavy metal contaminants (MIX+GO) even at environmentally relevant concentrations causes health risks that cannot be ignored.

Surfactant induced copper vanadate (β-Cu2V2O7, Cu3V2O8) for different textile dyes degradation

In this study, pristine β-Cu₂V₂O₇, CTAB-β-Cu₂V₂O₇ and PVP-Cu₃V₂O₈ were synthesized via hydrothermal method. The synthesized brown powder samples were exemplified using XRD, UV, PL, Raman and SEM studies. Further with XRD, we confirmed that the impurities were eradicated in addition of surfactant PVP. The bandgap obtained were 3.09 eV, 2.97 eV and 2.28 eV for β-Cu₂V₂O₇, CTAB-β-Cu₂V₂O₇ and PVP-Cu₃V₂O₈. The morphology of β-Cu₂V₂O₇ was found to be cluster of nanoparticles with high level of agglomeration. While adding the surfactants (CTAB, PVP) the nano platelets were grown and uniformly arranged. The PVP-Cu₃V₂O₈ sample exhibited 96%, 77% and 96% efficiency on reducing Methylene Blue, Rhodamine B and Malachite Green dyes. The enhancement of attaining complete efficiency by the PVP-Cu₃V₂O₈ photocatalyst is attributed by the appropriate phase of host material and the PVP itself acted as a trapper for electron and hole which induced the rate of degrading toxic pollutants. The PVP-Cu₃V₂O₈ photocatalyst will be enthusiastic and optimized aspirant for reducing organic pollutants and for wastewater management in future days.

Investigations on influences of MWCNT composite membranes in oil refineries waste water treatment with Taguchi route

Most of the 'oil refineries' severally pollutes the water resources by depleting their untreated waste water like cooling water, storm water and unsanitary sewage water. These wastewaters are to be treated with high care to protect the human, pebbles, plants, fish and other water animals and from harmful effects. The present study focused to treat the oil refinery wastewater by means of Multi wall carbon nanotube (MWCNT) coated Polyvinylidene Fluoride (PVDF) membrane. The main objectives are: to increases the life of filter, reduce the percolation flux and reduce the formation of antifouling in the filter by using MWCNT composite membrane in it. Different process parameters of the proposed water treatment process, like diameter of MWCNT (15 nm, 20 nm, 25 nm and 30 nm), operating pressure (3 bar, 4 bar, 5 bar and 6 bar), pH value (3, 5, 7 and 9) and temperature (25 °C, 30 °C, 35 °C and 40 °C) temperature. Taguchi statistical technique is employed for designing experiments and for optimizing the process parameters of wastewater treatment process of an oil refinery. The proposed filter for wastewater treatment exhibited appreciable performance in removal rate of Percolation flux, percentage of chemical oxygen demand removal and percentage of total carbolic rejection as 27.2 kg/m²h, 78.51% and 95.33% respectively.

Green Synthesis of Silver Nanoparticles Using Thespesia populnea Bark Extract for Efficient Removal of Methylene Blue (MB) Degradation via Photocatalysis with Antimicrobial Activity and for Anticancer Activity

The green synthesis method was used to effectively fabricate Ag-NPs by using Thespesia populnea bark extract. The structural, morphological, elemental composition, and optical properties of as-synthesized Ag-NPs were characterized by powder X-ray diffraction (P-XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), and UV-Vis spectroscopy. Their photocatalytic efficiency as a photocatalyst was examined by degradation of methylene blue (MB) dye under direct sunlight irradiation. After 120 minutes of sunlight irradiation, Ag-NPs show photocatalytic degradation efficiency (DE percent) of 92%. The hydroxyl and superoxide radicals were found to be responsible for biodegradation. To the best of our acquaintance, this is the first research to use Ag-NPs as a photocatalyst for the efficient degradation of MB dye and its antimicrobial activity by using Thespesia populnea bark extract. The cytotoxic viability against SK-MEL cell line with a median inhibitory concentration (IC50) of 45 μL/mg proved its potent anticancer property. Based on the findings, the study revealed the significance of as-synthesized green Ag-NPs over other physically/chemically prepared Ag-NPs.

Technological trends in nanosilica synthesis and utilization in advanced treatment of water and wastewater

Water and wastewater treatment applications stand to benefit immensely from the design and development of new materials based on silica nanoparticles and their derivatives. Nanosilica possesses unique properties, including low toxicity, chemical inertness, and excellent biocompatibility, and can be developed from a variety of sustainable precursor materials. Herein, we provide an account of the recent advances in the synthesis and utilization of nanosilica for wastewater treatment. This review covers key physicochemical aspects of several nanosilica materials and a variety of nanotechnology-enabled wastewater treatment techniques such as adsorption, separation membranes, and antimicrobial applications. It also discusses the prospective design and tuning options for nanosilica production, such as size control, morphological tuning, and surface functionalization. Informative discussions on nanosilica production from agricultural wastes have been offered, with a focus on the synthesis methodologies and pretreatment requirements for biomass precursors. The characterization of the different physicochemical features of nanosilica materials using critical surface analysis methods is discussed. Bio-hybrid nanosilica materials have also been highlighted to emphasize the critical relevance of environmental sustainability in wastewater treatment. To guarantee the thoroughness of the review, insights into nanosilica regeneration and reuse are provided. Overall, it is envisaged that this work's insights and views will inspire unique and efficient nanosilica material design and development with robust properties for water and wastewater treatment applications.

Remediation of microplastics using bionanomaterials: A review

Pollution by microplastics (MPs) formed by the physicochemical breakdown of plastics are a worldwide issue with long-lasting and hazardous natural effects. The natural expulsion of MPs takes several years and can be dangerous. Several effective technological innovations have been developed over the years to remediate harmful MPs. Among them, a blend of nanotechnological techniques using bionanomaterials has been investigated to a large extent. The objective of this review is to compile the MPs found in the environment and bionanomaterial-based approaches for their removal. This information is important for researchers who are exploring the adverse consequences of MPs and their remediation and developing advanced eco-friendly strategies to control and eradicate MPs in the future. The control and eradication of MPs depend on all of us; hence, the proper awareness of MPs pollution must be provided to every individual, as all of us are a part of the environment.

Remediation of noxious wastewater using nanohybrid adsorbent for preventing water pollution

Removal of toxic elements from wastewater effluent has got a lot of attention because of their severe negative effects on human and environmental health. In the past few years, rapid urbanization and industrial activities in developing countries have exacerbated the destruction of the environment. Most of the wastewater effluents are discharged untreated or inadequately treated, which has become a major concern due to its impact on sustainability and the environment. This is imperative to implement, innovative and resourceful wastewater treatment technologies requiring low investment. Among the various treatment technologies, cutting-edge processes in nano-material sciences have recently piqued the interest of scientists. Nanohybrid absorbents have the potential in improving wastewater treatment and increase water supply by utilizing unconventional water resources. Carbon nanotubes, titanium oxide, manganese oxide, activated carbon (AC), magnesium oxide, graphene, ferric oxides, and zinc oxide are examples of nano-adsorbents that are used to eliminate pollutants. This also demonstrated the effective removal of contaminants along with the harmful effects of chemicals, colorants, and metals found in wastewater. The present manuscript examines potential advances in nanotechnology in wastewater treatment for the prevention of water and soil pollution. This systematic review aims to highlight the importance of nanohybrid absorbents treatment technology for wastewater treatment and to explain how nanohybrid absorbents have the potential to revolutionize industrial pollution. There are also other published review articles on this topic but the present review covers an in-depth information on nano-adsorbents and their targeted contaminants.

Investigation of PEG directed Sb2WO6 for dyes removal from wastewater

Pristine and polyethylene glycol assisted antimony tungstate (Sb₂WO₆) was developed via hydrothermal route. The pristine and surfactant assisted Sb₂WO₆ were further exemplified to reveal the properties of the samples. The bandgap calculated for Sb₂WO₆, 5 ml PEG- Sb₂WO₆, 10 ml PEG- Sb₂WO₆ was 2.78 eV, 2.66 eV and 2.21 eV. The 10 ml PEG assisted sample exhibited narrow bandgap. The Fourier transform infrared spectroscopy (FTIR) spectra of the samples showed metal vibrations and stretching of the water molecules adsorbed. The Raman spectra showed the vibrational modes present in Sb₂WO₆. The morphology was analyzed employing transmission electron microscope (TEM) for all samples. Pristine Sb₂WO₆ showed growth of nanorods with higher dimensions with high agglomeration. 5 ml PEG- Sb₂WO₆ showed the growth of nanorods with lesser agglomeration. 10 ml PEG assisted Sb₂WO₆ exhibited distinct growth of nanorods with no agglomeration on the surface. The elemental composition was examined employing X-ray Photoelectron Spectroscopy. Prepared product photocatalytic behaviour was tested employing Rhodamine B dye degrading. Different catalyst loading were investigated for degrading the toxic pollutants. 0.2 g 10 ml PEG-Sb₂WO₆ showed 81% efficiency on degrading the toxic pollutant from wastewater. The OH radicals are accountable for photocatalytic behaviour of prepared photocatalyst. The 10 ml PEG-Sb₂WO₆ has the good reusability behavior and stable properties after three cycles. The prepared 10 ml PEG- Sb₂WO₆ photocatalyst will be the potential candidate for the remediation of the water treatment.

A Simple Yet Effective Preanalytical Strategy Enabling the Application of Aptamer-Conjugated Gold Nanoparticles for the Colorimetric Detection of Antibiotic Residues in Raw Milk

The misuse of antibiotics in the cattle sector can lead to milk contamination, with concomitant effects on the dairy industry and human health. Biosensors can be applied in this field; however, the influence of the milk matrix on their activity has been poorly studied in light of the preanalytical process. Herein, aptamer-conjugated gold nanoparticles (nanoaptasensors) were investigated for the colorimetric detection in raw milk of four antibiotics used in cattle. The effect of milk components on the colorimetric response of the nanoaptasensors was analyzed by following the selective aggregation of the nanoparticles, using the absorption ratio A₅₂₀/A₇₂₀. A preanalytical strategy was developed to apply the nanoaptasensors to antibiotic-contaminated raw milk samples, which involves a clarification step with Carrez reagents followed by the removal of cations through dilution, chelation (EDTA) or precipitation (NaHCO₃). The colorimetric signals were detected in spiked samples at concentrations of antibiotics as low as 0.25-fold the maximum residue limits (MRLs) for kanamycin (37.5 μg/L), oxytetracycline (25 μg/L), sulfadimethoxine (6.25 μg/L) and ampicillin (1 μg/L), according to European and Chilean legislation. Overall, we conclude that this methodology holds potential for the semiquantitative analysis of antibiotic residues in raw milk obtained directly from dairy farms.

Emerging concerns of infectious diseases and drug delivery challenges

Emerging infectious diseases are the infections that could be newly appeared or have existed demographic area with rapidly increasing in some geographic range. Among various types of emerging infectious diseases like Ebola, chikungunya, tuberculosis, SARS, MERS, avian flu, swine flu, Zika, and so on, very recently we have witnessed the emergence of recently recognized coronavirus infection as Covid-19 pandemic caused by SARS-CoV-2, which rapidly spread around the world. Various emerging factors precipitating disease emergence include environmental, demographic, or ecological that increase the contact of people with unfamiliar microbial agents or their host or promote dissemination. Here in this chapter, we reviewed the various emerging considerations of infectious diseases including factors responsible for emerging and re-emerging infectious diseases as well as drug delivery challenges to treat infectious diseases and various strategies to deal with these challenges including nanotheranostics. Nanotheranostics are showing potential toward real-time understanding, diagnosis, and monitoring the response of the chemotherapy during treatment with reduced nontarget toxicity and enhanced safety level in the recent research studies.

Photocatalysis: an effective tool for photodegradation of dyes-a review

The disposal of dye-contaminated wastewater is a major concern around the world for which a variety of techniques are used for its treatment. The photocatalytic treatment of dye-contaminated wastewater is one of the treatment methods. Semiconductor-assisted photocatalytic treatment of dye-contaminated wastewater has gained pronounced attention recently. This review outlines the recent advancements in the photocatalytic treatment of dye-contaminated wastewater. The photocatalytic degradation of dyes follows three types of mechanisms: (1) dye sensitization through charge injection, (2) indirect dye degradation through oxidation/reduction, and (3) direct photolysis of dye. Several experimental parameters like initial concentration of dyes, pH, and catalyst dosage significantly affect the photocatalytic degradation of dyes. The photocatalytic materials can be categorized into three generations. The single-component (e.g., ZnO, TiO₂) and multiple component semiconductor metal oxides (e.g., ZnO-TiO₂, Bi₂O₃-ZnO) are categorized as first-generation and second-generation photocatalysts, respectively. The photocatalysts dispersed on an inert solid substrate (e.g., Ag-Al₂O₃, ZnO-C) are classified as third-generation photocatalysts. Finally, we reviewed the challenges that affect the photocatalytic degradation of dyes.

Synthesis of Atmospherically Stable Zero-Valent Iron Nanoparticles (nZVI) for the Efficient Catalytic Treatment of High-Strength Domestic Wastewater

Here, we report the fabrication of nZVI by the wet chemical technique in the presence of ethanol using ferric iron and sodium borohydride as the reducing agents under ambient conditions. The obtained nZVI particles are mainly in a zero-valent oxidation state and do not undergo significant oxidation for several weeks. The structural and morphological parameters of nZVI were investigated by using UV, XRD, SEM, EDX, TEM, and DLS analysis. The optical nature, bandgap energy, and absorption edge were all revealed by the UV–visible spectrum. The phase development and crystallinity of nZVI particles were shown by the XRD pattern. The morphological investigation revealed that the nanoparticles were spherical with an average size of 34–110 nm by using ImageJ software, and the elemental analysis was analyzed using EDX. Furthermore, the catalytic treatment performance of domestic wastewater was evaluated in terms of pH, COD (chemical oxygen demand) solubilization, total solids (TS), volatile solids (VS), phosphorous, and total nitrogen (TN) reduction under aerobic and anaerobic operating conditions. The effluent was subjected to a process evaluation with a different range (100–500 mg/L) of nZVI dosages. The COD solubilization and suspended solids reduction were significantly improved in the anaerobic condition in comparison to the aerobic condition. Furthermore, the effect of nZVI on phosphorous (PO43−) reduction was enhanced by the electrons of iron ions. The high concentration of nZVI dosing has a positive impact on COD solubilization and phosphorous removal regardless of the aeration condition with 400 mg/L of nZVI dosage.

Functionalized Magnetic Nanomaterials in Agricultural Applications

The development of functional nanomaterials exhibiting cost-effectiveness, biocompatibility and biodegradability in the form of nanoadditives, nanofertilizers, nanosensors, nanopesticides and herbicides, etc., has attracted considerable attention in the field of agriculture. Such nanomaterials have demonstrated the ability to increase crop production, enable the efficient and targeted delivery of agrochemicals and nutrients, enhance plant resistance to various stress factors and act as nanosensors for the detection of various pollutants, plant diseases and insufficient plant nutrition. Among others, functional magnetic nanomaterials based on iron, iron oxide, cobalt, cobalt and nickel ferrite nanoparticles, etc., are currently being investigated in agricultural applications due to their unique and tunable magnetic properties, the existing versatility with regard to their (bio)functionalization, and in some cases, their inherent ability to increase crop yield. This review article provides an up-to-date appraisal of functionalized magnetic nanomaterials being explored in the agricultural sector.

Unlocking the potential of biosynthesized zinc oxide nanoparticles for degradation of synthetic organic dyes as wastewater pollutants

The azo dyes released into water from different industries are accumulating in the water bodies and bioaccumulating within living systems thereby affecting environmental health. This is a major concern in developing countries where stringent regulations are not followed for the discharge of industrial waste into water bodies. This has led to the accumulation of various pollutants including dyes. As these developing countries also face acute water shortages and due to the lack of cost-effective systems to remove these pollutants, it is essential to remove these toxic dyes from water bodies, eradicate dyes, or generate fewer toxic derivatives. The photocatalysis mechanism of degradation of azo dyes has gained importance due to its eco-friendly and non-toxic roles in the environment. The zinc nanoparticles act as photocatalysts in combination with plant extracts. Plant-based nanoparticles over the years have shown the potential to degrade dyes efficiently. This is carried out by adjusting the dye and nanoparticle concentrations and combinations of nanoparticles. Our review article considers increasing the efficiency of degradation of dyes using zinc oxide (ZnO) nanoparticles and understanding the photocatalytic mechanisms in the degradation of dyes and the toxic effects of these dyes and nanoparticles in different tropic levels.

Aqueous Adsorption of Heavy Metals on Metal Sulfide Nanomaterials: Synthesis and Application

Heavy metals pollution of aqueous solutions generates considerable concerns as they adversely impact the environment and health of humans. Among the remediation technologies, adsorption with metal sulfide nanomaterials has proven to be a promising strategy due to their cost-effective, environmentally friendly, surface modulational, and amenable properties. Their excellent adsorption characteristics are attributed to the inherently exposed sulfur atoms that interact with heavy metals through various processes. This work presents a comprehensive overview of the sequestration of heavy metals from water using metal sulfide nanomaterials. The common methods of synthesis, the structures, and the supports for metal sulfide nano-adsorbents are accentuated. The adsorption mechanisms and governing conditions and parameters are stressed. Practical heavy metal remediation application in aqueous media using metal sulfide nanomaterials is highlighted, and the existing research gaps are underscored.