Synergetic anaerobic digestion of food waste for enhanced production of biogas and value-added products: strategies, challenges, and techno-economic analysis.

The generation of food waste (FW) is increasing at an alarming rate, contributing to a total of 32% of all the waste produced globally. Anaerobic digestion (AD) is an effective method for dealing with organic wastes of various compositions, like FW. Waste valorization into value-added products has increased due to the conversion of FW into biogas using AD technology. A variety of pathways are adopted by microbes to avoid unfavorable conditions in AD, including competition between sulfate-reducing bacteria and methane (CH4)-forming bacteria. Anaerobic bacteria decompose organic matter to produce biogas, a digester gas. The composition depends on the type of raw material and the method by which the digestion process is conducted. Studies have shown that the biogas produced by AD contains 65-75% CH4 and 35-45% carbon dioxide (CO2). Methanothrix soehngenii and Methanosaeta concilii are examples of species that convert acetate to CH4 and CO2. Methanobacterium bryantii, Methanobacterium thermoautotrophicum, and Methanobrevibacter arboriphilus are examples of species that produce CH4 from hydrogen and CO2. Methanobacterium formicicum, Methanobrevibacter smithii, and Methanococcus voltae are examples of species that consume formate, hydrogen, and CO2 and produce CH4. The popularity of AD has increased for the development of biorefinery because it is seen as a more environmentally acceptable alternative in comparison to physico-chemical techniques for resource and energy recovery. The review examines the possibility of using accessible FW to produce important value-added products such as organic acids (acetate/butyrate), biopolymers, and other essential value-added products.

HighlightsPopulation growth globally increases the generation of FW.FW generation, recycling, and reuse have been discussed.Biogas and bio-fertilizers can be recovered from FW through AD.

Crosstalk and gene expression in microorganisms under metals stress.

Contamination of the environment with heavy metals (HMs) has led to huge global environmental issues. Industrialization activities such as mining, manufacturing, and construction generate massive amounts of toxic waste, posing environmental risks. HMs soil pollution causes a variety of environmental issues and has a detrimental effect on both animals and plants. To remove HMs from the soil, traditional physico-chemical techniques such as immobilization, electro-remediation, stabilization, and chemical reduction are used. Moreover, the high energy, trained manpower, and hazardous chemicals required by these methods make them expensive and non-environmentally friendly. Bioremediation process, which involves microorganism-based and microorganism-associated-plant-based approaches, is an ecologically sound and cost-effective strategy for restoring HMs polluted soil. Microbes adjust their physiology to these conditions to live, which can involve significant variations in the expression of the genes. A set of genes are activated in response to toxic metals in microbes. They can also adapt by modifying their shape, fruiting bodies creating biofilms, filaments, or chemotactically migrating away from stress chemicals. Microbes including Bacillus sp., Pseudomonas sp., and Aspergillus sp. has been found to have high metals remediation and tolerance capacity of up to 98% whether isolated or in combination with plants like Helianthus annuus, Trifolium repens, and Vallisneria denseserrulata. Several of the regulatory systems that have been discovered are unique, but there is also a lot of "cross-talk" among networks. This review discusses the current state of knowledge regarding the microbial signaling responses, and the function of microbes in HMs stress resistance.

A systematic review on potential microbial carbohydrases: current and future perspectives.

Various studies have shown that the microbial proteins are often more stable than belongs to other sources like plant and animal origin. Hence, the interest in microbial enzymes has gained much attention due to many potential applications like bioenergy, biofuel production, biobleaching, bioconversion and so on. Additionally, recent trends revealed that the interest in isolating novel microbes from harsh environments have been the main focus of many scientists for various applications. Basically, industrially important enzymes can be categorized into mainly three groups: carbohydrases, proteases, and lipases. Among those, the enzymes especially carbohydrases involved in production of sugars. Carbohydrases include amylases, xylanases, pectinases, cellulases, chitinases, mannases, laccases, ligninases, lactase, glucanase, and glucose oxidase. Thus, here, an approach has been made to highlight five enzymes namely amylase, cellulase, laccase, pectinase, and xylanase from different sources with special emphasis on their properties, mechanism, applications, production optimization, purification, molecular approaches for its enhanced and stable production, and also biotechnological perspectives of its future development. Also, green and sustainable catalytic conversion strategies using nanoparticles of these enzymes have also been discussed. This review will provide insight into the carbohydrases importance and their usefulness that will help to the researchers working in this field.

Enzyme mediated transformation of CO2 into calcium carbonate using purified microbial carbonic anhydrase.

In this study, a bacterial carbonic anhydrase (CA) was purified from Corynebacterium flavescens for the CO2 conversion into CaCO3. The synthesized CaCO3 can be utilized in the papermaking industry as filler material, construction material and in steel industry. Herein, the CA was purified by using a Sephadex G-100 column chromatography having 29.00 kDa molecular mass in SDS-PAGE analysis. The purified CA showed an optimal temperature of 35 °C and pH 7.5. In addition, a kinetic study of CA using p-NPA as substrate showed Vmax (166.66 µmoL/mL/min), Km (5.12 mM), and Kcat (80.56 sec-1) using Lineweaver Burk plot. The major inhibitors of CA activity were Na2+, K+, Mn2+, and Al3+, whereas Zn2+ and Fe2+ slightly enhanced it. The purified CA showed a good efficacy to convert the CO2 into CaCO3 with a total conversion rate of 65.05 mg CaCO3/mg of protein. In silico analysis suggested that the purified CA has conserved Zn2+ coordinating residues such as His 111, His 113, and His 130 in the active site center. Further analysis of the CO2 binding site showed conserved residues such as Val 132, Val 142, Leu 196, Thr 197, and Val 205. However, a substitution has been observed where Trp 208 of its closest structural homolog T. ammonificans CA is replaced with Arg 207 of C. flavescens. The presence of a hydrophilic mutation in the CO2 binding hydrophobic region is a further subject of investigation.

A sustainable, low-cost carbonaceous hydrochar adsorbent for methylene blue adsorption derived from corncobs.

In this study, activated carbon from corncobs was successfully synthesized by hydrothermal carbonization and hydrochemical activation at low temperatures, followed by pyrolysis. A developed method of hydrochemical activation of hydrochar that uses only small amounts of chemicals is a promising approach. After activation, the activator residues in the hydrothermal product can constantly act as a chemical activator during pyrolysis to form corncob-activated carbon (AHC-KOH), which had specific surface area of 965.028 m2/g and oxygenated functional groups of 0.3780 mmol/g, 31.67 and 4 times, respectively, of those of the inactivated sample. AHC-KOH was used to study the adsorption characteristics of methylene blue (MB). The MB adsorption efficiency of AHC-KOH was the highest at 489.560 mg/g, which was considerably higher than that of activated carbons produced from other biomasses. The isotherm equilibrium and adsorbent kinetics parameters of MB adsorption on AHC-KOH were also determined using the Langmuir isotherm model (R2 = 0.99) and pseudo-second-order kinetic model (R2 > 0.99). Thus, the results indicate that an inexpensive adsorbent produced from corncobs using the above method is a promising material for wastewater treatment.

Removal of beta-lactam antibiotic in water environment by adsorption technique using cationic surfactant functionalized nanosilica rice husk.

This study aims to investigate the adsorption characteristics of cationic surfactant, cetyltrimethylamonium bromide (CTAB) onto negatively nanosilica rice husk surface and the application for antibiotic treatment in water environment. Adsorption of CTAB onto nanosilica increased with an increase of solution pH, due to an enhancement of the electrostatic attraction between cationic methylamomethylamonium groups and negatively charged nanosilica surface enhanced at higher pH. Adsorption of CTAB decreased with a decrease of ionic strength while a common intersection point (CIP) was observed for adsorption isotherm at different ionic strengths, suggesting that hydrophobic interactions between alkyl chains in CTAB molecules significantly induced adsorption and admicelles with bilayer formation were dominant than monolayer of hemimicelles. The CTAB functionalized nanosilica (CFNS) was applied for removal of beta-lactam amoxicillin (AMX). The best conditions for AMX treatment using CFNS were selected as pH 10, contact time 60 min and CFNS dosage 10 mg/mL. Removal efficiency of AMX using CFNS reached to 100% under optimum conditions while it was only 25.01% using nanosilica without CTAB. The maximum AMX adsorption capacity using CFNS of about 25 mg/g was much higher than other adsorbents. The effects of different organics such as humic acid, anionic surfactant, and other antibiotics on AMX removal using CFNS were also studied. A two-step model can fit CTAB uptake isotherms onto nanosilica and AMX onto CFNS well at different KCl concentrations. Based on the desorption of CTAB with AMX adsorption as well as adsorption isotherms, the change in surface charge and functional vibration groups after adsorption, we indicate that AMX adsorption onto CFNS was mainly controlled by electrostatic interaction. We reveal that CFNS is an excellent adsorbent for antibiotic treatment from aqueous solution.

Effective adsorption of diclofenac and naproxen from water using fixed-bed column loaded with composite of heavy sugarcane ash and polyethylene terephthalate.

The contamination of water by pharmaceutical pollutants is a major issue these days due to excessive use of these ingredients in modern life. This study evaluated the adsorption and effectiveness of a low-cost composite prepared from heavy sugarcane ash (HSA) fused with polyethylene terephthalate (PET) and functionalized with iron (Fe3+) in a dynamic system through a fixed-bed column. The solution of synthetic drugs was prepared and placed in a reservoir, using a peristaltic pump the solution is run onto the fixed bed column at a flow rate of 2 mL min-1. Saturation time and adsorption capacity were evaluated by centrifugation and extraction after a regular interval of 2 h from the adsorption column. The samples were analyzed using high-performance liquid chromatography (HPLC) and the data was modeled for quantification. For DIC removal, an adsorption capacity of 324.34 µg. g-1 and a saturation time of 22 h were observed, while the adsorption capacity of NAP was 956.49 µg. g-1, with a saturation time of 8 h. Thus, the PETSCA/Fe3+ adsorbent proved to be quite efficient for removing the pharmaceutical pollutants, with a longer period of operation for DIC removal. These findings suggested that a highly efficient bed column made from a less expensive waste material and could be used to remove hazardous pharmaceutical contaminants.

Industrial applications of immobilized nano-biocatalysts.

Immobilized enzyme-based catalytic constructs could greatly improve various industrial processes due to their extraordinary catalytic activity and reaction specificity. In recent decades, nano-enzymes, defined as enzyme immobilized on nanomaterials, gained popularity for the enzymes' improved stability, reusability, and ease of separation from the biocatalytic process. Thus, enzymes can be strategically incorporated into nanostructured materials to engineer nano-enzymes, such as nanoporous particles, nanofibers, nanoflowers, nanogels, nanomembranes, metal-organic frameworks, multi-walled or single-walled carbon nanotubes, and nanoparticles with tuned shape and size. Surface-area-to-volume ratio, pore-volume, chemical compositions, electrical charge or conductivity of nanomaterials, protein charge, hydrophobicity, and amino acid composition on protein surface play fundamental roles in the nano-enzyme preparation and catalytic properties. With proper understanding, the optimization of the above-mentioned factors will lead to favorable micro-environments for biocatalysts of industrial relevance. Thus, the application of nano-enzymes promise to further strengthen the advances in catalysis, biotransformation, biosensing, and biomarker discovery. Herein, this review article spotlights recent progress in nano-enzyme development and their possible implementation in different areas, including biomedicine, biosensors, bioremediation of industrial pollutants, biofuel production, textile, leather, detergent, food industries and antifouling.

Emerging trends in environmental and industrial applications of marine carbonic anhydrase: a review.

Biocatalytic conversion of greenhouse gases such as carbon dioxide into commercial products is one of the promising key approaches to solve the problem of climate change. Microbial enzymes, including carbonic anhydrase, NAD-dependent formate dehydrogenase, ribulose bisphosphate carboxylase, and methane monooxygenase, have been exploited to convert atmospheric gases into industrial products. Carbonic anhydrases are Zn2+-dependent metalloenzymes that catalyze the reversible conversion of CO2 into bicarbonate. They are widespread in bacteria, algae, plants, and higher organisms. In higher organisms, they regulate the physiological pH and contribute to CO2 transport in the blood. In plants, algae, and photosynthetic bacteria carbonic anhydrases are involved in photosynthesis. Converting CO2 into bicarbonate by carbonic anhydrases can solidify gaseous CO2, thereby reducing global warming due to the burning of fossil fuels. This review discusses the three-dimensional structures of carbonic anhydrases, their physiological role in marine life, their catalytic mechanism, the types of inhibitors, and their medicine and industry applications.

Sustainable and green trends in using plant extracts for the synthesis of biogenic metal nanoparticles toward environmental and pharmaceutical advances: A review.

Conventionally utilized physical and chemical routes for constructing nanoparticles are not eco-friendly. They are associated with many shortcomings like the requirement of specially designed equipment, templates, extremely high temperature, and pressure. Biosynthesis seems to be drawn unequivocal attention owing to its upsurge of applications in different fields like; energy, nutrition, pharmaceutical, and medicinal sciences. To harness the biological sources, the present review describes an environment-friendly route to generate biogenic nanoparticles from the natural plant extracts and the followed mechanisms for their synthesis, growth, and stabilization. The present review summarizes the recent trends involved in the photosynthesis of metallic nanoparticles and their effective use in controlling malaria, hepatitis, cancer, like various endemic diseases. Also, various characterization approaches, such as UV-visible spectrophotometry, Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy, are discussed here examine the properties of as-fabricated nanoparticles. Various plant parts like leaves, stems, barks, fruit, and flowers are rich in flavonoids, phenols, steroids, terpenoids, enzymes, and alkaloids, thereby playing an essential role in reducing metal ions that generate metallic nanoparticles. Herein, the uniqueness of phytofabricated nanoparticles along with their distinctive antibacterial, antioxidant, cytotoxic, and drug delivery properties are featured. Lastly, this work highlights the various challenges and future perspectives to further synthesize biogenic metal nanoparticles toward environmental and pharmaceutical advances in the coming years.

Bioprocesses for the recovery of bioenergy and value-added products from wastewater: A review.

Wastewater and activated sludge present a major challenge worldwide. Wastewater generated from large and small-scale industries, laundries, human residential areas and other sources is emerging as a main problem in sanitation and maintenance of smart/green cities. During the last decade, different technologies and processes have been developed to recycle and purify the wastewater. Currently, identification and fundamental consideration of development of more advanced microbial-based technologies that enable wastewater treatment and simultaneous resource recovery to produce bioenergy, biofuels and other value-added compounds (organic acids, fatty acids, bioplastics, bio-pesticides, bio-surfactants and bio-flocculants etc.) became an emerging topic. In the last several decades, significant development of bioprocesses and techniques for the extraction and recovery of mentioned valuable molecules and compounds from wastewater, waste biomass or sludge has been made. This review presents different microbial-based process routes related to resource recovery and wastewater application for the production of value-added products and bioenergy. Current process limitations and insights for future research to promote more efficient and sustainable routes for this under-utilized and continually growing waste stream are also discussed.

Integrated catalytic insights into methanol production: Sustainable framework for CO2 conversion.

A continuous increase in the amount of greenhouse gases (GHGs) is causing serious threats to the environment and life on the earth, and CO2 is one of the major candidates. Reducing the excess CO2 by converting into industrial products could be beneficial for the environment and also boost up industrial growth. In particular, the conversion of CO2 into methanol is very beneficial as it is cheaper to produce from biomass, less inflammable, and advantageous to many industries. Application of various plants, algae, and microbial enzymes to recycle the CO2 and using these enzymes separately along with CO2-phillic materials and chemicals can be a sustainable solution to reduce the global carbon footprint. Materials such as MOFs, porphyrins, and nanomaterials are also used widely for CO2 absorption and conversion into methanol. Thus, a combination of enzymes and materials which convert the CO2 into methanol could energize the CO2 utilization. The CO2 to methanol conversion utilizes carbon better than the conventional syngas and the reaction yields fewer by-products. The methanol produced can further be utilized as a clean-burning fuel, in pharmaceuticals, automobiles and as a general solvent in various industries etc. This makes methanol an ideal fuel in comparison to the conventional petroleum-based ones and it is advantageous for a safer and cleaner environment. In this review article, various aspects of the circular economy with the present scenario of environmental crisis will also be considered for large-scale sustainable biorefinery of methanol production from atmospheric CO2.

Production and Characterization of Cross-Linked Aggregates of Geobacillus thermoleovorans CCR11 Thermoalkaliphilic Recombinant Lipase.

Immobilization of enzymes has many advantages for their application in biotechnological processes. In particular, the cross-linked enzyme aggregates (CLEAs) allow the production of solid biocatalysts with a high enzymatic loading and the advantage of obtaining derivatives with high stability at low cost. The purpose of this study was to produce cross-linked enzymatic aggregates (CLEAs) of LipMatCCR11, a 43 kDa recombinant solvent-tolerant thermoalkaliphilic lipase from Geobacillus thermoleovorans CCR11. LipMatCCR11-CLEAs were prepared using (NH4)2SO4 (40% w/v) as precipitant agent and glutaraldehyde (40 mM) as cross-linker, at pH 9, 20 °C. A U10(56) uniform design was used to optimize CLEA production, varying protein concentration, ammonium sulfate %, pH, glutaraldehyde concentration, temperature, and incubation time. The synthesized CLEAs were also analyzed using scanning electron microscopy (SEM) that showed individual particles of <1 µm grouped to form a superstructure. The cross-linked aggregates showed a maximum mass activity of 7750 U/g at 40 °C and pH 8 and retained more than 20% activity at 100 °C. Greater thermostability, resistance to alkaline conditions and the presence of organic solvents, and better durability during storage were observed for LipMatCCR11-CLEAs in comparison with the soluble enzyme. LipMatCCR11-CLEAs presented good reusability by conserving 40% of their initial activity after 9 cycles of reuse.

Agri-food waste as environmental pollutant: Root causes, challenges and solution.

In addition, wet solid waste can be converted to fuel components using hydrothermal liquefaction technology. To minimize the adversity of environmental pollution, some of the preventive measures need to be undertaken by following the principles of 3R's- Reuse, Reduce and Recycle, each one plant one, use of public transportation and adopt the use of carpooling to save fuel.

Microbial community profiling in bio-stimulated municipal solid waste for effective removal of organic pollutants containing endocrine disrupting chemicals.

The study was aimed to improve the degradation of organic pollutants in municipal solid waste (MSW) through the bio-stimulation process. The results showed that the physico-chemical properties of MSW (control) had a high value of pH (9.2 ± 0.02); total suspended solids (TSS: 1547 ± 23 mg/kg-1), and total dissolved solids (TDS:76 ± 0.67 mg/kg-1). After the biostimulation process (biostimulated MSW), the physico-chemical parameters of MSW were reduced as pH (7.1 ± 0.01); TSS (41 ± 0.01 mg/kg-1), and TDS (789 ± 03 mg/kg-1). Furthermore, the major organic pollutants detected from MSW by gas chromatography-mass spectroscopy (GC-MS) analysis at different retention time (RT) were hexadecane (RT-8.79); pentadecane (RT-9.36); and hexasiloxane (RT-9.43) while these organic pollutants were degraded after the biostimulation process. The whole-genome metagenome sequencing size (%) analyses showed major groups of bacteria (40.82%) followed by fungi (0.05%), virus (0.0032%), and archaea (0.0442%) in MSW. The species richness and evenness of the microbial community were decreased substantially due to the biostimulation treatment. The total number of genes in the biostimulated MSW (PS-3_11267) sample were 465302 whereas the number of genes in the control MSW (PS-4_11268) sample were 256807. Furthermore, the biostimulated MSW (PS-3_11267) aligned the reads to bacteria (19502525), fungi (40030), virus (3339), and archaea (12759) genomes whereas the control sample (PS-4_11268) aligned the reads to bacteria (17057259), fungi (19148), virus (1335), and archaea (18447) genomes. Moreover, the relative abundance at genus level in biostimulated MSW (PS-3_11267) (Ochrobactrum and Phenylobacterium), phylum; (Proteobacteria and Actinobacteria), and species (Chthoniobacter flavus and Vulgatibacter incomptus) level was the most abundant. The results provided valuable information regarding the degradation of organic pollutants in MSW by microbial communities through biostimulation for the prevention of soil pollution and health protection.

Recent advances in biochar amendments for immobilization of heavy metals in an agricultural ecosystem: A systematic review.

Over the last several decades, extensive and inefficient use of contemporary technologies has resulted in substantial environmental pollution, predominantly caused by potentially hazardous elements (PTEs), like heavy metals that severely harm living species. To combat the presence of heavy metals (HMs) in the agrarian system, biochar becomes an attractive approach for stabilizing and limiting availability of HMs in soils due to its high surface area, porosity, pH, aromatic structure as well as several functional groups, which mostly rely on the feedstock and pyrolysis temperature. Additionally, agricultural waste-derived biochar is an effective management option to ensure carbon neutrality and circular economy while also addressing social and environmental concerns. Given these diverse parameters, the present systematic evaluation seeks to (i) ascertain the effectiveness of heavy metal immobilization by agro waste-derived biochar; (ii) examine the presence of biochar on soil physico-chemical, and thermal properties, along with microbial diversity; (iii) explore the underlying mechanisms responsible for the reduction in heavy metal concentration; and (iv) possibility of biochar implications to advance circular economy approach. The collection of more than 200 papers catalogues the immobilization efficiency of biochar in agricultural soil and its impacts on soil from multi-angle perspectives. The data gathered suggests that pristine biochar effectively reduced cationic heavy metals (Pb, Cd, Cu, Ni) and Cr mobilization and uptake by plants, whereas modified biochar effectively reduced As in soil and plant systems. However, the exact mechanism underlying is a complex biochar-soil interaction. In addition to successfully immobilizing heavy metals in the soil, the application of biochar improved soil fertility and increased agricultural productivity. However, the lack of knowledge on unfavorable impacts on the agricultural systems, along with discrepancies between the use of biochar and experimental conditions, impeded a thorough understanding on a deeper level.

Emerging pollutants characterization, mitigation and toxicity assessment of sewage wastewater treatment plant- India: A case study.

India faces major challenges related to fresh water supply and the reuse of treated wastewater is an important strategy to combat water scarcity. Wastewater in Gorakhpur, India, is treated by a decentralised wastewater treatment system (DEWATS) and the treated wastewater is reused in the rural area. This research provides important scientific data that ascertain the safety of wastewater reuse in this region. The physicochemical characteristics, including pigment, ionic strength, BOD, COD, TDS, TSS, salinity, total N, ammonium N, phenolics, heavy metals, and sulphate, of the inlet and outlet sewage water samples (SWWs) from a wastewater treatment facility was conducted. These parameters were found to be significantly over the national limit. The inlet and outlet samples were further characterised by using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS). SEM showed microstructure and the presence of various metals, polymers, and other co-pollutants in the samples and FT-IR confirmed the presence of aldehyde, hard liquor, and nitrogen molecules in the SWW's discharge. Many endocrine disruptors and potentially mutagenic chemical substances (e.g., Dodecane, Hexadecane, Octadecane etc.) were identified in the outlet SWW by the GC-MS analysis. Toxicity of the SWW was assessed via phytotoxicity assessment using Phaseolus mungo L. and histological and biochemical analyses of Heteropneustes fossilis in a 24-h exposure study. Results confirmed the wastewater was harmful and inhibited germination of P. mungo L. by >80% compared to the control, destroyed gill laminae and significantly increased oxidative stress (above 5% increase in catalase production) in H. fossilis. This work clearly demonstrated that the quality of the treated wastewater in Gorakhpur was poor and immediate action is needed before it can be discharged or reused.

Prevalence and implications of microplastics in potable water system: An update.

Synthetic plastics, which are lightweight, durable, elastic, mouldable, cheap, and hydrophobic, were originally invented for human convenience. However, their non-biodegradability and continuous accumulation at an alarming rate as well as subsequent conversion into micro/nano plastic scale structures via mechanical and physio-chemical degradation pose significant threats to living beings, organisms, and the environment. Various minuscule forms of plastics detected in water, soil, and air are making their passage into living cells. High temperature and ambient humidity increase the degradation potential of plastic polymers photo-catalytically under sunlight or UV-B radiations. Microplastics (MPs) of polyethylene terephthalate, polyethylene, polystyrene, polypropylene, and polyvinyl chloride have been detected in bottled water. These microplastics are entering into the food chain cycle, causing serious harm to all living organisms. MPs entering into the food chain are usually inert in nature, possessing different sizes and shapes. Once they enter a cell or tissue, it causes mechanical damage, induces inflammation, disturbs metabolism, and even lead to necrosis. Various generation routes, types, impacts, identification, and treatment of microplastics entering the water bodies and getting associated with various pollutants are discussed in this review. It emphasizes potential detection techniques like pyrolysis, gas chromatography-mass spectrometry (GC-MS), micro-Raman spectroscopy, and fourier transform infrared spectroscopy (FT IR) spectroscopy for microplastics from water samples.

A rapid, high-yield and bioinspired synthesis of colloidal silver nanoparticles using Glycyrrhiza glabra root extract and assessment of antibacterial and phytostimulatory activity.

Silver nanoparticles (AgNPs) have emerged as highly effective antimicrobial agents against multidrug-resistant (MDR) pathogens. This study aims to employ green chemistry principles for AgNP synthesis involving phytochemical-rich extract from Glycyrrhiza glabra roots. The approach highlights using renewable feedstocks, safer chemicals, minimum byproducts, and process scale-up. The synthesis of AgNPs was assessed using a surface plasmon resonance band at 420 nm, and structural properties were characterized using TEM, x-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. This method enables the production of high-yield dispersions of AgNPs with desired physicochemical characteristics, including dark yellow solution, size (~20 nm), spherical to an oval shape, crystal structure, and stable colloidal properties. The antimicrobial activity of AgNPs was investigated against the MDR bacteria strains of gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli). This work reveals that the antimicrobial activity of AgNPs can be influenced by bacterial cell wall components. The results demonstrate the strong interaction between AgNPs and E. coli, exhibiting a dose-dependent antibacterial response. The green approach facilitated the safer, facile, and rapid synthesis of colloidal dispersions of AgNPs, providing a sustainable and promising alternative to conventional chemical and physical methods. Furthermore, the effect of AgNPs on various growth parameters, including seed germination, root and shoot elongation, and dry weight biomass, was assessed for mung bean seedlings. The results revealed phytostimulatory effects, suggesting the promising prospects of AgNPs in the nano-priming of agronomic seeds. RESEARCH HIGHLIGHTS: Glycyrrhiza glabra root extract enabled rapid, high-yield, and eco-friendly synthesis of silver nanoparticles (AgNPs). Spectrophotometric analysis examined the optical properties, scalability, and stability of AgNPs. Transmission electron microscopy provided insights into the size, shape, and dispersity of AgNPs. Scanning electron microscopy revealed significant damage to gram-negative bacterial cell morphology and membrane integrity. AgNPs were found to enhance seed germination, seedling growth, and biomass yield of Vigna radiata.

Adsorptive removal of dichlorophenoxyacetic acid (2,4-D) using novel nanoparticles based on cationic surfactant-coated titania nanoparticles.

A novel nanomaterial based on cationic surfactant-coated TiO2 nanoparticle (CCTN) was systematically fabricated in this work. Synthesized titania nanoparticles were thoroughly characterized by XRD, FT-IR, HR-TEM, TEM-EDX, SEM with EDX mapping, BET, and ζ potential measurements. The adsorption of cationic surfactant, cetyltrimethylammonium bromide (CTAB), on TiO2 was studied under various pH and ionic strength conditions. Adsorption of CTAB on TiO2 increased with ionic strength increment in the presence of hemimicelle monolayer structure, indicating that nonelectrostatic and electrostatic forces control CTAB uptake. CTAB adsorption isotherms on TiO2 were according to a two-step model. Potential application in pesticide removal of 2,4-dichorophenoxy acetic acid (2,4-D) using CCTN was also studied. Optimum parameters for 2,4-D treatment through adsorption technique were pH 5, adsorption time of 120 min, and CCTN dosage of 10 mg·mL-1. Very low 2,4-D removal efficiency using TiO2 without CTAB coating was found to be approximately 28.5% whereas the removal efficiency was up to about 90% by using CCTN under optimum conditions, and the maximum adsorption capacity of 12.79 mg·g-1 was found. Adsorption isotherms of 2,4-D on CCTN were more suitable with the Langmuir model than Freundlich. Adsorption mechanisms of 2,4-D on CCTN were mainly governed by Columbic attraction based on isotherms and surface charge changes.