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For separation and recovery of different but chemically similar metal from dilute wastewater with reduced process complexity and cost, a supported liquid membrane (SLM) system that utilizes a single carrier together with strip dispersion for selective stripping of coextracted metal ions was proposed to enable concurrent separation and recovery. This study aims to investigate the effectiveness of the proposed SLM system for separative recovery of copper and zinc from real plating wastewater. Solvent extraction experiments were conducted to understand the effect of feed pH and carrier concentration on organic phase migration to the aqueous phase. The effect of stirring speed on the SLM transport rate was studied using synthetic feed. Combined with the insights from our previous study, appropriate settings were identified and applied to the SLM system. The SLM system could recover 83.7% copper with 91.0% purity and 85.5% Zn with 99.3% purity from the plating wastewater in 30 h. The findings indicate the feasibility of using SLM with selective stripping for the concurrent separation and recovery of copper and zinc from a dilute aqueous waste stream predominantly containing these two metals.

Bioremediation is a sustainable and worthy approach for remediating textile industrial wastewater, which poses severe extortions to human and environmental health due to its toxic, mutagenic, and carcinogenic nature. The present study employed Acinetobacter baumannii 1005 isolated from industrial wastewater to emphasize its degradation potential and to characterize the azoreductase (AZA) gene to assess and optimize the biodegradation of reactive blue 224 (RB-224) textile dye. A. baumannii showed significant decolorization against RB-224, resulting in a change in color. Under optimized conditions (pH 6, 37 °C, and 100 mg/L), A. baumannii exhibited 91 % decolorization of RB-224 being analyzed by UV–vis after 24 h of incubation. UV–vis spectroscopy and FTIR analysis have shown the efficiency of A. baumannii for degrading RB-224. In the UV spectrum, the shifting of the peak from560 nm to 400 nm confirmed the decolorization. In the FTIR spectrum, the shift of several significant peaks related to the functional groups S = O C-N, C–H, C = C, and N–H, corresponding to the structure of RB-224 dye along with the emergence of new peaks indicating the formation of metabolites after degradation. The Azoreductase (AZA) gene of ∼600 bp was amplified and cloned in a pTz57R/T cloning vector. Subsequently, the AZA gene was sequenced and submitted to NCBI for accession number. This study explored the potential of A. baumannii isolate suitable for the bio-remediation of textile dyes.

Nano-structured materials gain a vast market acceptance mainly due to their overarching endurance. Nanofibrillar cellulose (NFC) is one example of an augmenting agent unviable for production by small and medium enterprises (SMEs) due to the underlying process complexity. This study aims to characterise the NFC-alternative cells denoted as TRX-cellsⓇ, which is a mix of cellulose and non-cellulose components, ruling out its status as ‘cellulose nanofibers, CNF’. The aim to test-fit the TRX-cells® production process into the circularity model was executed by deliberating on the usability of the byproduct. In doing so, fibrous oil palm empty fruit bunch (EFB) was treated with dioxydanyl radicals (DIOR) and homogenised. The rapid EFB-DIOR reaction at 70°C targeting dearomatisation reaction in a 10%-solid open system was performed before refining the DIOR-treated EFB to micro-scale fibres. Subjecting the micro-fibres to 17 kWh/mt PFI-milling yielded 85–95% of nano-scale fibrous mass. Relative to the stiff micro-fibres, the nano-scale cells web exhibit 34–41% softness enhancement judged from the web tear resistance profile associated with inter-fibre space reduction. Advanced chromatographic evidence for 27% xylan amongst TRX-cells®’ total aldo-sugars was one form of the non-cellulose nano-component. High-resolution Transmission Electron Microscopy hyphenated to Energy Dispersive Analysis of X-ray (HRTEM-EDX) elemental mapping showed a 0.4 atomic percentage of nano-biominerals, confirming the presence of the redistributed dearomatised cells adjacent to cellulose held in the web of the hemicellulose. Shearing at the dearomatised inter-cell wall layers by PFI mill peeled 5 nm–100 nm thickness laminae. The smorgasbord of cellulose and non-celluloses resulted in crystallinity comparable to softwood NFC of approximately 60%, with unique preservation and precision-printing enabling properties. Given the non-recyclability of the DIOR-treated EFB microfibres, nestling the rapid waste transformation process into the circularity model shed light on circular bio-nanotechnology to the spectrum of opportunity for zero-waste, reduced emission and net zero carbon practices on top of an added value from waste transformation to a product.

Demand for energy resources is increasing rapidly, leading to excessive exploitation of fossil fuels. The production of chicken, which is a popular source of protein, generates a huge amount of waste. Microbial fuel cells (MFC) have the potential to generate clean, sustainable, and environmentally benign electricity by utilizing electrogenic bacteria present in chicken manure (CM), while also decreasing the amount of waste. The present study was conducted to assess the effect of different temperatures and numbers of chambers in series and parallel circuits on the performance of membrane-less MFCs (ML-MFCs). The central composite design (CCD) based on response surface methodology (RSM) was applied to optimize the performance of ML-MFCs in series and parallel circuits, with a focus on chemical oxygen demand (COD) removal efficiency (R2 = 0.958 and 0.967), biomass (R2 = 0.995 and 0.836), and power density (R2 = 0.958 and 0.825). The study revealed that the highest COD removal (series: 89.554%, parallel: 84.994%), biomass (series: 1.095 mg/L, parallel: 2.267 mg/L), and power density (series: 0.551 W/m2, parallel: 0.360 W/m2) were achieved when the pre-treatment temperature was 40 °C. The best ML-MFC condition was plotted on the polarization curve in order to analyze the nature of ML-MFC. Findings of this study suggest that ML-MFCs have great potential for electricity generation and waste reduction, and the optimization of operating conditions can enhance their performance.

The current study report a convenient, simple, and low cost approach for the biogenic synthesis of CuO/Fe3O4 nanocomposites (NCs) from pumpkin seeds extract and their vitro cytotoxicity. The characterization of finally obtained CuO/Fe3O4 nanocomposites (NCs) performed using UV–Visible, FT-IR, XRD, XPS, GC-MS, SEM-EDX and TEM analysis. The formation and elemental analysis were determined using the energy-dispersive X-ray (EDX) microanalysis technique. The formation of rod-like monoclinic and spherical, having size range 5 nm–20 nm confirmed by scanning electron microscope (SEM) and transmission electron microscopy (TEM) respectively. Finally, the MTT assay of the synthesized composites was evaluated for toxicity against cancerous cell lines HCT-116 (Colon cancer cell) and A549 (human lung adenocarcinoma cell). The synthesized composite material showed moderate (IC50 = 199 μg/mL) to low (IC50 = 445 μg/mL) activity against HCT-116 and A549 cell lines, respectively.

Abstract This study aims to improve electron transfer and cobalt remediation efficiency through microbial fuel cells (MFCs) by modifying the electrode material. The fabrication and alteration of the anode can be accomplished by synthesizing biomass-derived graphene oxide (GO) and adding metal oxides (ZnO and TiO2) as modifiers. The prepared GO anode offered 0.148 mW/m2 power density while GO-ZnO delivered 8.2 times and GO-TiO2 composite anode delivered 5.3 times higher power density than GO. Similarly, the achieved current density of GO was 39.47 mA/m2 while GO-ZnO composite anode delivered 75.43 mA/m2 and GO-TiO2 composite anode offered 67.54 mA/m2. During the biological characterizations of biofilm, the Bacillus sp. and Klebsiella pneumoniae strains were majorly found as exoelectrogens and metal-reducing species. The maximum remediation efficiency of cobalt (II) was 80.10% (GO), 91% (GO-ZnO composite anode), and 88.45% (GO-TiO2 composite anode) on day 45. The remediation and SEM results of anode biofilm clearly show that the prepared anodes are highly biocompatible with the bacteria. Furthermore, the effect of pH and temperature on MFCs performance are also explained with prepared anodes. Each anode offered significant perspectives in parameter optimizations.

Mango has a high global demand. Fruit fungal disease causes post-harvest mango and fruit losses. Conventional chemical fungicides and plastic prevent fungal diseases but they are hazardous to humans and the environment. Direct application of essential oil for post-harvest fruit control is not a cost-effective approach. The current work offers an eco-friendly alternative to controlling the post-harvest disease of fruit using a film amalgamated with oil derived from Melaleuca alternifolia. Further, this research also aimed to assess the mechanical, antioxidant, and antifungal properties of the film infused with essential oil. ASTM D882 was performed to determine the tensile strength of the film. The antioxidant reaction of the film was assessed using the DPPH assay. In vitro and in vivo tests were used to evaluate the inhibitory development of the film against pathogenic fungi, by comparing the film with different levels of essential oil together with the treatment of the control and chemical fungicide. Disk diffusion was used to evaluate mycelial growth inhibition, where the film incorporated with 1.2 wt% essential oil yielded the best results. For in vivo testing of wounded mango, the disease incidence was successfully reduced. For in vivo testing of unwounded mango to which the film incorporated with essential oil was applied, although some quality parameters such as the color index were not significantly affected, weight loss was reduced, soluble solid content was increased, and firmness was increased, compared to the control. Thus, the film incorporated with essential oil (EO) from M. alternifolia can be an environmentally friendly alternative to the conventional approach and the direct application of essential oil to control post-harvest disease in mango.

The ultrafiltration mixed matrix membrane (UF MMMs) process represents an applicable approach for the removal of diluted acetic acid at low concentrations, owing to the low pressures applied. The addition of efficient additives represents an approach to further improve membrane porosity and, subsequently, enhance acetic acid removal. This work demonstrates the incorporation of titanium dioxide (TiO2) and polyethylene glycol (PEG) as additives into polysulfone (PSf) polymer via the non-solvent-induced phase-inversion (NIPS) method to improve the performance of PSf MMMs performance. Eight PSf MMMs samples designated as M0 to M7, each with independent formulations, were prepared and investigated for their respective density, porosity, and degree of AA retention. Morphology analysis through scanning electron microscopy elucidated sample M7 (PSf/TiO2/PEG 6000) to have the highest density and porosity among all samples with concomitant highest AA retention at approximately 92.2%. The application of the concentration polarization method further supported this finding by the higher concentration of AA solute present on the surface of the membrane compared to that of AA feed for sample M7. Overall, this study successfully demonstrates the significance of TiO2 and PEG as high MW additives in improving PSf MMM performance.

This study is focused on the production of biodiesel from waste cooking oils to turn the waste into energy by biological means. Physicochemical analysis of the oil samples was performed by measuring their density, acid value and saponification value for evaluating their efficacy towards biodiesel synthesis. Metal catalyzed glycerolysis and acid catalyzed esterification was carried out to reduce the free fatty acid number of oils. Transesterification of treated oils was done by using different alkalis and lipase (free and immobilized) as catalysts. Furthermore, the impact of all the reaction parameters including time, temperature, catalysts and methanol concentration was observed. Biodiesel was purified by wet and dry washing. Maximum product formation was achieved with 1% potassium hydroxide (KOH) followed by 4% free lipase and 6% immobilized lipase. Chemical composition analysis by gas chromatography and mass spectrometry (GCMS) showed the presences of about 97 and 93% fatty acid methyl esters for KOH and lipase based biodiesel, respectively. Fuel properties including distillation temperature, kinematic viscosity, flash, fire, cloud and pour point of the final product were found in accordance with the standard American Society Testing and Materials biodiesel specifications.

The present study investigated the uptake of polylactic acid (PLA) microplastics, the most commonly used biodegradable plastic by Eudrilus eugeniae. It was done by observing their weight changes, biomass, and microplastics concentration after feeding them with a mixture of PLA and cow dung for 16 days at the ratio of 0%, 10%, 30%, 60%, and 80% w/w dry weight. The mortality rate of the earthworms for all the PLA concentrations during the 16 days of the feeding period was 0%. However, the microplastic significantly affected the earthworms' weight (P-value 0.00027), especially at 80% of PLA concentration. The earthworms had the lowest weight gain at 80%, followed by 60%, 30%, and 10% of PLA, respectively. The earthworms subjected to 80% and 10% of PLA had a similar pattern with the control. The PLA microplastics concentration factor (CF) in the vermicast was the highest at the 10% PLA than other treatments because Eudrilus eugeniae did not degrade the PLA. This study concludes that even though PLA is biopolymer-based, the earthworm cannot assimilate it. However, in the long run, there is a possibility of further degradation of the PLA MPs ejected in the vermicast due to the rich microbial environment provided by the earthworms and vermicast.

The utilization of lignocellulose biomass as an alternative source of renewable energy production via green technology is becoming important, and is in line with sustainable development goal initiatives. Lignocellulolytic bacteria, such as Bacillus spp., can break down biomass by producing hydrolytic enzymes, which are crucial in the successful conversion of biomass or lignocellulosic material into renewable energy. This information gave rise to this study, where municipal solid waste sediments of a sanitary municipal solid waste landfill were sampled and screened, and lignocellulolytic bacteria were isolated and characterized. Samples were taken from four different locations at the Pulau Burung landfill site in Malaysia. Lignin and starch were used as sources of carbon to identify potential bacteria that exhibit multi-enzymatic activity. The growth rate and doubling time of bacterial isolates in lignin and starch were taken as the criteria for selection. Eleven bacterial isolates were screened for cellulase activity using iodine and Congo red dyes. The cellulase activity of these isolates ranged from 0.8 to 1.7 U/mL. We carried out 16S rRNA gene sequencing to identify the phyla of the selected bacterial isolates. Phylogenetic analysis was also conducted based on the 16S rRNA sequences of the bacterial isolates and related Bacillus species, and a tree was generated using the Neighbor-Joining method. In this study, Bacillus proteolyticus, Bacillus Sanguinis, Bacillus spizizenii, Bacillus paramycoides, Bacillus paranthracis and Neobacillus fumarioli were identified as promising bacteria capable of expressing lignocellulolytic enzymes and degrading the lignocellulosic biomass present in municipal solid waste.

The hybridization between polymers and carbon materials is one of the most recent and crucial study areas which abstracted more concern from scientists in the past few years. Polymers could be classified into two classes according to the source materials synthetic and natural. Synthetic polymeric materials have been applied over a floppy zone of industrial fields including the field of biomedicine. Carbon nanomaterials including (fullerene, carbon nanotubes, and graphene) classified as one of the most significant sources of hybrid materials. Nanocarbons are improving significantly mechanical properties of polymers in nanocomposites in addition to physical and chemical properties of the new materials. In all varieties of proposed bio-nanocomposites, a considerable improvement in the microbiological performance of the materials has been explored. Various polymeric materials and carbon-course nanofillers were present, along with antibacterial, antifungal, and anticancer products. This review spots the light on the types of synthetic polymers-based carbon materials and presented state-of-art examples on their application in the area of biomedicine.

Hybrid materials are classified as one of the most highly important topics that have been of great interest to many researchers in recent decades. There are many species that can fall under this category, one of the most important of which contain biopolymeric materials as a matrix and are additionally reinforced by different types of carbon sources. Such materials are characterized by many diverse properties in a variety industrial and applied fields but especially in the field of biomedical applications. The biopolymeric materials that fall under this label are divided into natural biopolymers, which include chitosan, cellulose, and gelatin, and industrial or synthetic polymers, which include polycaprolactone, polyurethane, and conducting polymers of variable chemical structures. Furthermore, there are many types of carbon nanomaterials that are used as enhancers in the chemical synthesis of these materials as reinforcement agents, which include carbon nanotubes, graphene, and fullerene. This research investigates natural biopolymers, which can be composed of carbon materials, and the educational and medical applications that have been developed for them in recent years. These applications include tissue engineering, scaffold bones, and drug delivery systems.

The increase in the industrial revolution, urbanization, and deficit in crude oil resources urged scientists to look for sustainable and renewable energy resources. Microbial fuel cells (MFCs) are bio-electrochemical devices that convert the chemical energy of bio mass into electrical energy utilizing microorganisms as biocatalysts. MFC is an enthralling technology, and it has many important applications. There are different designs of MFC currently in use, each having their pros and cons; however, the stacked MFC is so far generating the highest power output. Different factors, discussed in this review, contribute toward the efficiency of the process. An ample amount of research has been done to convert the theoretical framework of MFC into a practical application; however, the later still remains a big challenge. A plethora of technical problems is in the way for MFC to be driven toward up-scaling and real-world applications. This review discusses electron transfer mechanisms in MFCs and important factors affecting the performance of MFC. Reactor design is a main limiting factor in MFC technology, and this review also focuses on recent improvements in reactor designs and modifications. Moreover, some main applications of MFC technology, limitations, recent advancements, and future prospects are discussed.

Massive generation of natural waste fiber from agricultural industries followed by improper disposal management might result in a detrimental effect on our ecosystem contributing to various types of environmental pollution. With the growing significance of climate change, an effort is being undertaken by utilizing natural waste fiber into eco-friendly insulation panels to reduce the environmental impact of buildings. In this research, a composite panel was developed from spent mushroom substrate (SMS) and empty fruit bunch (EFB) fibers via a sandwich technique. Five samples were made, each with a different fiber ratio (100 SMS: 0 EFB, 80 SMS: 20 EFB, 60 SMS: 40 EFB, 40 SMS: 60 EFB, and 0 SMS: 100 EFB) at density 0.8 g/cm3. Fourier transformation infrared (FTIR) Soxhlet extraction followed by thermogravimetric analysis (TGA) indicated that the SMS and EFB fibers were relevant for fabrication into a composite panel for thermal insulation. Thermal conductivity, thermal resistance, and thermal diffusivity values for these five composite samples were 0.231 to 0.31 W/(mK), 0.0194 to 0.0260 m2K/W, and 0.2665 to 0.3855 mm2/s, respectively. The flexural strength of the composite was at the range 15.61 to 23.62 MPa. These research findings suggest that the fabrication of a sandwich composite panel from SMS and EFB fiber is a promising alternative way to utilize natural waste fiber.

Patent Blue (PB) dye removal from an aqueous medium was investigated using pineapple fruit peel biochar (PFPB). The presence of functional groups and surface characteristics of PFPB was studied using Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM). A study was conducted to assess the pH effect, contact time, concentration of dye, biochar dose, speed of agitation, and temperature on removal of PB (Patent Blue) dye from an aqueous medium by PFPB. The highest 95% elimination of PB dye was reported at pH 2 by PFPB with 600 mg/L concentration of PB dye. Equilibrium studies divulged the favorable adsorption that followed the Langmuir isotherm with a monolayer uptake potential of 10.29 mg/g. Findings of kinetics disclosed that adsorption results were properly explained by the pseudo second-order model. The adsorption phenomenon was exothermic and spontaneous, as observed by thermodynamic variables. PFPB reflected a 37% uptake capacity of PB dye for up to five consecutive cycles in the adsorption and desorption study. A phytotoxicity study exhibited that PFPB-treated PB dye solution enhanced the growth of seedlings and biochemical constituents of lentils. The findings of the present study indicate the immense potential of pineapple fruit peel biochar for anionic dye removal from wastewater systems. Thus, pineapple fruit peel biochar can be utilized as a promising green sorbent for the elimination of Patent Blue dye in industrial effluents, as it is widely available and converts wastewater into reusable assets.

The authors wish to make the following correction to this paper [...]

The use of microalgae for the removal of contaminants such as total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD), and other pollutants from palm oil mill effluent (POME) has recently received much attention. This study aimed to investigate the impact of POME as a nutrient on microalgal growth and the rate at which nutrients were removed. Three green microalgae species were isolated from Penang, Malaysia’s palm oil mill. The polyphasic approach, which combines morphological and molecular observations, was used for species identification. The three green microalgae were identified as Chlorella sorokiniana, Scenedesmus quadricauda, and Chlorococcum oleofaciens. All three green microalgae were cultivated in 25%, 50%, and 75% (v/v) of lab-scale palm oil mill effluent (LABT-POME) to investigate the growth of these three green microalgae in 100 mL of BBM. Under a light microscope and a scanning electron microscope (SEM), the morphological changes of those three green microalgae (before and after cultivation in 25%, 50%, and 75% dilution of (LABT-POME)) were observed. When cultivated in LABT-POME, C. oleofaciens showed the highest growth rate compared to the other two species of green microalgae. C. oleofaciens was able to remove more than 90% of total phosphorus (TP), total nitrogen (TN), and ammonia nitrogen from LABT-POME, as well as minimise soluble chemical oxygen demand (SCOD) by about 65%. The growth of C. oleofaciens was well fitted to the Verhulst growth kinetic model with an R2 value of 0.99 and a growth rate of 0.3195 day−1 (d−1). The results of this study show the ability of newly isolated green microalgae to remove nutrients (TP, TN, NH3–N, and SCOD) from POME, which could be used as an effective and environmentally friendly method to remove pollutants.

Recently, the contribution of earthworms to plastic degradation and their capability to swallow smaller plastic fragments, known as microplastics, has been emphasized. The worm physically changes the size of microplastics and enhances microbial activities to increase the possibility of degradation. However, no research has shown that earthworms can chemically degrade microplastics to an element form, CO2 or H2O. In this review, previous research has been thoroughly explored to analyse the role that earthworms could play in plastic degradation in the soil. Earthworms can significantly affect the physical characteristics of plastics. However, earthworms’ abilities to chemically degrade or change the chemical structure of plastics and microplastics have not been observed. Additionally, earthworms exhibit selective feeding behaviour, avoiding areas containing a high plastics concentration and rejecting plastics. Consequently, earthworms’ abilities to adapt to the microplastics in soil in the environment can cause a problem. Based on this review, the challenges faced in earthworm application for plastic degradation are mostly expected to be associated with the toxicity and complexity of the plastic material and environmental factors, such as the moisture content of the soil and its temperature, microbial population, and feeding method.

Cadmium and lead soil contamination is a widespread environmental problem that requires profound and sustainable solutions. These toxic elements can be naturally occurring on the Earth’s crust or from man-made origins. Cadmium and lead could accumulate and translocate in soil over the long term. Thus, their risk of entering the food chain is extremely elevated and their effects on the living organisms in the food web are of great concern. The main purpose of this review study is to emphasize the risk to human health of cadmium and lead as an environmental contaminant in soil and plants. Human exposure to cadmium and lead can cause severe illness; for instance, long-term exposure to cadmium can alter kidney health and cause dysfunction. Additionally, lead threatens the nervous system and causes countless diseases. Hence, the remediation of cadmium and lead from soil before they enter the food chain remains essential, and regular monitoring of their principal sources is crucially needed for a sustainable soil ecosystem.

The aim of the present work is to investigate the potential use of banana peel waste as a natural coagulant and to enhance its coagulation performance using a green modification approach for the removal of synthetic water turbidity and river water treatment. Here, the regular banana peel powder had an average particle size and diameter of 978 ± 37 nm and 602 ± 13 nm, respectively, while the modified powder possessed 571 ± 41 nm and 360 ± 19 nm particle size and diameter, respectively. The coagulation performance was investigated at different pH levels, doses, sedimentation times, and NaCl quantities. The optimum dose was found to be 0.4 g/L for modified banana peel with turbidity removal of up to 90%. NaCl slightly enhanced the coagulation performance at low quantities of less than 0.4 g/L, but the activity was reduced at higher concentrations even in the modified powder. Banana peel powder had a weaker turbidity reduction of 76 and 84% for non-modified and modified powders in river water, respectively, in addition to significant reduction in water color, total dissolved and suspended solids, and chemical and biochemical oxygen demand. SEM and FT-IR characterization were performed to investigate and confirm the coagulation mechanism. Such a green modification of banana peel powder can be an alternative with significantly potential as a low cost and easily available bio-coagulant, which can certainly contribute to the waste reduction.

The increase in urbanization and industrialization has led to the discharge of wastes in environment causing more pollution. Textile industries are playing a havoc role in water pollution natural aquatic ecosystems. Bioremediation is the one of the cost effective and ecofriendly achievement of biotechnological novelty. Bioremediation is the key to waste management. It can remove textile dyes that are considered to be heterologous biological compounds and are difficult to degrade. In the present bio-remedial method, Klebsiella pneumoniae GM-04 was used promising microbial tool for the decolorization of disperse blue 284 dye. Klebsiella pneumoniae was isolated from industrial wastewater. Under optimum conditions (37 °C and pH 7) Klebsiella pneumoniae led to 95% decoloration of DB-284 (200 ppm) within 24 hrs. The increase in dye concentration and temperature decreased the bacterial growth results in low decoloration of dye. UV–Vis and FTIR analysis suggested that the parent dye degraded into different products. The data was statistically analyzed.

The nanomaterials synthesis is an intensifying research field due to their wide applications. The high surface-to-volume ratio of nanoparticles and quick interaction capacity with different particles make them as an attractive tool in different areas. Conventional physical and chemical procedures for development of metal nanoparticles become outmoded due to extensive production method, energy expenditure and generation of toxic by-products which causes significant risks to the human health and environment. Hence, there is a growing requirement to search substitute, non-expensive, reliable, biocompatible and environmental friendly methods for development of nanoparticles. The nanoparticles synthesis by microorganisms has gained significant interest due to their potential to synthesize nanoparticles in various sizes, shape and composition with different physico-chemical properties. Microbes can be widely applied for nanoparticles production due to easy handling and processing, requirement of low-cost medium such as agro-wastes, simple scaling up, economic viability with the ability of adsorbing and reducing metal ions into nanoparticles through metabolic processes. Biogenic synthesis of nanoparticles offers clean, non-toxic, environmentally benign and sustainable approach in which renewable materials can be used for metal reduction and nanoparticle stabilization. Nanomaterials synthesized through microbes can be used as a pollution abatement tool as they also contain multiple functional groups that can easily target pollutants for efficient bioremediation and promotes environmental cleanup. The objective of the present review is to highlight the significance of micro-organisms like bacteria, actinomycetes, filamentous fungi, yeast, algae and viruses for nanoparticles synthesis and advantages of microbial approaches for elimination of heavy metals, dyes and wastewater treatment.

In addition to disposal issues, the abundance of sludge and chicken manure has been a rising issue in Malaysia. Membrane-less microbial fuel cell (ML-MFC) technology can be considered as one of the potential solutions to the issues of disposal and electricity generation. However, there is still a lack of information on the performance of an ML-MFC powered by sludge and chicken manure. Hence, with this project, we studied the performance of an ML-MFC supplemented with sludge and chicken manure, and its operating parameters were optimized using response surface methodology (RSM) through central composite design (CCD). The optimum operating parameters were determined to be 35 °C, 75% moisture content, and an electrode distance of 3 cm. Correspondingly, the highest power density, COD removal efficiency, and biomass acquired through this study were 47.2064 mW/m2, 98.0636%, and 19.6730 mg/L, respectively. The obtained COD values for dewatered sludge and chicken manure were 708 mg/L and 571 mg/L, respectively. COD values were utilized as a standard value for the substrate degradation by Bacillus subtilis in the ML-MFC. Through proximate analyses conducted by elemental analysis and atomic absorption spectrometry (AAS), the composition of carbon and magnesium for sludge and chicken manure was23.75% and 34.20% and 78.1575 mg/L and 71.6098 mg/L, respectively. The proposed optimal RSM parameters were assessed and validated to determine the ML-MFC operating parameters to be optimized by RSM (CCD).

Prior to applying supported liquid membranes (SLM) with strip dispersion for separation of chromium (VI), copper and zinc, suitable chemical settings were determined through solvent extraction and stripping studies. More than 90% of copper and zinc could be simultaneously extracted with at least 3% (v/v) di-(2-ethylhexyl)phosphoric acid (D2EHPA) at a feed equilibrium pH in the range of 3.5–5.0. For stripping, theoretical model equations derived and experimental results revealed that suitable concentrations of lower acid strength reagents can strip metals that have weaker metal-extractant bond without significantly stripping metals that have a stronger metal-extractant bond. Therefore, in a setup comprising three compartments separated by two SLM, we propose to fill the three compartments in the following order: feed—strip dispersion containing low acid strength reagent—strong acid. An organic phase with 4% (v/v) D2EHPA was used. From stripping experiments, 0.2 mol/L pH 3 citrate buffer, which resulted in the highest copper recovery (88.8%) and solution purity (99.0%), was employed as the low acid strength reagent while the strong acid consisted of 1 mol/L sulfuric acid. In 26 h, 99.1% copper was recovered by citrate buffer with 99.8% purity and 95.1% zinc was recovered by sulfuric acid with 98.4% purity. Chromium (VI), copper and zinc could be separated effectively using this separation strategy.

The need for energy resources is growing all the time, which means that more fossil fuels are needed to provide them. People prefer to consume chicken as a source of protein, and this creates an abundance of waste. Thus, microbial fuel cells represent a new technological approach with the potential to generate electricity through the action of electrogenic bacteria toward chicken manure, while reducing the abundance of chicken manure. This study investigated the effect of different pretreatment (thermal, alkaline, and sonication pretreatment) of chicken manure to improve the performance of a membrane-less microbial fuel cell (ML-MFC). Statistical response surface methodology (RSM) through a central composite design (CCD) under a quadratic model was conducted for optimization of the ML-MFC performance focusing on the COD removal efficiency (R2 = 0.8917), biomass (R2 = 0.9101), and power density response (R2 = 0.8794). The study demonstrated that the highest COD removal (80.68%), biomass (7.8539 mg/L), and power density (220 mW/m2) were obtained when the pretreatment conditions were 140 °C, 20 kHz, and pH 10. The polarization curve of the best condition of ML-MFC was plotted to classify the behavior of the ML-MFC. The kinetic growth of Bacillus subtillis (BS) showed that, in treated chicken manure, the specific growth rate µ = 0.20 h−1 and doubling time Td = 3.43 h, whereas, in untreated chicken manure, µ = 0.11 h−1 and Td = 6.08.

The present study demonstrates the thermal stability and photocatalytic activity of TiO2-based nanotubes with respect to post-hydrothermal treatment. Titanate nanotubes were synthesized by adapting an alkali hydrothermal method from TiO2 sol using NaOH as a catalyst. The effect of post-hydrothermal heating on the properties—such as structure, morphology, textural properties, and activity—of as-synthesized one-dimensional titania nanostructure is investigated in detail. The characterizations are carried out using SEM, EDX, TEM, XRD, and a BET surface area analyzer. When heated in the presence of water in an autoclave, the protonated titanate phase of the nanotubes converts to anatase phase. Meanwhile, the tubular morphology is gradually lost as the post-hydrothermal heating duration increases. The photocatalytic activity was assessed utilizing the photo-oxidation of an amaranth dye. It is discerned that the as-prepared nanotubes are photocatalytically inactive but become active after post-hydrothermal processing. The activity trend follows the formation of the active phase—the titanate phase crystallizes into a photocatalytically-active anatase phase during post-hydrothermal heating. The effect of experimental parameters, such as reaction pH, dye concentration, and amount of catalyst, on the dye removal is studied. The findings also highlight that the role of holes/OH• is more prominent as compared to conduction band electron/O2−• for the removal of the dye. In addition, the photocatalyst exhibited excellent stability and reusability.

These days, many countries have a water shortage and have limited access to clean water. To overcome this, a new treatment is emerging, namely, the photocatalytic processing of greywater. Photocatalytic processes to remove the organic matter from different greywater sources are critically reviewed. Their efficiency in degrading the organic matter in greywater is scrutinized along with factors that can affect the activity of photocatalysts. Modified TiO2, ZnO and TiO2 catalysts show great potential in degrading organic materials that are present in greywater. There are several methods that can be used to modify TiO2 by using sol-gel, microwave and ultrasonication. Overall, the photocatalytic approach alone is not efficient in mineralizing the organic compounds, but it works well when the photocatalysis is combined with oxidants and Fe3+. However, factors such as pH, concentration and catalyst-loading of organic compounds can significantly affect photocatalytic efficiency.

Polycyclic aromatic hydrocarbons are compounds with 2 or more benzene rings, and 16 of them have been classified as priority pollutants. Among them, pyrene has been found in higher concentrations than recommended, posing a threat to the ecosystem. Many bacterial strains have been identified as pyrene degraders. Most of them belong to Gram-positive strains such as Mycobacterium sp. and Rhodococcus sp. These strains were enriched and isolated from several sites contaminated with petroleum products, such as fuel stations. The bioremediation of pyrene via Mycobacterium strains is the main objective of this review. The scattered data on the degradation efficiency, formation of pyrene metabolites, bio-toxicity of pyrene and its metabolites, and proposed degradation pathways were collected in this work. The study revealed that most of the Mycobacterium strains were capable of degrading pyrene efficiently. The main metabolites of pyrene were 4,5-dihydroxy pyrene, phenanthrene-4,5-dicarboxylate, phthalic acid, and pyrene-4,5-dihydrodiol. Some metabolites showed positive results for the Ames mutagenicity prediction test, such as 1,2-phenanthrenedicarboxylic acid, 1-hydroxypyrene, 4,5-dihydropyrene, 4-phenanthrene-carboxylic acid, 3,4-dihydroxyphenanthrene, monohydroxy pyrene, and 9,10-phenanthrenequinone. However, 4-phenanthrol showed positive results for experimental and prediction tests. This study may contribute to enhancing the bioremediation of pyrene in a different matrix.

The growing problems of environmental damage have been caused by the continuous outrush of heavy metals from industrial wastewater. To resolve this issue, bioremediation is playing a safe and eco-friendly role in the removal of these heavy metals from environmental wastewater bodies. It has provoked demand with regard to understanding the mechanisms of bioaccumulation and detoxification developed by the organisms living in the heavy metal-exposed industrial wastewater. The present investigation focuses on Paramecium multimicronucleatum, a ciliated protozoan isolated from industrial wastewater, with the objective of assessing its capabilities as an environmental bioremediator. Purified cell culture was maintained in bold basal salt medium and optimum growth conditions were determined. A maximum growth rate of 6.0–9.0 × 103 cells/mL at 25–30 °C and pH 7.0 was observed, and therefore revealed to be the optimal growth conditions for this species. It can tolerate 40–50 µg/mL of copper ion stress with little effect on growth rate as compared to control. It is able to uptake more than 80% of copper ions from the medium in 96 h. A significant twofold rise in glutathione content and non-protein thiols was recorded as an indication of a defensive mechanism in place to fight against the oxidative stress caused by the copper treatment. A notable increase of 50–70 µg/mL in total protein content of stressed cells in comparison to non-stressed was also observed as potential induction of some particular proteins for the purpose of resistance against copper stress.

The manuscript presents the first report to produce silver nanoparticles (AgNPs) using soil-inhabiting Purpureocillium lilacinum fungus cell filtrate as a promising fungicide and nematicide on two microorganisms causing high economic losses in agriculture. Methods: A fungus biomass was used as a reducing and stabilising agent in the process of NPs synthesis and then characterisation done by SEM, TEM, UV-Vis. Finally, the antimicrobial activity of the synthesised AgNPs was determined. Results: Synthesised AgNPs with a spherical and quasi-spherical shape with an average diameter of 50 nm were effective to inhibit A. flavus fungi and M. incognita root knot nematode, which are extremely pathogenic for plants. Application of the AgNPs led to 85% reduction of proliferation of A. flavus, to a 4-fold decrease of hatching of M. incognita plant-parasite juveniles from eggs, and to a 9-fold increase of M. incognita nematode mortality. Conclusions: Biosynthesised AgNPs can be used as an effective fungicide and nematicide for food safety and security and improvement of agricultural production, but further agricultural field trials are required to observe their effect on environment and other factors.

Here, we present an innovative and creative sustainable technique for the fabrication of titania (TiO2) using Acorus calamus (A. calamus) leaf extract as a new biogenic source, as well as a capping and reducing agent. The optical, structural, morphological, surface, and thermal characteristics of biosynthesized nanoparticles were investigated using UV, FTIR, SEM, DLS, BET, and TGA-DSC analysis. The phase formation and presence of nanocrystalline TiO2 were revealed by the XRD pattern. FTIR analysis revealed conjugation, as well as the presence of Ti–O and O–H vibrational bands. The nanoparticles were noticed to be globular, with an average size of 15–40 nm, according to the morphological analysis, and the impact of size quantification was also investigated using DLS. The photocatalytic activity of bare, commercial P-25 and biosynthesized TiO2 (G-TiO2) nanoparticles in aqueous solution of rhodamine B (RhB) dye was investigated under visible light irradiation at different time intervals. The biosynthesized TiO2 nanoparticles exhibited strong photocatalytic activity, degrading 96.59% of the RhB dye. Different kinetic representations were utilized to analyze equilibrium details. The pseudo-first-order reaction was best suited with equilibrium rate constant (K1) and regression coefficients (R2) values 3.72 × 10−4 and 0.99, respectively. The antimicrobial efficacy of the prepared nanoparticles was investigated using the disc diffusion technique. Further, biosynthesized TiO2 showed excellent antimicrobial activity against the selected gram-positive staining (B. subtilis, S. aureus) over gram-negative (P. aeruginosa, E. coli) pathogenic bacteria in comparison to bare TiO2.

In this study, we aimed to observe how different operating parameters influenced the photocatalytic degradation of rhodamine B (RhB, cationic dye) and bromophenol Blue (BPB, anionic dye) over ZnO/CuO under visible light irradiation. This further corroborated the optimization study employing the response surface methodology (RSM) based on central composite design (CCD). The synthesis of the ZnO/CuO nanocomposite was carried out using the co-precipitation method. The synthesized samples were characterized via the XRD, FT-IR, FE-SEM, Raman, and BET techniques. The characterization revealed that the nanostructured ZnO/CuO formulation showed the highest surface area (83.13 m2·g−1). Its surface area was much higher than that of pure ZnO and CuO, thereby inheriting the highest photocatalytic activity. To substantiate this photocatalytic action, the investigative analysis was carried out at room temperature, associating first-order kinetics at a rate constant of 0.0464 min−1 for BPB and 0.07091 min−1 for RhB. We examined and assessed the binary interactions of the catalyst dosage, concentration of dye, and irradiation time. The suggested equation, with a high regression R2 value of 0.99701 for BPB and 0.9977 for RhB, accurately matched the experimental results. Through ANOVA we found that the most relevant individual parameter was the irradiation time, followed by catalyst dose and dye concentration. In a validation experiment, RSM based on CCD was found to be suitable for the optimization of the photocatalytic degradation of BPB and RhB over ZnO/CuO photocatalysts, with 98% degradation efficiency.

In the current study, a variety of sulfonated polyethersulfone (SPES)-based ion-exchange membranes were prepared and utilized as efficient and selective solid adsorbents for the detection of Co(II) ions in aquatic solutions. SPES membranes were treated with a variety of cations at a 2:1 ratio overnight. The produced materials were assessed via XRD, FT-IR, SEM, and TGA analyses. The structure of these materials was confirmed by FT-IR and XRD, which also confirmed the inclusion of Na+, NH4+, and amberlite on the SPES surface successfully. TGA analysis showed that the thermal stabilities of these materials were enhanced, and the order of stability was NH4-SPES > SPES > Na-SPES > A-SPES. Furthermore, the efficiency of these modified membranes for the determination and adsorption of a variety of metal ions was also examined by the ICP-OES analytical technique. A-SPES expressed a powerful efficiency of adsorption, and it showed an efficient as well as quantitative adsorption at pH = 6. Moreover, A-SPES displayed the highest adsorption capacity of 90.13 mg/g for Co(II) through the Langmuir adsorption isotherm.

Water is an essential part of life, however, with continued modernization, it has become a dumping place for many pollutants including dyes. The polluted water can severely affect human health. Polluted water can enter into the human body through different channels, including the food web. Thus, it is very important for human beings and animals to have access to pollution free water. To get the knowledge of the pollutants, in this case, a dye, we need sensitive analytical procedure which could tell the amount of dye in water and also steps to get the pollutant removed from water. In this work, a liquid chromatography–mass spectrometry (LC-MS/MS) based analytical method was developed to determine malachite green. The method was developed after proper optimization of the experimental conditions, where finally, ethanol, a green solvent and formic acid, a food additive was selected to constitute the mobile phase in ratio 1.5:1.0. Different validation parameters were used to authenticate the reliability of the method. Based on the experiment results, the method was found to be linear in the range of 0.1 to 10 mg/L with an excellent correlation coefficient of 0.9995. The corresponding linear regression equation was found to be A = −6863.2 + 105,520 C; where A is the area of the peak and C is the concentration of malachite green. The precision study proves the reproducibility of LC-MS/MS procedure, throughout the precision experiment percent relative standard deviation (% RSD) was found to be between 0.709–1.893%. Similarly, the experiments on the recovery suggest a recovery of 97.28–98.75%. The new method was applied to check the amount of malachite green in environmental samples including the industrial wastewater. The wastewater sample was extracted using the solid phase extraction (SPE) technique, where a new adsorbent—wood apple hydrochar—was synthesized and used as the solid phase for the preparation of a solid phase extraction column to extract the malachite green. The synthesized adsorbent was characterized using different techniques. To conclude, the developed method can be used for determination of malachite green in environmental samples, and the SPE technique using wood apple hydrochar can successfully extract the dye from the water samples.

The physical properties, such as the fibre dimension and crystallinity, of cellulose nanofibre (CNF) are significant to its functional reinforcement ability in composites. This study used supercritical carbon dioxide as a fibre bundle defibrillation pretreatment for the isolation of CNF from bamboo, in order to enhance its physical properties. The isolated CNF was characterised through zeta potential, TEM, XRD, and FT-IR analysis. Commercial CNF was used as a reference to evaluate the effectiveness of the method. The physical, mechanical, thermal, and wettability properties of the bamboo and commercial CNF-reinforced PLA/chitin were also analysed. The TEM and FT-IR results showed the successful isolation of CNF from bamboo using this method, with good colloidal stability shown by the zeta potential results. The properties of the isolated bamboo CNF were similar to the commercial type. However, the fibre diameter distribution and the crystallinity index significantly differed between the bamboo and the commercial CNF. The bamboo CNF had a smaller fibre size and a higher crystallinity index than the commercial CNF. The results from the CNF-reinforced biocomposite showed that the physical, mechanical, thermal, and wettability properties were significantly different due to the variations in their fibre sizes and crystallinity indices. The properties of bamboo CNF biocomposites were significantly better than those of commercial CNF biocomposites. This indicates that the physical properties (fibre size and crystallinity) of an isolated CNF significantly affect its reinforcement ability in biocomposites. The physical properties of isolated CNFs are partly dependent on their source and production method, among other factors. These composites can be used for various industrial applications, including packaging.

Omics have given rise to research on sparsely studied microbial communities such as the landfill, lignocellulolytic microorganisms and enzymes. The bacterial diversity of Municipal Solid Waste sediments was determined using the illumina MiSeq system after DNA extraction and Polymerase chain reactions. Data analysis was used to determine the community’s richness, diversity, and correlation with environmental factors. Physicochemical studies revealed sites with mesophilic and thermophilic temperature ranges and a mixture of acidic and alkaline pH values. Temperature and moisture content showed the highest correlation with the bacteria community. The bacterial analysis of the community DNA revealed 357,030 effective sequences and 1891 operational taxonomic units (OTUs) assigned. Forty phyla were found, with the dominant phyla Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidota, while Aerococcus, Stenotrophomonas, and Sporosarcina were the dominant species. PICRUSt provided insight on community’s metabolic function, which was narrowed down to search for lignocellulolytic enzymes’ function. Cellulase, xylanase, esterase, and peroxidase were gene functions inferred from the data. This article reports on the first phylogenetic analysis of the Pulau Burung landfill bacterial community. These results will help to improve the understanding of organisms dominant in the landfill and the corresponding enzymes that contribute to lignocellulose breakdown.

The adsorption of rhodamine B (RhB) using acid modified banana peels has been examined. Chemical characteristics of the adsorbents were observed in order to determine active functional groups. The major functional groups on the surface were OH, C = O, C = C and C-O-C. Interactions between operational parameters were studied using the central composite design (CCD) of response surface methodology (RSM). The predictions of the model output indicated that operational factors influenced responses at a confidence level of 95% (P

The industrial contamination of marine sediments with mercury, silver, and zinc in Penang, Malaysia was studied with bio-remediation coupled with power generation using membrane less open (aerated) and closed (non-aerated) sediment microbial fuel cells (SMFCs). The prototype for this SMFC is very similar to a natural aquatic environment because it is not stimulated externally and an oxygen sparger is inserted in the cathode chamber to create the aerobic environment in the open SMFC and no oxygen supplied in the closed SMFC. The open and closed SMFCs were showed the maximum voltage generation 300.5 mV (77.75 mW/m2) and 202.7 mV (45.04 (mW/m2), respectively. The cyclic voltammetry showed the oxidation peak in open SMFCs at +1.9 μA and reduction peak at -0.3 μA but in closed SMFCs oxidation and reduction peaks were noted at +1.5 μA and -1.0 μA, respectively. The overall impedance (anode, cathode and solution) of closed SMFCs was higher than open SMFCs. The charge transfer impedance showed that the rates of substrate oxidation and reduction were very low in the closed SMFCs than open SMFCs. The Nyquist arc indicated that O2 act as electron acceptor in the open SMFCs and CO2 in the closed SMFCs. The highest remediation efficiency of toxic metals [Hg (II) ions, Zn (II) ions, and Ag (I) ions] in the open SMFCs were 95.03%, 86.69%, and 83.65% in closed SMFCs were 69.53%, 66.57%, and 65.33%, respectively, observed during 60–80 days. The scanning electron microscope and 16S rRNA analysis showed diverse exoelectrogenic community in the open SMFCs and closed SMFCs. The results demonstrated that open SMFCs could be employed for the power generation and bioremediation of pollutants.

Microbial electrosynthesis is a new approach to converting C1 carbon (CO2) to more complex carbon-based products. In the present study, CO2, a potential greenhouse gas, was used as a sole carbon source and reduced to value-added chemicals (acetate, ethanol) with the help of bioelectrochemical reduction in microbial electrosynthesis systems (MES). The performance of MES was studied with varying electrode materials (carbon felt, stainless steel, and cobalt electrodeposited carbon felt). The MES performance was assessed in terms of acetic acid and ethanol production with the help of gas chromatography (GC). The electrochemical characterization of the system was analyzed with chronoamperometry and cyclic voltammetry. The study revealed that the MES operated with hybrid cobalt electrodeposited carbon felt electrode yielded the highest acetic acid (4.4 g/L) concentration followed by carbon felt/stainless steel (3.7 g/L), plain carbon felt (2.2 g/L), and stainless steel (1.87 g/L). The alcohol concentration was also observed to be highest for the hybrid electrode (carbon felt/stainless steel/cobalt oxide is 0.352 g/L) as compared to the bare electrodes (carbon felt is 0.22 g/L) tested, which was found to be in correspondence with the pH changes in the system. Electrochemical analysis revealed improved electrotrophy in the hybrid electrode, as confirmed by the increased redox current for the hybrid electrode as compared to plain electrodes. Cyclic voltammetry analysis also confirmed the role of the biocatalyst developed on the electrode in CO2 sequestration.

Agglomeration and restacking can reduce graphene oxide (GO) activity in a wide range of applications. Herein, GO was synthesized by a modified Hummer’s method. To minimize restacking and agglomeration, in situ chemical oxidation polymerization was carried out to embed polyaniline (PANI) chains at the edges of GO sheets, to obtain GO-PANI nanocomposite. The GO-PANI was tested for the adsorptive removal of brilliant green (BG) from an aqueous solution through batch mode studies. Infrared (FT-IR) analysis revealed the dominance of hydroxyl and carboxylic functionalities over the GO-PANI surface. Solution pH-dependent BG uptake was observed, with maximum adsorption at pH 7, and attaining equilibrium in 30 min. The adsorption of BG onto GO-PANI was fit to the Langmuir isotherm, and pseudo-second-order kinetic models, with a maximum monolayer adsorption capacity (qm) of 142.8 mg/g. An endothermic adsorption process was observed. Mechanistically, π-π stacking interaction and electrostatic interaction played a critical role during BG adsorption on GO-PANI.

This study investigates the separation of two heavy metals, Cd(II) and Cu(II), from the mixed synthetic feed using a liquid-liquid extraction. The current study uses tri-octyl methylammonium chloride (Aliquat 336) as the extractant (with tributyl phosphate (TBP) as a phase modifier), diluted in toluene, in order to investigate the selective extraction of Cd(II) over Cu(II) ions. We investigate the use of ethylenediaminetetraacetic acid (EDTA) as a masking agent for Cu(II), when added in aqueous feed, for the selective extraction of Cd(II). Five factors that influence the selective extraction of Cd(II) over Cu(II) (the equilibrium pH (pHeq), Aliquat 336 concentration (Aliquat 336), TBP concentration (TBP), EDTA concentration (EDTA), and organic to aqueous ratio (O:A)) were analyzed. Results from a 25–1 fractional factorial design show that Aliquat 336 significantly influenced Cd(II) extraction, whereas EDTA was statistically significant for the antagonistic effect on the E% of Cu(II) in the same system. Moreover, results from optimization experiment showed that the optimum conditions are Aliquat 336 concentration of 99.64 mM and EDTA concentration of 48.86 mM—where 95.89% of Cd(II) was extracted with the least extracted Cu(II) of 0.59%. A second-order model was fitted for optimization of Cd(II) extraction with a R2 value of 0.998, and ANOVA results revealed that the model adequately fitted the data at a 5% significance level. Interaction between Aliquat 336 and Cd(II) has been proven via FTIR qualitative analysis, whereas the addition of TBP does not affect the extraction mechanism.

Benthic microbial fuel cells (BMFCs) are a kind of microbial fuel cell (MFC), distinguished by the absence of a membrane. BMFCs are an ecofriendly technology with a prominent role in renewable energy harvesting and the bioremediation of organic pollutants through electrogens. Electrogens act as catalysts to increase the rate of reaction in the anodic chamber, acting in electrons transfer to the cathode. This electron transfer towards the anode can either be direct or indirect using exoelectrogens by oxidizing organic matter. The performance of a BMFC also varies with the types of substrates used, which may be sugar molasses, sucrose, rice paddy, etc. This review presents insights into the use of BMFCs for the bioremediation of pollutants and for renewable energy production via different electron pathways.

Four strains of bioflocculant-producing bacteria were isolated from a palm oil mill effluent (POME). The four bacterial strains were identified as Pseudomonas alcaliphila (B1), Pseudomonas oleovorans (B2), Pseudomonas chengduensis (B3), and Bacillus nitratireducens (B4) by molecular identification. Among the four bacterial strains, Bacillus nitratireducens (B4) achieved the highest flocculating activity (49.15%) towards kaolin clay suspension after eight hours of cultivation time and was selected for further studies. The optimum conditions for Eriochrome Black T (EBT) flocculation regarding initial pH, type of cation, and B4 dosage were determined to be pH 2, Ca2⁺ cations, and a dosage of 250 mL/L of nutrient broth containing B4. Under these conditions, above 90% of EBT dye removal was attained. Fourier transform infrared spectroscopic (FT-IR) analysis of the bioflocculant revealed the presence of hydroxyl, alkyl, carboxyl, and amino groups. This bioflocculant was demonstrated to possess a good flocculating activity, being a promissory, low-cost, harmless, and environmentally friendly alternative for the treatment of effluents contaminated with dyes.

A wide variety of pollutants are discharged into water bodies like lakes, rivers, canal, etc. due to the growing world population, industrial development, depletion of water resources, improper disposal of agricultural and native wastes. Water pollution is becoming a severe problem for the whole world from small villages to big cities. The toxic metals and organic dyes pollutants are considered as significant contaminants that cause severe hazards to human beings and aquatic life. The microbial fuel cell (MFC) is the most promising, eco-friendly, and emerging technique. In this technique, microorganisms play an important role in bioremediation of water pollutants simultaneously generating an electric current. In this review, a new approach based on microbial fuel cells for bioremediation of organic dyes and toxic metals has been summarized. This technique offers an alternative with great potential in the field of wastewater treatment. Finally, their applications are discussed to explore the research gaps for future research direction. From a literature survey of more than 170 recent papers, it is evident that MFCs have demonstrated outstanding removal capabilities for various pollutants.

A novel method of preparing reduced graphene oxide (RGOX) from graphene oxide (GOX) was developed employing vegetable extract, Chenopodium album, as a reducing and stabilizing agent. Chenopodium album is a green leafy vegetable with a low shelf life, fresh leaves of this vegetable are encouraged to be used due to high water content. The previously modified ‘Hummers method’ has been in practice for the preparation of GOX by using precursor graphite powder. In this study, green synthesis of RGOX was functionally verified by employing FTIR and UV-visible spectroscopy, along with SEM and TEM. Our results demonstrated typical morphology of RGOX stacked in layers that appeared as silky, transparent, and rippled. The antibacterial activity was shown by analyzing minimal inhibitory concentration values, agar diffusion assay, fluorescence techniques. It showed enhanced antibacterial activity against Gram-positive and Gram-negative bacteria in comparison to GOX. It has also been shown that the synthesized compound exhibited enhanced antibiofilm activity as compared to its parent compound. The efficacy of RGOX and GOX has been demonstrated on a human breast cancer cell line, which suggested RGOX as a potential anticancer agent.

The recycling and treatment of wastewater using microbial fuel cells (MFCs) has been attracting significant attention as a way to control energy crises and water pollution simultaneously. Despite all efforts, MFCs are unable to produce high energy or efficiently treat pollutants due to several issues, one being the anode’s material. The anode is one of the most important parts of an MFC. Recently, different types of anode materials have been developed to improve the removal rate of pollutants and the efficiency of energy production. In MFCs, carbon-based materials have been employed as the most commonly preferred anode material. An extensive range of potentials are presently available for use in the fabrication of anode materials and can considerably minimize the current challenges, such as the need for high quality materials and their costs. The fabrication of an anode using biomass waste is an ideal approach to address the present issues and increase the working efficiency of MFCs. Furthermore, the current challenges and future perspectives of anode materials are briefly discussed.

Herein, commercially available Dowex 5WX8, a cation exchange polymeric resin, was modified through solvent impregnation with t-butyl phosphate (TBP) to produce a solvent impregnated resin (SIR), which was tested for the removal of rhodamine B (RhB) from water in batch adsorption experiments. The effect of SIR dosage, contact time, and pH on RhB adsorption was studied and optimized by response surface methodology (RSM), interaction, Pareto, and surface plots. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were respectively used for characterizing SIR surface morphology and identifying active binding sites before and after RhB adsorption. SEM showed that the pristine SIR surface was covered with irregular size and shape spots with some pores, while RhB saturated SIR surface was non-porous. FTIR revealed the involvement of electrostatic and π−π interactions during RhB adsorption on SIR. Dosage of SIR, contact time, and their interaction significantly affected RhB adsorption on SIR, while pH and its interaction with dosage and contact time did not. The optimum identified experimental conditions were 0.16 g of SIR dose and 27.66 min of contact time, which allowed for 98.45% color removal. Moreover, RhB adsorption equilibrium results fitted the Langmuir isotherm with a maximum monolayer capacity (qmax) of 43.47 mg/g.

Batch desorption experiments of methylene blue (MB) dye from a clay adsorbent coating were carried out to evaluate the maximum desorption conditions. Combination of thermal and chemical regeneration techniques were used for the desorption process. The desorption of MB was found to be 70% using an HCl solvent after heating adsorbent coating at 160 °C. The optimization study was carried out to identity the optimum desorption conditions using MINITAB 14 software. The individual and interaction effects of three factors, temperature, dye concentration and contact time for desorption of dye were determine by applying response surface methodology (RSM). The optimization results showed that all three factors have main effects whereas the interaction of concentration−time is significant as compared to other interactions. The findings exhibit a maximum desorption efficiency 23 mg/g at 60 °C for 100 mg/L of dye and 150 min of contact time.