Environment-friendly Approach Research Articles

Surface-mediated periodate activation by nano zero-valent iron for the enhanced abatement of organic contaminants

Periodate (PI)-based advanced oxidation processes have recently received increasing attentions. Herein, PI was readily activated by nano zero-valent iron (nZVI) and subsequently led to the enhanced oxidation of organic contaminants, with the removal performance of sulfadiazine (SDZ) in the nZVI/PI process even higher than that in the nZVI/peroxydisulfate process under identical conditions. Kinetic experiments indicated that the decay of SDZ was susceptible to the dosage of nZVI and PI, but was barely affected by pH values (4.0–7.0) under buffered conditions, suggesting the promising performance of the nZVI/PI process in a relatively wide pH range. Selective degradation of contaminants and 18O-isotope labeling assays collectively demonstrated that iodate radical (•IO3), high-valent iron-oxo species (Fe(IV)) and hydroxyl radical (•OH) were responsible for the abatement of organic contaminants. More importantly, due to the relatively weak steric hindrance effect of PI, PI easily adsorbed on the surface of nZVI and no iron leaching was detected throughout the reaction, implying that PI activation induced by nZVI was a surface-mediated process. Besides, PI was not transformed into harmful reactive iodine species. This study proposed an environmental-friendly approach for PI activation and shed new lights on the PI-based processes.

Integrating high-efficiency oxygen evolution catalysts featuring accelerated surface reconstruction from waste printed circuit boards via a boriding recycling strategy

Converting electronic wastes into high-efficiency energy conversion catalysts is a win-win strategy in addressing the metal resources shortage and sustainable energy challenges. Herein, a facile boriding strategy is developed to directly convert the leachates of waste printed circuit boards into magnetic mixed metal borides (FeNiCuSnBs) for oxygen evolution reaction (OER) catalysts. Via the boriding process, a metal cation recovery rate of 99.78 %, 99.98 %, 99.96 %, and 99.49 % has been attained for Fe, Ni, Cu, and Sn, respectively. The obtained catalysts with a higher ratio of Ni and Fe show better OER performance. The optimal FNCSB-4 attains 10 mA cm−2 at a low overpotential of 199 mV, as well as good stability in alkaline solution. Remarkably, FNCSB-4 represents a record‐high activity among waste-derived OER electrocatalysts. In-depth study suggests that the superior OER performance is mainly owing to accelerated surface self-reconstruction by B/Sn co-etching under OER potential region, and the newly formed multimetal (oxy)hydroxides act as the active species for OER. Additionally, the efficient mass/charge transfer, the amorphous feature, and hierarchical structure also benefit OER. Apart from providing an insight into the correlation between surface self-reconstruction and OER activity of multimetal boride-based catalysts, this study also offers a general strategy for the high-efficiency recovery and advanced energy-driven applications of critical metals from other urban mines in a sustainable and environment-friendly approach.

Designing of Energy-efficient Vehicle on Existing Challenges of Electric Vehicle, a Cost Effective and Environment-friendly Approach

An electric vehicle has an electric drive motor which is coupled to drive train for converting the rotational movement of the motor into linear motion of the vehicle and an energy storage device to provide power for the motor uses. Present invention takes advantage of the powerful wind force generated by the vehicle motion. Wind driven turbine of particular design is mounted to rotate the wind energy capturing device upon or in the upper portion of the roof and other is installed under the bonnet area of an electric vehicle to transform wind energy into electrical energy for feeding such energy into the battery pack as the vehicle is being driven forward. At least six wind energy capturing devices are coupled for generating a fast electric potential for recharging the power source. Said wind energy capturing devices would be mounted on particular designed housing and suitable clamps. The motive power of the air rotates the wind-turbines, which are rotatably engaged with an armature shaft to produce electrical energy that is used to continuously recharge the batteries in all phases of road travel, that power the vehicle. Thereby driving range is extended of the vehicle between external charging cycles and reduces time required for that. The design is also prioritized Energy-efficiency and cost-effectiveness of electric vehicles. It also becomes an approach to more environment-friendly rather than the conventional vehicles.

Acceleration of polychlorinated biphenyls remediation in soil via sewage sludge amendment

Bioremediation of polychlorinated biphenyls (PCBs) is impeded by difficulties in massively cultivating bioinoculant. Meanwhile, sewage sludge is rich in pollutant-degrading microorganisms and nutrients, drawing our attention to investigate their potential to be used as a supplement for bioremediation of PCBs. Here we reported extensive microbial reductive dechlorination of PCBs by waste activated sludge (WAS) and digestion sludge (DS), which were identified to harbor multiple putative organohalide-respiring bacteria (i.e., Dehalococcoides, Dehalogenimonas, Dehalobacter, and uncultivated Dehalococcoidia) and PCB reductive dehalogenase genes (i.e., pcbA4 and pcbA5). Consequently, amendment of 1–20% (w/w) fresh WAS/DS enhanced the attenuation of PCBs by 126–544% in a soil microcosm compared with the control soil, with the fastest dechlorination of PCBs being achieved when spiked with 20% fresh WAS. Notably, dechlorination pathways of PCBs were also changed by sludge amendment. Microbial and physicochemical analyses revealed that the enhanced dechlorination of PCBs by sludge amendment was largely attributed to the synergistic effects of sludge-derived nutrients, PCB-dechlorinating bacteria, and stimulated growth of beneficial microorganisms (e.g., fermenters). Finally, risk assessment of heavy metals suggests low potential ecological risks of sludge amendment in soil. Collectively, our study demonstrates that sewage sludge amendment could be an efficient, cost-effective and environment-friendly approach for in situ bioremediation of PCBs.

Structured aluminium surfaces with tunable wettability fabricated by a green approach

In present article, we have fabricated micro/nano hierarchical structured aluminium surfaces with a vivid range of wettability and controllable adhesion using a facile and environment-friendly approach. The micropatterned surfaces show hydrophobicity with high adhesion due to impregnated wetting state, analogous to rose petal effect. Interestingly, the micro/nano hierarchical structured surfaces become superhydrophilic due to formation of aluminium oxide and hydroxide nanoflakes. After fluorination, these surfaces become superhydrophobic with a very low contact angle hysteresis. They also exhibit a very high chemical and thermal stability along with excellent self-cleaning capability.

Water quality assessment of East Kolkata Wetland with a special focus on bioremediation by nitrifying bacteria.

East Kolkata Wetlands (EKW) is designated as International Ramsar site and are the hotspot for large-scale wastewater aquaculture practices. However, the continued surveillance of physicochemical properties of water and application of an eco-friendly approach are essential to ensure safe aquaculture practices. In the present study, we assessed the seasonal variation in physicochemical parameters of water across EKW and investigated the role of nitrifying bacteria as probiotics. We statistically analyzed various physicochemical properties of water samples from EKW. Results of the statistical analysis indicated a significant variation in all the physicochemical parameters across the selected water bodies of EKW (p < 0.01). We isolated and enumerated Nitrosomonas sp. and Nitrobacter sp. and assessed their ability to degrade trichloroethylene (TCE). The role of Nitrosomonas sp. and Nitrobacter sp. were further investigated and established through a small-scale experiment. Two microbial isolates, NSW3 and NBW2, displayed superior TCE degradation ability at pH 5, and the application of these strains as probiotics were found to improve the quality of water and survival rate of fishes in the treated experimental tanks. Our findings suggest that the application of the above mixed bacterial cultures in aquaculture could be an effective and environment-friendly approach for safe and productive aquaculture operations.

Bi-atom active sites embedded in a two-dimensional covalent organic framework for efficient nitrogen reduction reaction

An economical and environment-friendly approach for N2 reduction reaction (NRR) under mild conditions is currently urgent. The development of single-atom catalysts (SACs) offers a new strategy for reaching this goal. However, the single active site of SAC makes limitation for achieving high NRR performance. The synergetic reaction centers in bi-atom catalysts (BACs) are proposed to further boost reaction activity. On the basis of a newly-synthesized two-dimensional (2D) binuclear Cu-salphen covalent organic framework (COF), we predict four promising BACs for NRR with transition metal (TM) atoms (TM = Fe, Co, Mo, W and Ru) embedded in this COF. The low limiting potentials (-0.29 to -0.57 V) and high theoretical Faradaic efficiency (FE) (76–100%) of these BACs can be correlated to the asymmetrical charge depletion of metal dimers and the synergistic effect between the metal atoms and the 2D COF. The thermal stability and realistic feasibility of M1M2-COFs were also assessed. Our work offers a group of promising candidates of ultra-efficient COF-based NRR BACs, as well as a rational guidance for catalyst design.

Inhibitory effects and mechanisms of low-molecular-mass organic acids (LMMOAs) toward Cr(III) oxidation

Photo-reduction of Cr(VI) into Cr(III) has been extensively studied for the alleviation of Cr(VI) hazards. However, knowledge in regard to the Cr(III) oxidation back into Cr(VI), which serves an equally important role in controlling Cr pollution, is limited. To this end, inhibitory effects and related mechanisms of low-molecular-mass organic acids (LMMOAs), including citric acid, oxalic acid and acetic acid, toward Cr(III) oxidation in the presence of Fe(III) under UV-irradiation were determined in this study. Results showed that the most prominent Cr(III) oxidation (~4 μM out of 300 μM Cr(III)) occurred at pH 3.0 in the presence of 400 μM Fe(III) and 12 h of UV-irradiation, yet such Cr(III) oxidation could be entirely or partially suppressed upon the addition of LMMOAs. Both citric and oxalic acids triggered a nearly complete inhibition of Cr(III) oxidation, even with the lowest dosage of 50 μM, ascribed to promoted generation of Fe(II) that scavenged OH• radicals. Regarding acetic acid, the addition of 50 μM only yielded 75% inhibitory efficiency, and further decreased to 50% as its amount increased to 400 μM. In contrast with citric/oxalic acids, acetic acid tended not to complex with Fe(III). While such free acetic acid reacted with OH• radicals generated from photolysis of Fe(OH)2+, additional OH• radicals were produced. Furthermore, the Fe(II) generation in the acetic acid system was about 28–35% of that in the citric/oxalic acid systems. In the case of supplementary OH• radicals and insufficient Fe(II), less OH• radicals could be consumed, and thereby the amendment of acetic acid showed a relatively weak inhibitory effect toward Cr(III) oxidation. This study evidenced that all three LMMOAs are effective toward the inhibition of Cr(III) oxidation in the presence of Fe(III). This feasible, practical, and environmental friendly approach is promising to prevent the secondary pollution caused by Cr(III) oxidation.

Cytotoxic effects of the synthesized Citrus aurantium peels extract nanoparticles against MDA-MB-231 breast cancer cells

Currently, nanoparticle is at fastest pace due to the enhanced implication in drug delivery system. The synthesis of chitosan nanoparticles through ionic gelation methods is becoming increasingly relevant due to the low cost involved and environment-friendly approach. In this study, cytotoxic effect of chitosan-Citrus aurantium peels extract nanoparticles (NPs-CA) against MDA-MB-231 breast cancer cells was investigated. The initial confirmations of NPs-CA were using Particles size analysis (PSA), which showed the size of NPs-CA. The Zeta potential was measured to check the stability of NPs-CA. The cytotoxic effect was carried out in MDA-MB-231 breast cancer cells under MTT assay. Based on PSA analysis, the size of F1 and F2 were ranging between 372 – 4472 nm and 94 – 373 nm, respectively. The zeta potential mean value of F2 NPs-CA 34,9 mV, it can be concluded that the particles show less chances for agglomeration. On the various test concentration, the F2 NPs-CA performed better cytotoxic effects than Citrus aurantium peels extract with IC50 value of 83 μg/mL and 320 μg/mL, respectively. These findings pose a positive impact to expand further studies in the development of nanoparticle to cancer therapy.

Antifouling membranes employing a 2D planar nanobiocatalyst of crosslinked glucose oxidase aggregates wrapping extra-large graphene oxide

This paper presents highly effective antimicrobial surfaces employing a 2D structured nanobiocatalyst composed of graphene oxide (GO) and glucose oxidase (GOD). Enzyme molecules are immobilized onto extra-large GO pieces with a plane dimension of approximately 100 μm via an enzyme adsorption, precipitation, and crosslinking (EAPC) approach. This enables the effective wrapping of extra-large GO pieces by a matrix of crosslinked enzyme aggregates, which improves the enzyme loading. Consequently, the measured GOD activities of the EAPC sample via 50% (w/v) ammonium sulfate precipitation are 4,940 and 3,820 times higher than those of the control samples, i.e, the enzyme adsorption (EA) and enzyme adsorption/crosslinking (EAC) samples, respectively. The preservation of the planar GO geometry with an extra-large surface also allows the effective binding of EAPC onto a commercial membrane filter via a polydopamine coating, thus yielding a biocatalytic EAPC membrane. Compared to the commercial membrane with no bound EAPC, the in situ generation of H2O2via the EAPC-catalyzed oxidation of glucose on the membrane surface demonstrated enhanced filterability against a mixed bacterial population of activated sludge obtained from a municipal sewage plant as well as two model bacteria: gram-negative Pseudomonas aeruginosa and gram-positive Staphylococcus aureus. The bacterial decontamination of the EAPC-bound membrane surface can also be activated on demand by simply adding glucose to the bulk solution. This newly proposed mechanism of antifouling surfaces employing a localized nanobiocatalytic conversion of nontoxic glucose to bactericidal H2O2 can provide insights for biofouling control via a highly effective and environment-friendly approach.

Genome-Wide Association Analysis and Genomic Prediction for Adult-Plant Resistance to Septoria Tritici Blotch and Powdery Mildew in Winter Wheat.

Septoria tritici blotch (STB) caused by the fungal pathogen Zymoseptoria tritici and powdery mildew (PM) caused by Blumeria graminis f.sp tritici (Bgt) are among the forefront foliar diseases of wheat that lead to a significant loss of grain yield and quality. Resistance breeding aimed at developing varieties with inherent resistance to STB and PM diseases has been the most sustainable and environment-friendly approach. In this study, 175 winter wheat landraces and historical cultivars originated from the Nordic region were evaluated for adult-plant resistance (APR) to STB and PM in Denmark, Estonia, Lithuania, and Sweden. Genome-wide association study (GWAS) and genomic prediction (GP) were performed based on the adult-plant response to STB and PM in field conditions using 7,401 single-nucleotide polymorphism (SNP) markers generated by 20K SNP chip. Genotype-by-environment interaction was significant for both disease scores. GWAS detected stable and environment-specific quantitative trait locis (QTLs) on chromosomes 1A, 1B, 1D, 2B, 3B, 4A, 5A, 6A, and 6B for STB and 2A, 2D, 3A, 4B, 5A, 6B, 7A, and 7B for PM adult-plant disease resistance. GP accuracy was improved when assisted with QTL from GWAS as a fixed effect. The GWAS-assisted GP accuracy ranged within 0.53–0.75 and 0.36–0.83 for STB and PM, respectively, across the tested environments. This study highlights that landraces and historical cultivars are a valuable source of APR to STB and PM. Such germplasm could be used to identify and introgress novel resistance genes to modern breeding lines.

Functionalization of boron nitride nanosheets via thiol terminated polyethyleneimine to enhance aqueous dispersibility and efficiency as carriers for essential oils and pesticides

The development of an efficient and environmental-friendly approach for the functionalization of boron nitride nanosheets (BNNSs) with response to pathogen microenvironment (i.e., reductive environment) is a critical issue pertaining to nanocarriers in the agricultural field. Herein, a strategy for BNNS functionalization was designed via thiol terminated polyethyleneimine (PEI-SH) linked with biocompatible poly(ethylene glycol) diacrylate (PEG), while simultaneously introducing disulfide bonds through thiol oxidation. The incorporation of hydrophilic polymer chains promoted aqueous dispersibility of BNNS at high concentrations of 30 mg mL−1. The attached hydrophilic chains could detach from BNNS in reducing environment ascribed to disulfide bond cleavage. Such features promote BNNS-PEI-PEG as an efficient and safe carrier with very low cytotoxicity for controlled release by redox stimuli. The presence of abundant positive charges on BNNS-PEI-PEG surface was found to favor the loading capacity of pesticides and essential oils with value of 338 and 389 mg g−1, respectively, while enhancing lipid foliar wettability with a reduced contact angle of 35.7 ± 1.9°. Furthermore, the antibacterial activity of essential oils was determined based on inhibition of volatilization by BNNS-PEI-PEG, with larger initial inhibition zone diameter against Escherichia coli and only reducing 34.4% after placing for 12 days. Our system provides an aqueous dispersible and controllable platform response to redox stimuli to load and release pesticides and essential oils in the field of agriculture.

A floating solar still inspired by continuous root water intake

Floating solar still is considered as a land-saving, easy-operating and environmental-friendly approach for freshwater production. However, the low yield and work instability in actual weather conditions limits its application. To overcome these disadvantages, a bionic floating solar still inspired by water intake of plant roots was presented in this paper. The channels for water supply were distributed in array and wrapped in a whole thermal insulation sheet. With the design of simulating roots, the present desalination system achieves low heat losses, water-absorbing uniformity and structural stability. Cellulose fabric and glass were separately selected as evaporation and condensation materials of the experimental prototype after preliminary test. The outdoor experiment was conducted in Xingtai, China, and the accumulated radiation in the test day was 21.96 MJ/m2. The maximum evaporation temperature and daily freshwater yield reached 59.2 °C and 1.5 kg/m2/d, respectively, which were the highest in comparison with existing floating solar stills. Next, the effect of rolling motion on humid air flow inside the still was investigated by CFD simulation. The results of this study will contribute to the further development of floating solar still, as well as the application of such small-scale desalination technologies.

A COMPREHENSIVE REVIEW ON EVALUATION OF ENVIRONMENTAL FRIENDLY MACHINABILITY, CUTTING FLUIDS AND TECHNIQUES IN METAL CUTTING OPERATION

Todays, due to the environmental concerns, growing contamination and pollution regulations, the demand for renewable and biodegradable cutting fluids is increasing day by day. Environmental friendly machining is one of the latest approach which is economical and also eco-friendly that improve the machinability. Different types of environmental friendly machining techniques are available e.g. MQL machining, cryogenic machining, dry machining and high pressure cooling approach. In this article, an attempt is made regarding environmental friendly machining processing, including different types of cutting fluids and machining techniques. The Knowledge of cutting fluid and its processing conditions is of critically importance to maximize the efficiency of cutting fluids in any machining process. In general, the generation of heat in the cutting zone due to friction at the tool-chip interface and the friction between the safety surface of the tool and the work piece is always the deciding factor on the quality of the work piece surface. In any manufacturing industries or company two factors play important role in machinability and productivity e.g. surface quality and tool wear. The main objective of this review article that analysis the different environmental friendly machining techniques and encourages the cooling approach in metal cutting operation. So finally, after the literature survey found that environmental friendly machining approach is cost effective machining process and also eco-friendly machining process.

Landscape composition mediates suppression of major pests by natural enemies in conventional cruciferous vegetables

BackgroundConservation biological control provides an environment-friendly approach to improve the efficacy of natural enemies. Although numerous studies have demonstrated the potential of semi-natural habitats in promoting biological control in organic or unsprayed agroecosystems, few studies were conducted in conventional agricultural fields. In this study, we investigated the effects of landscape composition on the major pests of cruciferous vegetables and on the assemblages of their natural enemies in southeastern China. ResultsHabitat diversity, particularly increasing grassland proportion in the landscape, had a positive impact in controlling both small-sized pests (aphids, leaf miners, thrips and flea beetles) and Plutella xylostella. This increasing proportion also promoted greater abundance and diversity of canopy-dwelling predators, more forests supported a higher diversity of airborne enemies (parasitoids and canopy-dwelling predators) as well as a higher abundance of ground-dwelling predators. A general increase in habitat diversity was beneficial to parasitoids and ground-dwelling predators. Additionally, the proportion of forest, grassland, and non-cruciferous vegetable area, as well as habitat diversity, affected the compositions of natural enemy communities. Moreover, inconsistent effects of non-cruciferous and grassland habitats were found between sampling locations for small-sized pests and canopy-dwelling predators. Moreover, the scale at which pests' and natural enemies’ abundance and richness responded most to landscape composition varied with their feeding range and dispersal ability. ConclusionOur study provides evidence that increasing the amount of semi-natural habitats and habitat diversity can result in lower pest and higher natural enemy abundance in conventional cruciferous agroecosystems. Regional conditions and spatial scales also should be considered in designing the agricultural landscape mosaic.

Purification of Wickerhamomyces anomalus Keratinase and Its Prospective Application in Poultry Feed Industries

Animal wastes emanating from cow horns, hooves and feathers are keratinous in nature which can only be degraded by keratinolytic microorganisms. Consequently, the pollution resulting from the accumulation of these wastes in response to growing livestock demand is posing a significant threat to human health and the environment. This study was carried out using cow hooves as the substrate for the production of keratinase from fungal identified as Wickerhamomyces anomalus 9 (18S rDNA gene sequencing) was isolated from soil rich hooves using basal salt agar medium and potato dextrose agar. The keratinase of the isolate was assessed using skim milk agar and the enzyme was produced by solid-state fermentation. The crude enzyme was purified using ammonium sulphate precipitation, ion exchange and gel-filtration chromatography. The specific activity of the enzyme was 0.29 U/mg with a yield of 45% and a 7.25 purification fold. The optimal pH and temperature of the enzyme were 8.0 and 60 oC respectively. The enzyme was observed to be thermo-stable at 50oC between for 30 minutes. The kinetics revealed that the Vmax was 0.384U/min with Km 86.95mg/ml. The native molecular weight of the enzyme was found to be 34KDa. There were significant differences at 95% confidence with poultry feed treated with Wickerhamomyces anomalus keratinase in moisture, ash content, crude fibre, crude fat, nitrogen content, crude protein and carbohydrate compare to the untreated feed. These results suggest an environment-friendly approach for biodegradation of cow hooves wastes for the production of keratinases, animal waste management as well as a promising tool for chicken feed additives. Keywords: Biodegradation, Chromatography, Cow hooves, Keratinase, Pollution

Role of environmental friendly machining on machinability

The present for supporting in market any industries need to bring the balance among ecological, social viewpoints and efficient. Environmental friendly machining e.g. high pressure cooling, MQL machining, cryogenic machining, dry machining is one of the latest approach which is economical and also eco-friendly that improve machinability. In present article main focus on understanding of environmental friendly machining techniques and investigate various experiences from the past writing which can help the better appropriation of ecological friendly machining approach. For study and examination of environmental friendly machining approach, roughly 100 papers are chosen. They chose articles are ordered dependent on climate of machining, year, diaries, distributor, and ecological friendly machining approach measurements. After the literature survey it was observed that in metal cutting operation heat are generated in the cutting zone due to tool chip interface so quality of surface finish are poor and tool wear. In any manufacturing industries two factors play important role in term of quality e.g. surface roughness and tool wear so in this situation some techniques are need which is environmental friendly and also improve machinability. So finally, it was observed that environmental friendly machining techniques are cost effective and eco-friendly machining compared to other convention machining approach. The main motives of this paper that studies and encourage environmental friendly machining approach.

Room-temperature synthesis of various allotropes of carbon nanostructures (graphene, graphene polyhedra, carbon nanotubes and nano-onions, n-diamond nanocrystals) with aid of ultrasonic shock using ethanol and potassium hydroxide

The exploration of the synthesis methods of sp2 and sp3 carbon nanomaterials under ambient conditions is very meaningful towards their industrial applications. The existing bottom-up synthesis methods usually need high temperature or high pressure conditions. We report a facile and environmentally-friendly approach enabling the synthesis of almost all types of known carbon nanostructures at room temperature and under atmosphere pressure. They include both sp3-structured n-diamond (not cubic diamond) nanocrystals and sp2-structured graphene, defective multiwalled carbon nanotubes, defective carbon nano-onions as well as graphene polyhedra. The reaction of ethanol and potassium hydroxide at ambient conditions yields n-diamond nanocrystals. To synthesize the sp2 carbon nanomaterials, the assistance of the ultrasonic shock at the early stage of crystallization is necessary to ensure the formation of the carbon ring nucleation seeds. The synthetic yields of n-diamond nanocrystals, graphene polyhedra, defective carbon nano-onions, and graphene are estimated to be 0.37%, 0.30%, 0.04%, and 0.01% (carbon mass ratio), respectively, and all of them have good crystallinity. These results improve our understanding of the low-temperature crystal growth process of the carbon nanostructures.

Au/Ag nanoparticles-decorated TiO2 with enhanced catalytic activity for nitroarenes reduction

A straightforward and environmentally-friendly approach for the fabrication of TiO2 supported nano-Au and Ag catalysts with enhanced activity in nitroarenes reduction is presented. The immobilization of the metal nanoparticles (NPs) onto TiO2 was performed through a first step of metal precursors adsorption (tetrachloroauric(III) acid trihydrate or silver(I) nitrate) onto TiO2, followed by a step of in situ metal cations reduction using three types of reducing agents: citric acid, NaBH4 and simulated sunlight irradiation. The type of reducing agent influenced the size, the oxidation state and loading of the grafted metal NPs. The Au-based nanocomposites contained Au NPs with sizes ranging between 19.3 and 28.2 nm and Au loadings in the range of 7.2–19.8 wt%. NaBH4 was the best reducing agent for the Au NPs immobilization onto TiO2, leading to the highest Au loading (19.8 wt%) and lowest Au+/Au0 ratio (0.07). In the case of the Ag-based materials, citric acid revealed to be the best reducing agent for the Ag NPs immobilization onto TiO2, leading to ultrasmall grafted NPs, 10.1 wt% Ag loading and the highest amount of metallic silver (Ag+/Ag0 ratio = 0.03).The catalytic performance of the Au/Ag-based TiO2 nanocomposites was evaluated in the reduction of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA) in aqueous medium, at room temperature, using NaBH4 as reducing agent (substrate:reducing agent:catalyst weight ratio = 0.007:1.89:1). The Au- and Ag-based nanocomposites (prepared with NaBH4 and citric acid, respectively) led to 100% conversion of 4-NP within 260 and 40 s, respectively, with rate constants (k) of 19.1 × 10−3 and 94.2 × 10−3 s−1 (pseudo-first-order kinetics), respectively, demonstrating the higher performance of the Ag-based catalyst. In contrast, in the case of the 4-NA reduction, the highest catalytic performance was achieved for the Au-based material, promoting the total substrate conversion within 90 s (k = 29.4 ×10−3 s−1), while for the Ag-based catalyst the total 4-NA conversion was achieved within 120 s (k = 16.6 ×10−3 and 27.5 ×10−3 s−1). Both catalysts were reused in nine consecutive cycles in both 4-NP and 4-NA reduction, with the Au-based material presenting higher stability, especially for 4-NA reduction, with only a small reaction time increment.

Green molten salt modification of cobalt oxide for lithium ion battery anode application

The clean and low-cost preparation of advanced materials for green energy storage applications is a critical step towards sustainable development. Here, the rapid modification of CoO in molten salt is proposed as a low-cost approach for the scalable preparation of Co-based oxides with enhanced Li-storage performance. The phase evolution of CoO upon molten salt treatment is investigated by X-ray diffraction (XRD), electron microscopy, N2 adsorption–desorption and Raman spectroscopy. The molten salt treatment of CoO under dry and humid Ar atmosphere leads to the formation of dual-phase structured CoO/Co3O4 and Li0.065Co0.935O, respectively. High resolution transmission electron microscopy and fast Fourier transform analysis of samples after Li insertion and extraction process confirm the formation of nanostructured Co-Li2O. The Co phase formed from CoO/Co3O4 and Li0.065Co0.935O is found to have hexagonal close packed (hcp) and face central cubic (fcc) structure, respectively. The Li-storage performances of these materials are correlated to their structural/microstructural characteristics. This article presents a simple, scalable and environmentally-friendly approach for modification of Co-oxide materials for lithium ion battery anode applications.