Metformin-modified polyethersulfone magnetic microbeads for effective arsenic removal from apatite soil leachate water.

Arsenic is the hazardous species and still is the global challenge in water treatment. Apatite soil is highly rich in arsenic species, and its mining presents various environmental issues. In this study, novel magnetic microbeads as adsorbent were developed for the elimination of hazardous arsenic ions from apatite soil's aqueous leachate before discharging into environment. The microbeads were fabricated with metformin polyether sulfone after being doped with zero-valent iron (Met-PES/ZVI). The microbeads were characterized using various techniques, including FTIR, XRD, SEM-EDX, VSM, and zeta potential analysis. The developed adsorbent demonstrated a significant elimination in arsenic in aqueous leachate, achieving 82.39% removal after 30 min of contact time, which further increased to 90% after 180 min of shaking. The kinetic analysis revealed that the pseudo-second-order model best represented the adsorption process. The intra-particle diffusion model indicated that the adsorption occurred in two steps. The Langmuir model (R2 = 0.991), with a maximum adsorption capacity of 188.679 mg g-1, was discovered to be the best fit for the experimental data as compared Freundlich model (R2 = 0.981). According to the thermodynamic outcome (ΔG < -20 kJ/mol), the adsorption process was spontaneous and involved physisorption. These findings demonstrate the potential of magnetic Met-PES/ZVI microbeads as an efficient adsorbent for the removal of arsenic from apatite soil aqueous leachate.

Harnessing artificial intelligence-driven approach for enhanced indole-3-acetic acid from the newly isolated Streptomyces rutgersensis AW08.

Indole-3-acetic acid (IAA) derived from Actinobacteria fermentations on agro-wastes constitutes a safer and low-cost alternative to synthetic IAA. This study aims to select a high IAA-producing Streptomyces-like strain isolated from Lake Oubeira sediments (El Kala, Algeria) for further investigations (i.e., 16S rRNA gene barcoding and process optimization). Subsequently, artificial intelligence-based approaches were employed to maximize IAA bioproduction on spent coffee grounds as high-value-added feedstock. The specificity was the novel application of the Limited-Memory Broyden-Fletcher-Goldfarb-Shanno Box (L-BFGS-B) optimization algorithm. The new strain AW08 was a significant producer of IAA (26.116 ± 0.61 µg/mL) and was identified as Streptomyces rutgersensis by 16S rRNA gene barcoding and phylogenetic inquiry. The empirical data involved the inoculation of AW08 in various cultural conditions according to a four-factor Box Behnken Design matrix (BBD) of Response surface methodology (RSM). The input parameters and regression equation extracted from the RSM-BBD were the basis for implementing and training the L-BFGS-B algorithm. Upon training the model, the optimal conditions suggested by the BBD and L-BFGS-B algorithm were, respectively, L-Trp (X1) = 0.58 %; 0.57 %; T° (X2) = 26.37 °C; 28.19 °C; pH (X3) = 7.75; 8.59; and carbon source (X4) = 30 %; 33.29 %, with the predicted response IAA (Y) = 152.8; 169.18 µg/mL). Our findings emphasize the potential of the multifunctional S. rutgersensis AW08, isolated and reported for the first time in Algeria, as a robust producer of IAA. Validation investigations using the bioprocess parameters provided by the L-BFGS-B and the BBD-RSM models demonstrate the effectiveness of AI-driven optimization in maximizing IAA output by 5.43-fold and 4.2-fold, respectively. This study constitutes the first paper reporting a novel interdisciplinary approach and providing insights into biotechnological advancements. These results support for the first time a reasonable approach for valorizing spent coffee grounds as feedstock for sustainable and economic IAA production from S. rutgersensis AW08.

Optimizing refuse-derived fuel production from scheduled wastes through Aspen plus simulation.

This study aims to improve the quality of fuel with high calorific value namely Sfuel - a commercial high-quality refuse-derived fuel (RDF) from hazardous waste via modifying the process design and operating parameters of thermal conversion process. The study analyses key parameters of RDF quality, such as calorific value and heavy metal content, before and after process modifications based on the combination of experimental and simulation using Aspen Plus. In this study, the temperature and pressure of the simulation system are varied from 100 to 700 °C and from 1 to 5 bar, respectively. Findings indicate that there are a total of eleven heavy metals and 179 volatile compounds in the "Sfuels". The quality of the targeted product is greatly improved by the metal evaporation at high temperatures and pressures. However, the calorific value of RDF significantly decreases at 700 °C due to a large amount of the carbon content being evaporated. Although the carbon content at high temperatures is significantly lost, the heat from the vapour stream reactor outlet, which is reused to preheat the nitrogen gas stream supplied to the system, reduces energy consumption while improving the thermal conversion efficiency of the system. Besides, low pressure along with high temperature are not the optimal conditions for quality Sfuels improvement by thermal conversion. Results also indicate that electric heating is more economically efficient than natural gas heating.

Modeling approach for Ti3C2 MXene-based fluorescent aptasensor for amoxicillin biosensing in water matrices.

Amoxicillin, a member of the penicillin family, is primarily utilized for the treatment of various bacterial infections affecting ears, nose, throat, urinary tract, and skin. Given its widespread application in medicine, agriculture, environment, and food industry, the precise and sensitive detection of amoxicillin is important. This study introduces a novel approach to developing a sensitive and selective fluorescent aptasensor relying on fluorescence resonance energy transfer (FRET) for the specific detection of amoxicillin. The carboxyfluorescein-labeled aptamer serves as a energy donor, while MXene functions as an energy acceptor, and acting as a quencher. To achieve optimal detection efficiency, a dual optimization strategy utilizing RSM-CCD and ANN-GA was used to fine-tune experimental conditions. The fluorescence measurements revealed an expansive linear range extending from 100 to 2400 ng mL-1, accompanied by an exceptionally low detection limit of 1.53 ng mL-1. Additionally, it shows an excellent selectivity towards amoxicillin over other antibiotics commonly found in water matrices. The aptasensor demonstrates good stability and reproducibility; effectiveness of the aptasensor was validated by testing in real water samples. This remarkable sensitivity and broad dynamic range affirm the efficacy aptasensor in accurately detecting varying concentrations of amoxicillin in wastewater bodies.

A novel photocatalytic degradation of mixed dye through chemically synthesized ZnO/Fe2O3 nanocomposite.

This study reported the synthesis and assessment of zinc oxide/iron oxide (ZnO/Fe2O3) nanocomposite as photocatalysts for the degradation of a mixture of methylene red and methylene blue dyes. X-ray diffraction analysis confirms that the crystallite of zinc oxide (ZnO) has a hexagonal wurtzite phase and iron oxide (Fe2O3) has a rhombohedral phase. Fourier Transform Infra-Red spectrum confirms the presence of Zn-O vibration stretching at 428, 480 and 543 cm-1 stretching confirming Fe-O bond formation. Scanning Electron Microscope images exhibited a diverse size and shape of the nanocomposites. The ZnO-90%/Fe2O3-10% and ZnO-10%/Fe2O3-90% nanocomposites reveal good photocatalytic activity with reaction rate constants of 1.5 × 10-2 and 0.66 × 10-2; and 1.3 × 10-2 and 0.60 × 10-2 for methylene blue and methyl red dye respectively. The results revealed that the synthesized ZnO/Fe2O3 nanocomposite is the best catalyst for dye degradation and can be used for industrial applications in future.

Sustainable approach for the expulsion of metaldehyde: risk, interactions, and mitigation: a review.

All pests can be eliminated with the help of pesticides, which can be either natural or synthetic. Because of the excessive use of pesticides, it is harmful to both ecology and people's health. Pesticides are categorised according to several criteria: their chemical composition, method of action, effects, timing of use, source of manufacture, and formulations. Many aquatic animals, birds, and critters live in danger owing to hazardous pesticides. Metaldehyde is available in various forms and causes significant impact even when small amounts are ingested. Metaldehyde can harm wildlife, including dogs, cats, and birds. This review discusses pesticides, their types and potential environmental issues, and metaldehyde's long-term effects. In addition, it examines ways to eliminate metaldehyde from the aquatic ecosystem before concluding by anticipating how pesticides may affect society. The metal-organic framework and other biosorbents have been appropriately synthesized and subsequently represent the amazing removal of pesticides from effluent as an enhanced adsorbent, such as magnetic nano adsorbents. A revision of the risk assessment for metaldehyde residuals in aqueous sources is also attempted.

Biochar/layered double hydroxides composites as catalysts for treatment of organic wastewater by advanced oxidation processes: A review.

Heterogeneous advanced oxidation process has been widely studied as an effective method for removing organic pollutants in wastewater, but the development of efficient catalysts is still challenging. This review summaries the present status of researches on biochar/layered double hydroxides composites (BLDHCs) as catalysts for treatment of organic wastewater. The synthesis methods of layered double hydroxides, the characterizations of BLDHCs, the impacts of process factors influencing catalytic performance, and research advances in various advanced oxidation processes are discussed in this work. The integration of layered double hydroxides and biochar provides synthetic effects for improving pollutant removal. The enhanced pollutant degradation in heterogeneous Fenton, sulfate radical-based, sono-assisted, and photo-assisted processes using BLDHCs have been verified. Pollutant degradation in heterogeneous advanced oxidation processes using BLDHCs is influenced by process factors such as catalyst dosage, oxidant addition, solution pH, reaction time, temperature, and co-existing substances. BLDHCs are promising catalysts due to the unique features including easy preparation, distinct structure, adjustable metal ions, and high stability. Currently, catalytic degradation of organic pollutants using BLDHCs is still in its infancy. More researches should be conducted on the controllable synthesis of BLDHCs, the in-depth understanding of catalytic mechanism, the improvement of catalytic performance, and large-scale application of treating real wastewater.

Photocatalytic removal of ceftriaxone from wastewater using TiO2/MgO under ultraviolet radiation.

Pharmaceutical compounds are among the environmental contaminants that cause pollution of water resources and thereby threaten ecosystem services and the environmental health of the past decades. Antibiotics are categorized as emerging pollutants due to their persistence in the environment that are difficult to remove by conventional wastewater treatment. Ceftriaxone is one of the multiple antibiotics whose removal from wastewater has not been fully investigated. In this study, TiO2/MgO (5% MgO) the efficiency of photocatalyst nanoparticles in removing ceftriaxone was analyzed by XRD, FTIR, UV-Vis, BET, EDS, and FESEM. The results were compared with UVC, TiO2/UVC, and H2O2/UVC photolysis processes to evaluate the effectiveness of the selected methods. Based on these results, the highest removal efficiency of ceftriaxone from synthetic wastewater was 93.7% at the concentration of 400 mg/L using TiO2/MgO nano photocatalyst with an HRT of 120 min. This study confirmed that TiO2/MgO photocatalyst nanoparticles efficiently removed ceftriaxone from wastewater. Future studies should focus on the optimization of reactor conditions and improvements of the reactor design to obtain higher removal of ceftriaxone from wastewater.

Removal of lead ions from wastewater using magnesium sulfide nanoparticles caged alginate microbeads.

In this study, an adsorbent made of alginate (Alg) caged magnesium sulfide nanoparticles (MgS) microbeads were used to treat lead ions (Pb2+ ions). The MgS nanoparticles were synthesized at low temperatures, and Alg@MgS hydrogel microbeads were made by the ion exchange process of the composite materials. The newly fabricated Alg@MgS was characterized by XRD, SEM, and FT-IR. The adsorption conditions were optimized for the maximum removal of Pb2+ ions by adjusting several physicochemical parameters, including pH, initial concentration of lead ions, Alg/MgS dosage, reaction temperature, equilibration time, and the presence of co-ions. This is accomplished by removing the maximum amount of Pb2+ ions. Moreover, the adsorbent utilized more than six times with a substantial amount (not less than 60%) of Pb2+ ions was eliminated. Considering the ability of sodium alginate (SA) for excellent metal chelation and controlled nanosized pore structure, the adsorption equilibrium of Alg@MgS can be reached in 60 min, and the highest adsorption capacity for Pb2+ was 84.7 mg/g. The sorption mechanism was explored by employing several isotherms. It was found that the Freundlich model fits the adsorption process quite accurately. The pseudo-second-order model adequately described the adsorption kinetics.

Equilibria of semi-volatile isothiazolinones between air and glass surfaces measured by gas chromatography and Raman spectroscopy.

Trace amounts of semi-volatile organic compounds (SVOCs) of the two isothiazolinones of 2-methylisothiazol-3(2H)-one (MIT) and 2-octyl-4-isothiazolin-3-one (OIT) were detected both in the air and on glass surfaces. Equilibria of SVOCs between air and glass were examined by solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS). Surface to air distribution ratios of Ksa for MIT and OIT were determined to be 5.10 m and 281.74 m, respectively, suggesting more abundant MIT in the gas phase by a factor of ∼55. In addition, a facile method of silver nanocube (AgNC)-assisted surface-enhanced Raman scattering (SERS) has been developed for the rapid and sensitive detection of MIT and OIT on glass surfaces. According to MIT and OIT concentration-correlated SERS intensities of Raman peaks at ∼1585 cm-1 and ∼1125 cm-1, respectively. Their calibration curves have been obtained in the concentration ranges between 10-3 to 10-10 M and 10-3 to 10-11 M with their linearity of 0.9986 and 0.9989 for MIT and OIT, respectively. The limits of detection (LODs) of the two isothiazolinones were estimated at 10-10 M, and 10-11 M for MIT and OIT, respectively. Our results indicate that AgNC-assisted SERS spectra are a rapid and high-ultrasensitive method for the quantification of MIT and OIT in practical applications. The development of analytical methods and determination of the Ksa value obtained in this study can be applied to the prediction of the exposure to MIT and OIT from various chemical products and dynamic behaviors to assess human health risks in indoor environments.

Microalgae-enhanced bioremediation of Cr(VI) ions using spent coffee ground-derived magnetic biochar MoS2-Ag composites.

Composites of magnetic biochar derived from spent coffee grounds were prepared using MoS2 decorated by plasmonic silver nanoparticles (MoS2-Ag), which were used for the bioremediation Cr6+ ions. The composites were characterized by electron microscopy, X-ray diffraction, Raman, and UV-VIS spectroscopy. The bioremediation of Cr6+ ions was enhanced almost two times compared to microalgae, Spirulina maxima. Such an increased activity is attributed to heterojunction formation of Biochar@MoS2-Ag composite due to the synergetic effects of surface plasmon resonance of AgNPs inducing amplified local electric field, thus simultaneously increasing the absorption of MoS2 under visible or near-infrared light. The combination of Biochar@MoS2-Ag and Spirulina maxima powder was effective for the separation (microalga-based absorption and accumulation of Cr6+ ions) of photo-induced carriers (composite-assisted to breakdown Cr6+ ions). This study offers efficient eco-friendly treatment of Cr6+ ions by reporting the first enhanced bioremediation of Cr(VI) ions by microalgae using MoS2-Ag-modified biochar obtained from consumed coffee grounds.

Recent advances in MXene-based nanomaterials for desalination at water interfaces.

The best exceptional Physico-chemical attributes of MXenes including high conductivity, high surface area, high functionalization, hydroxide site, and other interesting properties have attracted recently the attention of scientists in the applications of MXene (Mn+1XnTx)-based nanomaterials for water treatment. To provide a full and comprehensive vision of the current state of the art, and improve the treatment performance, and motivate new researches in this area, this review focused on the uses of these novel 2D transition metal carbides for desalination of water and the general methods of fabrication of MXenes; thus, MXene-based nanomaterials are very efficient candidates in water desalination processes, in this review, the main properties of previous and current works about MXenes applications in this area were properly investigated. Moreover, a particular overview about the different properties of MXenes in desalination such as etching method, hydrophobicity, structural modification, and chemical modification has been performed; meanwhile, the investigation of MXenes and MXenes-based composites would be an excellent candidate in the future of water purification and environmental remediation fields, since they have several good properties compared to the other 2D materials.

Adsorption of rutin from olive mill wastewater using copolymeric hydrogels based on N-vinylimidazole: Kinetic, equilibrium, and thermodynamics assessments.

Olive mill wastewater, also known as olive wastewater, contains biologically active components with various beneficial effects on health. The development of novel adsorbent materials for the recovery of these biologically active substances is important area of research. In this study, copolymeric hydrogels based on N-vinylimidazole (VIm), a new material that has never been used as an adsorbent in the separation of phenolic components, were synthesized. The hydrogels synthesized in this study is copolymer structures based on N-vinylimidazole (VIm) containing [2- (methacryloxy) ethyl] dimethylpentylammonium bromide (QDMAC5) in different moles. QDMAC5 was obtained by quaternization of 2- (dimethylamino) ethyl methacrylate (DMA) with 1-bromopentane (C5). The production of copolymer hydrogels was carried out by free radical solution polymerization. The syntheses were carried out only by changing the monomer composition so that the crosslinker ratio remained constant (1.2 mol%). The QDMAC5 content in the copolymers was 5, 10, 20, 30, and 50 mol%. So, the resulting structures were named PVQ-5%, PVQ-10%, PVQ-20%, PVQ-30%, and PVQ-50%, respectively. Functional group characterizations of hydrogels were made by Fourier Transform Infrared Spectrometry (FTIR). The surface of the hydrogels was analyzed by Scanning Electron Microscopy (SEM). Finally, thermogravimetric analyzes (TGA) were performed to investigate the thermal degradation behavior. The recovery of the rutin present in olive mill wastewater has been investigated as a model study. Kinetic data has been represented by the selected models (pseudo-first order, pseudo-second order, and intraparticle diffusion) convincingly (R2 > 0.76), while the equilibrium findings have fitted well to Langmuir, Freundlich, and Temkin equations (R2 > 0.77). Rutin adsorption process on N-vinylimidazole (VIm) based copolymeric hydrogels has been found as exothermic and spontaneous chemisorption process depending on the thermodynamic analysis.

Occurrences and removal of pharmaceutical and personal care products from aquatic systems using advanced treatment- A review.

Pharmaceuticals, personal care items, steroid hormones, and agrochemicals are among the synthetic and indigenous products that make up micropollutants, also known as emerging contaminants. Pharmaceutical and personal care products (PPPs) are a class of developing micropollutants that can harm living organisms even at low concentrations. Many are detected in surface water and wastewater from the treatment process, with quantities ranging from ng L-1 to gL-1; however, residual PPPs at dangerously high levels have indeed recently been recognized in the ecosystem. Residential sewage treatment plant (STP) dump the largest majority of these pollutants into the environment on a regular basis. As a result of its robust structure, it has a longer lifespan in the environment. This review article discusses how surface water pollutants such pesticides, petroleum hydrocarbons, and perfluorinated compounds affect water quality, as well as the most cost-effective adsorbents for removing these PPPs. The goal of this study is to provide information about the origins of PPP, as well as diagnostic procedures and treatment options. Research on developing contaminants is also aimed at evaluating the efficacy and affordability of adsorption.

Existence of Ti3+ and dislocation on nanoporous CdO-TiO2 heterostructure applicable for degrading chlorophenol pollutant.

This study addresses the significance of wastewater recuperation by a simple and facile treatment process known as photocatalyst technology using visible light. Titanium di-oxide (TiO2) is the most promising photocatalyst ever since longing decades, has good activity under UV light, owing to its small band gap. Hence, TiO2 has been modified with metal oxides for the positive response against visible light. Since this is an efficient process, the novelty has been made on nanometal oxide CdO (cadmium oxide) combined with TiO2 to acquire the best efficiency of degrading organic chlorophenol contaminant. Initially, the composites were synthesized by sol-gel and thermal decomposition methods and investigated for their various outstanding properties. The characterized outcomes have exhibited heterostructures with reduced crystallite size from the X-ray diffraction studies. Then, the determination of nanoporous feature was recognized through HR-TEM analysis which was also detected with some dislocations. The EDX spectrum was identified the perfect elemental composition. The nitrogen adsorption-desorption equilibrium was attained that offers many pores measured with high surface area. The XPS result convinced that Ti3+ was accessible along with TIO2/CdO composite. Further the absorption towards higher wavelength was obtained from UV-vis spectra. Finally, for the photocatalytic application of chlorophenol, the composite shows higher percentage of degrading efficiencies than the pristine TiO2. The photocatalytic mechanism was discussed in detail.

Electrospun composite nanofibers as novel high-performance and visible-light photocatalysts for removal of environmental pollutants: A review.

Environmental pollution caused by industries and human manipulations is coming a serious global challenge. On the other hand, the world is facing an energy crisis caused by population growth. Designing solar-driven photocatalysts which are inspired by the photosynthesis of plant leaves is a fantastic solution to use solar energy as green, available, and unlimited energy containing ∼50% visible light for the removal of environmental pollutants. The polymeric and non-polymeric-based electrospun composite nanofibers (NFs) are as innovative photocatalytic candidates which increase photocatalytic activity and transition from UV light to visible light and overcome the aggregation, photocorrosion, toxicity, and hard recycling and separation of the nanosized powder form of photocatalysts. The composite NFs are fabricated easily by either embedding the photocatalytic agents into the NFs during electrospinning or via their decorating on the surface of NFs post-electrospinning. Polyacrylonitrile-based, tungsten trioxide-based, zinc oxide-based, and titanium dioxide-based composite NFs were revealed as the most reported composite NFs. All the lately investigated electrospun composite NFs indicated long-term stability, high photocatalytic efficiency (∼> 80%) within a short time of light radiation (10-430 min), and high stability after several cycles of use. They were applied in various applications including degradation of dyes/antibiotics, water splitting, wastewater treatment, antibacterial usage, etc. The photogenerated species especially holes, O2∙-, and .OH were mostly responsible for the photocatalytic mechanism and pathway. The electrospun composite NFs have the potential to use in large-scale productions in condition that their thickness and recycling conditions are optimized, and their toxicity and detaching are resolved.

Advancements on sustainable microbial fuel cells and their future prospects: A review.

A microbial fuel cell (MFC) is a sustainable device that produces electricity. The main components of MFC are electrodes (anode & cathode) and separators. The MFC's performance is ascertained by measuring its power density. Its components and other parameters, such as cell design and configuration, operation parameters (pH, salinity, and temperature), substrate characteristics, and microbes present in the substrate, all influence its performance. MFC can be scaled up and commercialized using low-cost materials without affecting its performance. Hence the choice of materials plays a significant role. In the past, precious and non-precious metals were mostly used. These were replaced by a variety of low-cost carbonaceous and non-carbonaceous materials. Nano materials, activated compounds, composite materials, have also found their way as components of MFC materials. This review describes the recently reported modified electrodes (anode and cathode), their improvisation, their merits, pollutant removal efficiency, and associated power density.

Biosynthesis, characterization, and evaluation of antibacterial and photocatalytic methylene blue dye degradation activities of silver nanoparticles from Streptomyces tuirus strain.

Silver nanoparticles (AgNPs) are a promising technology for the design of antimicrobial agents against drug-resistant pathogens. It could also be used for the photocatalytic degradation of dyes used in industries such as methylene blue (MB). In this study, 17 different actinomycetal strains isolated from hydrocarbon-contaminated soils collected from an oil distribution company in Algeria were evaluated for their ability to produce NPs. After a selection process, S16 was the main strain capable of synthesizing AgNPs extracellularly. The strain S16 was determined using molecular identification based on the sequencing of the 16S rDNA gene. Among various techniques used for the synthesis of AgNPS, a technique using a temperature of 30 °C, pH of 7, a metal salt concentration of 1 mM, and a period of 72 h in the dark were found to be more effective in the biosynthesis of the AgNPs. The biosynthesized AgNPs that were analyzed by UV-visible spectroscopy resulted in a specific peak at a wavelength of (λ = 400 nm). The DRX analyses showed characteristic peaks of the AgNPs at (1 1 1), (2 0 0), (2 2 2), and (3 1 1), which validated the presence and crystalline nature of the biosynthesized NPs. Zetasizer analysis showed an average size and zeta potential of 64 nm (-32.3 mV), while the SEM-EDS analysis confirmed the spherical shape of AgNPs and the presence of Ag atoms in the elemental composition. The biosynthesized AgNPs indicated adequate antibacterial activity against 5 out of the 6 strains tested in this study, using minimum inhibitory concentration (MIC) that ranged from 217.18 µg/mL to 1137.5 µg/mL. The AgNPs were combined with commercial antibiotics and the synergistic effect of the combination was also assessed against MRSA which resulted in increased antibacterial activity of AgNPs in the presence of the strain S16. Furthermore, the photocatalytic degradation of the methylene blue (MB) was evaluated under sunlight and UV irradiations using biosynthesized AgNPs. The AgNPs showed photocatalytic decolorization potential of 71.3% for MB dye (20 ppm) under sunlight irradiation within 6 h of incubation, while only 11.25% of the MB dye degraded using UV irradiation.

Electrochemical detection of hydrogen peroxide using micro and nanoporous CeO2 catalysts.

In this research work, focus has been made on a glassy carbon electrode (GCE) modified commercial micro and synthesized nano-CeO2 for the detection of hydrogen peroxide (H2O2). Firstly, CeO2 nanoleaves were prepared by solvothermal route. Both commercially available micro CeO2 and synthesized nano-CeO2 structures were analyzed by different characterization techniques. The Raman spectra of synthesized nano CeO2 has more oxygen vacancies than micro CeO2. SEM images revealed that the synthesized CeO2 acquired leaf-like morphology. The catalyst nano CeO2 offered mesoporosity from nitrogen adsorption-desorption isotherms with massive sites of activation for increasing efficiency. Experiments on determining H2O2 using micro CeO2 or nano-CeO2/GCE was conducted using cyclic voltammetry (CV) and amperometry. Enhanced H2O2 reduction peak current with lower potential was observed in nano-CeO2/GCE. The influence of scan rate and H2O2 concentration on the performance of nano-CeO2/GCE were also studied. The obtained results have indicated that nano-CeO2/GCE showed improved electrochemical sensing behavior towards the reduction of H2O2 than micro-CeO2/GCE and bare GCE. A linear relationship was obtained over 0.001 µM-0.125 µM concentration of H2O2, with good sensitivity 141.96 µA µM-1 and low detection limit of 0.4 nM. Hence, the present nano-CeO2 system will have a great potential with solvothermal synthesis approach in the development of electrochemical sensors.

Nickel and iron-based metal-organic frameworks for removal of organic and inorganic model contaminants.

Metal-organic frameworks (MOFs) are a promising class of porous nanomaterials in the field of environmental remediation. Ni-MOF and Fe-MOF were chosen for their advantages such as structural robustness and ease of synthesis route. The structure of prepared MOFs was characterized using FE-SEM, XRD, FTIR, and N2 adsorption-desorption. The efficiency of MOFs to remove organic model contaminants (anionic Alizarin Red S (ARS) and cationic malachite green (MG) and inorganic fluoride was studied. Fe-MOF and Ni-MOF adsorbed 67, 88, 6% and 32, 5, and 9% of fluoride, ARS, and MG, respectively. Further study on ARS adsorption by Fe-MOF showed that the removal efficiency was high in a wide range of pH from 3 to 9. Moreover, dye removal was directly increased by adsorbent mass (0.1-0.75 g/L) and decreased by ARS concentration (25-100 mg/L). The pseudo-first-order kinetic model and Langmuir isotherm model with a qmax of 176.68 mg/g described the experimental data well. The separation factor, KL, was in the range of 0-1, which means the adsorption process was favorable. In conclusion, Fe-MOF showed remarkable adsorption of organic and inorganic model contaminants.