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Hybrid lead halide perovskites will potentially lead the future energy scenario if highly efficient cells have long-term stability. Here we combine state-of-the art mixed-cation formulations containing formamidinium (FA) and methylammonium (MA), with optimal guanidinium (Gua)/Cs ratios, enabling the realization of cells providing stability at their maximum efficiency.

The increasing demand of a sensitive and portable electrochemical sensing platform in pharmaceutical analysis has developed widespread interest in preparing electrode materials possessing remarkable properties for the electrochemical determination of target drug analytes. Herein, we report the synthesis, characterization and application of bimetallic cobalt-iron diselenide (FeCoSe2) nanorods as electrode modifiers for the selective detection of a commonly used anti-tuberculosis drug Isoniazid (INZ). We prepared FeCoSe2 nanorods by a simple hydrothermal route and characterized these by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and temperature-programmed reduction (TPR) techniques. The electrochemical characterization of FeCoSe2 modified GCE was performed by cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV). Under optimized experimental conditions, a linear current-concentration response was obtained for INZ in the range of 0.03–1.0 μM, with very low limit of detection 1.24 × 10−10 M. The real applicability of the designed FeCoSe2/GCE sensing platform was adjudicated by the detection of INZ in biological samples.

Hydrogels are natural or synthetic polymeric networks, insoluble in water, or sometimes found as colloidal gel where the dispersion medium is water. Hydrogels can absorb approximately 90% water and are regarded as superabsorbent materials; hence these resemble the natural living tissues more than any other biological- based materials. Because of their ability to absorb water, they are used to investigate the properties of swollen polymer networks and have wide applications in different fields such as contact lenses, drug delivery systems for proteins, and many others. To make them biodegradable, labile chemical bonds are introduced in the main backbone through crosslinking. These unstable bonds can then be broken down by various agents chemically, physically, or enzymatically, generally by hydrolysis or through some controlled parameters. Hydrogels are frequently used in the medical field. For instance, pH and temperature-sensitive hydrogels may be used in the targeted drug delivery which have been explained in detail in the current review. The other applications of hydrogels are also explained with regard to personal health care products, biomedical, bio-separation, wound healing, tissue engineering, and drug delivery, etc., which make them promising materials in pharmaceutics. They are also used in agriculture and environmental remediation. The purpose of this review is to expose their salient features and biomedical applications.

In this study, a selective separation of tungsten W (VI) from a mixed salt solution was done through a liquid-membrane technology. The transport of W (VI) across the supported liquid membrane was also applied on real sample. Tertiary amine (Tri-n-dodecylamine) was used as an organic carrier and a supported liquid membrane of polypropylene separator (celgard 2400) was used in this experimental work. The selective separation of W (VI) was optimized by various parameters i.e., concentration of metal in feed, concentartion of stripping agent, type of stripping reagents, carrier concentration and pH effect. The extraction of W(VI) was maximized by the concentration of carrier up to 0.2 mol/dm3 diluted in n-hexane. The optimum concentration of sodium hydroxide was 0.2 mol/dm3 in the strip phase. The transport of tungsten increases by the increase of the pH of feed solution to basic from acidic up to the pH 8. At pH 8 in the feed phase, tri-n-dodecylamine efficiently extracted W (VI) from feed through anion exchange mechanism. The time duration for the transport of tungsten was 6 h at room temperature. The optimized reaction of W(VI) for the selective separation was applied on the scheelite ore with 93% recoved. The single membrane was used in all experiments, which confirmed the durability and stability of polypropylene membrane.

Environmental pollutants are considered as the main concern for human life because it can affect health, especially via water sources. An enormous effort is needed to detect and monitor such contaminants from natural waters. Nanotechnology field offered combined benefits in regards to sensitive detection of environmental contaminants from water. This review describes the main types of water contaminants and recent approaches used for effective electrochemical detection of environmental pollutants with the aid of nanostructured materials.

In this experimental study, a novel bionanocomposite of gelatin as a polypeptide hydrogel consisting of copper (II) oxide nanomaterial (GL–CuO) was prepared. After dispersing the synthesized CuO nanoparticles (NPs) within the GL aqueous solution, they were cross-linked by the addition of a formaldehyde solution. The resulting GL–CuO nanocomposite hydrogels were further characterized by FESEM, EDX, XRD, XPS, and FTIR. The FESEM micrographs confirmed the uniform distribution of CuO NPs in the hydrogel matrix, with dimensions ranging from 60 to 80 nm. The XRD patterns confirmed the presence of the monoclinic crystalline form of CuO NPs embedded in the GL hydrogel. The GL–CuO catalyst was tested in the reduction of two azo dyes. All the reactions were carried out in the presence of a strong reducing agent, NaBH4, with the catalyst demonstrating high activities toward methyl orange and congo red with reaction rate constants of 9.91 × 10−1 min−1 and 5.8 × 10−1 min−1, respectively. The reduction of these dyes was followed by UV–visible spectroscopy that confirmed complete reduction of the dye.

In this study simple, facile and highly active silver coated ZnO-chitosan (Ag/ZnO-CH) textile cotton supported nanocomposites were developed. The nanocomposites were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-rays spectroscopy (EDX), fourier transform infrared spectroscopy (FTIR) and X-rays diffraction (XRD). The prepared nanocomposite fibers were used for the selective removal of seven model pollutants, including para-nitrophenol (p-NP), meta-nitrophenol (m-NP), ortho-nitrophenol (o-NP), 2,4,6-trinitrophenol (TNP), and dyes of methyl orange (MO), congo red (CR), and methyl red (MR). The apparent rate constant (Kapp) of pseudo first order kinetic for p-NP was 2.813 × 10−3 s−1 and 1.663 × 10−3 s−1 for MO dye. Among the different nitroarenes, the reaction rate matched the ordered of p-NP >TNP > m-NP > o-NP, while for the dyes it was MO > CR > MR. Ag/ZnO-CH nanocomposites were recycled multiple times without any significant loss of its catalytic activity. The higher stability of the Ag/ZnO-CH nanofibers also allows the catalyst to be separated easily by just pulling the catalyst from the reaction mixture and reused. The clean and facile, simple synthesis procedure, outstanding properties and low-cost supports allow these catalysts to be used in the reduction of the organic pollutants individually as well as collectively in the mixture of dyes in wastewater at room temperature.

This study was focused to synthesize silver nanoparticles (AgNps) from the aqueous extract of Bistorta amplexicaule and to evaluate their antimicrobial, antifungal, and 4-nitrophenol (4-NP) degradation potential. The AgNps from B. amplexicaule were characterized by field emission scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy studies. The biological activity of the AgNps was checked against the three bacterial and two fungal strains. The inhibition activities of the synthesized nanoparticles on pathogenic bacteria and fungi were equally studied using the colony-forming unit method. The AgNps synthesized showed excellent bactericidal and fungicidal activities against pathogenic Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Candida albicans, and Candida tropicalis. The removal of nitrophenols is one of the most demanding tasks, due to their injurious impact on the health of the living organisms. The AgNps showed superior performance compared with the pure plant extract. The AgNps also displayed efficient catalytic ability in reducing toxic 4-NP into harmless 4-aminophenol in the presence of NaBH4 solution. Hence, the synthesized AgNps can be effectively used against bacterial and fungal infections and in the decontamination of 4-NP polluted water.

Nowadays, considerable attention has been gained for metal-based nanocatalysts due to their high catalytic activity. Herein, copper-cotton cellulose (Cu-CC) and metal nanoparticles supported on Cu-CC (MNPs@Cu-CC) were prepared. Zero-valent nanoparticles (NPs) of silver (Ag), and iron (Fe) were grown on Cu-CC and utilized as catalyst in few important organic reduction reactions. The prepared Cu-CC, Fe@Cu-CC and Ag@Cu-CC catalysts were utilized in catalytic reduction of nitrophenols and dyes for their evaluation. Among all the tested catalysts, Cu-CC efficiently reduced 4-nitrophenol (4-NP) and methyl orange dye (MO). The reduction rate constants of 4-NP and MO were 9.94 × 10−3 and 1.12 × 10−2 s–1, respectively. Further the catalytic activity of the more efficient Cu-CC was optimized by varying its amount, nitophenols and dyes, and NaBH4 concentrations. The stability, re-usability and loss in catalytic activity of the NPs were analyzed by the recyclability, in which the Cu-CC was utilized several times for the reduction of 4-NP and MO which suggest that the designed catalyst can be easily prepared, recovered simply by discarding the dye after completion of reaction, recyclable and have good catalytic activity.

Water beads made from polyacrylamide polymer p-(AAm) were decorated with high efficient metal nanoparticles by inexpensive, fast, simple, and environmental friendly method. These water beads balls were kept in the metal salt solutions for 4 h; to adsorb the metals ions from these aqueous solutions. The metal ions decorated on the p-(AAm) water beads were converted to metal nanoparticles by its reduction with aqueous solution of NaBH4. The prepared materials p-(AAm) loaded with MNPs (M@p-(AAm)) were characterized by ATR-FTIR, XRD, XPS, FESEM, and EDS which show the successful preparation of MNPs over the surface and within p-(AAm). Afterwards the M@p-(AAm) were investigated as a catalyst for the generation of hydrogen from the methanolysis of NaBH4. The Ag@p-(AAm) show good catalytic activity for NaBH4 methanolysis reaction as compared to the other loaded MNPs. In addition, different parameters which effecting H2 generation were also investigated such as; MNPs types, catalyst amount and temperature of the reaction. Low activation energy (Ea) of 21.37 ± 0.67 kJ mol−1, was calculated for NaBH4 methanolysis reaction at temperature ranging from 5.0 °C to 35 °C. Moreover, the catalyst reusability was also studied and found no decrease in percent conversion, however percent efficiency was decreases about 37% after completion of four cycles.

A facile, cheap and efficient system has been developed for selective detection and removal of 4-nitrophenol. Herein, cerium oxide-copper oxide (CeO2-Cu2O) and CeO2-Cu2O/chitosan (CeO2-Cu2O/CH) nanocomposites were coated on glassy carbon electrode to evaluate their electrochemical behavior toward 4-nitrophenol via cyclic voltammetry. The response of coated electrodes toward 4-nitrophenol were remarkable, in which the reduction peak current of 4-nitrophenol was increased as compared to bare electrode. This specifies that such nanocomposites significantly boost the electrochemical reduction of 4-nitrophenol and therefore, we demonstrated that the nanocomposites exhibit outstanding selectivity and sensitivity toward 4-nitrophenol detection. The effects of different parameters including pH and scan rate were tested. The reduction peak current of 4-nitrophenol is proportionate with its concentration in the range 74–375 μM, and the correlation coefficient was 0.998. The detection limit is 2.03 μM (S/N = 3). This simplistic system was effectively implemented to the detection of 4-nitrophenol in real water samples, with reasonable recovery values (92.5–99.85%). Furthermore, we demonstrated that the nanocomposite displays an excellent catalytic ability for the transformation reaction of 4-nitrophenol to 4-aminophenol by NaBH4. Such a system could be applicable for diverse applications in catalysis, sensing and environmental sciences.

Plant based materials are considered to have broad applications in the remediation of toxic materials. In this report, we present an environmental friendly and economic Cicer arietinum, named as (CP) supported for the synthesis of Ni nanoparticles (NPs) designated as Ni@CP. The in situ Ni@CP NPs were obtained using aqueous medium in the presence of sodium borohydride (NaBH4) as a reducing agent. The prepared catalysts were applied for the hydrogenation/degradation of p-nitrophenol (PNP), o-nitrophenol (ONP), and 2,4-dinitrophenol (DNP), as well as congo red (CR), methyl orange (MO), methylene blue (MB) and rhodamine B (RB) dyes. The amount of total metal ions adsorbed onto the CP was evaluated by flame atomic absorption spectroscopy. The Ni@CP catalyst was characterized through PXRD, FTIR, FESEM and EDX analyses.

Presence of Escherichia coli in water is mainly responsible for contamination of drinking water. Currently, organic materials are being used for disinfection of drinking water. However, antimicrobial inorganic materials have more potential due to their thermal resistance, chemical stability, and long lasting action period. In this work silver nanoparticles (AgNPs) were synthesized by chemical and biological methods and then impregnated with different support materials including Activated carbon, Zeolite and Magnesium oxide. Formation of nanoparticles was confirmed by UV/visible spectrophotometer due to their surface plasmon resonance, in which AgNPs showed a peak at 445 nm. XRD patterns gave characteristic patterns to AgNPs on support. AgNPs on support material were further verified by FE-SEM and EDX analyses. AgNPs supported catalysts were more active and all the bacteria were inhibited in drinking water. Beside antibacterial activity, the prepared catalysts shows excellent activity in the reduction of azo dye methyl orange. Among all, MgO impregnated silver catalysts show an outstanding methyl orange reduction with the rate constant of 7.48 × 10−3 s−1. So, it indicates that different supported AgNPs have the potential to be used for removal of microbial and organic pollutants from drinking water.

In this report, copper nanoparticles templated at chitosan-coated graphene oxide (GO) nanocomposite fibers (Cu@CH + GO) were prepared via solution-based fiber formation followed by treatment with a metal salt solution and NaBH4 and utilized for the detection and catalytic reduction of 4-nitrophenol (4-NP). Cu@CH + GO exhibited a high sensitivity of 1.729 ± 0.027 μAmM–1 cm–2 and a detection limit of 3.5 mM toward 4-NP. In addition, high catalytic activity was observed for the reduction of 4-NP with an apparent rate constant of 1.310 ± 0.093 min–1 using 7 mg of Cu@CH + GO catalyst. Besides the good catalytic activities of Cu@CH + GO, it could be easily recovered by simply pulling the fiber from the reaction medium. Moreover, Cu@CH + GO catalyst was also examined in real samples and found to be efficient in the detection and reduction of 4-NP. This novel approach provides a new route for simultaneous detection and reduction of 4-NP and can be a time and cost-effective tool for environmental safety.

Cellulose cotton fibers (CF) are coated with chitosan (CH) by simple, economic, and environmental friendly method. The CFs are kept in aqueous acetic acid solution to protonate the fibers before coated with CH solution (1.5% w/v in acetic acid aqueous solution (20% v/v)), represented as CF-A-CH. These materials are characterized by ATR-FTIR, XRD, FE-SEM and EDS which shows the successful coating of the CH on the CF surface. The prepared materials are exploited as an effective catalyst for the production of hydrogen (H2) from NaBH4 methanolysis reaction. In addition, other polymers (gelatin and agarose) and surfactants (brij-56, pluronic F-127 and urea) as well as CH in solution form are testified as catalyst for NaBH4 methanolysis reaction. High generation rate (8 times) and increase in amount of H2 (150 mL) is observe using only 50 μL CH solution. Furthermore, influences of various constraints, which affect the H2 production, like catalyst types, catalyst amount, NaBH4 amount, effect of temperature are also explored. A low activation energy (Ea), almost 14.41 ± 0.46 kJ mol−1 is calculated for NaBH4 methanolysis reaction in presence of CF-A-CH at temperature range 0 °C - 45 °C. Moreover, the catalyst reusability is also analyzed and no decline in percent conversion is found, whereas a little reduction in percent performance is detected after every cycle and only 18% lost is observed in its percent activity after completion of five successive cycles.

Spectroscopic studies-based on 1D (1H NMR, 13C NMR), 2D-NMR (COSY, HMBC, HSQC), UV–visible, FTIR techniques and quantum chemical studies established on the density functional theory (DFT) were carried out for the natural withanolide glycosides, isolated from Withania Coagulans Dunal. The new glycoside withanolide named as (20R,22R)-14α,17,20β,27-trihydroxy-1-oxowitha-5,24-dienolide-27β-(O-β- d -glucopyranoside) (1), and a known withanolide (20R,22R)-14α-20β,27-trihydroxy-1-oxowitha-5,24-dienolide-3β-(O-β- d -glucopyranoside) (2) are reported here from W. coagulans. The molecular mass of these compounds were confirmed through Fast Atom Bombardment Mass Spectrometry (FAB-MS). Geometric and spectroscopic detailed were obtained from DFT calculations. 1H and 13C NMR theoretical values were found a little higher than the experimental values, but the trend in the chemical shift correlates well with the experimental values. The RMSD values of 1H and 13C NMR of 1 and 2 were 0.4 and 0.38, and 4.94 and 5.02 respectively. The calculated band gap was found 4.93 and 5.00 eV for 1 and 2 respectively which indicated the stable nature of these compounds towards redox reactions.

In this study, plant-mediated copper nanoparticles (CuNPs) were synthesized. Due to its direct synthesis mechanism and eco-friendly nature, the current method accounts for the green chemistry approach using the fruit extract ofDuranta erectafor the first time. The UV-visible spectrum of the CuNPs solution showed a distinct absorption peak at 588 nm. Fourier transform infrared spectroscopy confirmed that the fruit extract is responsible for the reduction as well as the stabilization of CuNPs. X-ray diffraction patterns conform the crystalline nature of CuNPs. Energy-dispersive X-ray spectroscopy was performed for elemental analysis whereas field emission scanning electron microscopy was carried out for surface morphology. Prepared CuNPs were used for the reduction of carcinogenic azo dyes methyl orange (MO) and congo red (CR). CuNPs exhibit outstanding catalytic reduction for MO and CR in the presence of NaBH4as reducing agents with the pseudo-first-order rate constants of 8.6×10−3s−1and 5.07×10−3s−1for MO and CR, respectively. Thus, natural plant materials act as cheap and environmentally friendly support for the synthesis of CuNPs and could be used for the purification of water from organic dye effluents.

The aim of the presented work was to assess the potential of Medicago polymorpha extract to synthesize silver nanoparticles (AgNPs) as a green method. It was a simple one-step synthesis approach and the product obtained was characterized by UV-visible spectroscopy, Fourier transform infrared (FTIR), powder X-ray diffraction, thermogravimetric analysis, and field-emission scanning electron microscopy (FE-SEM). At room temperature, the optimum time for the completion of the reaction (i.e. the formation colloidal solution) was just 5 min. FE-SEM images showed that AgNPs were predominantly in spheres, whereas FTIR spectrum analysis inferred that gallic acid present in the extract initially reduced silver ions to elemental silver. The carboxylic and hydroxyl groups of biomolecules present in the extract stabilized AgNPs by passivating the surface to prevent aggregation, resulting in uniform distribution. The antibacterial activity of synthesized AgNPs showed effective inhibitory effects against waterborne pathogens, including Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), at a minimum inhibitory concentration of 10 μg/ml. Membrane permeability and respiration studies were also performed to assess the surface role of the synthesized AgNPs. The prepared AgNPs exhibited excellent antioxidant activity and catalytic reduction of methyl orange with a rate constant of 6.8×10−3 s−1.

Plant-based materials are reported to have a wide range of applications in the environmental and biomedical sectors. In this report, we present an economic and environmentally friendly supported turmeric powder (TP) biomass for the support of Ag, Ni and Cu nanoparticles (NPs) designated as Ag@TP, Ni@TP and Cu@TP. The in situ syntheses of the stated NPs were achieved in aqueous medium using NaBH4 as a reducing agent. The prepared NPs were applied for the degradation of o-nitrophenol (ONP), m-nitrophenol (MNP), p-nitrophenol (PNP), methyl orange (MO), Congo red (CR), rhodamine B (RB) and methylene blue (MB). Initially, Ag@TP, Ni@TP and Cu@TP were screened for the MO dye and antibacterial activity, where Ag@TP displayed the strongest catalytic activity for MO and bactericidal activities as compared to Ni@TP and Cu@TP. The quantity of metal ions adsorbed onto the TP was investigated by atomic absorption spectroscopy. The Ag@TP, Ni@TP and Cu@TP were characterized through X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM) analysis.

In this work, cellulose acetate polymer (CA) sheet and 2% ZnAl grafted on activated carbon grown in the form of layered double hydroxide (ZnAl/C-LDH) incorporated into CA polymer (CA-ZA2) 5 wt% (CA-ZA5) and 10 wt% of ZnAl/C-LDH (CA-ZA10) sheets were synthesized by simple casting method. All the stated sheets were fabricated with zero-valent Ni nanoparticles by adsorption of Ni+2 ions followed by subsequent reduction with NaBH4 and named as CA@Ni, CA-ZA2@Ni, CA-ZA5@Ni, and CA-ZA10@Ni NPs. The synthesized Ni NPs were investigated through FESEM, FTIR, XRD and EDS techniques. These supported and stabilized Ni NPs were largely used for the reduction of 4-nitrophenol (PNP), and 2-nitrophenol (ONP) in the presence of NaBH4 which act as a reducing agent. Similarly, the catalytic efficiency was also assessed against the removal of dyes. The linear relationship and Kapp were obtained from pseudo-first-order kinetics. The rate constant Kapp of CA@Ni NPs for the reduction of PNP is 1.5 × 10−1 and CA-ZA2@Ni (Kapp = 2.6 × 10−1), CA-ZA5@Ni (Kapp = 3.2 × 10−1), and CA-ZA10@Ni is 5.7 × 10−1 min−1. The highest rate constant for PNP reduction was observed with CA-ZA10@Ni NPs. The rate of CR removal with ZA10@Ni NPs is 2.05 × 10−1 while the adjacent R2 is 0.9013. Similarly, the rate constant and adjacent R2 values were calculated for the degradation of other dyes and nitrophenols.

The present study describes a developed methodology for selective extraction of yttrium ions based on cerium oxide‑cadmium oxide (CeO2‑CdO) nanomaterials. The elaborated characterization of CeO2‑CdO nanomaterial was provided by SEM, EDS, XRD, XPS and FTIR techniques. CeO2‑CdO nanomaterial was employed as solid-phase extractant for heavy metal ions from aqueous media. Based on the results, CeO2‑CdO nanomaterial exhibited high selectivity for Y(III) with a maximum uptake capacity of 84.67 mg g−1 at pH 6.0. Adsorption isotherm data were well-correlated with Langmuir isotherm and pseudo-second order models. Yttrium ions were easily recovered from CeO2‑CdO nanomaterial using 0.3 M HCl solution, and the adsorbent showed high stability for reusing several times. Ultimately, the developed methodology was successfully applied for real water specimens.

In this report, we used facile, active, cheap, re-usable and high surface area catalyst for the synthesis of green substrate turmeric (Curcuma longa) powder support mixed silver copper (Ag–Cu/TP), copper nickel (Cu–Ni/TP) and nickel silver (Ni–Ag/TP) nanoparticles. For nanoparticles synthesis the turmeric powder were kept in 0.5 M aqueous metal salt solution and then treated with aqueous solution of NaBH4 for in situ conversion of metal ions into their nanoparticles. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDX) confirm the formation of nanomaterials. Silver mix nanoparticles show excellent activities against Escherichia coli (E. coli). The prepared nanoparticles were employed for the reduction of fluoroquinolone antibiotics ciprofloxacin (CIP) and levofloxacin (LVO) as well as for Methyl orange (MO), Congo red (CR), Methylene blue (MB) and Rhodamine B (RhB) dyes. Ag–Cu/TP catalyst showed excellent catalytic activity for the reductive transformation of antibiotics as well as for the remediation of MO, CR, MB and RhB dyes. The rate constants of pseudo first order reaction for CIP and LVO were 1.27 × 10−3 s−1 and 1.52 × 10−3 s−1 respectively. Ag–Cu/TP also showed excellent recyclability till the 5th cycle for MO reduction. The abundant nature, low cost, excellent reusability and effective catalytic degradation make Ag–Cu/TP suitable candidates for the reduction of organic molecules.

A facile and single-step green synthesis of silver nanoparticles dispersed on taro (Colocasia esculenta) plant rhizome powder (TP) is reported here. In the current study, we describe for the first time, the successful adsorption-based assembly of the silver/taro power (Ag/TP) nanocomposites using the rhizome of taro as a stabilizing/supporting agent. The Ag/TP nanocomposites exhibited very high efficiency in the catalytic reduction of nitroarenes such as picric acid/trinitrophenol (TNP), 4-nitroaniline (4-NA), 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP) to the corresponding amines. The prepared catalyst also showed a high activity in the catalytic reduction of organic azo dyes such as Methyl Orange (MO), Congo Red (CR), Methyl Red (MR) and Rhodamine B (RhB) by sodium borohydride (NaBH4). The morphology, structure and crystallite size of the prepared nanocomposites were evaluated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photo electron spectroscopy (XPS) and X-ray diffraction analysis (XRD). The calculated turnover frequency was 3.846 min−1 for 4-NP and 1.104 min−1 for 2-NP. However, the pseudo-first-order constant was 5.27 × 10−3 s−1 for 4-NP and 1.23 × 10−3 s−1 for 2-NP. The prepared Ag/TP catalyst was also tested for the reduction of a mixture of nitroarenes and dyes. Ag/TP catalyst emerged as a promising, easily recoverable and reusable, with at least in 5 successive reactions and stable for 3 days.

Chenisterol (1), a new steroid, has been isolated from the EtOAc soluble subfraction of Chenopodium badachschanicum Tzvelev, along with ergosterol (2), stigmasterol (3), fucosterol (4), morin (5), sinapic acid (6), and thymol (7), reported for the first time from this species. Their structures were elucidated with the help of spectroscopic techniques including 2D NMR. Compound 1 showed significant antimicrobial activity against three Gram-positive and one Gram-negative bacterial strains.

The current study is focussed on bio-fabrication of single step Durenta erecta (D. erecta ) fruit extract synthesis of silver nanoparticles (Ag NPs). The prepared materials were examined through UV–Vis spectrophotometry due to localized surface plasmon resonance (SPR) and were found highly stable. X-ray diffraction (XRD) revealed face centered cubic (fcc) crystalline nature of Ag NPs. Morphologies and average size of Ag NPs was evaluated by field emission-scanning electron microscopy (FE-SEM), while elemental analysis was carried out by energy dispersive X-rays spectroscopy (EDS) and X-ray photo electron spectroscopy (XPS). Fourier transform infrared spectroscopy (FTIR) displayed the presence of the functional groups responsible for reducing as well as stabilizing of Ag NPs. The prepared Ag NPs were applied as colorimetric optical sensors for the detection of carcinogenic hexavalent chromium (Cr 6+) and ammonia and the kinetic shift in λmax and change in color for both Cr6+ and ammonia was found to be extremely fast and took a few seconds. Characteristic SPR, low-cost, high sensitivity, simplicity, lower detection limit up to 0.1 ppm and fast response time of Ag NPs are very useful for the colorimetric detection of Cr 6+ and ammonia and can be used as an optical sensor for clinical diagnosis at room temperature.

Environmental remediation based on catalytic technologies has gained prominence as highly effective mean of removing toxic organic pollutants. Herein, mixed metal nanoparticles were decorated onto lignocellulose based support material, namely oil palm frond (OPF) biomass to fabricate a nanocatalyst (Cu + Co@OPF) via. facile chemical route. Various microscopic properties of as-prepared Cu + Co@OPF were examined using XRD, FTIR, FESEM, EDS and TGA. To check the universal applicability of as-prepared catalyst in wastewater decontamination, reduction of eight models pollutants was investigated such as dyes viz., Congo red (CR), Methyl orange (MO), Rhodamine B (RB), Methylene blue (MB) and different nitrophenols such as Ortho-nitrophenol (ONP), Meta-nitrophenol (MNP), Para-nitrophenol (PNP), 2, 4-dinitrophenol (DNP). Using Cu + Co@OPF heterostructure platform, complete reduction of organic pollutants was achieved in shorter time using NaBH4 as a hydrogen and electron source. The rate of catalytic reduction of pollutants followed order as; MO ˃ RB ˃ MB ˃ CR and PNP ˃ MNP ˃ ONP ˃ DNP in case of dyes and nitrophenols, respectively. The Cu + Co@OPF based heterostructure demonstrated multifunctional properties, for instance enhanced diffusion of pollutants, excellent catalytic activity as well as easy recovery. In addition to being renewable and eco-friendly, the porous and rough three-dimensional structure of biomass provided a large surface area for the formation of high-density of mixed metal NPs as possible catalytic sites, also allowing more contact between NPs and pollutant molecules in subsequent reduction reactions. The results reported herein present the potential of Cu + Co@OPF as highly efficient, cheaper, recoverable, universally applicable nanocatalyst and we advocate that its mass production would be highly useful in wastewater treatment.

Different metal nanoparticles (MNPs) templated on chitosan-silica (CH-SiO2) nanocomposite fiber were prepared via simple and fast method of the metal ions uptake by fiber and their subseqent reduction using strong reducing agent. The performance difference of CH-SiO2 templated with Cu, Co, Ag and Ni nanoparticles for both reduction of 4-nitroaniline (4-NA) and decolorization of congo red (CR) was investigated. The Cu nanoparticles loaded CH-SiO2 (Cu/CH-SiO2), showed high catalytic efficiencies in the reduction of 4-NA and CR, as compared to other loaded MNP fibers. The apparent rate constants of 6.17 × 10−3 s−1 and 1.68 × 10−2 s−1 and turnover frequencies (TOF) of 4.693 h−1 and 3.965 h−1 were observed for the reduction of 4-NA and CR, respectively. In addition, the catalytic activity of Cu/CH-SiO2 catalyst was also examined and found efficient in the reduction of nitrophenols (2-NP, 3-NP and 4-NP), and other dyes. Thus, Cu/CH-SiO2 with excellent catalytic activity can also be employed for other applications.

In the present study, ginger rhizome powder based catalysts were synthesized for the reduction of 2‑nitrophenol (2-NP), 4‑nitrophenol (4-NP), methyl orange (MO), congo red (CR), and rhodamine B (RhB). Three different bimetallic catalysts copper-silver (Cu-Ag/GP), copper-nickel (Cu-Ni/GP) and nickel-silver (Ni-Ag/GP) loaded on ginger powder were prepared via novel and robust adsorption method. The size, morphology and structure of the synthesized catalysts were measured through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). Cu-Ag/GP and Cu-Ni/GP exhibit outstanding catalytic activity for the reduction of all tested organic compounds. Turnover frequency of Cu-Ag/GP in the case of 2-NP and 4-NP were outstanding and reached 45.86 and 81.34 h−1, respectively, while for Cu-Ni/GP, it was 27.16 and 85.83 h−1 for 2-NP and 4-NP respectively. For Cu-Ag/GP catalyst the rate constants were 1.21 × 10−3 s−1, and 4.05 × 10−3 s−1 for 2-NP and 4-NP respectively, while for Cu-Ni/GP, it was 1.11 × 10−3 s−1, and 6.08 × 10−3 s−1 for 2-NP and 4-NP respectively. The prepared catalysts were also used for the reduction of a mixture of dyes and NPs. Besides, the synthesized catalysts showed excellent reusability and stability.

Chemical sensing and electrical transport properties of neodymium coblate, NdCoO3, was investigated in this work. It was prepared by using co-precipitation method. Pure neodymium chloride and cobalt chloride were mixing in the presence of sodium hydroxide and the obtained co-precipitated powder was calcined at 850 and 1000 °C. The synthesized composites, as-grown (NdCoO3-I), calcined at 850 °C (NdCoO3-II), and calcined at 1000 °C (NdCoO3-III) were studied in details in terms of their morphological and structural properties. The X-ray analysis confirmed that the synthesized products are well crystalline possessing single phase orthorhombic crystal system of space group Pbnm (62). The crystallite size of NdCoO3-I, NdCoO3-II, and NdCoO3-III is 22, 111, and 338 nm, respectively which reflect that crystallite size is increasing with increase in firing temperature. The DC resistivity was measured as a function of temperature in the temperature range from room temperature up to 200 °C. All NdCoO3 are semiconductor in this range of temperature but showed different activation energy which strongly depends on the crystallite size of the products. The activation energy decreased with increase in crystallite size, 0.798, 0.414 and 0.371 eV for NdCoO3-I, NdCoO3-II, and NdCoO3-III, respectively. Thus resistivity increases with increase in crystallite size of NdCoO3. All NdCoO3 products were tested as chemical sensor for acetone by electrochemical approaches and showed excellent sensitivity. Among the NdCoO3 samples, NdCoO3-III showed the highest sensitivity (3.4722 μAcm−2 mM−1) compared to other compositions and gradually decreased to 3.2407 μAcm−2 mM−1 with decreasing the crystallite size of NdCoO3-II. It is also observed that the sensitivity drastically decreased to 0.76253 μAcm−2 mM−1 in the case of NdCoO3-I. It is introduced an efficient route for the detection of environmental unsafe chemicals by electrochemical approach for the safety of healthcare and environmental fields in broad scales.

Water contamination by toxic compounds has become one of the most serious problems worldwide. Catalytic reduction using metal nanoparticles offer opportunities for environmental benefits. In this study, cellulose acetate-ferric oxide nanocomposite (CA/Fe2O3) was prepared and used as support for metal nanoparticles. After adsorption of Ag, Cu or Ni ions from aqueous solutions, metal ions associated with CA/Fe2O3 were treated with sodium borohydride to prepare Ag, Cu and Ni nanoparticles loaded CA/Fe2O3. The CA/Fe2O3 supported Ag, Cu or Ni nanoparticles was evaluated as a catalyst for pollutants degradation. Silver nanoparticles (Ag@CA/Fe2O3) exhibit remarkable decomposition for methyl orange dye and p-nitrophenol in short time. The rate constant for methyl orange and p-nitrophenol were 8.58×10-3 and 4.77×10-3s-1, respectively. Besides the good catalytic activities of Ag@CA/Fe2O3, the catalyst could be easily recovered from the reaction medium by pulling the catalyst after completion of the reduction reaction. The recovered catalyst can be recycled several times if their exposure time to air was minimal.

We designed and synthesized a metal-free organic sensitizer based on phenothiazine as the core moiety for application in dye-sensitized solar cells (DSCs). The structure of the donor–π–bridge–acceptor (D–π–A) dye 3-(5-(7-((E)-3,4,5-trimethoxystyryl)-10-octyl-10H-phenothiazin-3-yl)thiophen-2-yl)-2-cyanoacrylic acid (TMPTZT) has tri-methoxy phenyl as a donor segment on a phenothiazine core and cyanoacrylic acid as an acceptor group. In this study, we investigated the influence of iodide/triiodide and Co(bpy)32+/3+ complexes as redox electrolytes on the DSC device performance. The maximal monochromatic incident photon to current conversion efficiency (IPCE) reached a value of 70%. The solar light to electrical energy conversion efficiency of the devices with a volatile solvent based iodide/triiodide electrolyte reached up to 5.1% at AM 1.5G illumination, whereas the devices with Co(bpy)32+/3+ and ionic liquid electrolytes showed efficiencies of 4.9% and 4.5%, respectively. The DSC devices were characterized using charge extraction and Voc decay techniques to understand the difference in the photovoltaic performance of this metal free organic dye with these three types of redox electrolytes.

Nanoparticles were synthesized on the surface of green nanocomposite based on carbon black dispersed in chitosan (CB–CS) fibres. The nanoparticles were monometallic Co, Ag and Cu and bimetallic Co + Cu and Co + Ag. The CB–CS fibres were prepared and introduced into separate metal salt solutions containing Co 2+ , Ag + and Cu 2+ and mixed Co 2+ +Cu 2+ and Co 2+ +Ag + ions. The metal ions immobilized on the surface of CB–CS were reduced using sodium borohydride (NaBH 4 ) as reducing agent to synthesize the corresponding zero-valent metal nanoparticles-loaded CB–CS fibres. All the nanoparticles-loaded CB–CS samples were characterized using field emission-scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. When tested as catalysts, the nanoparticles-loaded CB–CS showed excellent catalytic ability for the reduction of toxic and environmentally unwanted pollutants of para -nitrophenol, congo red and methyl orange dyes. Afterwards, the antimicrobial activities of virgin and metal-loaded CB–CS fibres were tested and the metal-loaded CB–CS fibres were found to be effective against Escherichia coli . In addition, the catalyst can be recovered easily by simply removing the fibres from the reaction mixture and can be recycled several times while maintaining high catalytic efficiency.

In this study, cellulose acetate (CA)/iron oxide nanocomposites (NC1 and NC2) were synthesized and utilized as extractors for the selective separation of fluorene from aqueous samples. The selectivity of nanocomposites to different organic compounds was assessed. Based on the results, fluorene was the most quantitatively adsorbed on NC2. Batch method was performed by varying the initial fluorene concentrations and contact time. Langmuir and Freundlich isotherms were used for modeling the experimental data and were best correlated by the Langmuir model. Adsorption data were also followed the pseudo-second-order kinetic model. Finally, validation of the developed method was achieved for fluorene determination in real water samples.

The study concentrate on the biosynthesis of silver nanoparticles (AgNps) from the leaves extract of Guiera senegalensis with focus on its; antiproliferation effect on prostate (PC3), breast (MCF7) and liver (HepG2) cancer cell lines, antibacterial effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) and the degradation on 4-nitrophenol (4-NP) and congo red dye (CR). The synthesized AgNps were characterized by FTIR, TEM, FESEM, XRD and EDX analysis. The EDS spectrum revealed that the synthesized nanoparticles (Nps) were composed of 55.45% Ag atoms of spherical shape with approximately 50nm size, identified from TEM and FESEM data. The antiproliferation effect of the AgNps varies with cell lines in a concentration dependent manner. The result showed that the AgNps were more effective on PC3 (IC50 23.48μg/mL) than MCF7 (29.25μg/mL) and HepG2 (33.25μg/mL) by the virtue of their IC50 values. The AgNps were highly effective against E. coli and S. aureus by killing 99% colonies. The AgNps also shows a good catalytic reduction of the toxic organic pollutants in which only 3mg of the AgNps degraded 95% of both CR dye and 4-NP in 22 and 36min respectively. Therefore, the green synthesis of AgNps may have potential applications in pharmacology and industries for the treatment of cancers, bacterial infections and in degrading toxic organic pollutants in water.

In this report, we prepared chitosan (CS) membrane, CS/zinc phthalocyanine (ZnPc-CS) composite fibers and pellets as support for the synthesis of zero valent metal nanoparticles. The composite fibers and pellets of ZnPc-CS were prepared by simply dispersing 5wt% of ZnPc in CS solution. ZnPc-CS composite were applied as economical host material for the development of metallic and bimetallic zero valent nanoparticles. The composites of ZnPc-CS were put in 0.1M metals salt solutions (mono- and bi-metallic) for the adsorption of metal ions. The metal ions adsorbed ZnPc-CS fibers were treated with 0.1M sodium borohydride (NaBH4) aqueous solution for conversion of metal ions into nanoparticles. Thus, through water based in-situ preparation process, metals nanoparticles loaded on ZnPc-CS composite fibers and pellets were achieved. The presence of respective metals nanoparticles on the composite fibers was confirmed using FE-SEM, XRD and FTIR. Moreover, we determined that these composites exhibit excellent catalytic efficiency and recyclability in the reduction reactions of 4-nitrophenol (4-NP), methyl orange (MO) and cango red (CR). In addition, these composites displayed high antibacterial activity as tested against pathogenic bacteria Escherichia coli.

A simple method to prepare cobalt nanoparticles (CoNPs) in an aqueous environment was developed utilizing 4-aminophenol as a reducing agent and the gemini surfactant (14-4-14)/polyvinylpyrrolidone (PVP) as a stabilizer. The localized surface plasmon resonance band of cobalt nanoparticles in the UV-Vis spectrum was used to determine the rate of formation of cobalt nanoparticles and to assess the beginning of the oxidation process. The effect of the concentration cobalt nitrate, 4-aminophenol, 14-4-14 and PVP was investigated on the growth rate of CoNPs. The data obtained in this work provide valuable information on the rate of reaction at the nanoscale.

In the present study, Ce based catalysts were synthesized for the degradation of acridine orange (AO). The Ce-Sr and Ce-Cd oxides were synthesized through sol-gel method and applied for the degradation of acridine orange dye (AO) under visible light influence for environmental remediation. 0.03 mM AO was prepared and 1 g/L of the Ce-Cd and Ce-Sr oxides were applied for degradation of AO. The structure and morphology of the synthesized materials were examined through field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR) and the HOMO and LUMO energy differences were determined through diffuse reflectance spectroscopy (DRS). Both the catalysts were grown in sheet morphology; and the average size of each sheet in Ce-Cd oxide is approximately equal to 790 nm while its average particle size is approximately equal to 20–25 nm, but Ce-Sr oxide average sheet size and particle size were smaller than Ce-Cd oxide. The band gap 2.65 and 2.7 eV for a Ce-Sr and Ce-Cd oxides signifies the high catalytic performance under visible light. The photocatalytic performances of Ce-Cd and Ce-Sr were evaluated against AO dye which resulted 90.2 and 86.6% degradation in 3 h under visible light. These studies showed the high efficiency of Ce based catalysts for environmental remediation.

Humidity and temperature sensing electric properties of pristine Fe 2 O 3 -Co 3 O 4 nanoparticles and its nanocomposites were measured after fabrication of the sensors. Fe 2 O 3 -Co 3 O 4 nanoparticles were synthesized via cheap, simple and low temperature method while its nanocomposite were prepared by mixing with different ratio of polymer adhesive. It was found that the impedance magnitude of the pristine and its composite samples decreased 3.33 and (2.31–3.00) times while the capacitance increased 3.50 and (1.89–3.33) times with an increment of relative humidity in the range 25–95% at 1 kHz respectively. It was found that with the change of temperature in the range of 25–70 °C, the value of impedance of the samples decreases 1.34 and (1.33–1.8) times. The average temperature sensitivity of the samples was found to be − 0.533%/°C and −(0.555–0.988)% °C − 1 .

Sensor technology demands to design a sensing system having higher sensitivity, sufficient selectivity, fast response time and efficient reproducibility with simple operating and recognition methodology. The chemical and biosensors with aforementioned features have been still challenging since several decades. Therefore we effectively designed graphene oxide nanocomposite based sensing system which exhibited remarkable electrocatalytic performance towards the recognition of key biomolecule, i.e., hydrogen peroxide (H 2 O 2 ) in a single step which reflects strong interaction between graphene oxide based nanocomposite and H 2 O 2 . Graphene oxide based nanocomposite was prepared by low cost and low temperature facile method and characterized by different spectroscopic techniques. The electrochemical sensing of as prepared nanocomposite towards H 2 O 2 was assessed using cyclic voltammetry (CV) and DC potential amperometry (DCPA at potential −0.570 V vs. Ag/AgCl reference electrode) in a phosphate buffer (pH = 7.0). The designed H 2 O 2 biosensor displayed high sensitivity (−0.2844 ± 0.0169 µA nM −1 cm −2 ), low detection limit (5 nM) with wide linear dynamic range (0.01–0.05 µM) and fast response time of less than 3 s. The performance of the sensor was optimized with various pH and different scan rates. Selectively, the biosensor recognized H 2 O 2 in the presence of glucose, uric acid and ascorbic acid, as interfering agent. Further evaluation of designed biosensor was made on commercially available cosmetic product with state of the art percent recovery value. Precisely, the designed biosensor would be a promising candidate for the electrochemical recognition and quantification of H 2 O 2 .

In present study, magnetic chitosan-graphene oxide composite (ᶆC-GO) has been synthesized and used for the removal of two common textile dyes; acid red-17 (AR-17) and bromophenol blue (BPB). The effect of various parameters including pH (2–8), time (10–100 min), adsorbent dosage (2–10 mg), initial dye concentration (2–30 μg mL−1) as well as temperature (303, 313, and 323 K) was investigated. The point of zero charge of composite was determined using pH drift method in an attempt to better understand the adsorption process. Present work revealed fast adsorption kinetics with removal efficiency of around 79 and 97% for AR-17 and BPB, respectively, under optimized conditions. Besides, equilibrium relationships were studied using Langmuir and Freundlich models. Thermodynamic analysis uncovered the spontaneous and endothermic nature of dye-composite interation. Synthesized material showed profound stability after five successive adsorption-desorpion cycle of reuse. Importantly, spiked real water samples were used to check the suitability of composite adsorbent for practical applications. High % recoveries were obtained which indicated that complex matrix presented insignificant interference effects. Also, comparative study revealed that composite material offers superior performance for the removal of dyes relative to precursors (C, Fe3O4 nanoparticles, GO). Improvement in removal efficiency of synthesized composite toward selected dyes can be attributed to intrinsic qualities of C and incorporated functionalities; exceptionally high surface area as well as excellent mechanical properties of GO and convenience of magnetic separation because of Fe3O4 nanoparticles. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

Zinc–iron–selenide (ZnSe–FeSe) composite was successfully prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer Emmett–Teller (BET), X-ray photoelectron microscopy (XPS), Fourier transform infrared microscopy (FT-IR), and ultraviolet visible spectroscopy (UV/VIS). The developed nanomaterial having particle size of less than 10 nm was very sensitive to the visible light and an excellent photocatalyst selected for acridine orange (AO) degradation. ZnSe–FeSe has the ability to selectively degrade acridine orange (AO) in the presence of methyl orange (MO) and indigo carmine (IC) and its activity is as high as compared to other reported in degradation of AO dye by visible light irradiation. Reusability up to three cycles without decrease in catalytic activity and stability makes ZnSe–FeSe suitable for practical applications under visible light. Further the pH was optimized to degrade maximum AO. Minimum recombination rate of photogenerated carries of ZnSe–FeSe is the reason of its maximum photocatalytic activity. This innovative loom provides a novel itinerary for synchronized degradation of AO in single step, so for environmental safety it is the most economic and fast contrivance.

Nanocomposite membrane (PES-CA-Ag2O) with disinfection properties were developed by inclusion of silver oxide (Ag2O) in polyethersulfone (PES) and cellulose acetate (CA) polymers. Pure PES, CA, PES-CA and nanocomposite membranes were prepared by casting method. Further copper (Cu) nanoparticles were grown on the surface of PES-CA membrane (Cu0@PES-CA) and nanocomposite membrane (Cu0@PES-CA-Ag2O). Structures, compositions and morphologies of all the prepared membranes were confirmed by XRD, FTIR and FESEM techniques. Various properties of PES, CA, PES-CA, PES-CA-Ag2O, Cu0@PES-CA and Cu0@PES-CA-Ag2O were comprehensively studied including water permeation flux, porosity, bovine serum albumin (BSA) rejection, mechanical properties and contact angle measurement. Permeability of the PES-CA and PES-CA-Ag2O was around 63.3 and 92.88 L·h− 1·m− 2 bar− 1 while after growing Cu nanoparticles on the surface of PES-CA and PES-CA-Ag2O, the water permeability reached 72.5 and 100.2 L·h− 1·m− 2 bar− 1. PES-CA-Ag2O and Cu0@PES-CA-Ag2O also showed reasonable porosity. PES-CA-Ag2O and Cu0@PES-CA-Ag2O displayed a marked increase in BSA rejection (88.8 and 89.5, respectively) and the contact angle decreased from 73° to 63.5° and 60.25°, respectively proving the hydrophilic nature of the synthesized materials. Removal of toxic p-nitrophenol from aqueous media is challenging task due to its sorption fouling and tough degradation at lower concentrations. Catalytic reduction capacity of the Cu0@PES-CA and Cu0@PES-CA-Ag2O membranes for different substituted phenols were studied comprehensively Conclusively, unprecedented catalytic potential was observed. Finally, in vitro anti-bacterial activity of the synthesized materials was also investigated against E. coli with promising potential.

Water pollution due to waste effluents of the textile industry is seriously causing various health problems in humans. Water pollution with pathogenic bacteria, especially Escherichia coli (E. coli) and other microbes is due to the mixing of fecal material with drinking water, industrial and domestic sewage, pasture and agricultural runoff. Among the chemical pollutants, organic dyes due to toxic nature, are one of the major contaminants of industrial wastewater. Adequate sanitation services and drinking quality water would eliminate 200 million cases of diarrhea, which results in 2.1 million less deaths caused by diarrheal disease due to E. coli each year. Nanotechnology is an excellent platform as compared to conventional treatment methods of water treatment and remediation from microorganisms and organic dyes. In the current study, toxicity and carcinogenicity of the organic dyes have been studied as well as the remediation/inactivation of dyes and microorganism has been discussed. Remediation by biological, physical and chemical methods has been reviewed critically. A physical process like adsorption is cost-effective, but can’t degrade dyes. Biological methods were considered to be ecofriendly and cost-effective. Microbiological degradation of dyes is cost-effective, eco-friendly and alternative to the chemical reduction. Besides, certain enzymes especially horseradish peroxidase are used as versatile catalysts in a number of industrial processes. Moreover, this document has been prepared by gathering recent research works related to the dyes and microbial pollution elimination from water sources by using heterogeneous photocatalysts, metal nanoparticles catalysts, metal oxides and enzymes.

Substances at nanoscale commonly known as “nanomaterials” have always grabbed the attention of the researchers for hundreds of years. Among these different types of nanomaterials, magnetic nanomaterials have been the focus of overwhelming attention during the last two decades as evidenced by an extraordinary increase in number of research papers. Iron oxide magnetic nanoparticles have occupied a vital position in imaging phenomena; as drug vehicles, controlled/sustained release phenomena and hyperthermia; atherosclerosis diagnosis; prostate cancer. In fact, these are wonderful “theranostic” agents with some are under clinical trials for human use. In this review, we have attempted to highlight the advances taking place in the field of magnetic nanoparticles as theranostic agents. Extensive progress has been made in the two most important parameters viz. control over size and shape which decide the importance of iron oxide magnetic nanoparticles by developing suitable procedures like precipitation, co-precipitation, thermal decomposition, hydrothermal synthesis, microemulsion synthesis and plant mediated synthesis. After suitable synthetic route, workers encounter the most daunting task linked with the materials at nanoscale i.e. the protection against corrosion. Only properly protected iron oxide magnetic nanoparticles can be further connected to different functional systems to make building blocks for application in catalysis, biology and medicines. Finally, iron oxide magnetic nanoparticles play a key role in imaging applications for diagnostic purposes, drug delivery vehicles and above all the combined effect of previous two phenomena “theranostics”. With all the potential uses, toxicity of the of iron oxide magnetic nanoparticles has also been discussed. In the end, attention has been drawn to address the future of research trends of iron oxide magnetic nanoparticles in theranostics.

This study describes an effective method developed for the removal of hexavalent chromium, Cr(VI), from an aqueous environment. In this study, the Ni– $$\hbox {SiO}_{{2}}$$ nanomaterial was synthesized by the sol–gel method and then characterized by field emission scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy. The prepared nanomaterial was then employed as an adsorbent with significant properties of high surface area and uptake capacity. Adsorption conditions of Cr(VI) onto the Ni– $$\hbox {SiO}_{{2}}$$ nanomaterial were optimized by altering different parameters (pH, initial Cr(VI) concentration and different periods of time). An amount of 100.75 mg $$\hbox {g}^{-1}$$ was estimated as the maximum uptake capacity of the Ni– $$\hbox {SiO}_{{2}}$$ nanomaterial at pH 4.0. The experimental data of Cr(VI) adsorption onto the Ni– $$\hbox {SiO}_{{2}}$$ nanomaterial were fitted well to the Langmuir isotherm and pseudo second-order kinetic models. Moreover, the adsorption of Cr(VI) onto the Ni– $$\hbox {SiO}_{{2}}$$ nanomaterial was not influenced even in the presence of different coexisting ions. Finally, the recommended methodology was applied on several environmental water samples.

Cost-effective and efficient electrocatalysts for hydrogen generation are appealing and highly required. Here, we present copper oxide-nickel oxide nanospheres (CuO-NiO@GP), copper oxide-cobalt oxide nanospheres (Cu2O-Co3O4@GP), CuO-NiO/carbon nitride nanocomposite (CuO-NiO/CN@GP) and Cu2O-Co3O4/carbon nitride nanocomposite (Cu2O-Co3O4/CN@GP) decorated graphite pencil as effective electrocatalysts for oxygen and hydrogen evolution reactions (OER, HER). CuO-NiO@GP, Cu2O-Co3O4@GP, CuO-NiO/CN@GP and Cu2O-Co3O4/CN@GP were used as working electrode and revealed tremendous OER and HER activity at low over-potentials in KOH and H2SO4 solutions. Among, CuO-NiO@GP, CuO-NiO/CN@GP, Cu2O-Co3O4@GP and Cu2O-Co3O4/CN@GP, the superior catalytic activity is displayed by CuO-NiO/CN@GP which gave current density of 20 mAcm−2 at potential of 1.411 V (overpotential = 0.181 V) by using 1.0 M KOH concentration. CuO-NiO/CN@GP demonstrated higher catalytic performance toward OER as comparing to CuO-NiO@GP, Cu2O-Co3O4@GP and Cu2O-Co3O4/CN@GP. Similarly, CuO-NiO/CN@GP need the lowest potential of −0.762 and −0.858 V to obtain the current density of 10 mAcm−2 and 20 mAcm−2 in HER catalytic performance utilizing 0.5 M H2SO4 solution. Thus, it was observed from the LSVs of CuO-NiO@GP, CuO-NiO/CN@GP, Cu2O-Co3O4@GP and Cu2O-Co3O4/CN@GP that CuO-NiO/CN@GP shows greater catalytic activity and found more efficient and active in both OER and HER because CuO-NiO/CN@GP requires a low over potential, which produced 10 mAcm−2 and 20 mAcm−2 in both OER and HER. CuO-NiO/CN@GP demonstrates lower Tafel slopes of 171 mV dec−1 and 129 mV dec−1 in HER and OER, respectively.

In this work, an efficient electrochemical sensor has been designed by simple coating on the surface of glassy carbon electrode (GCE) using zinc oxide doped iron oxide (Zn/Fe) nanocomposite, which was employed for the simultaneous detection of Cd(II), Pb(II) and Cu(II) in real water samples. Zn/Fe nanocomposite was prepared and characterized by different spectroscopic techniques. It was casted on GCE surface and employed to detect metal ions sensitively. The electrocatalytic behavior of Zn/Fe coated GCE toward the redox reactions of Cd(II), Pb(II) and Cu(II) was studied via the electrochemical technique. The analytical performance for the detection of the metal ions was assessed individually and simultaneously. It was found that the Zn/Fe coated GCE can sense Cd(II), Pb(II) and Cu(II) simultaneously and their detection is feasible, however, it is more sensitive toward the detection and quantification of Pb(II) in the multi-component sample. The developed sensor exhibited tremendous sensing performance and rapid response toward Pb(II) with higher sensitivity (0.235 μALmg −1cm−2) and lower limit of detection (0.04 mgL−1). Further various analytical parameters were optimized for investigating Cd(II), Pb(II) and Cu(II) in real samples. The results suggested that the design of a very simple, fast and efficient electrochemical sensing system for toxic heavy metals in low-level determination is effectively possible.

A series of La-Sn oxide catalysts were synthesized by facile low temperature hydrothermal procedure. La-Sn oxide nanoparticles were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and UV-visible spectroscopy. The FESEM and XRD analysis revealed the growth of nanoparticles with homogeneous morphology, high crystallinity and particle size of < 20 nm. The synthesized nanoparticles showed excellent catalytic activity for the synthesis of cyclohexanones. The effect of variations in La and Sn contents on the progress of reaction was estimated by yield of the products. The recovery of the catalysts after the completion of reactions was also assessed.

The article describes synthesis and sensing properties of SnO2–Co3O4 spheres composed of aggregated nanoparticles. Co3O4 was doped with pristine SnO2, and the resulting nanocomposite spheres were incorporated into a silicon adhesive. This material is shown to enable impedimetric sensing of relative humidity (RH). The impedance of the material decreases by 80% at a 1.0 kHz working frequency and by a factor of 2500 at 100 Hz. Capacitance increases by 70% at 1.0 kHz frequency and by a factor of 1509 at 100 Hz. The sensor works in the 10–90% RH range at temperatures from 10 to 80 °C. SnO2–Co3O4 based humidity sensor exhibited high sensitivity which makes it suitable material for the utilization in humidity meter.