Mebrahtu H . Kahsay

Health concerns about the toxicity of arsenic compounds have therefore encouraged the development of new analytical tools for quick monitoring of arsenic in real samples with improved sensitivity, selectivity, and reliability. An overview of advanced optical colorimetric sensor techniques for real-time monitoring of inorganic arsenic species in the environment is given in this review paper. Herein, several advanced optical colorimetric sensor techniques for arsenite (As +3) and arsenate (As +5) based on doping chromogenic dyes/reagents, biomolecule-modified nanomaterials, and arsenic-binding ligand tethered nanomaterials are introduced and discussed. This review also highlights the benefits and limitations of the colorimetric sensor for arsenic species. Finally, prospects and future developments of an optical colorimetric sensor for arsenic species are also proposed. For future study in this sector, particularly for field application, authors recommend this review paper will be helpful for readers to understand the design principles and their corresponding sensing mechanisms of various arsenic optical colorimetric sensors.

AbstractWe report, an aqueous pod extract of Dolichos lablab L. mediated synthesis of magnetite nanoparticles (Fe3O4 NPs) for an efficient adsorption of organic dye pollutant from contaminated water. The Fe3O4 NPs were capped and stabilized with phytoconstituents of D. lablab L. The product Fe3O4 NPs was characterized by range of instrumental facilities such as Ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, FT-Raman spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, Energy dispersive X-ray spectroscopy, Transmission electron microscopy, vibrating sample magnetometer, and thermogravimetric analysis. The synthesized 12.5 nm spherical shaped Fe3O4 NPs were used as adsorbent for elimination of crystal violet (CV) from contaminated water. It is found that the dye removal efficiency of Fe3O4 NPs was critically depends on pH of the reaction medium and dosage of Fe3O4 NPs. Adsorption data were analyzed using Langmuir, Freundlich, and Temkin isotherms as well as pseudo-first-order and pseudo-second-order kinetic models. The overall outcome of adsorption best fitted to Langmuir and psepseudo-second-order with their corresponding correlation coefficients of (R2 = 0.996) and (R2 = 0.977), respectively The biomolecules capped can act as a valuable adsorbent for removal of pollutant organic dyes from industrial outflow. Graphical abstractᅟ

Abstract In this paper, we report for the first time an eco-friendly method for the preparation of silver nanoparticles (Ag NPs) using an aqueous leaf extract of Dolichos lablab as reducing and capping agents using UV–vis, FT-IR, XRD, FE-SEM, EDX and TEM. The crystallinity, phase purity, size and morphology of Ag NPs were investigated by UV–vis, FT-IR and XRD. The spectroscopic and microscopic results revealed the formation of Ag NPs. The morphology of Ag NPs is found to be spherical with an average diameter of 9 nm. As prepared Ag NPs effectively reduced the 4-Nitrophenol to 4-Aminophenol in the presence of NaBH4. The Ag NPs showed potent antimicrobial activity against Escherichia coli and Bacillus subtilis. Ag NPs also exhibited anticancer activity against human liver cancer (Hep G2) cell line.

We have reported a facile, green synthesis of reduced graphene oxide (RGO) grafted Ag/ZnO (RGO-Ag/ZnO) nanocomposite in the presence of L-Methionine (L-Met) for synergetic photocatalytic degradation of methylene blue (MB) and antibacterial activities. L-Met shows an excellent efficiency as stabilizing and reducing agents for the synthesis of both Ag NPs and RGO. The successful synthesis of pure phase L-Met-RGO-Ag/ZnO was confirmed by XRD. According to UV-DRS analysis, the doping of Ag resulted in a decrease bandgap energy of ZnO from 3.34 eV to 3.18 eV. The mixed morphologies of the nanocomposite were studied by SEM and TEM. The photocatalytic degradation efficiency of L-Met-RGO-Ag/ZnO towards MB dye was investigated at varying initial concentrations of MB dye, H 2 O 2 , and ultrasonication. The optimum degradation efficiency of the nanocomposite (50 mg) at room temperature (25°C) was found to be 99% with an initial MB dye concentration of 10 mg/L and 120 min contact time. The fast degradation of MB dye was observed in the presence of H 2 O 2. The ultrasonication of the catalyst vanishes the synergetic interface of the nanocomposite, as a result, poor photocatalytic performance (85%) was observed even at a long period of contact time (210 min). Moreover, RGO-Ag/ZnO nanocomposites have shown strong antibacterial activity against both Gram-positive bacteria (B. Subtilis) and Gramnegative bacteria (E. coli). In conclusion, RGO-Ag/ZnO nanocomposite shows a promising photocatalyst for the degradation of organic dyes and antibacterial activities.

Facile and green one pot hydrothermal method was used for synthesis of fluorescent carbon quantum dots (CQDs) using citrus lemon juice as precursor. The synthesized CQDs were characterized using UV–Vis spectrophotometer, fluorescence spectrometer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscope equiped with energy dispersive X-ray spectroscopy (FESEM-EDS) and fluorescence microscopy. The obtained CQDs have high photoluminescence of 10.20% quantum yield. The photoluminescence intensity of CQDs depends on pH of the solution and maximum intensity obtained at pH of 6. The particle size of the carbon dots were distributed in narrow range of 2–10 nm with an average of 5.8 nm. The highly water soluble CQDs have high cell viability even at high concentration which rich up to 85%. MTT assay was used to investigate the potential application of CQDs and the results indicated that the ma...

Nanotechnology is a recent field of modern research dealing with synthesis, strategy and manipulation of particle’s structure in size range of 1–100 nm. This study introduces one of the methods of synthesis of nanoparticles, i.e., green synthesis of ZnO NPs using aqueous leaf extract of Becium grandiflorum (AM: ‘Yedegamentisie’). The biomolecules of the plant extract (such as phenols, flavonoids, saponins, glycosides, steroids, tannins and alkaloids) were used as capping and reducing agent during synthesis of ZnO NPs. Response surface methodology coupled with Box-Behnken design (RSM-BBD) was used to optimize the synthesis of ZnO NPs and adsorption studies of the as-synthesized ZnO NPs. Then, ZnO NPs was characterized using different spectroscopic and microscopic instruments such as UV–Vis spectroscopy, FTIR, XRD and SEM–EDS to consider its purity, shape and crystallinity. UV–Vis analysis showed peaks in the range 305–312 nm due to synthesis of ZnO NPs. FTIR analysis showed the avail...

Carbon quantum dots (CQD) as the result of their exceptional physical and chemical properties show tremendous potential in various field of applications like cell imaging and doping of CQDs with elements like nitrogen and phosphorous increase its fluorescence property. Herein, we have synthesized fluorescent nitrogen and phosphorous codoped carbon quantum dots (NPCQDs) via a one-pot hydrothermal method. Sesame oil, L-Aspartic acid, and phosphoric acid were used as carbon, nitrogen, and phosphorous sources, respectively. UV-Vis spectrophotometer, fluorescence spectrometer, Fourier transform infrared spectrometer (FTIR), X-ray diffraction spectrometer (XRD), field emission scanning microscopy (FESEM), and transmission electron microscopy (TEM) were employed to characterize the synthesized fluorescent NPCQDs. The as-synthesized NPCQDs with a particle size of 4.7 nm possess excellent water solubility, high fluorescence with high quantum yield (46%), high ionic stability, and resistance to photobleaching. MTT assay indicated the biocompatibility of NPCQDs and it was used for multicolor live-cell imaging. Besides, the NPCQDs show an effective probe of iron ions (Fe3+) in an aqueous solution with a high degree of sensitivity and selectivity. The DPPH assay showed its good antioxidant activity.

L-Aspartic acid (L-Asp) functionalized magnetite nanoparticles (Fe3O4 NPs) were synthesized through a facile co-precipitation method using L-Asp as a capping agent. UV–Vis, FTIR, XRD, SEM, EDS, TEM, and VSM techniques were used to investigate the formation, morphology, elemental composition, and magnetic properties of the synthesized Fe3O4 NPs. Highly crystalline and spherical shaped pure phase Fe3O4 NPs were successfully synthesized using amino acid as a capping agent. The magnetic measurement analysis confirms the superparamagnetic nature of the synthesized L-Asp capped Fe3O4 NPs. The adsorption efficiency of L-Asp capped Fe3O4 NPs was assessed by the removal of Rhodamine B (RhB). The optimum removal efficiency was found to be 7.7 mg g−1 using 1 mg mL−1 adsorbent, and 30 mg L−1 RhB at pH 7 and 25 °C. The regression (R2adj) and standard deviation (SD) analysis were used to validate both kinetic and isotherm models. Avrami fractional-order and Liu models were selected as the best ki...

Facile and green one pot hydrothermal method was used for synthesis of fluorescent carbon quantum dots (CQDs) using citrus lemon juice as precursor. The synthesized CQDs were characterized using UV–Vis spectrophotometer, fluorescence spectrometer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscope equiped with energy dispersive X-ray spectroscopy (FESEM-EDS) and fluorescence microscopy. The obtained CQDs have high photoluminescence of 10.20% quantum yield. The photoluminescence intensity of CQDs depends on pH of the solution and maximum intensity obtained at pH of 6. The particle size of the carbon dots were distributed in narrow range of 2–10 nm with an average of 5.8 nm. The highly water soluble CQDs have high cell viability even at high concentration which rich up to 85%. MTT assay was used to investigate the potential application of CQDs and the results indicated that the ma...

Abstract In this paper, we report for the first time an eco-friendly method for the preparation of silver nanoparticles (Ag NPs) using an aqueous leaf extract of Dolichos lablab as reducing and capping agents using UV–vis, FT-IR, XRD, FE-SEM, EDX and TEM. The crystallinity, phase purity, size and morphology of Ag NPs were investigated by UV–vis, FT-IR and XRD. The spectroscopic and microscopic results revealed the formation of Ag NPs. The morphology of Ag NPs is found to be spherical with an average diameter of 9 nm. As prepared Ag NPs effectively reduced the 4-Nitrophenol to 4-Aminophenol in the presence of NaBH4. The Ag NPs showed potent antimicrobial activity against Escherichia coli and Bacillus subtilis. Ag NPs also exhibited anticancer activity against human liver cancer (Hep G2) cell line.

In this study, disinfection of water using a simple and green approach using natural Solar Radiation Disinfection (SODIS) techniques has been investigated. The water samples in a colorless polyethylene plastic were irradiated with solar radiation. The reduction of Total Coliform (TC) using solar radiation further investigated by introducing aluminum foils and mirrors as activators for the sterilization of TC. The raw water samples were obtained from local municipal drinking water and ponds in Shoa Robit and the surrounding rural areas. The total coliform reduction potential of SODIS results 99.9 % decontamination at the end of six hours. Moreover, the results were showed that the disinfection process succeeded at the end of six hours using either of activators or not at Shoa Robit and neighboring rural kebeles. However, the relative disinfection efficiency varies with the following order; treatment using mirrors > aluminum foil > treatment without activators.

This work reports the synthesis and application of magnetic rGO/Fe3O4 NCs using a pod extract of Dolichos lablab L. as areducing agent. GO was synthesized by a modified Hummers method, however GO was reduced using the plant extract to produce rGO. The as-synthesized rGO/Fe3O4 NCs were characterized by UV-vis spectrophotometer, Fourier transform infrared (FT-IR) spectroscopy, FT-Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy supported with energy dispersed X-ray spectroscopy (FESEM-EDX), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The synthesis of magnetic rGO/Fe3O4 NCs was confirmed from characterization results of FT-Raman, TEM and VSM. The FT-Raman results showed the D and G bands at 1306.92 cm À1 and 1591 cm À1 due to rGO and a peak at around 589 cm À1 due to Fe3O4 NPs that were anchored on rGO sheets; TEM results showed the synthesis of Fe 3 O 4 with an average particle size of 8.86 nm anchored on the surface of rGO sheets. The VSM result confirmed the superparamagnetic properties of the rGO/Fe3O4 NCs with a saturation magnetization of 42 emu g À1. The adsorption capacity of rGO/Fe3O4 NCs towards crystal violet (CV) dye was calculated to be 62 mg g À1. The dye removal behavior fitted well with the Freundlich isotherm and the pseudo-second-order kinetic model implies possible chemisorption. Besides, rGO/Fe 3 O 4 NCs showed antifungal activities against Trichophyton mentagrophytes and Candida albicans by agar-well diffusion method with a zone inhibition of 24 mm and 21 mm, respectively. Therefore, rGO/Fe3O4 NCs can be used as an excellent adsorbent to remove organic dye pollutants and kill pathogens.

In this study, we report a green and economical hydrothermal
synthesis of fluorescent-nitrogen-doped carbon quantum dots (NCQDs) using
citrus lemon as a carbon source. The prepared NCQDs possess high water
solubility, high ionic stability, resistance to photobleaching, and bright blue
color under ultraviolet radiation with a high quantum yield (∼31%). Highresolution
transmission electron microscopy (HRTEM) results show that the
prepared NCQDs have a narrow size distribution (1−6 nm) with an average
particle size of 3 nm. The mercury ion (Hg2+) sensing efficiency of the NCQDs
was studied, and the result indicated that the material has high sensitivity, high
precision, and good selectivity for Hg2+. The limit of detection (LOD) is 5.3
nM and the limit of quantification (LOQ) is 18.3 nM at a 99% confidence
level. The cytotoxicity was evaluated using MCF7 cells, and the cell viabilities
were determined to be greater than 88% upon the addition of NCQDs over a
wide concentration range from 0 to 2 mg/mL. Based on the low cytotoxicity, good biocompatibility, and other revealed interesting
merits, we also applied the prepared NCQDs as an effective fluorescent probe for multicolor live cell imaging.

We report a facile one-pot green synthesis of zinc oxide (ZnO) nanostructures using aqueous leaf extract of Dolichos Lablab L. as the reducing and capping agent. The optical properties, structure and morphology of the as-synthesized ZnO nanostructures have been characterized by UV-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) supported with energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). TEM analysis revealed that the as-synthesized ZnO nanostructures have an average particle diameter of 29 nm. XRD patterns confirmed the formation of phase-pure ZnO nanostructures with a hexagonal wurtzite structure. The synthesized ZnO nanostructures were used as a catalyst in the photodegradation of methylene blue (MB), rhodamine B (RhB) and orange II (OII) under visible and near-UV irradiation. The results showed the highest efficiency of photodegradation of ZnO nanostructures for MB (80%), RhB (95%) and OII (66%) at pH values of 11, 9 and 5, respectively, in a 210 min time interval. In addition, the antimicrobial activity of the ZnO nanostructures using the agar well diffusion method against Bacillus pumilus and Sphingomonas paucimobilis showed the highest zones of inhibition of 18 mm and 20 mm, respectively. Hence, ZnO nanostructures have the potential to be used as a photocatalyst and bactericidal component.

We report, an aqueous pod extract of Dolichos lablab L. mediated synthesis of magnetite nanoparticles (Fe3O4 NPs) for an efficient
adsorption of organic dye pollutant from contaminated water. The Fe3O4 NPs were capped and stabilized with phytoconstituents of
D. lablab L. The product Fe3O4 NPs was characterized by range of instrumental facilities such as Ultraviolet–visible spectroscopy,
Fourier transform infrared spectroscopy, FT-Raman spectroscopy, X-ray diffraction, Field emission scanning electron microscopy,
Energy dispersive X-ray spectroscopy, Transmission electron microscopy, vibrating sample magnetometer, and thermogravimetric
analysis. The synthesized 12.5 nm spherical shaped Fe3O4 NPs were used as adsorbent for elimination of crystal violet (CV) from
contaminated water. It is found that the dye removal efficiency of Fe3O4 NPs was critically depends on pH of the reaction medium
and dosage of Fe3O4 NPs. Adsorption data were analyzed using Langmuir, Freundlich, and Temkin isotherms as well as pseudofirst-
order and pseudo-second-order kinetic models. The overall outcome of adsorption best fitted to Langmuir and psepseudosecond-
order with their corresponding correlation coefficients of (R2 = 0.996) and (R2 = 0.977), respectively The biomolecules
capped can act as a valuable adsorbent for removal of pollutant organic dyes from industrial outflow.
Keywords Adsorption . Crystal violet . Fe3O4 NPs . Dolichos lablab pod . Green synthesis . Pseudo-second-order

Levels of essential and toxic metals in fenugreek seeds (Trigonella Foenum-Graecum L.) cultivated in different parts of Ethiopia Níveis de metais essenciais e tóxicos em sementes de fenacho (Trigonella Foenum-Graecum L.) cultivados em diferentes partes de Etiópia Summary The levels of the major (Ca, K, Na, Mg), trace (Fe, Cr, Ni, Zn, Mn, Cu, Co), and toxic (Pb, Cd) metals in the seeds of fenugreek cultivated in different regions of Ethiopia were determined by flame atomic absorption spectrophotometry (FAAS). Wet ashing was used to digest 0.5 g of fenugreek seed flour using 1.5 mL of HNO 3 and HClO 4 acid mixtures (5:1 ratio), 30 min pre-digestion time, 45 min total digestion time and a temperature of 150 °C. Thirteen elements were determined, obtaining concentrations in the following ranges: Ca (15353-36771 mg kg-1) > Fe (6041-18584 mg kg-1) ≈ K (6789-11517 mg kg-1) > Pb (615-2624 mg kg-1) > Na (201-1559 mg kg-1) > Cd (285-464 mg kg-1) > Cr (3-552 mg kg-1) > Ni (31-108 mg kg-1) > Mg (31-102 mg kg-1) > Zn (15-33 mg kg-1) > Mn (16-28 mg kg-1) > Cu (ND-35 mg kg-1) > Co (4-15 mg kg-1). A statistical analysis of variance (ANOVA) at the 95% confidence level revealed there were significant differences between the mean metal contents of fourteen sample means, except for Zn. Pearson's correlation revealed weak positive or negative linear relationships, which implies that the presence of one metal did not affect the presence of the other metals within the plant, except for a few metals. The study showed that fenugreek seeds were a good source of essential metals. However, they also contained large amounts of the toxic metals Cd and Pb and therefore should not be consumed daily. Resumo Os níveis dos metais majoritários (Ca, K, Na, Mg), traços (Fe, Cr, Ni, Zn, Mn, Cu, Co) e tóxicos (Pb, Cd) nas sementes de fenacho, cultivadas em regiões diferentes de Etiópia, foram determinados por espectrofotometria de absorção atómica com chama (EAAC). A incineração á úmido foi usada para digerir 0,5 g da farinha das sementes de fenacho, usando 1,5 mL de uma mistura dos ácidos HNO 3 e HClO 4 (relação de 5:1), com 30 min de digestão prévia, 45 min de digestão total a temperatura de 150 ºC. Treze elementos foram determinados, obtendo-se concentrações nas seguintes faixas: Ca (15353-36771 mg kg-1) > Fe (6041-18584 mg kg-1) ≈ K (6789-11517 mg kg-1) > Pb (615-2624 mg kg-1) > Na (201-1559 mg kg-1) > Cd (285-464 mg kg-1) > Cr (3-552 mg kg-1) > Ni (31-108 mg kg-1) > Mg (31-102 mg kg-1) > Zn (15-33 mg kg-1) > Mn (16-28 mg kg-1) > Cu (ND-35 mg kg-1) > Co (4-15 mg kg-1). Uma análise estatística de variância (ANOVA), a nível de confiança de 95%, revelou que houve diferenças significativas entre os teores médios dos metais das quatorze amostras, exceto para Zn. A correlação de Pearson revelou relações lineares fracamente positivas ou negativas, o que implica que a presença de um metal não afeta a presença de outros metais dentro da planta, com exceção de alguns metais. O estudo demonstrou que as sementes de fenacho são uma boa fonte dos metais essenciais. Contudo, também continham quantias grandes dos metais tóxicos Cd e Pb e, portanto, não devem ser consumidas diariamente. Cite as: Levels of essential and toxic metals in fenugreek seeds (Trigonella Foenum-Graecum L.) cultivated in different parts of Ethiopia. Braz. Levels of essential and toxic metals in fenugreek seeds (Trigonella Foenum-Graecum L.) cultivated in different parts of Ethiopia Hagos, M.; Chandravanshi, B. S.