Removal of organic pollutants through hydroxyl radical-based advanced oxidation processes.

The use of Advance Oxidation Process (AOPs) has been extensively examined in order to eradicate organic pollutants. This review assesses the efficacy of photolysis, O3 based (O3/UV, O3/H2O2, O3/H2O2/UV, H2O2/UV, Fenton, Fenton-like, hetero-system) and sonochemical and electro-oxidative AOPs in this regard. The main purpose of this review and some suggestions for the advancement of AOPs is to facilitate the elimination of toxic organic pollutants. Initially proposed for the purification of drinking water in 1980, AOPs have since been employed for various wastewater treatments. AOPs technologies are essentially a process intensification through the use of hybrid methods for wastewater treatment, which generate large amounts of hydroxyl (•OH) and sulfate (SO4·-) radicals, the ultimate oxidants for the remediation of organic pollutants. This review covers the use of AOPs and ozone or UV treatment in combination to create a powerful method of wastewater treatment. This novel approach has been demonstrated to be highly effective, with the acceleration of the oxidation process through Fenton reaction and photocatalytic oxidation technologies. It is clear that Advance Oxidation Process are a helpful for the degradation of organic toxic compounds. Additionally, other processes such as •OH and SO4·- radical-based oxidation may also arise during AOPs treatment and contribute to the reduction of target organic pollutants. This review summarizes the current development of AOPs treatment of wastewater organic pollutants.

A Theoretical Study on the Degradation Mechanism, Kinetics, and Ecotoxicity of Metronidazole (MNZ) in •OH- and SO4•--Assisted Advanced Oxidation Processes.

Metronidazole (MNZ), a typical example of nitroimidazole antibiotics, is widely used in the treatment of infectious diseases caused by anaerobic bacteria. The degradation mechanism and kinetics of MNZ in the presence of HO• and SO4•- were studied using density functional theory (DFT). It was confirmed that both HO• and SO4•- easily added to the carbon atom bonded to the NO2 group in the MNZ molecule as the most feasible reaction channel. This study shows that subsequent reactions of the most important product (M-P) include the O2 addition, hydrogen abstraction and bond breakage mechanisms. The rate constants of HO• and SO4•--initiated MNZ in the aqueous phase were calculated in the temperature range of 278-318 K. The total rate constants of MNZ with HO• and SO4•- were determined to be 8.52 × 109 and 1.69 × 109 M-1s-1 at 298 K, which were consistent with experimental values of (3.54 ± 0.42) × 109 and (2.74 ± 0.13) × 109 M-1s-1, respectively. The toxicity of MNZ and its degradation products to aquatic organisms has been predicted. The results proposed that the toxicity of the initial degradation product (M-P) was higher than that of MNZ. However, further degradation products of MNZ induced by HO• were not harmful to three aquatic organisms (fish, daphnia, and green algae). This study provides a comprehensive theoretical basis for understanding the degradation behavior of MNZ.

Green synthesis of lead oxide nanoparticles for photo-electrocatalytic and antimicrobial applications.

Synthesis of nanoparticles (NPs) for many different uses requires the development of environmentally friendly synthesis protocols. In this article, we present a simple and environmentally friendly method to synthesize lead oxide (PbO) NPs from the plant material of the Mangifera indica. Analytical techniques such as spectroscopy, X-ray diffraction, and microscopy were used to characterize the synthesized PbO NPs, and their photo-electrocatalytic and antifungal properties were also evaluated. H2O2 was used to investigate the efficacy of removing methylene blue dye. At a range of pH values, H2O2 was used to study the role of hydroxyl radicals in the breakdown of methylene blue dye. Methylene blue dyes are more easily eliminated due to increased generation of the *OH radical during removal. Dye degradation was also significantly affected by the aqueous medium's pH. Additionally, the electrocatalytic properties of the PbO NPs adapted electrode were studied in CH3COONa aqueous solution using cyclic voltammetry. Excellent electrocatalytic properties of the PbO NPs are shown by the unity of the anodic and cathodic peaks of the modified electrode in comparison to the stranded electrode. Aspergillus flavus, Aspergillus niger, and Candida glabrata were some fungi tested with the PbO NPs. Against A. flavus (40%) and A. niger (50%), and C. glabrata (75%), the PbO NPs display an excellent inhibition zone. Finally, PbO NPs were used in antioxidant studies with the powerful antioxidant 2, 2 diphenyl-1-picrylhydrazyl (DPPH). This study presents a simple and environmentally friendly method for synthesizing PbO NPs with multiple uses, including photo-electrocatalytic and antimicrobial activity.

Photocatalytic response in water pollutants with addition of biomedical and anti-leishmanial study of iron oxide nanoparticles.

Public health is a major concern globally, owing to the presence of industrial dyes in the effluent. Nanoparticles with green synthesis are an enthralling research field with various applications. This study deals with investigating the photocatalytic potential of Fe-oxide nanoparticles (FeO-NPs) for the degradation of methylene blue dye and their potential biomedical investigations. Biosynthesis using Anthemis tomentosa flower extract showed to be an effective method for the synthesis of FeO-NPs. The freshly prepared FeO-NPs were characterized through UV/Vis spectroscopy showing clear peak at 318 nm. The prepared FeO-NPs were of smaller size and spherical shape having large surface area and porosity with no aggregations. The FeO-NPs were characterized using XRD, FTIR, HRTEM, SEM and EDX. The HRTEM results showed that the particle size of FeO-NPs was 60-90 nm. The antimicrobial properties of FeO-NPs were investigated against two bacterial Staphylococcus aureus 13 (±0.8) and Klebsiella pneumoniae 6(±0.6) and three fungal species Aspergillus Niger, Aspergillus flavus, and Aspergillus fumigatus exhibiting a maximum reduction of 57% 47% and 50%, respectively. Moreover, FeO-NPs exhibited high antioxidant properties evaluated against ascorbic acid. Overall, this study showed high photocatalytic, antimicrobial, and antioxidant properties of FeO-NPs owing to their small size and large surface area. However, the ecotoxicity study of methylene blue degradation products showed potential toxicity to aquatic organisms.

Enhanced solar light photocatalytic performance of Fe-ZnO in the presence of H2O2, S2O82-, and HSO5- for degradation of chlorpyrifos from agricultural wastes: Toxicities investigation.

This study reported Fe doped zinc oxide (Fe-ZnO) synthesis to degrade chlorpyrifos (CPY), a highly toxic organophosphate pesticide and important sources of agricultural wastes. Fourier transform infrared, X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopic analyses showed successful formation of the Fe-ZnO with highly crystalline and amorphous nature. Water collected from agricultural wastes were treated with Fe-ZnO and the results showed 67% degradation of CPY by Fe-ZnO versus 39% by ZnO at 140 min treatment time. Detail mechanism involving reactive oxygen species production from solar light activated Fe-ZnO and their role in degradation of CPY was assessed. Use of H2O2, peroxydisulfate (S2O82-) and peroxymonosulfate (HSO5-) with Fe-ZnO under solar irradiation promoted removal of CPY. The peroxides yielded hydroxyl (OH) and sulfate radical () under solar irradiation mediated by Fe-ZnO. Effects of several parameters including concentration of pollutant and oxidants, pH, co-existing ions, and presence of natural organic matter on CPY degradation were studied. Among peroxides, HSO5- revealed to provide better performance. The prepared Fe-ZnO showed high reusability and greater mineralization of CPY. The GC-MS analysis showed degradation of CPY resulted into several transformation products (TPs). Toxicity analysis of CPY as well as its TPs was performed and the formation of non-toxic acetate imply greater capability of the treatment technology.

Green synthesis of Zno@GO nanocomposite and its' efficient antibacterial activity.

Nanotechnologyapplications in the field of biomedicine like drug delivery, cell labeling, and bacterial inhibition are growing . New nano-materials having less toxicity and excellent antibacterial activity attract research interest. In the current study, while taking advantage of green synthesis we have decorated zinc oxide on the surface of grephene oxide forming Zno@GO nanocomposite. The Transmission electron microscopy (TEM) study showed successfully synthesized trigonal small sizes ZnO on the surface of GO nanosheets. The as-synthesized ZnO@GO was used against MDR gram-negative pathogen E-coli (BL21 DE3) and showed excellent antibacterial activity killing about 95 % toxic bacteria within 5 h due to electrostatic interaction between cell membrane of E. coli (BL21 DE3) and ZnO@GO complex. Hence the nano composite subsequently penetrated into the cytoplasm by damaging the cell membrane of bacteria, as a result production of ROS into the cytoplasm led to imbalance of metabolic system in the cell. Moreover, the cell membrane damage of gram-negative bacteria verified through zeta potential and propidium iodide (PI) study. Thus, our study develops a way to solve the challenge of efficient design of a drug delivery system for dissolution enhancement according to the need for required drug release.

Photoinhibition and photocatalytic response of surfactant mediated Pt/ZnO nanocomposite.

Water pollution and bacterial resistance are universal problems. Drugs and protocols have been employed to deal with involved microbes and pollutants but these customary chemicals have many limitations. It is essential to produce new methods and materials to deal with these deleterious microbes. In the present contribution, highly efficient and stable nanocomposite of platinum activated zinc oxide was synthesized by a new plant extract and surfactant assisted protocol. The cetylpyridinium chloride was applied as surfactant to obtain high dispersion of spherical ZnO. The platinum ions were reduced on the ZnO surface by the use of Rhazya stricta plant extract. The prepared nanomaterial was used for photoinactivation of multidrug resistant bacterium Escherichia coli (E. coli). The synthesized nanomaterial showed strong E. coli inhibition efficiency in the presence of light and the observed diameter of zone of inhibition was 21 ±0.4. The effect of light on the inhibition of E.coli was studied by measuring the activated oxygen radicals inside the bacterium cell. The surface morphology of E.coli before and after treatment with Pt/ZnO was studied by SEM. Such effect was not observed in dark. The toxicity of the synthesized nanomaterials was also studied through haemolytic activity and the result shows that the nanomaterial prepared by the said method has very low toxicity. The photocatalytic degradation of methylene blue (MB) was also investigated in the presence of the synthesized nanomaterials. Effect of different parameters such as concentration of Pt/ZnO, Irradiation time and dye concentrations were also studied. An incredible photocatalytic deprivation of MB (98 %) was observed for Pt/ZnO nanocomposite as compared to individual Pt (48%) and ZnO (71%) nanoparticles after 5 minutes of irradiations. Further research is required to investigate the applications of Pt/ZnO nanocomposite.

Distribution and health risk assessment of trace elements in ground/surface water of Kot Addu, Punjab, Pakistan: a multivariate analysis.

Water is a key component for living beings to sustain life and for socio-economic development. Anthropogenic activities contribute significantly to ground/surface water contamination particularly with trace elements. The present study was designed to evaluate distribution and health risk assessment of trace elements in ground/surface water of the previously unexplored area, Tehsil Kot Addu, Southern-Punjab, Pakistan. Ground/surface water samples (n = 120) were collected from rural and urban areas of Kot Addu. The samples were analyzed for physicochemical characteristics: total dissolved solids (TDS), pH, and EC (electrical conductivity), cations, anions, and trace elements particularly arsenic (As), lead (Pb), cadmium (Cd), and zinc (Zn). All of the water characteristics were evaluated based on the water quality standards set by World Health Organization (WHO). Results revealed the suitability of water for drinking purpose with respect to physicochemical attributes. However, the alarming levels of trace elements especially As, Cd, and Pb make it unfit for drinking purpose. Noticeably, 23, 96, and 98% of water samples showed As, Cd, and Pb concentrations higher than the permissible limits. Overall, the estimated carcinogenic and non-carcinogenic risk to the exposed community was higher than the safety level of USEPA, suggesting the probability of cancer and other diseases through long-term exposure via ingestion routes. Therefore, this study demonstrated an urgent need for water filtration/purification techniques, and some quality control measures are warranted to protect the health of the exposed community in Tehsil Kot Addu.

Biomedical response under visible-light irradiation promoted by new hydrothermally synthesized SiO2-Zn@Fe2O3 nanofibers.

In the presence of Fe3O4 nano-fibers, we prepared SiO2-Zn@Fe2O3 hybrid Nano-fibers through a novel and simple one-pot redox reaction between ZnSO4 & SiO2. The Fe3O4 exterior nano-fibers would be homogenously covered by SiO2 coating to arrange a distinctive core-shell construction and then Zn nanoparticles are intercalated in the covering of SiO2. The synthesized nanofibers were tested for photodegradation of methylene blue (MB). The result showed that 99 % MB was degraded in 60 min. Furthermore, the antibacterial potential of SiO2-Zn@Fe2O3 nanofibers was tested against E. coli and S. aureus bacteria both in light and dark. The impact of different analysis such as Reactive oxygen species (ROS) analysis, irradiation effect on bacterial inhibition, concentration effect of SiO2-Zn@Fe2O3 nanofibers and reduction of DPPH studied. The findings clearly demonstrate that ROS is produced in the presence of SiO2-Zn@Fe2O3 nanofibers in bacterial cells and is responsible for their inhibition. Findings have shown that synthesized nanostructures can also increase the stability of DPPH radicals with increasing concentrations of nanomaterials, making them a strong candidate for DPPH reduction. The overall results show that the efficacy of SiO2-Zn@Fe2O3 nanofibers for inhibition was more pronounced than that of individual iron oxides.

Biosynthesis of silver capped magnesium oxide nanocomposite using Olea cuspidata leaf extract and their photocatalytic, antioxidant and antibacterial activity.

Green chemistry is a modern area of research which covers synthesis of nanomaterials through useful, environmentally, economically friendly techniques and their use in different fields. The synthesis involves the formation of bimetallic nanomaterials to enhance their synergistic relationship and achieve special modulated properties. That's why bimetallic nanomaterials are extremely important and gaining interest among researchers in the field of medicinal chemistry for the treatment of various diseases. In this particular study, bimetallic nanoparticles synthesis was done by reduction procedure using leaf extract of Olea cuspidata. The phytochemicals in leaf extract act as stabilizing and capping agent in reduction of precursor's salts. The characterization of green synthesized Ag@MgO nanocomposite was done through several analytical techniques such as ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), High resolution transmission electron microscope (HRTEM) and Zeta potential. To explore the biological potential of synthesized nanocomposite, antibacterial activities against gram negative (Escherichia coli) bacteria and gram positive (Staphylococcus aureus) has been evaluated. The photocatalytic activity in contrary to methylene blue (MB) decomposition was seen efficiently. Moreover, the antioxidant nature of green synthesized Ag@MgO nanocomposite was analyzed by destabilizing and scavenging maximum percentage (93 %) of dangerous and harmful 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical. The best and surprising results provided the information for the presence of essential and vital components in Olea Cuspidata in the form of organic acids (Citrus Acid) aids in stabilizing the entire structure with enhanced properties. Up to the best of our knowledge, the facts and results obtained regarding the structure of Ag@MgO nanocomposite clearly illustrates the uniqueness of green chemistry and also its role in future developing multifunctional nanoparticles in the field of nanobiotechnology.

Nano-zerovalent manganese/biochar composite for the adsorptive and oxidative removal of Congo-red dye from aqueous solutions.

Congo-red (CR), a precursor of textile products and a contaminant of great concern, has contaminated aquatic environments. Here, we explored the synthesis of mesoporous nano-zerovalent manganese (nZVMn) and Phoenix dactylifera leaves biochar (PBC) composite for the removal of CR from water. The nZVMn/PBC adsorbed 117.647 mg/g of CR versus 25.316 mg/g by PBC at [CR]0 = 20 mg/L and [PBC]0 = [nZVMn/PBC]0 = 500 mg/L. Variation of [nZVMn/PBC]0, [CR]0 and pH influenced the adsorption of CR. Freundlich adsorption isotherm and pseudo-first-order kinetic models best fitted CR adsorption. The H2O2 coupling with nZVMn/PBC promoted removal of CR possibly due to the formation of hydroxyl radical (●OH) and caused 95 % removal of CR versus 77 % by nZVMn/PBC alone. The ●OH scavengers inhibited the removal of CR. The nZVMn/PBC showed a good reusability and efficient removal of CR up to the seventh cycle of treatment. Results reveal that nZVMn improved performance, thermal stability and reusability of biochar. Degradation products from ●OH-mediated degradation of CR were studied by ultraperformance liquid chromatography with mass spectrometric detector to establish degradation pathways. The ion-chromatographic analysis showed the formation of non-toxic inorganic acetate product, which suggests high potential of the newly fabricated adsorbent in the removal of CR.

An Astragalus membranaceus based eco-friendly biomimetic synthesis approach of ZnO nanoflowers with an excellent antibacterial, antioxidant and electrochemical sensing effect.

Nowadays featuring outstanding eco-friendliness, the phytochemical fabrication method of nanostructures is very popular. Here, we propose to utilize the Astragalus membranaceus extract as the reducing and capping agent to stabilize the metal and to avoid the aggregations of nanoparticles during ZnO nanoflowers synthesis procedure. As a result, the whole fabrication procedure was highly efficient and cost-effective without requiring a special environment of high pressure or elevated temperature and without chemical hazards used or produced. After the fabrication, detailed characterization about material morphology and crystal structure was carried out, including scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscope (FTIR). Moreover, the ZnO nanoflowers demonstrated distinctive antibacterial, antioxidant and electrochemical sensing effect. Specifically, ZnO nanoflowers had an antibacterial inhibition zone of 19(±0.7) and 15(±0.8) mm in diameter against the concentration of 50 µL (1 mg/mL) Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which is greatly improved compared to the reference drug (Kanamycin). Besides, antioxidant activity was also tested using H2O2 free radical scavenging assay and 60% 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition of 0.5 mg/mL was reported. Finally, controlled by the diffusion process during the charge transfer procedure, 4-nitorphenol was dramatically reduced and a limit of detection of 0.08 µM by ZnO nanoflowers modified electrode was observed during the cyclic voltammetry (CV) experiment. Because the phenolic compounds originating from Astragalus membranaceus helped to facilitate the electron transfer, the limit of detection was lower compared to other materials, such as copper oxide nanoparticles (Cu2O-NPs), silicon dioxide/silver nanoparticles (SiO2/Ag-NPs), zinc oxide nanoparticles (ZnO-NPs), activated carbon (AC) and cobalt oxide nanocubes (Co3O4). Therefore, featuring easy operation, low-cost and eco-friendliness, our proposed ZnO nanoflowers fabrication method will have a great potential in biomedical and electro-catalytic fields.

Synthesis, characterization and application of novel MnO and CuO impregnated biochar composites to sequester arsenic (As) from water: Modeling, thermodynamics and reusability.

The present study aimed at enhancing the adsorption potential of novel nanocomposites of Sesbania bispinosa biochar (SBC) with copper oxide (SBC/CuO) and manganese oxide nanoparticles (SBC/MnO) for the efficient and inexpensive removal of environmentally concerned contaminant arsenic (As) from contaminated water at batch scale. The scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray (EDX), X-ray diffraction (XRD) and point of zero charge (PZC) analyses proved successful impregnation of the metallic nanoparticles on SBC surface. The results revealed the maximum As removal (96 %) and adsorption (12.47 mg/g) by SBC/CuO composite at 10 mg As/L, optimum pH-4, dose 1.0 g/L and ambient temperature (25 ± 1.5 °C) as compared with SBC (7.33 mg/g) and SBC/MnO (7.34 mg/g). Among four types of adsorption isotherms, Freundlich isotherm demonstrated best fit with R2 > 0.997. While pseudo second-order kinetic model revealed better agreement with kinetic experimental data as matched with other kinetic models. The thermodynamic results depicted that As adsorption on the as-synthesized adsorbents was endothermic and spontaneous in nature with increased randomness. The SBC/CuO displayed excellent reusability and stability over four adsorption/desorption cycles and proved that the as-synthesized SBC/CuO composite may be the efficient adsorbent for practical removal of As from contaminated water.

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Facile and eco-benign fabrication of Ag/Fe2O3 nanocomposite using Algaia Monozyga leaves extract and its' efficient biocidal and photocatalytic applications.

Noble metal/metal oxide nanocomposites are pet and spellbound candidates in biomedical and catalytic fields because of their awestruck properties. This report put forward the facile and environmentally friendly fabrication of Ag/Fe2O3 nanocomposite using the eqeous extract of Algaia Monozyga leaves. The Ag/ Fe2O3 bimetallic nanocomposite was prepared using AgNO3, FeCl3 (anhydrous) and plant leaves extract as a natural source for reduction and stabilization of this nanocomposite. We prepared a separate solution of Silver and Iron salts and upon addition of this solution to the plant extract, the conversion of colour to brown appears within 10 min at constant stirring at 350 rpm. To confirm the synthesis of nanocomposite, UV-vis spectroscopy, Scanning electron microscopy (SEM), EDX and X-ray diffraction spectroscopy were used. The as prepared nanocomposite was used for photocatalytic activity in degradation of Methylene Blue (MB) in the presence of light which shows effective photocatalytic activity. The antimicrobial activities were also determined for nanocomposite which were found to be efficient against human pathogenic multidrug resistant bacteria. The Ag/Fe2O3 nanocomposite significantly preventing the growth of Staphylococcus aureus, E.coli QH4 and Pseudomonas putida with zones of inhibition 23 (±0.5), 21 (±0.4) and 19 (±0.4) mm, respectively.The eco-benignly synthesized Ag/Fe2O3 nanocomposite could be a desired material for efficient remediation of toxic organic pollutants and microbes.

Effect of Silver Nanoparticles on Biofilm Formation and EPS Production of Multidrug-Resistant Klebsiella pneumoniae.

Antibiotic resistance against present antibiotics is rising at an alarming rate with need for discovery of advanced methods to treat infections caused by resistant pathogens. Silver nanoparticles are known to exhibit satisfactory antibacterial and antibiofilm activity against different pathogens. In the present study, the AgNPs were synthesized chemically and characterized by UV-Visible spectroscopy, scanning electron microscopy, and X-ray diffraction. Antibacterial activity against MDR K. pneumoniae strains was evaluated by agar diffusion and broth microdilution assay. Cellular protein leakage was determined by the Bradford assay. The effect of AgNPs on production on extracellular polymeric substances was evaluated. Biofilm formation was assessed by tube method qualitatively and quantitatively by the microtiter plate assay. The cytotoxic potential of AgNPs on HeLa cell lines was also determined. AgNPs exhibited an MIC of 62.5 and 125 µg/ml, while their MBC is 250 and 500 µg/ml. The production of extracellular polymeric substance decreased after AgNP treatment while cellular protein leakage increased due to higher rates of cellular membrane disruption by AgNPs. The percentage biofilm inhibition was evaluated to be 64% for K. pneumoniae strain MF953600 and 86% for MF953599 at AgNP concentration of 100 µg/ml. AgNPs were evaluated to be minimally cytotoxic and safe at concentrations of 15-120 µg/ml. The data evaluated by this study provided evidence of AgNPs being safe antibacterial and antibiofilm compounds against MDR K. pneumoniae.

Eco-benign approach to synthesize spherical iron oxide nanoparticles: A new insight in photocatalytic and biomedical applications.

Iron oxide nanoparticles (Fe2O3NPs) are an interested and attractive area of research as they have numerous effective environmental and biomedical applications. Herein we have reported a simple and eco-benign synthesis Fe2O3NPs using Tamarix aphylla extract. The extract of the Tamarix aphylla acts both as a reducing and capping agent which leads to the fast and successful eco-benign synthesis of Fe2O3NPs.UV/Vis spectroscopy, XRD, EDX, SEM and TEM techniques were used to characterize and explore different features of Fe2O3NPs. UV/Vis studies showed asharppeak at 390 nm due to surface plasmon resonance absorption of Fe2O3NPs. XRD studies indicated that Fe2O3NPs were crystalline in nature. Structural features, elemental composition and geometry of Fe2O3NPswere confirmed by SEM, EDX and TEM. The as synthesized Fe2O3NPs showed efficient efficacy to degrade 100% of Methylene blue (MB) dye by 4 mg/25 ml MB and revealed 90% scavenging of the more stable DPPH free radical(1 mg/ml). Furthermore, Fe2O3NPs showed excellent antimicrobial activity against pathogenic multidrug resistant bacterial strains. The results of the present study explored the potential reducing, capping property of Tamarix aphylla extract, photocatalytic and biomedical applications of eco-benignly synthesized Fe2O3NPs which could be an alternative material for effective remediation of lethal organic pollutants and microbes.

Effect of biochar modified with magnetite nanoparticles and HNO3 for efficient removal of Cr(VI) from contaminated water: A batch and column scale study.

Chromium (Cr) poses serious consequences on human and animal health due to its potential carcinogenicity. The present study aims at preparing a novel biochar derived from Chenopodium quinoa crop residues (QBC), its activation with magnetite nanoparticles (QBC/MNPs) and strong acid HNO3 (QBC/Acid) to evaluate their batch and column scale potential to remove Cr (VI) from polluted water. The QBC, QBC/MNPs and QBC/Acid were characterized with SEM, FTIR, EDX, XRD as well as point of zero charge (PZC) to get an insight into their adsorption mechanism. The impact of different process parameters including dose of the adsorbent (1-4 g/L), contact time (0-180 min), initial concentration of Cr (25-200 mg/L) as well as solution pH (2-8) was evaluated on the Cr (VI) removal from contaminated water. The results revealed that QBC/MNPs proved more effective (73.35-93.62-%) for the Cr (VI) removal with 77.35 mg/g adsorption capacity as compared with QBC/Acid (55.85-79.8%) and QBC (48.85-75.28-%) when Cr concentration was changed from 200 to 25 mg/L. The isothermal experimental results follow the Freundlich adsorption model rather than Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherm models. While kinetic adsorption results were well demonstrated by pseudo second order kinetic model. Column scale experiments conducted at steady state exhibited excellent retention of Cr (VI) by QBC, QBC/MNPs and QBC/Acid at 50 and 100 mg Cr/L. The results showed that this novel biochar (QBC) and its modified forms (QBC/Acid and QBC/MNPs) are applicable with excellent reusability and stability under acidic conditions for the practical treatment of Cr (VI) contaminated water.

Facile and eco-benign synthesis of Au@Fe2O3 nanocomposite: Efficient photocatalytic, antibacterial and antioxidant agent.

The development of eco-benign experimental procedures for the synthesis of nanomaterials is a fundamental developing branch of green nanotechnology. In this paper, green synthetic route was followed to synthesize novel Au@Fe2O3nanocomposite using Citrus sinensis fruit extract as a reducing and stabilizing agent. The as synthesized Au@Fe2O3nanocomposite was successfully characterized by UV-visible spectroscopy, X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy-dispersive X-ray (EDX), Fourier transform infrared (FT1R) spectrophotometry and Zeta potential. UV-vis spectroscopy showed two SPR peaks for Fe2O3 and coated Au at 290 and 520 nm respectively. XRD confirmed the crystallinity of Au@Fe2O3. Au@Fe2O3 nanocomposite showed better antioxidant activity to effectively scavenge DPPH. The Au@Fe2O3 has been also tested for antibacterial activity which showed an effective antibacterial activity against multi drug resistant E.coli and Bacillus subtilis. Furthermore, Au@Fe2O3 also demonstrated better photo catalytic activity for methylene blue (MB) degradation. We proposed that the existence of organic acids (citric acids) also played a significant role in the stabilization of Au@Fe2O3, and plant (Citrus sinensis Var Kozan yerly) containing such component may be more effective for the green synthesis of Au@Fe2O3 nanocomposite. The findings of this study prove the overwhelming therapeutic and photocatalytic potential of bio-inspired Au@Fe2O3nanocomposite which can be a novel candidate for the effective remediation of microbes and toxic organic pollutants.