Fe3O4 nanoparticles functionalized GO/g-C3N4 2D/2D nanocomposite: An efficient magnetic nanoadsorbent for adsorptive removal of organic pollutants

Contamination of toxic organic pollutants is a worldwide problem and needs to develop an eco-friendly and highly effective adsorbent material for its removal. Recently, 2D graphene oxide (GO) and graphitic carbon nitride (g-C3N4) is mostly used as an adsorbent for the efficient removal of organic pollutants. Here we have prepared a novel 2D/2D GO/g-C3N4 sheets decorated with Fe3O4 nanoparticles (GO/g–C3N4–Fe3O4) using the hydrothermal method. The structural properties, formation, morphology, and bonding were analyzed by different analytical techniques. Then the obtained GO/g–C3N4–Fe3O4 nanocomposite was used as an adsorbent to eliminate both toxic tetracycline (TC) antibiotic and methylene blue (MB) dye. The adsorption of TC and MB were pH-dependent and maximum adsorption capacity (120 mg/g) was achieved at pH = 3 for TC and (220 mg/g) at pH = 9 for MB. The high adsorption efficiency of GO/g–C3N4–Fe3O4 for TC and MB was mainly due to Ï€-Ï€ and hydrogen bonding interaction. The introduction of Fe3O4 nanoparticles onto 2D/2D GO/g-C3N4 not only increases the adsorption capacity but also can make it easily separable from treated water. Adsorption data obtained were best fitted to the Langmuir and pseudo-second-order kinetics model. The adsorbed TC and MB on GO/g–C3N4–Fe3O4 surface were recovered and can be reused up to 5 cycles.

In-situ functionalization of GO sheets with AlOOH-FeOOH composite nanorods: An eco-friendly nanoadsorbent for removal of toxic arsenate ions from water

Water contaminated with arsenic (As) has become a worldwide problem due to its obligatory toxicity. Therefore, there is a great challenge for researchers to develop a cost-effective and highly efficient nanoadsorbent material for As removal. In this work, we have synthesized boehmite-lepidocrocite (AlOOH-FeOOH) composite nanorods mounted onto previously prepared graphene oxide (GO) surface (GO/AlOOH-FeOOH) by one step hydrothermal method. Then the prepared GO/AlOOH-FeOOH nanocomposite was sintered at 400 °C to form GO/Al2O3-Fe2O3 nanocomposite. Both the obtained GO functionalized nanocomposites were used as adsorbents for As(V) removal from water. The XRD, HRTEM confirmed the formation of γ (AlOOH-FeOOH) and γ (Al2O3-Fe2O3). TEM images revealed the formation of rod shape composite nanomaterials on GO surface. The GO/Al2O3-Fe2O3 showed magnetic properties with saturation magnetization value of 5.8emug−1. Among the two prepared nanoadsorbents the GO/AlOOH-FeOOH shows better adsorption properties with maximum uptake capacity of 24.6 mgg-1. The kinetics and isotherm experiments suggested that the adsorption process obeyed pseudo second order kinetic and Freundlich isotherm model. The presence of common coexisting anions including Cl-, SO42-, NO3- showed no significant effect on adsorption except PO43-. The mechanism of As(V) adsorption on GO/AlOOH-FeOOH includes electrostatic interaction and surface complexation reaction.

Amine-Functionalized GO Decorated with ZnO-ZnFe2O4 Nanomaterials for Remediation of Cr(VI) from Water

Amine functionalized graphene oxide (NH2-GO) decorated with ZnO-ZnFe2O4 nanomaterials (NH2-GO/ZnO-ZnFe2O4) was successfully synthesized by organic transformation reaction followed by hydrothermal method. The formation, composition, bonding, size, morphology, and surface area of synthesized nanomaterial were analyzed by XRD, FTIR, Raman, XPS, FESEM, HRTEM, and BET analytical techniques. The formation of ZnO-ZnFe2O4 binary phase onto the amine functionalized GO was confirmed by XRD and HRTEM. The surface composition and functionalization of prepared nanocomposite were confirmed by XPS and FTIR analysis. The FESEM images revealed the formation of fine spherical ZnO-ZnFe2O4 nanoparticle onto the NH2-GO surface. From TEM image, the average particle size of the composite nanomaterials was observed to be 8 nm. From N2 adsorption–desorption study, it was found that NH2-GO/ZnO-ZnFe2O4 composite nanomaterials show higher surface area (122 mg/g) than GO/ZnO-ZnFe2O4 and NH2-GO. The obtained nanocomposite was used as novel adsorbent for remediation of chromium (Cr(VI)) from water. Batch adsorption experimental studies revealed that the Cr(VI) adsorption onto NH2-GO/ZnO-ZnFe2O4 surface was pH dependent and maximum adsorption takes place at pH = 4. Compared to other prepared nanomaterials, adsorption capacity of NH2-GO/ZnO-ZnFe2O4 was found to be higher because of the presence of more surface active sites by functionalizing ZnO-ZnFe2O4 nanomaterials and also introducing amine group on the GO surface. Adsorptive removal of Cr(VI) onto nanocomposite surface follows a pseudo second order kinetics. Langmuir model was best fitted to the adsorption data. The process of adsorption was spontaneous and endothermic in nature. The maximum uptake capacity of NH2-GO/ZnO-ZnFe2O4 was observed to be 109.89 mg/g and was higher than that of NH2-GO and GO/ZnO-ZnFe2O4 nanocomposites. The mechanism of Cr(VI) adsorption follows electrostatic attraction and formation of chelate with amine groups.

Surface functionalization of GO with MgO/MgFe2O4 binary oxides: A novel magnetic nanoadsorbent for removal of fluoride ions

In the present works, we have successfully synthesized novel magnetic MgO-MgFe2O4 nanocomposite anchored onto graphene oxide (GO) substrate (MgO-MgFe2O4/GO) and MgO-Fe2O3 nanocomposite by hydrothermal methods. The prepared GO based nanocomposites were used as efficient adsorbents for removal of fluoride ions from aqueous system. The formation, morphology, size, crystalline phases, surface area and magnetic behaviors of these prepared nanocomposites were characterized by FE-SEM, HR-TEM, XRD, FT-IR, Raman, BET and VSM analytical techniques. From XRD, confirmed that GO based nanocomposite achieved a magnetic performance by forming new spinel MgFe2O4 crystal structure instead of α-Fe2O3 phase. It was observed that presence of GO not only plays a significant role in the structural transformation but also enhance the surface area of the nanocomposites. Batch adsorption studies were carried out to investigate the influence of various parameters such as adsorbent dosage, contact time, pH and initial concentration of solution towards removal of fluoride ions. The maximum uptake capacity of MgO-MgFe2O4/GO for fluoride ions removal is found to be 34 mg g−1 which is higher as compared to that of MgO-Fe2O3. From the kinetic study, it is observed that the adsorption of fluoride ions onto the adsorbent surface follows pseudo second order kinetic equation and obeys the Langmuir isotherm model. Thermodynamic study indicates that the adsorption process was the endothermic in nature. The mechanism of adsorption of fluoride onto the adsorbent surface includes electrostatic interactions, anion exchange, and inner-sphere complexation.

Oral administration of graphene oxide nano-sheets induces oxidative stress, genotoxicity, and behavioral teratogenicity in Drosophila melanogaster

The current study checks the effect of various concentrations of dietary graphene oxide (GO) nano-sheets on the development of Drosophila melanogaster. GO was synthesized and characterized by XRD, FTIR, FESEM, and TEM analytical techniques. Various concentrations of GO were mixed with the fly food and flies were transferred to the vial. Various behavioral and morphological as well as genetic defects were checked on the different developmental stages of the offspring. In the larval stage of development, the crawling speed and trailing path change significantly than the control. GO induces the generation of oxygen radicals within the larval hemolymph as evidenced by nitroblue tetrazolium assay. GO induces DNA damage within the gut cell, which was detected by Hoechst staining and within hemolymph by comet assay. Adult flies hatched after GO treatment show defective phototaxis and geotaxis behavior. Besides behavior, phenotypic defects were observed in the wing, eye, thorax bristles, and mouth parts. At 300 mg/L concentration, wing spots were observed. Altogether, the current study finds oral administration of GO which acts as a mutagen and causes various behavioral and developmental defects in the offspring. Here for the first time, we are reporting GO, which acts as a teratogen in Drosophila, besides its extensive medical applications.

In-situ synthesis of mixed phase electrospun TiO2 nanofbers: a novel visible light photocatalys

MgFe2O4-Fe2O3 Heterostructured Nanomaterials: Synthesis and Photocatalytic Study

MgFe2O4-Fe2O3 composites nanostructures were synthesized by different wet chemical methods such as: precipitation, reflux and hydrothermal method. XRD confirmed the formation of composite MgFe2O4-Fe2O3 phase by precipitation, reflux methods and single MgFe2O4 phase by hydrothermal method with well crystalline nature. From FTIR study, the shifting of adsorption bands of metal-oxygen bond corresponding to the vibration of tetrahedral and octahedral complexes of MgFe2O4-Fe2O3 composites was observed than single MgFe2O4 phase. From FESEM images, it is observed that the MgFe2O4-Fe2O3 nanocomposites prepared by precipitation method contains very smooth particles with average diameters around 20–40 nm, the MgFe2O4-Fe2O3 nanocomposites prepared by reflux method contains both uniform microspheres and flower-like hierarchical nanostructures with thickness around 100–200 nm and the MgFe2O4 nanomaterials synthesized by hydrothermal method contains irregular spherical nanoparticles with diameter around 60–100 nm. The prepared nanomaterials were used as photocatalysts to degrade methylene blue dye in aqueous media under solar light irradiation. The MgFe2O4-Fe2O3 nanocomposite prepared by precipitation method was regarded as a superb photocatalyst; 0.1 g of the photocatalyst performed the degradation of 99.9% of methylene blue dye from 100 ml of 10 mg/L solution within 120 mins of irradiation time.

Functionalization of graphene oxide with metal oxide nanomaterials: Synthesis and application towards the removal of inorganic toxic environmental pollutants from water, Handbook of Functionalized Nanomaterials for industrial applications

Green synthesis of Fe2O3-Ag nanocomposite using Psidium guajava leaf extract: An eco-friendly and recyclable adsorbent for remediation of Cr(VI) from aqueous media

Abstract: An environmental friendly and cost effective method was used for the preparation of silver‑iron oxide (α-Fe2O3-Ag) nanocomposite using guava (Psidium guajava) leaf extract, which can be used as an adsorbent for decontamination of chromium (VI) ions from aqueous media. XRD analysis revealed that both Iron oxide and silver nanoparticles are crystalline in nature with face-centered cubic and rhombohedral geometry respectively. The FESEM micrographs of Fe2O3-Ag nanocomposite displayed irregular shaped particles with an average size of 50–90 nm. BET surface area analysis suggests that the prepared Fe2O3-Ag nanocomposites are mesoporous in nature with surface area of 122.72 m2/g. The adsorption of Cr(VI) was pH dependent and maximum adsorption occurred at pH = 4 with maximum adsorption capacity of 71.34 mg/g. Thermodynamic parameters reveals that the Cr(VI) adsorption on Fe2O3-Ag surface is endothermic and spontaneous in nature. The adsorbed Cr(VI) on Fe2O3-Ag surface was recovered and can be reused up to five cycles.

Adsorption of methylene blue from aqueous media using graphene oxide Synthesised from bio-soot wastes

In the present work, we have successfully synthesised graphene oxide (GO) from the Bio-soot wastes where Bio-soot was used as a graphite source. The prepared GO has been characterised by using XRD, FTIR, Raman, BET, FE-SEM analytical techniques and has been used as an adsorbent for decontamination of highly noxious Methylene blue (MB) dye from aqueous media. The adsorption studies have been investigated by changing the different parameters like adsorbent dosages, pH of the solution, contact time and initial concentration. The obtained adsorption data have been fitted into various kinetic and isotherm models and concluded that adsorption of MB follows second order kinetics and Langmuir models with maximum adsorption capacities 90.20 mg/g which is double as compared to Bio-soot that was 41.42 mg/g. This is due to the increase in adsorption active sites by introducing oxygen-containing groups on Bio-soot surface.

Removal oongo red dye from aqueous solution using zinc oxide nanoparticles synthesised from Ocimum sanctum (Tulsi leaf): a green approach

In this study, we synthesised ZnO (zinc oxide) NPs from Ocimum sanctum (Indian Tulsi leaves) through green approach using zinc nitrate and sodium hydroxide as main materials and Ocimum sanctum leaf extract as a precursor. The resulting product was characterised by UV-visible, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), Energy-dispersive X-ray (EDX), Transmission electron microscopy (TEM), High-resolution Transmission electron microscopy (HR-TEM) BET isotherm and Thermo gravimetric analysis. Our investigation on adsorption of Congo red (CR) dye from dye contaminated water by green synthesised ZnO NPs was found to be more efficient (97%) than the conventional commercially available zinc oxide (78%). The maximum CR dye removal (97% by ZnO-T and 78% by ZnO-C) was obtained with initial pH 4.0, contact time 30 min, adsorbent dosage 0.20 g, initial CR concentration 40 mg/L, shaking speed 300 rpm and the adsorption experiment was carried out in room temperature. To understand deep into the mechanism of CR dye adsorption on the adsorbent, we have investigated adsorption kinetics both by pseudo-first order and pseudo-second order. Due to high correlation coefficient value (R2 = 0.99) of the pseudo-second order kinetics, the adsorption process followed chemisorptions where the experimental data for the isotherm followed the Langmuir isotherm model. Reusability efficiency of the NPs was explored using ethanol and based on the results it can be inferred that ZnO-T NPs can be reused for dye removal. The outcome of this research suggested that the green synthesised zinc oxide NPs could be a potential adsorbent material for removal of CR dye from aqueous solution.

Preparation of graphene oxide from Bio-soot wastes: As an efficient adsorbent for highly noxious Congo red dye

In this study, the morphological structure of Bio-soot obtained from diesel engine was first investigated. It is observed that Bio-soot has a higher level of graphitization than Carbon Black or activated charcoal. Graphene oxide was prepared by oxidizing the Bio-soot powder using modified Hummer’s method. The prepared graphene oxide was characterized by using X-ray diffractometer (XRD), Fourier transformation infrared (FTIR), Raman, Brunauer-Emmett-Teller (BET), Field emission scanning electron microscopy (FESEM) and High resolution transmission electron microscopy (HRTEM) analytical techniques. The prepared graphene oxide was used as adsorbent for decontamination of highly toxic Congo red from aqueous media. The adsorption studies were carried out using UV–visible Spectroscopy while changing the different parameters such as adsorbent dosages, pH of the solution, contact time and initial concentration. The obtained adsorption results were fitted with kinetic and isotherm models and was concluded that adsorption of Congo red follows second order kinetic and Langmuir isotherm models with maximum adsorption capacities of 120.20 mg/g. This reflects the significance of graphene oxide over Bio-soot which owes due to increase of the adsorption sites after introducing oxygen containing groups on Bio-soot surface. Thermodynamic studies revealed that Congo red adsorption on graphene oxide surface is spontaneous and endothermic in nature.

Magnesium oxide nanoparticles decorated iron oxide nanorods: Synthesis, characterization and remediation of Congo red dye from aqueous media

Iron oxide based nanomaterials for remediation of highly toxic arsenic ions from water

Graphene based metal oxide nanomaterials for energy applications

Co-axial electrospun hollow MgO nanofibers for efficient removal of fluoride ions from water

Porous and hollow metal oxide nanomaterials receive more attraction towards adsorption of various contaminates from water due to extremely high surface area. Co-axial electrospinning is an advance method to easily fabricate long length hollow nanotubes/nanofibers. Herein, hollow MgO nanofibers were synthesized using co-axial electrospinning method followed by post annealing. The co-axial electrospinning was performed by maintaining applied voltage (15 kV), needle tip to collector distance (12 cm) and flow rate of core and shell solutions (0.3 and 0.5 mL/h respectively). The formation, morphologies, bonding and surface area of the prepared nanofibers was analysed by XRD, FESEM, TEM and BET analytical techniques. The inner pore diameter of hollow MgO nanofibers was 32 nm. The surface area was found to be 527 m2/g which is much higher as compared to solid MgO nanofibers. The prepared hollow MgO nanofibers were used for the adsorption of fluoride ions from water. The effect of dose, contact time, pH and concentration were analysed. The fluoride adsorption process follows Pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity of hollow MgO was found to be 294 mg/g which is almost three-time greater than that of solid MgO nanofibers (92 mg/g). All the co-existing ions have showed negligible effect on fluoride adsorption except CO32- and PO43- ions. The adsorption energy of fluoride adsorbed MgO was calculated. The adsorption energy is found to be ? 6.9004 eV. The negative value of adsorption energy indicates the feasibility of adsorption process.

Heavy metal ions and dyes removal from aqueous solution using aloevera-based biosorbent: A systematic review

Aloe vera has been harvested for decades due to its diverse medicinal and nutritional potential. Researchers are presently concentrating on an additional application of aloe vera that is pertinent to industrial usages such as techniques for pollutant removal and water purification. For decades, inorganic and organic pollutants from home and industrial wastewater have been decontaminated using aloe vera biomass, either in its natural state or modified state. This review article gives a detailed summary of the classification of synthetic dyes and heavy metals, their toxicity, and different removal methods using bare and modified aloe vera-based biosorbents. The botany, origin, taxonomy, and utilization of Aloe vera in different sectors have also been summarized. In addition, this paper emphasizes the preparation of biosorbent using aloe vera biomass either in its unmodified form or modified form under different physicochemical conditions. Moreover, acid and base-treated Aloe vera and metal oxide-modified Aloe vera was used and discussed in detail. The physicochemical factors influencing the adsorption capability of biosorbent such as initial pollutant concentrations, contact period, pH, and shaking or stirring speed have been thoroughly discussed. Finally, conclusions have been drawn based on the reviewed literature and also proposed a few possible suggestions for future research for Aloe vera biomass-based biosorbents.

Microbased biorefinery for gold nanoparticle production: recent advancements, applications and future aspects

Multifaceted utility of nanomaterials is indispensable to meet the environmental challenges across the globe. Nanomaterials substantially contribute in delineating the rapidly advancing field of nanotechnology. Recently, primary emphasis has been laid down on augmenting the biological methodologies for the synthesis of nanomaterials. In this aspect, green nanotechnology has revolutionized the entire process of nanosynthesis. Essentially biofabrication of nanoparticles have long-range applications, primarily in the field of medical applications such as drug delivery, cancer diagnostics and genetic engineering processes. Biocompatible and stable nanoparticles synthesized from biological source can be an effective approach against the chemically synthesized owing to their non-expensive and eco-friendly attributes. Biological systems including bacteria, yeasts, fungi and plants have already been exploited in the field of nanotechnology. Use of fungi seems to be a very effective and economical approach for the synthesis of gold nanoparticles. Gold nanoparticles possess anti-oxidation activity, are highly stable and biocompatible in nature. Fungi-mediated nanoparticle biosynthesis is more advantageous as compared to bacterial synthesis. Fungi secrete large amounts of enzymes, whereas the enzyme secretion of yeasts is weak. Here, we have reported the recent advancements and future implications in the field of gold nanoparticle production and applications.

Adsorptive sequestration of noxious uranium (VI) from water resources: A comprehensive review

Groundwater is usually utilized as a drinking water asset everywhere. Therefore, groundwater defilement by poisonous radioactive metals such as uranium (VI) is a major concern due to the increase in nuclear power plants as well as their by-products which are released into the watercourses. Waste Uranium (VI) can be regarded as a by-product of the enrichment method used to produce atomic energy, and the hazard associated with this is due to the uranium radioactivity causing toxicity. To manage these confronts, there are so many techniques that have been introduced but among those adsorptions is recognized as a straightforward, successful, and monetary innovation, which has gotten major interest nowadays, despite specific drawbacks regarding operational as well as functional applications. This review summarizes the various adsorbents such as Bio-adsorbent/green materials, metal oxide-based adsorbent, polymer based adsorbent, graphene oxide based adsorbent, and magnetic nanomaterials and discuss their synthesis methods. Furthermore, this paper emphasis on adsorption process by various adsorbents or modified forms under different physicochemical conditions. In addition to this adsorption mechanism of uranium (VI) onto different adsorbent is studied in this article. Finally, from the literature reviewed conclusion have been drawn and also proposed few future research suggestions.

Nanotechnology for precision and sustainable agriculture: recent advances, challenges and future implications

Sustainable agriculture is extremely critical for sustenance of all the life forms owing to the exceedingly demand of food products for an ever-increasing population across the globe. Essentially, sustainable agriculture involves holistic management of livestock, crops and fisheries, so as to make the farming process self-sustaining for a longer period. Food and agriculture sector contributes heavily in meeting the human demands and thus sustainable agricultural practices would result in positive and long-lasting consequences. Sustainable growth in the field of agriculture can be achievable by the intervention of advanced technologies such as nanotechnology. Conventional farming methods failed to fully utilize the available resources. To circumvent these limitations, nanotechnology can be effectively used to enhance the crop quality and productivity. Applications of nanotechnology in the field of agriculture will lead to improved plant growth, stabilization of soil and microbes, targeted usage of chemicals and most importantly nanotechnology contributes profoundly for waste management. The enhanced activity displayed by the nanoparticles is essentially because of their extremely small size resulting in larger surface area. Nanoparticles are used as seed priming agents resulting in enhanced seed germination rate, consequently favouring for overall growth of the plant. Nanocapsulated fertilizers and pesticides brought a revolutionary change encouraging for betterment of crop and animal health without affecting the environment. Nanotechnology bears tremendous potential to effectively integrate manifold activities of agriculture practices with sustainable productivity. Although the potential benefits of nanotechnology are countless, the environmental safety concerns needs to be cautiously examined. Nanotechnology improves their performance and adequacy by increasing viability, security and, eventually, lowering social insurance costs. In this review, we highlight the nanotechnological interventions aiming towards sustainability in agricultural and food processing sectors primarily by deploying modified nanoparticles and also emphasized several challenges and their impact on the environment.

Adsorptive Sequestration of Toxic Congo Red Dye from Aqueous Solution Using Fe3O4/Sugarcane Bagasse Biochar Nanocomposite

In the current scenario, removal of toxic dyes from dye contaminated water has become a major challenging task to world researchers because disposal of untreated dye effluents into water bodies have adverse effect towards the ecosystem. Keeping this in mind, the present study aims to utilize the sugarcane bagasse biochar (SBB) and its composite with iron oxide nanoparticle (Fe3O4/SBB) to estimate for the decontamination their batch scale potential of Congo red (CR) dye from aqueous solution. The synthesized adsorbent were characterized by FT-IR, XRD, FE-SEM, TEM, VSM, EDX, and BET surface area analysis. The effect of adsorbent dosages (50-130 mg), initial CR concentration (10-100 mg/L), pH (3-11), and contact time (5-240 min) were evaluated CR removal on Fe3O4/SBB at room temperature. The adsorption data well fit with Langmuir isotherm (R2 = 0.99) and pseudo second order kinetics (R2 = 0.99). The maximum adsorption capacity was found to be 74.07 mg/g.

Biological synthesis of GO-MgO nanomaterial using Azadirachta indica leaf extract: A potential bio-adsorbent for removing Cr (VI) ions from aqueous media

Chromium (Cr) contaminated water possesses a serious threat to the entire environment. Hence, approaches leading to the reduction of Cr concentration from aqueous media must be employed, primarily in industries so as to check the efflux of contaminants directly to water source. Recently chemical free synthesized nanoadsorbents have received much more attention essentially for the removal of different toxic metals from water. Therefore, in this work we have developed a plant-mediated synthetic route for the production of graphene oxide (GO) decorated MgO nanomaterial (GO-MgO) using Azadirachta indica (Neem) leaf extract and subsequently applied it as an efficient adsorbent for the removal of highly carcinogenic Cr(VI) ions from water. Different types of analytical techniques such as XRD, FTIR, Raman, BET, FESEM and HRTEM were used to estimate the formation, bonding, functionality, surface area and morphology of GO-MgO nanocomposite. The effect of adsorbent dose, pH of the solution, reaction time, concentration and co-existing ions were studied to estimate the Cr(VI) adsorption on GO-MgO surface. Maximum adsorption efficiency occurred at pH = 4 through electrostatic attraction between Cr(VI) species and GO-MgO surface with maximum uptake capacity value of 132.72 mg/g. The adsorption process followed Pseudo-second-order (PSO) kinetic and Langmuir isotherm models. The Cr(VI) adsorbed GO-MgO is recyclable and thus was reused up to five consecutive cycles.

Rice husk and rice straw based materials for toxic metals and dyes removal: a comprehensive and critical review

This review investigated depth literature survey on the removal of various heavy metals and dyes contamination. The current study is a broad review of the different methods of preparation of biowaste adsorbent from rice husk and rice straw that has been implemented for the adsorption of many hazardous heavy metals and dyes in order to reduce their harmful effect on the environment. The selection of rice waste-based material for the adsorption process was considered due to its cost-effectiveness, easy availability, high adsorption efficiency, and reusability. This study is a comprehensive review of the adsorption of toxic heavy metals and dyes using rice husk and rice straw-based adsorbents either in bare or in modified forms under different physicochemical processes. In addition, some parameters affecting adsorption capability like pH, initial dye concentration, equilibrium time, temperature, adsorbent dosage, and shaking or stirring speed influence the adsorption mechanism have been discussed thoroughly. The applicability of various adsorption isotherm models and adsorption kinetic models for dye adsorption by various rice husk and straw biomass adsorbents is also reported here. Finally, from the literature reviewed conclusions have been drawn and also proposed a few future research suggestions.

Bio-hydrothermal synthesis of ZnO–ZnFe2O4 nanoparticles using Psidium guajava leaf extract: Role in waste water remediation and plant immunity

Here in, an environmental friendly and chemical free bio-hydrothermal method was developed to synthesize ZnO–ZnFe2O4 nanoparticles (NPs) using Psidium guajava leaf extract. The prepared NPs effectively mediate water remediation process as well as enhance plant immunity. The phase formation, functionality, chemical composition, morphological feature and surface area of the prepared material was analyzed by XRD, XPS, TEM and BET analytical techniques. The average size of the prepared special shaped NPs was found to be 17.8 nm. The synthesized composite material is used for the removal of highly toxic Congo red (CR) and Methylene blue (MB) dyes from water by batch adsorption method. The adsorption processes follow Pseudo-second order kinetics and Langmuir isotherm models. The maximum adsorption capacity was found to be 120.32 mg/g for CR and 90.35 mg/g for MB at the solution pH = 6 and pH = 8 respectively. Strikingly, the fabricated ZnO–ZnFe2O4 NPs enhance the plant immune response and promote plant growth, potentially by preventing transpirational water loss. Specifically, the protein levels of key immune responsive genes including BAK1, FLS2, PR1, MPK3 and MPK6 were elevated for the plants treated with NPs as compared with the control plants.

Bioactive molecules from plants: A prospective approach to combat SARS-CoV-2

The emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) or 2019 Novel Coronavirus (2019-nCoV) has put the entire globe into unrest, primarily due to unavailability of specific drug against the viral proteins. In the last two decades the world has withstood many contagious disease crashes. SARS-CoV-2 has put the world and the mankind in danger. It is spreading unstoppably all over the world. The virus is evolving and thus the pathogenicity of SARS-CoV-2 strains has been different and making it difficult to develop a broad-spectrum anti-viral molecule that would be effective against all the SARS-CoV-2 variants. This imperative situation demands development of molecules for effective treatment against SARS-CoV-2. The phytomolecules or the bioactive molecules of plants could be a great alternative to combat SARS-CoV-2. The bioactive molecules with their antiviral properties and the secondary metabolites may effectively deactivate the functioning of viral proteins. The structural configuration of 2019-nCoV proteins and genomic information are available, thus contributing immensely for fast molecular docking studies and hence, enables screening of numerous accessible phytomolecules. In the current study, we have essentially highlighted common phytomolecules against the known viral proteins and described the mode of action of few plant-derived molecules which have the potential to suppress the activity of the viral proteins.

Electrospun magnetic polyacrylonitrile-GO hybrid nanofibers for removing Cr (VI) from water

Graphene based nanocomposites powder posses an immense potential and contributes significantly in the field of water treatment applications. However, the major challenge is to separate these powder materials from the treated water, otherwise it may result in environmental pollution. In this work, Graphene oxide (GO) and Fe3O4 nanoparticles embedded polyacrylonitrile (PAN) nanofibers membrane (PAN-GO-Fe3O4) was developed by simple electrospinning technique, maintaining needle to collector distance of 15 cm, solution flow rate of 1 mL/h and applied DC voltage of 15 kV. The formation, composition, bonding, surface morphology, size, surface area, and magnetic properties of the prepared nanocomposites was analyzed by XRD, FTIR, Raman, XPS, FESEM, HRTEM, BET and VSM analytical techniques. The formation of cubic crystal structure of Fe3O4 was confirmed by XRD and HRTEM. The functionalization and surface composition of PAN-GO-Fe3O4 was confirmed by FTIR, Raman, XPS and FESEM-EDX analysis. The FESEM images revealed the formation of fine fibers of PAN-GO-Fe3O4 with diameter of 150–170 nm. The TEM image revealed that the spherical nanoparticles having diameter of 10–20 nm were decorated on the surface of PAN-GO. From the N2 adsorption-desorption experiment, it was found that PAN-GO-Fe3O4 composite shows higher surface area (90.62 mg/g) than that of GO, PAN and Fe3O4. The saturation magnetization value of the PAN-GO-Fe3O4 nanofibers membrane was found to be 28.72 emu/g. The prepared PAN-GO-Fe3O4 membrane was used for remediation of highly toxic hexavalent chromium (Cr(VI)) ions from water by batch adsorption method. The effect of Cr(VI) adsorption was investigated by varying different parameters such as amount of adsorbent, pH, time and concentration. The above experimental results revealed that Cr(VI) adsorption by PAN-GO-Fe3O4 was pH dependent and maximum adsorption capacity was found to be 124.34 mg/g. Pseudo second order kinetic model and Langmuir isotherm model were best fitted to the experimental data of Cr(VI) removal with higher correlation coefficient (R2) values. The negative value of ?G0 and positive value of ?H0 highlighted that the adsorption of Cr(VI) onto PAN-GO-Fe3O4 was spontaneous and endothermic process. The effect of co-existing ions and reusability test were carried out to reveal the effectiveness of the adsorbent material.

Graphene based nanocomposites powder posses an immense potential and contributes significantly in the field of water treatment applications. However, the major challenge is to separate these powder materials from the treated water, otherwise it may result in environmental pollution. In this work, Graphene oxide (GO) and Fe3O4 nanoparticles embedded polyacrylonitrile (PAN) nanofibers membrane (PAN-GO-Fe3O4) was developed by simple electrospinning technique, maintaining needle to collector distance of 15 cm, solution flow rate of 1 mL/h and applied DC voltage of 15 kV. The formation, composition, bonding, surface morphology, size, surface area, and magnetic properties of the prepared nanocomposites was analyzed by XRD, FTIR, Raman, XPS, FESEM, HRTEM, BET and VSM analytical techniques. The formation of cubic crystal structure of Fe3O4 was confirmed by XRD and HRTEM. The functionalization and surface composition of PAN-GO-Fe3O4 was confirmed by FTIR, Raman, XPS and FESEM-EDX analysis. The FESEM images revealed the formation of fine fibers of PAN-GO-Fe3O4 with diameter of 150–170 nm. The TEM image revealed that the spherical nanoparticles having diameter of 10–20 nm were decorated on the surface of PAN-GO. From the N2 adsorption-desorption experiment, it was found that PAN-GO-Fe3O4 composite shows higher surface area (90.62 mg/g) than that of GO, PAN and Fe3O4. The saturation magnetization value of the PAN-GO-Fe3O4 nanofibers membrane was found to be 28.72 emu/g. The prepared PAN-GO-Fe3O4 membrane was used for remediation of highly toxic hexavalent chromium (Cr(VI)) ions from water by batch adsorption method. The effect of Cr(VI) adsorption was investigated by varying different parameters such as amount of adsorbent, pH, time and concentration. The above experimental results revealed that Cr(VI) adsorption by PAN-GO-Fe3O4 was pH dependent and maximum adsorption capacity was found to be 124.34 mg/g. Pseudo second order kinetic model and Langmuir isotherm model were best fitted to the experimental data of Cr(VI) removal with higher correlation coefficient (R2) values. The negative value of ?G0 and positive value of ?H0 highlighted that the adsorption of Cr(VI) onto PAN-GO-Fe3O4 was spontaneous and endothermic process. The effect of co-existing ions and reusability test were carried out to reveal the effectiveness of the adsorbent material.