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In this work, the potential of a novel and highly efficient composite of Eleocharis dulcis biochar with magnetite nanoparticles and siltstone was explored for removing chromium from water. Characterization of the prepared biochar composite was carried out using thermal gravimetric analysis (TGA), X-ray photon spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy, point of zero charge and BET. XRD confirmed magnetite and quartz to be the main phases in biochar composite. TGA results showed higher thermal stability of the composite after the addition of siltstone. Batch adsorption mode was employed for studying the adsorption capacity of sample for the decontamination of chromium as a function of concentrations, time, temperatures and pHs. Kinetic modelling confirmed pseudo second order to fit best to the kinetic data for chromium adsorption on the composite biochar. An increase of adsorption was observed with the rise in temperature from 303 to 318 K showing the endothermic nature of the process whereas pH study showed higher removal efficiency of chromium in the acidic pH range. Langmuir model was applicable to the data with higher value of correlation. The thermodynamic parameter ΔH° (40.46 kJ mol−1) and negative but higher values of (ΔG°) shows the endothermic and spontaneous nature of the adsorption process respectively. Higher value of activation energy (15.08 kJ mol−1) confirmed the chemical nature of the process. Post adsorption FTIR and XPS confirmed the adsorption of chromium on the surface of the composite. The adsorption capacity obtained in the present study was found to be higher as compared to many other reported adsorbents used for chromium removal. [ABSTRACT FROM AUTHOR]

The mixed phase Nickel-Zinc Nanocomposite (NiZn-NC) was synthesized via microemulsion method using Tween-80 as an emulsifying agent. The Brunauer, Emmett, Teller (BET) and Barrett, Joyner, Halenda (BJH) methods were utilized to measure the surface area (53.84 m2/g) and pore size (1.9 nm) respectively. The crystallographic aspects were analyzed through X-ray diffractometer (XRD) and the derived average crystallite size was 24.78 nm. The surface structure was explored via scanning and transmission electron microscopies (SEM and TEM) whereas the elemental composition was analyzed through energy dispersive X-ray (EDX). The Fourier transform infrared (FTIR) spectroscopic investigation was made to identify chemical moieties. The batch process was followed for the sorption of Cr(VI) ions under the influence of initial electrolyte concentration, temperature and pH. A sets of mathematical equations were utilized to explore mechanism, theoretical modelling and thermodynamic behavior of the adsorption process. The simulated solar light driven degradation of rhodamine 6G (Rh-6G) was examined in the presence and absence of NiZn-NC. The study reveals that 92.86% of Rh-6G was degraded with degradation rate of 0.0063 min−1 in 390 min. [ABSTRACT FROM AUTHOR]

The titanium dioxide nanocatalyst (TiO2:NC) was fabricated by chemical precipitation method and annealed at different temperatures. The texture parameters was estimated by Barrett–Joyner–Halenda (BJH) and Brunauer–Emmett–Teller (BET) utilizing nitrogen adsorption–desorption data. The crystal phase transition, enhanced crystallinity and increase in crystallite sizes with temperature were studied by using X-ray diffractograms (XRD). Coinciding with an increase in crystallite size supervising annealing temperatures, the surface area of the TiO2:NC decreases. The average grain size as calculated from scanning electron microscopy (SEM) initially decreases with increasing annealing temperature (300 °C), whereas further increase in annealing temperature (600 °C), is accompanied by the increase in grain size. A red shift was observed in the diffuse reflectance spectra (DRS) caused by a decrease in band gap energy with rising annealing temperatures. The chemical composition was examined by using Fourier transform infrared (FTIR) and energy dispersive X-ray (EDX) spectroscopies. All the annealed TiO2:NC samples were used as photocatalysts for the degradation of rhodamine 6G (R6G) under simulated solar light source. The TiO2:NC annealed at 600 °C have a higher degradation rate constant than the other samples. [ABSTRACT FROM AUTHOR]

In this work, cost-effective reduced graphene oxide/copper oxide (rGO/CuO) nanocomposite was synthesized by the reduction of GO to rGO and deposition of CuO on the surface of rGO using single step simple chemical method. The prepared nanocomposite was characterized using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet–visible (UV–Vis) and Fourier-transform infrared (FT-IR) spectroscopy. The appearance of peak at 2θ = 11.03° confirmed the synthesis of GO and peaks at 25.65°, 36.14°, 43.09°, 49.91° and 69.52° indicated the synthesis of the nanocomposite. It was found that the normal particulate size of the prepared nanocomposite was in range of 30 to 50 nm. SEM analysis was done to demonstrate the external morphology of the prepared GO and the nanocomposite. The prepared rGO/CuO nanocomposite was analyzed towards photo-catalytic activity for the degradation of methylene blue (MB) and for the catalytic reduction of 4-nitrophenol (4-NP) to 4- aminophenol (4-AP). It was found that about 81% of MB was degraded in 240 min under UV light and complete conversion of 4-NP to 4-AP was done in only 2 min. The prepared rGO/CuO nanocomposite was also analyzed for anti-microbial activity. It was found that the rGO/CuO nanocomposite exhibits better anti-bacterial and anti-fungal activities than GO. The results indicated the increased biocompatibility of the rGO/CuO nanocomposites than GO. [ABSTRACT FROM AUTHOR]

Poor separation of powdered biochar from the liquid phase during toxic heavy metals adsorption poses serious environmental and human health challenges. The current study therefore investigated the removal of toxic heavy metal i.e., cadmium using a magnetically modified biochar derived from Eleocharis dulcis to combine its easy separation from liquid phase with enhanced adsorption capacity obtained from Eleocharis dulcis biochar. The synthesized adsorbent was characterized by using various characterization techniques and its performance for cadmium adsorption was studied at varying parameters of time, temperature, pH and concentration. Both equilibrium and kinetic studies were performed at 30, 35, 40 and 45 °C. The equilibrium data was subjected to Langmuir equation and the thermodynamic parameters like ∆S°, ∆H° and ∆G° were calculated. The kinetic data fitted well to pseudo second order equation and the activation energy was calculated by using Arrhenius equation. The adsorption capacity of cadmium was found to be higher on the surface of magnetite biochar derived from Eleocharis dulcis as compared to many of the reported adsorbents proving it to be an effective adsorbent to remove cadmium from aqueous solutions. [ABSTRACT FROM AUTHOR]

Water pollution is one of the key ecological issues of the present time. Water pollution causes serious problems to human beings. Industries of cosmetics, mining, dyeing, pigments, batteries, PVC stabilizers, metallurgical engineering, nuclear power operations, printing, electric appliances, electroplating, etc. produce several types of the pollutants that are usually discharged into the running water, which make the water unfit for drinking and other domestic purposes. It is need of present time to develop simple and cost effective advance technology for the purification of the contaminated water. In this regard, the nanocomposites play a key role in wastewater treatment. In this study, we reported the single step preparation of rGO/Ag2O nanocomposite for the wastewater treatment. The prepared rGO/Ag2O nanocomposite was characterized using EDX, SEM, XRD, UV–Vis and FT-IR spectroscopy. XRD data confirmed the synthesis of rGO/Ag2O nanocomposite. The appearance of peak at 2θ = 10.9° indicated the formation of graphene oxide (GO). The four diffraction peaks at 2θ = 38.12°, 44.28°, 64.43° and 77.47° indicated the successful synthesis of rGO/Ag2O nanocomposite. SEM analysis of the rGO/Ag2O nanocomposite showed that the sheet of carbon was randomly decorated with Ag2O. The average particle-size of the rGO/Ag2O nanocomposite was calculated to be 24.62 nm. The rGO/Ag2O nanocomposite showed effective catalytic reduction of 4-nitrophenol to 4-aminophenol. The rGO/Ag2O nanocomposite also displayed extraordinary photocatalytic activity for the degradation of methyl blue and brilliant green. [ABSTRACT FROM AUTHOR]

The nano-sized zinc titanate heterojunction was synthesized via co-precipitation method and its texture parameters were studied via nitrogen adsorption/desorption method. The surface area (214 m2/g) and pore size (2.3 nm) were determined by BET and BJH methods. The phase composition and crystalline nature was investigated using X-ray diffractometer (XRD) and resulting crystallite sizes for TiO2 and ZnO were 44.0 and 70.85 nm respectively. The scanning electron and transmission electron microscopies (SEM and TEM) were operated to examine the surface morphology. The energy dispersive spectroscopy (EDX) reveals that the sample is highly pure and Fourier transform infrared (FTIR) spectroscopy was used for the chemical analysis. The synthesized zinc titanate used for the removal of Cr(VI) ions following batch method and adsorption nature was explained by applying Freundlich and Langmuir equations to batch adsorption data. The endothermic nature of the adsorption process was exposed through thermodynamic investigation and 1:1 exchange ratio was determined for hydrogen and Cr(VI) ions. The zinc titanate heterojunction was used as a photocatalyst under irradiation of simulated sun light for the degradation of Rh-6G and almost all dye was degraded with degradation arte of 1.48 × 10−2 min−1. [ABSTRACT FROM AUTHOR]

Currently, wastewater treatment is one of the most important issues related to the toxic effects of the pathogens and hazardous water pollution impact on human beings, agriculture and animals. In this study, we synthesized reduced graphene oxide/zinc oxide (rGO/ZnO) nanocomposite using a chemical method. The synthesized rGO/ZnO nanocomposite was characterized by XRD, SEM, EDX, FT-IR and UV–Vis spectroscopy. The rGO/ZnO nanocomposite was analyzed for reduction of methylene blue (MB) and 4-nitrophenole (4-NP). The antibacterial activity of GO and rGO/ZnO was also analyzed. The degradation rate of MB under UV lamp by rGO/ZnO nanocomposite was found to be 80% after 5 h. The reduction of 4-NP into 4-aminophenol (4-AP) was completed in 10 min in the absence of reducing agent, whereas in the presence of reducing agent (NaBH4), the reduction time was reduced to 3 min. Furthermore, rGO/ZnO nanocomposite was also analyzed for anti-bacterial activity on Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli bacterial strains using agar well disk diffusion method. The results of anti-bacterial activity showed that rGO/ZnO nanocomposite exhibits better anti-bacterial activity than GO. This indicated the increased biocompatibility of the rGO/ZnO nanocomposite than GO. It was found that rGO/ZnO nanocomposites has great potential for reduction of 4-NP to 4-AP, shows superior antibacterial activity and can be used for biomedical application. [ABSTRACT FROM AUTHOR]