Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan-magnetite nanocomposite strip. Magnetite nanoparticles (Fe 3 O 4 ) were synthesized using chemical co-precipitation method at 80°C. The nanoparticles were characterized using UVvisible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15-30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K 2 Cr 2 O 7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan-magnetite nanocomposite strip from aqueous solution was evaluated using UV-visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan-magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

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Many oxidative and reductive processes have made extensive use of supported vanadium oxide catalysts. Understanding surface-active speciation and support interactions in these materials is critical to the development of heterogeneous catalysts. In this context, the vanadium incorporated on Mobil Composition of Matter No. 41 (V-MCM-41) catalysts were prepared with ethanol (AM) and without ethanol (NAM) at room temperature. The chemical and structural properties of the V-MCM-41 (AM) and V-MCM-41 (NAM) materials were studied by X-ray diffraction (XRD), N 2 physisorption, inductively coupled plasma-optical emission spectrometry (ICP-OES), diffuse reflectance UV−vis spectroscopy (DRUV−vis), temperature-programmed reduction with hydrogen (H 2 -TPR), X-ray photoelectron spectroscopy (XPS), 51 V NMR analysis, and high-resolution transmission electron microscopy (HRTEM) analysis. The TEM images showed that the V-MCM-41(AM) sample pores were arranged radially with nanosized particles. Further, the elemental analysis reports confirmed that the majority of the vanadium species were successfully loaded onto the pristine siliceous materials. However, the local environment of the vanadium and support interaction was entirely different due to the influence of ethanol in the synthesis medium. The NMR and DRUV−vis results showed that the incorporated vanadium oxide species were highly dispersed on both catalysts with an octahedral coordination environment under hydrated conditions. The detailed investigation from the XPS analysis combined with the TPR results confirmed that the fraction of the V 5+ ion on the mesoporous nanospherical V-MCM-41 (AM) catalyst was significantly larger than the bulk V-MCM-41 (NAM) catalyst. The efficiency of catalysts was tested for diphenylmethane (DPM) oxidation reaction using CO 2 -free air as an oxidant, and catalytic experiments revealed that nanospherical V-MCM-41 (AM) showed a higher catalytic activity than bulk V-MCM-41 (NAM). Differences in catalytic activity were mainly encountered by the concentration of surface-active sites, which were influenced by the radial arrangements of nanospherical particles and the diffusion capability of vanadium oxides. The Raman and NMR studies also showed that a V 5+ ion in a distorted coordination environment with a terminal VO bond is required to activate the O 2 molecule for the selective oxidation reaction. The calculated activation energies for V-MCM-41 (AM) and V-MCM-41 (NAM) were found to be 15 and 35 kJ/mol, respectively. This research paves the way to developing the nanosized MCM-41 material for a variety of shape-selective reactions and storage applications.

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Citric acid (CA) is an important organic acid that is produced on a large scale by the fermentation process. The CA recovery in fermentation technology requires a large amount of CaSO4 as waste and involves a multi-step complex process. Similarly, the production of methanol by the conventional route requires harsh reaction conditions. Therefore, in the present investigation, zinc metal was extracted as zinc oxide from the used alkaline battery material and subsequently employed for CA recovery and methanol production in a more economical way. The phase formation and surface area of the metal oxides (Fe2O3, MnO2, TiO2, and ZnO) were confirmed by the X-ray diffraction and sorption analysis. In the series of materials used in this study, the ZnO exclusively reacted with CA in the waste fruit sample to produce the zinc citrate complex. The maximum uptake of CA was found to be 68% (933.3 mg/g) on ZnO material after 10 min of contact time, which is much higher uptake in the series of the studied materials. Furthermore, the upgrading strategy was developed to produce methanol by the dry distillation method from the recovered zinc citrate complex. The decomposed gaseous products (CH3OH, CO2, and ethylene) were confirmed by thermogravimetric analysis–mass spectrometry (TGA-MS) probe analysis. At first, a loss in mass of about 23% was seen between 100 and 300 °C on the zinc citrate complex’s surface owing to the dehydration reaction of CA-containing hydroxyl groups. The decarboxylation process of the citrate molecule resulted in the second mass loss. During the decarboxylation reaction, the three-carboxylate anion readily breaks down into zinc oxide and CO2 at higher temperatures, as seen by the significant amount of CO2 production. Based on the TGA-MS analysis, we strongly suggest that the ketonization reaction does not occur between the ketones. The proposed green technology enables the use and recycling of electronic and food waste into value-added raw materials for the production of fine chemicals.

A novel mesoporous Mn -organophosphate was synthesized for the first time. It is characterized by several physicochemical techniques. Small angle X-ray diffraction analysis shows the first peak in 2.5 o with 39 A o pore width. Elemental analysis shows that the composition is [(C 12 H 23 40 Mn. Scanning electron microscopic picture shows the flag morphology with 1-15 µm particle size. Thermogravimetry/Differentaial thermal analysis shows almost 80% exothermic weight loss. Nitrogen adsorption isotherm shows type III with 300 m 2 /g BET surface area. Fourier transform Infrared spectroscopic analysis shows that the framework vibrations are comparable to other well known silica mesoporous materials. Electron spin resonance spectroscopic analysis shows the absence of hyperfine splitting indicates the presence of Mn 3+ species. Ultraviolet -visible spectroscopic analysis shows that most of the Mn is in tetrahedral co-ordination beside small square pyramidal species. A plausible synthesis mechanism also proposed.