Rakshit Ameta

Photocatalytic Degradation of Organic Pollutants: A Review

Water pollution is increasing at an ever increasing pace and the whole world is in the cancerous grip of this pollution. Various industries are discharging their untreated effluents into the nearby water resources; thus, adding to the existing water pollution to a great extent. Hence, there is a pressing demand to develop an alternate technology for wastewater treatment and in this context; photocatalysis has emerged as an Advanced Oxidation Process with green chemical approach for such a treatment. This chapter deals with photocatalytic degradation of different kinds of organic pollutants; mainly surfactants, pesticides, dyes, phenols, chloro compounds, nitrogen containing compounds etc. Mechanisms of their degradation have also been discussed with hydroxyl and allied radicals as the main active oxidizing species.

An Overview of Rubber Recycling

Since the discovery of vulcanisation, rubber has become an indispensable material for the technological development of civilisation, starting from a simple balloon to complex rocket propellant. Rubber Industry worldwide is using on an average 50% of raw materials. These materials are mostly petroleum-based, except natural rubber (NR), steel cord and bead wire. Use of these petroleum-based raw materials not only depletes natural resources, but also produces more extreme environmental hazards. Escalation of petroleum prices, greater awareness of the environment has resulted in different recycling and environmental friendly technologies. Furthermore, the new concept of ‘Cradle to Grave’ has created a significant concern to the manufacturer about present use of petroleum-based raw materials in the rubber industry worldwide. For both environmental and economic reasons, there is also a continuing broad-based interest in the recycling of scrap rubber and rubber recycled materials and therefore in the development of recycling technologies.

Photocatalytic Reduction of Carbon Dioxide

World is facing problems of global warming as well as energy crisis. Both these problems can be solved to a reasonable extent by photoreduction of carbon dioxide. Here, photocatalysis enters the scene. Photocatalytic reduction to synthetic organic fuels like formaldehyde, methanol, formic acid, acetic acid, methane, etc. will provide a solution to the problem of energy crisis as it will give us alternate fuels, which can be burnt into fuel cells to generate electricity. Once we get electricity at the cost of carbon dioxide, one can convert this form of energy to any other form of energy. Secondly, it will give a solution to put a check on the increasing amount of carbon dioxide, which is the main culprit of global warming. Any conventional fuel on burring will add some molecules of carbon dioxide in the atmosphere, but synthetic fuels derived by photocatalytic reduction of carbon dioxide will not add even a single molecule of carbon dioxide in the environment. It can be considered as a short term loan of carbon dioxide from the atmosphere as the carbon dioxide molecules utilized in the synthesis of alternate fuels are generated back on burning it in fuel cell.

Synthesis, Characterization, and Antimicrobial Properties of p-Chloroacetophenone Oxime-Based Furan Resins

A copolymer resin, p-chloroacetophenone oxime-furfuraldehyde (CAOFU), and a terpolymer resin, p-chloroacetophenone oxime-formaldehyde-benzoic acid (CAOFUBA), were synthesized in the presence of hydrochloric acid as catalyst. The structures of copolymer and terpolymer were established by FT-IR and 1H NMR techniques. Molecular weight and polydispersity index were determined by gel permeation chromatography. The thermal stability was evaluated by thermogravimetric analyses (TGA). Softening temperatures (Ts) of these polymers were obtained from differential scanning calorimetry (DSC). All the synthesized polymers have shown reasonably good antimicrobial activities.

Role of copper pyrovanadate as heterogeneous photo-Fenton like catalyst for the degradation of neutral red and azure-B: An eco-friendly approach

The heterogeneous photo-Fenton like process is a green chemical pathway. It has an edge over conventional Fenton and photo-Fenton processes as it does not require the removal of ferrous/ferric ions in the form of sludge. We prepeared copper pyrovanadate or Volborthite (Cu3V2(OH)2O7∙2H2O) composite photocatalyst by wet chemical method. The photocatalyst was characterized by SEM, XRD, IR, TGA/DSC, EDX and BET. Experiments demonstrated that catalyst could effectively catalyze degradation of neutral red and azure-B in presence of H2O2 in visible light. Moreover, the photo-Fenton-like catalytic activity of Cu3V2(OH)2O7∙2H2O was much higher than CuO and V2O5, when used alone as photocatalyst. The effect of variation of different parameters, i.e., pH, amount of photocatalyst, concentration of dye, amount of H2O2 and light intensity was also investigated. The degradation was well fitted under pseudo-first-order reaction with a rate constant of 2.081×10−4 sec−1 and 3.876×10−4 sec−1 for neutral red and azure-B, respectively. Quality parameters of dye solutions before and after photo-Fenton degradation were also determined. A tentative mechanism involving •OH radical as an oxidant has been proposed. The high catalytic activity may be due to the Cu3V2(OH)2O7∙2H2O shell, which not only increased the surface hydroxyl groups, but also enhanced the interfacial electron transfer. The catalyst has been found to possess good recyclability.

Cadmium sulfide photocatalysed reduction of malachite green by ascorbic acid and EDTA as reductants

The photoreduction of malachite green in presence of CdS as photocatalyst and ascorbic acid/EDTA as reductants has been carried out. The effect of different parameters like pH, concentration of malachite green, reductants, amount of semiconductor and light intensity on the rate of photocatalytic reaction has been studied. On the basis of observed data, a tentative mechanism for the photoreduction of malachite green has been proposed.

Spectral and thermal characterization of halogen-bonded novel crystalline oligo(p-bromoacetophenone formaldehyde).

A novel oligomer p-bromoacetophenone-formaldehyde (OPBAF) was prepared by condensation polymerization in the presence of an acid as catalyst. It was characterized by FT-IR, NMR, pyrolysis GC/MS, XRD, GPC, and TG-DTG. The crystallographic parameters and space group for hexagonal OPBAF were a = b = 2.0810 Å and c = 9.2340 Å and P3̅m1, respectively. The degradation activation energy of the oligomer was studied by the Kissinger method. The kinetic parameters were also obtained. Halogen bonding interactions in the crystalline oligomers are identified between halogen···carbonyl and halogen···halogen. Little correlation was found in the halogen bonding motifs exhibited as a function of bromine present in this oligomer, and a unique bifurcated Br···Br/Br···O═C halogen bonding synthon was identified. This newly developed oligomer may be used as an interesting material for the development of 3D-designed structural products.

Synthesis and Characterization of Functionalized Polyaniline Having Methyl Violet as Pendant Groups

Methyl violet–substituted polyaniline is prepared by oxidative polymerization of aniline in an aqueous acidic media using tosic acid as dopant and ammonium persulphate as oxidant. Substitution of methyl violet (dye moieties) on polyaniline backbone takes place in the presence of butyl lithium. The structures of methyl violet–substituted polyanilinewas elucidated by Fourier transform infrared (FT-IR), fluorescence spectra, XRD and differential scanning calorimetery (DSC). Molecular weight is determined by gel permeation chromatography (GPC) and viscosity method. Conductivity and band gap of methyl violet–substituted polyaniline was computed by a two-probe conductometer.

Heterogeneous photo-Fenton-like catalysts Cu2V2O7 and Cr2V4O13 for an efficient removal of azo dye in water

Abstract This work deals with the degradation of non-biodegradable azo-dye (Evans blue) by the heterogeneous photo-Fenton-like process using copper pyrovanadate (Cu2V2O7) and chromium tetravanadate (Cr2V4O13) as catalysts, which have been prepared by wet chemical method. These catalysts were characterized by different techniques such as scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller surface area analysis. The effect of various parameters such as initial pH, concentration of dye, amount of catalyst, amount of H2O2, and light intensity on the reaction rate has also been studied. Photodegradation efficiency was found 77.78 and 79% for copper pyrovanadate (Cu2V2O7) and chromium tetravanadate (Cr2V4O13), respectively. A tentative mechanism involving ·OH radicals as an oxidant for the degradation of dye has also been proposed. The observations revealed that the rate of photo-Fenton-like degradation of dye follows pseudo-first-order kinetics.

Microwave-Assisted Synthesis of Some 1,3,4-Oxadiazole Derivatives and Evaluation of Their Antibacterial and Antifungal Activity

A series of substituted 1,3,4-oxadiazole derivatives (3a–f) and (6a–f) have been synthesized from diphenylacetic acid hydrazide under microwave irradiation in various reaction conditions. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, and 1H NMR. These targeted compounds have been tested for their antibacterial and antifungal activities compared to ampicillin and griseofulvin as standard drug. Compounds 3a, 3e, 3f, 6c, 6d, 6e, and 6d exhibited the maximum antibacterial activities while 3b, 3c, 3d, 3e, 6a, 6d, and 6e exhibited the maximum antifungal activities.