M.V.S. Suryanarayana

Effect of Iron, Nickel and Cobalt on Bacterial Activity and Dynamics During Anaerobic Oxidation of Organic Matter

The present study reports on the effect of Fe2+, Ni2+ and CO2+ on anaerobic bacterial activity and dynamics during anaerobic mineralization of organic matter. Fe2+ stimulated biogas yield and methane content at 37 °C, but inhibited same marginally at low temperatures (10 and 20 °C). Ni2+ and CO2+ inhibited methane production; the toxicity increased with decreasing temperature. Fe2+ stimulated sulfate reducing bacterial (SRB) and methane producing bacterial (MPB) counts while Ni2+ and CO2+ inhibited the same. All the metals had no effect on obligate proton reducing bacterial (OPRB) counts. Fe2+ stimulated, Ni2+ severely and CO2+ appreciably inhibited H2 uptake and acetate/propionate utilization irrespective of presence/absence of sulfate. Thus, Ni2+ and CO2+ inhibited the overall anaerobic degradative process by inhibiting SRB and MPB activity.

Kinetics of adsorptive removal of DEClP and GB on impregnated Al2O3 nanoparticles

Nanoparticles of AP-Al(2)O(3) (aero-gel produced alumina) have been produced by an alkoxide based synthesis involving aluminum powder, methanol, toluene and water. Thus produced alumina nanoparticles were characterized and the data indicated the formation of nanoparticles of alumina in the size range of 2-30 nm with high surface area (375 m(2)/g). Thereafter, these nanoparticles were impregnated with reactive chemicals. Adsorptive removal kinetics for DEClP (diethylchlorophosphate) and GB (isopropylmethylphosphonofluoridate, sarin) was monitored by GC-FID (gas chromatograph coupled with flame ionization detector) technique and found to be following pseudo first order reaction kinetics. Among impregnated AP-Al(2)O(3) nanoparticles based sorbent systems AP-Al(2)O(3) impregnated with 9-molybdo-3-vanadophosphoric acid (10%, w/w) was found to be the most reactive with least half-life values of 7 and 30 min for the removal of DEClP and GB, respectively, whereas unimpregnated AP-Al(2)O(3) nanoparticles showed the best adsorption potential among all studied systems. In addition to this, hydrolysis reaction {identified using GC/MS (gas chromatograph coupled with mass spectrometer) technique} was found to be the route of degradation of DEClP and GB on impregnated alumina nanoparticles.

The reaction of thiodiglycol on metal-impregnated carbon

Abstract In order to investigate the reactive removal of persistent chemical warfare (CW) gases, active carbons, grade 80 CTC, and active carbon impregnated with cobalt(II), chromium(VI), nickel (II), cadmium(II) or copper(II) salts were saturated at room temperature with the vapours of thiodiglycol (TDG), a hydrolysis product of sulphur mustard. The carbons exposed to TDG were subjected to thermogravimetric analysis (TGA). The thermograms indicated the reactions of metal salts with the adsorbate, as was confirmed by GC-MS after extracting the reaction products from TDG-exposed carbon impregnated with a mixture of chromium(VI) salt and sodium hydroxide. The extractants used were dichloromethane and methanol. 1,4-Oxathiane and 1,4-oxathiane,4-oxide were the reaction products on Cr(VI) plus NaOH impregnated carbon.The reaction mechanisms are also proposed.

Thermal decomposition studies of riot control agent ω-chloroacetophenone (CN) by pyrolysis-gas chromatography-mass spectrometry.

Pyrolysis-GC/MS system with on-line micro-furnace was used to make rapid evaluation of ω-chloroacetophenone (CN) decomposition under inert thermal atmospheres. The volatile products evolved during pyrolysis were analyzed by thermal gravimetric analysis (TGA) and Py-GC/MS to obtain specific thermogram and pyrogram. Thermal gravimetric analysis results showed that CN undergoes sublimation at 167°C prior to its decomposition at 229°C. Totally 45 degradation products were identified based on mass spectral library matching with the aid of correlation of the values of boiling point (bp) and retention time. A large number of mono-aromatics and polycyclic aromatic hydrocarbons were observed beyond 600°C. In addition to the aromatic hydrocarbons, oxygenated compounds were also observed during the pyrolysis process. The pyrolysis mechanism was proposed based on the determined pyrolysates and their relative abundance with temperature. The investigation results can provide significant information for understanding the thermal behavior of CN and evaluation of the potential influence of the pyrolysates to living being and the environment.

A Simple and Efficient Chemical Decontamination of Sulfur Mustard (HD) Using 1,8-Diazabicyclo[5,4,0]Undec-7-Ene Hydrobromide-Perbromide

Abstract A simple and efficient chemical decontamination method was developed against sulfur mustard (HD), an extremely toxic and persistent chemical warfare agent. The method involves treatment of chemical warfare agent HD and its simulants, i.e., methyl p-tolyl sulfide, 2-chloroethyl phenyl sulfide, and 2-chloroethyl ethyl sulfide, with 1,8-diazabicyclo[5,4,0]undec-7-ene hydrobromide-perbromide at room temperature in 1:3 acetonitrile–water system as well as in aqueous medium. The reagent has efficiency to oxidize sulfur mustard in a controlled manner to form nontoxic sulfoxide avoiding overoxidation to the toxic sulfone. Reaction products of the oxidation were isolated and analyzed by gas chromatography-mass spectrometry and 1H NMR. GRAPHICAL ABSTRACT

Direct detection of alkylphosphonic acids in environmental matrices by proton coupled phosphorus NMR.

A simple, convenient, and direct one‐dimensional (1D) 31P NMR technique is demonstrated for the detection of alkylphosphonic acids (marker of nerve agents). The results of detection were validated after conducting various in‐house exercises. The confidence generated by this study was found very useful in detection of different alkylphosphonic acids spiked in various official interlaboratory proficiency tests conducted by Organisation for the Prohibition of Chemical Weapons (OPCW). Copyright

Complete 1H, 13C, 19F and 31P NMR data assignment of CWC-related chemicals N,N-dialkyl-P-alkyl phosphonamidic fluorides

The complete multinuclear 1H, 13C, 31P and 19F NMR data of symmetrically substituted amines containing N,N‐dialkyl‐P‐alkyl phosphonamidic fluorides are presented. Assignment was achieved, using various one‐and two‐dimensional NMR experiments. Copyright