| || Effect of sodium dioctylsulphosuccinate on the dropping mercury electrode capacity
Author : Venkatesan, V.K. ;Menon, Sarada
Source : Defence Science Journal ; Vol:9(1) ; 1959 ; pp 14-22
Subject : 54 Chemistry
Keywords : Sodium ;Mercury ;Magnitude ;Manaxol
Abstract : Sodium dioctylsulphosuccinate (Manoxol OT) is shown to exhibit in the tensammetric curve, a hump from -0.7 to -1.0 V and a desorption peak at -1.35V. It has been shown that the hump is caused by dissolved oxygen. Effect of (a) concentration of Manaxol OT and (b) the magnitude of the a.c. ripple on the tensammetric curves has been studied and the results discussed. The D.C. polarograms indicate two waves, the first being caused by oxygen and second mainly by desorption, although the latter is also enhanced by the presence of oxygen.
| || Low cost adsorbents for the removal of Mercury (II) from aqueous solution : A comparative study
Author : Meena, Ajay Kumar;Mishra, G. K.;Kumar, Satish;Rajagopal, Chitra;Nagar, P. N.
Source : Defence Science Journal ; Vol:54(4) ; 2004 ; pp 537-548
Subject : 504 Environmental Sciences
Keywords : Hazardous heavy metals;Waste water;Evironmental pollution;Toxicity;Mercury;Adsorbents;Water contamination
Abstract : The establishments of the Ministry of Defence, specifically ordnance factories and public sector undertakings (like Bharat Electronics Ltd), carry out operations like electroplating, metal/surface finishing, solid-state wafer processing, and initiatory manufacturing (lead azide, mercury fulminate), which generate waste water contaminated with hazardous heavy metals. Mercury and its compounds are known to be highly toxic, both for the living organisms and the environment. To protect public health, a regulatory discharge standard of mercury, as low as 0.01 mg/l, has been imposed and is expected to be even stricter in the future. A promising method for effective mercury discharge control is to employ suitable adsorbents for the removal of mercury from the contaminated aqueous stream. This paper describes the effectiveness of low cost and locally available, untreated and chemically-treated adsorbents for the removal of mercury from the aqueous solution. Their effectiveness has been compared with that of chemically treated granular activated carbon. Treated sawdust and untreated weathered coal were found to be the most suitable low-cost adsorbents in addition to treated granular activated carbon for the removal of mercury from aqueous solution. Under the optimised conditions, ie, adsorbent dose 10 g/l, pH 6, contact time 48 h, and initial concentration of mercury 3 mg/l, the removal of mercury was found to be 99.8 per cent, 99.8 per cent, and 99.7per cent, using treated granular activated carbon, treated sawdust, and untreated weathered coal, respectively. The adsorption parameters were determined using both Langmuir and Freundlich isotherm models. Surface complexation and ion exchange were the major removal mechanisms involved. The adsorption isotherm studies clearly indicated that the Langmuir model is in good agreement with the experimental data on the adsorptive behaviour of mercury on treated granular activated carbon, whereas, the experimental data on adsorptive behaviour of mercury on weathered coal and treated sawdust follow both Langmuir and Freundlich isotherm models. The paper presents the results of the experimental studies as well as the model parameters.
| || Evaluation of Efficacy of Melamine Treatment on Cotton Fabrics
Author : Bhandari, N.D.;Singh, Amar;Agarwal, P.N.
Source : Defence Science Journal ; Vol:18(2) ; 1968 ; pp 21-28
Subject : 687 Textiles and Clothing
Keywords : Mercury;Copper;Nickel Naphthenate
Abstract : Melamine resin treated cotton fabric was exposed to outdoor weathering for 12 months at Kanpur to study its efficacy against weathering. Along with this, fabric treated with (i) hydrated oxides of copper+manganese(ii) nickel naphthenate and (iii) urea formaldehyde resin, were also exposed to find out the most efficacious treatment of these. Pre monsoon exposure of the three sets commenced from 29th of April, May and June ' 65 respectively. Breaking strength and tear strength data for 12 months exposure have revealed that treatment with hydrated oxides of copper + manganese affords maximum protection to cotton fabrics against weathering degradation irrespective of the month of exposure. Urea formaldehyde resin and nickel naphthenate treatment are the next best. Melamine treatment is equally good as hydrated oxides of copper+manganese if the results are based on breaking strength alone but considering loss in tear strength it gave a poor performance. All the treatment have been found to afford protection against irradiation from mercury arc lamp (rich in ultra violet light). Melamine and urea formaldehyde resin treatments were found completely resistant to microbiological attack in soil burial.