NOPR Collection:

Solar photocatalytic oxidation and removal of arsenic from ground water

2005-04-01T00:00:00Z

Title: Solar photocatalytic oxidation and removal of arsenic from ground water Authors: Majumder, Ayan; Chaudhuri, Malay Abstract: In a laboratory study, the effectiveness of combined tartrate and citrate as photocatalyst in solar photocatalytic oxidation and removal of arsenic from ground water was studied and a method, using a naturally occurring tartrate-citrate photocatalyst that can be used at the household level to treat small quantities of drinking water was developed. Kinetic tests performed with 250 µg/L, As(III)-spiked ground water in presence of 5 mg/L Fe(II) and 50 µM photocatalyst, showed equal efficiency of tartrate and citrate in combination for oxidation and removal of arsenic from ground water in 6 h solar illumination. Presence of silicate moderately decreased the removal of arsenic, while phosphate had more drastic effect on arsenic removal. With the increase in initial As(III) concentration above 250 µg/L, 5 mg/L Fe(II) did not achieved the removal to below 50 µg/L, although the maximum removal efficiency was 80%. Extract of tamarind (fruit of the tree Tamarindus indica), a natural source of tartrate-citrate (equivalent to 50 IlM tartrate and citrate) achieved the arsenic oxidation and removal from 250-260 µg/L arsenic-bearing water to below 50 µg/L. The method performed within a l-L closed PET bottle showed similar removal and can be applied at the household level to treat small quantities of drinking water. Page(s): 122-128

Burr size minimization in drilling using Taguchi technique

2005-04-01T00:00:00Z

Title: Burr size minimization in drilling using Taguchi technique Authors: Gaitonde, V N; Achyutha, B T; Siddeswarappa, B Abstract: Burr formation in drilling is one of the serious problems in precision engineering and mass production. The exit burr degrades the precision of products and causes additional cost of deburring. Since deburring processes are not yet well automated, the productivity of advanced manufacturing systems is often reduced. However, these processes are labour intensive and add to the total cost of components. Therefore, understanding the drilling burr formation and its dominant parameters is essential for controlling the burr size. This paper describes the Taguchi method based robust design philosophy for minimization of burr size- in drilling. Four parameters, namely, cutting speed, feed rate, point angle and clearance angle were identified and the ranges of the parameters for the present investigation was determined from preliminary experiments. Each parameter was investigated at three levels to study the non-linearity effect of the parameters. Taguchi method based L₉ orthogonal array was selected and experiments were conducted as per experimental layout plan. Based on signal to noise ratio analysis, the optimal settings of the process parameters have been determined. Confirmation tests have also been performed to predict and verify the adequacy of the additive models for determining the optimal burr size. Page(s): 91-96

Correlations for predicting detonation temperature of pure and mixed CNO and CHNO explosives

2005-04-01T00:00:00Z

Title: Correlations for predicting detonation temperature of pure and mixed CNO and CHNO explosives Authors: Keshavarz, M H Abstract: In this paper, detonation temperature of CNO and CHNO explosives is evaluated by the base of atomic composition and heat of formation. It is shown here how only atomic composition and condensed phase heat of formation of CNO and CHNO explosives are sufficient for reliable prediction of detonation temperature as compared to complicated computer codes. New correlations are introduced so that they can easily be applied for determining detonation temperature via specified different pathways of decomposition of explosives. Calculated detonation temperatures by this procedure for both pure and explosive formulations show good agreement with respect to measured and the BKWS-EOS predictions of detonation temperatures. Page(s): 158-164

Preparation of ferrites from the combustion of metal nitrate-oxalyl dihydrazide solutions

2005-04-01T00:00:00Z

Title: Preparation of ferrites from the combustion of metal nitrate-oxalyl dihydrazide solutions Authors: Randhawa, B S; Dosanjh, H S; Kaur, Manpreet Abstract: Spinel ferrites, MFe₂O₄ (M= Co, Ni, Cu, Zn) have been prepared by a redox chemical reaction between aqueous solutions of metal nitrates, ferric nitrate and oxalyl dihydrazide (ODH). On rapid heating the reaction mixture undergoes an abrupt exothermic redox chemical reaction that facilitates atomic scale mixing of the cations. This leads to the formation of stoichiometrically pure and single-phase nanoparticle ferrites at comparatively reduced temperature (400^oC) and in less time than possible by the conventional ceramic method. The final thermolysis products (ferrites) have been characterized by various physico-chemical techniques, i.e., XRD, IR, SEM and magnetic studies (saturation magnetization and Curie temperature). Page(s): 151-154