Studies on Solvent Degreasing of Skins in Tanneries

-- S Kirubanandan and U Dinesh Babu

The amount of natural fat in sheep’s skin varies significantly, and this depends upon the animal origin, sex, age, etc. In wool acquired from sheep’s skin from Australia and New Zealand, this content can account for up to 50% of dry skin weight. Fats are triglycerides of saturated fatty acids. These fats can cause complications in the presence of excessive natural fat, rancidification and oxidation; due to tanning, dyeing and finishing operations become tedious. The defects reveal themselves in the form of spume and objectionable odor in leather. If the natural fat content in the raw material is high, as is usually the case with sheep’s skin, it must be removed. The process of fat or grease removal is called degreasing which is best carried out after pickling process. Fat dissolving solvents such as kerosene, methylene chloride, and trichloroethylene are employed for degreasing. Since these solvents are water insoluble, they cannot be effectively used for degreasing wet pelts. These solvents are therefore used along with emulsifiers (preferably non-ionic), which disperse the solvent in water, thus facilitating its entry inside the pelt. This paper attempts to study the degreasing action of secondary butyl ether and formulation (solvent and emulsifier) in comparison with a commercial product which is the global market leader in leather degreasing segment. This experimental study shows that an improved degreasing action was achieved with the formulation comparable to the commercial degreasing agent.

© 2011 IUP. All Rights Reserved.

Adsorption of Fluoride from Aqueous Solution by Aluminium Oxide

--V Venkatesham, G M Madhu, S V Satayanarayana,
Varsha N Bhat and H S Preetham

Groundwater in several parts of India is highly polluted with fluoride. Fluoride, although beneficial to humans in small quantities, causes dental fluorosis, brittle bones and stunted growth when consumed in larger quantities over a period of time. In the present investigation, Aluminum oxide (Al2O3) synthesized by gel combustion process was used as on adsorbent to remove fluoride from aqueous solution. The synthesized adsorbent was characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The effects of pH, initial fluoride concentration and adsorbent dosage on adsorption were studied. Maximum fluoride adsorption on Al2O3 results at lower initial fluoride concentration (1 ppm), high adsorbent dosage (2.5 g/50 mL) and in acidic medium (2 pH). Statistically based experimental designs like Central Composite Design (CCD) and Box Behnken Method (BBM) were used to study the effect of variables on adsorption. The predicted and experimental values are in good agreement with regression coefficient more than 0.9.

© 2011 IUP. All Rights Reserved.

Modeling and Simulation of Fluidized Bed Oxychlorination of Ethylene Process

--T Bala Narsaiah, G Karunya and G Venkat Reddy

A mathematical model has been developed for predicting the outlet gas composition of a fluidized bed reactor in which the oxychlorination of ethylene process takes place. The oxychlorination of ethylene is a two-step process. In the first reactor, ethylene is passed through a bed of cupric chloride particles in which ethylene is converted to ethylene dichloride. In the second reactor, the cuprous chloride generated in the first reactor is converted back into cupric chloride by reacting with a mixture of HCl and oxygen gases. In the present paper, a mathematical model is developed for predicting the outlet concentration and conversion of ethylene in the first reactor, which is fluidized bed reactor. A three-phase fluidization has been assumed in which bubble phase, cloud-wake phase and emulsion phase exist. A first order reaction between cupric chloride and ethylene has been assumed. The model predicts the outlet concentration of ethylene, Ethylene Dichloride (EDC) and percentage conversion of ethylene. Further, the model predicts the variation of concentration of gaseous species along with bed height. The results have been compared with the results available in the literature. The results reveal a good agreement between the model and the literature.

© 2011 IUP. All Rights Reserved.

Coupled Filtering of Environmental Noise and Ligand Binding Noise Through Neural Networks to Improve the Chemotaxis of E. coli

-- Pratap R Patnaik

The chemotaxis of Escherichia coli (E. coli) and other bacteria in real environments is subject to noise from outside, in addition to that within the cells. While the cells have internal mechanisms to filter intracellular noise, external intervention is needed for noise from the environment. In previous microbial applications, neural networks have been more effective in filtering environmental noise than algorithmic devices. On this basis, a number of neural network configurations are explored for their effectiveness as external filters in consonance with internal filtering in the chemotaxis of E. coli. Simulations showed significant improvements with neural filters, with the auto-associative filter being the best. The results also revealed the possibility of stochastic resonance between the filtered internal and external noise being a cause of such improvement, and this likelihood is supported by previous reports in different applications.

© 2011 IUP. All Rights Reserved.