Factors affecting aromatization functionality of n-heptane onto Cr[2]O[3]-Al[2]O[3] catalysts doped with K[2]O

CHROMIA/ALUMINA catalysts containing 2, 4, 8, 16 and 32 mol% Cr[2] O[3]. were prepared using the co-precipitation technique. Doping of the precipitated gels with 2 mol% K[2]O was made prior to calcinations at 500, 700 and 900 [degree sign] C. The structures of the calcinations products were determined from their XRD patterns and their textural properties were determined from the adsorption of nitrogen at 77 K. The dehydrocyclization of n-heptane was carried out at 520-580[degree sign] C. using helium as a gas carrier at a rate of 20-60 ml/min, in a pulse micro-reactor directly attached to a flame ionization detector. Samples containing 2 or 4 mol% Cr[2]O[3] did not show any crystalizied chromia phase, whereas those containing higher Cr[2]O[3] content showed gamma- and/or alpha- Cr[2]O[3] depending on their chromia content and calcination temperature. The surface area decreased and the pore size increased with increase of chromia content and with the rise of the calcinations temperature. Chromia/alumina catalysts calcined at 700 [degree sign] C exhibited the highest dehydrocyclization activities compared with the corresponding catalysts calcined either at 500 at 900 [degree sign] C. The conversion of n-heptane proceeded mainly via dehydrocyclization to toluene [major] and benzene [minor], with very low yield of cracking products of C[5]-naphthenes

Adsorption of anionic dyes on to waste Fe (III)/Cr (III).

Waste Fe (III)/Cr (III) hydroxide was investigated for the removal of anionic dyes, namely acid brilliant blue (acidic dye) and procion red (reactive azo dye) from aqueous solution. In batch experiments, parameters studied include contact time, adsorbate concentration, pH, adsorbent dose and temperature. Adsorption followed Langmuir isotherm with adsorption capacity of 10.37 and 3.28 mg/g for acid brilliant blue and procion red, respectively. Adsorption kinetic studies showed second order with respect to acid brilliant blue and first order with respect to procion red. Thermodynamic parameters such as free energy, enthalpy and entropy of adsorption were also evaluated.

Value added eco-friendly products from tannery solid wastes.

Chrome shavings are the prominent solid wastes in tanning industry. Since chromium is known for its toxicity, the disposal of chrome shavings has been identified as a serious problem from the environmental point of view. At present, the popular utilization mode for chrome shavings is the manufacture of leather boards and related products. But this does not offer complete utilization of chrome shavings. Moreover, return per ton of chrome shavings is low if used for leather board production. In view of this, two processes have been developed to offer an alternative and better solution for the disposal of chrome shavings.The first process is preparation of parchment like membrane and the second process is related to development of leather like material. These products are analyzed for their mechanical behavior and other physicochemical properties. Parchment membrane can be used in the preparation of lampshades, chandeliers, wall hangers, table tops etc. and leather like material can be used in the preparation of chappal uppers, hand bags, purses, valets etc. The utilization of the chrome shavings in preparation of those two products not only reduces the environmental pollution but at the same time value added products can also be obtained.