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Sarita Yadav ¹, D. K. Tyagi ¹, O. P. Yadav ²

Affiliations
1 Department of Chemistry, D.A.V. Post Graduate College, Dehradun-248 001, Uttrakhand, IN
2 Department of Chemistry, C. C. S. Haryana Agricultural University, Hisar-125 001, Haryana, IN

Abstract

Equilibrium and kinetic data for the adsorption of Congo-red dye from aqueous solution onto activated rice husk carbon have been reported. The effects of dye initial concentration, adsorbent-adsorbate contact time, temperature, adsorbent's amount and particle size on the percent adsorption of the dye on the adsorbent have been investigated. Kinetics of adsorption of Congo-red onto the adsorbent in aqueous solution was monitored spectrophotometrically. At the specified dye initial concentration, percent adsorption of dye increases with increase in temperature as well as the adsorbate-adsorbent contact period. However, at the given temperature, % adsorption of Congo-red decreases with the increase in dye initial concentration. The observed adsorption data were analysed in light of Langmuir and Freundlich adsorption isotherms. Dye adsorption rate constant (k_ad) follows the first order kinetics. Activation energy (E_a) of adsorption, intra-particle diffusion rate constant and thermodynamic parameters of Congo-red adsorption on the rice-husk carbon have been evaluated and interpreted.

Keywords

Congo-Red Dye, Rice Husk Carbon, Equilibrium, Kinetics of Adsorption.

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Sarita Yadav ¹, D. K. Tyagi ¹, O. P. Yadav ²

Affiliations
1 Department of Chemistry, D.A.V.P.G. College, Dehradun- 248001, Uttrakhand, IN
2 Chemistry Department, CCS Haryana Agricultural University, Hisar-125001, IN

Abstract

Wastewater effluents from textile, paper, tannery and beverage industries are contaminated with variety of pollutants including dyes. Dyes are skin irritant, carcinogenic and can cause allergic dermatitis and mutation. Environmental legislations are now becoming more stringent to control the release of dyes into the environment. Biological treatment of effluent requires a large land area and is constrained by toxicity of some chemicals, and less flexibility in design and operation. Chemical treatments for the removal of dyes from the polluted effluents are not cost effective. Photocatalytic dye degradation techniques suffer from their low efficiency. Adsorption method has been found to be efficient, economical, renewable and eco-friendly solution in treating effluents contaminated with dyes. An overview of the treatments of dye contaminated effluents by biological, chemical and physical methods have been presented.

Keywords

Adsorption, Biological, Chemical, Dyes, Industrial Effluents, Pollutants.

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Sarita Yadav ¹, D. K. Tyagi ¹, O. P. Yadav ²

Affiliations
1 Department of Chemistry, D.A.V.P.G. College, Dehradun- 248001, Uttrakhand, IN
2 Chemistry Department, CCS Haryana Agricultural University, Hisar-125001, IN

Abstract

Kinetic and equilibrium studies for the adsorption of Rhodamine-B dye from aqueous solution onto activated rice husk carbon have been reported. The effect of parameters such as: contact time, dye initial concentration, temperature, adsorbent's amount and particle size on the color removing efficiency of the activated rice husk carbon has been investigated. Kinetics of adsorption of dye at adsorbent in aqueous solution was monitored spectrophotometrically. At the given initial dye concentration, its percent adsorption increases with increase in temperature as well as the adsorbate-adsorbent contact period and the equilibrium was established after 120 minutes. However, at the given temperature, % adsorption of the dye decreases with the increase in its initial concentration. The curves representing adsorption isotherms are single and continuous leading to saturation, suggesting monolayer coverage of the dye on the adsorbent surface. The observed adsorption data was analysed in the light of Langmuir and Freundlich adsorption isotherms. Dye adsorption rate constant (k_ad) follows the first order kinetics. Activation energy (Ea), intra-particle diffusion rate constant and thermodynamic quantities of dye adsorption on the rice-husk carbon have been evaluated and interpreted.

Keywords

Equilibrium, Rhodamine-B, Adsorption, Activation Energy, Thermodynamic.

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Sarita Yadav ¹, Prerna Burathoki ², V. D. Hegde ¹

Affiliations
1 North Eastern Regional Centre, Zoological Survey of India, Risa colony, Shillong - 793003, Meghalaya, IN
2 3rd Mile, Upper Shillong − 793005, Meghalaya, IN

Abstract

Based on the studies of order Dermaptera (Insecta) deposited in the National Zoological Collections of Zoological Survey of India, Shillong, Meghalaya, the current paper deals with 22 species belonging to 11 genera under seven subfamilies, four families and three superfamilies. This study revealed six new records from the state of Meghalaya, three species from Manipur and one each from Assam and Arunachal Pradesh. The distributional records of each species are also provided.

Keywords

Assam, Arunachal Pradesh, Ear-wigs, Manipur, Meghalaya, Mizoram, New Records

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