Use of Silk Industry Waste – Silkworm Pupa: A Remediation of Environmental Pollution

Abstract

The main concern of every industry is the clean and green production. In spite of all the efforts to achieve this goal the byproducts which are sometimes considered as waste are always a problem. In silk industry the pupa which is a protein rich material in many places is considered as waste. In this work silkworm pupa has been used as a natural adsorbent for the removal of cationic and acid dyes from textile industry waste water. The amino acid nature of the pupa provided a reasonable capability for dye removal. Equilibrium adsorption isotherms were investigated. The adsorption equilibrium data were analyzed by using various adsorption isotherm models and the results showed that the adsorption behavior of the dye could be described reasonably well by either Langmuir or Freundlich models. The characteristic parameters for each isotherm have been determined. The adsorption was dependent on the pH of the solution because of the ionization of amino and acid groups existing on the surface of the adsorbent. Results showed that silkworm pupa not only can be used as an effective natural source for adsorbent but also has a desirable adsorption capability for the removal of dyes from colored wastewater. Chitin and chitosan has been extracted from silk pupa and their properties have been investigated. The silk worm pupa has been treated with HCl and NaOH to extract chitin and then treated with 50% NaOH under nitrogen atmosphere to convert it in to chitosan. Results show that it contains up to 6% chitin. The degree of deacetylation of chitosan obtained determined by FTIR was 82%.