Abstract

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Pulp and paper industries produce a large amount of waste lignin which creates a disposal problem. A few works has been carried out for its utilization to some extent, one of the methods of its maximum and efficient utilization is thermal degradation. In this research work the industrial waste lignin was subjected to thermal degradation at temperature of 500°C in N₂ atmosphere without catalyst and in presence of catalyst ZnCl₂. The major product obtained after degradation is the carbonaceous residue (coke). The cokes obtained in both the cases were characterized with proximate analysis, CHN analysis, FTIR, SEM and surface textural properties. The proximate and CHN analysis of coke showed about 60% of carbon content. FTIR spectra of the cokes showed that many peaks present in lignin are lost during thermal degradation and there is flattening of remaining peaks. The surface morphology of the cokes reveals that they posses high porosity and surface area, hence it can be utilized for adsorption of heavy metal ions. In the present study, adsorption studies of Cu²⁺ ions on the prepared cokes were carried out. The adsorption studies of Cu²⁺ ions were carried out through various parameters such as pH, adsorbent dosage and contact time. It was observed that the coke obtained from degradation of lignin in presence of activating agent ZnCl₂ showed better adsorption capacity than the coke obtained in absence of activating agent. The adsorption data was fitted well into the Langmuir and Freundlich isotherm equation.

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