Evaluation of Paper Pulp Industry Waste as a Conductivity and Water Colour Reducer

Abstract

This work consists in exploring the preparation, characterisation and application of adsorbents based on lignocellulosic materials obtained from waste from the paper pulp industry, namely “Knots and Rejects - KR” and “Primary Sludge - PS”. These carbon materials were prepared by carbonisation under nitrogen flow, N2, and by chemical activation with the activating agent phosphoric acid, H3PO4. The materials were characterised by FTIR and point of zero charge (pHpzc). Selected samples were applied to reduce the conductivity and colour of an effluent from the pulp industry (Biotek, S.A.—Vila Velha de Rodão). The application of these materials showed that some of the samples have the potential to reduce the conductivity of the effluent as well as to diminish its colour. It was possible to reduce the conductivity between 13.2% (KR600) and 20.3% (PS600), with the best results obtained with the samples prepared from PS waste. More interesting results were also observed in terms of colour attenuation of the effluent, with values ranging from 7.3% (KR600) to 69.1% (PS-H3PO4). Also in this case, the best results were obtained with the samples prepared from the PS waste. These results validate the strategy adopted and place it within a typical circular economy approach.