Activation of waste paper: Influence of varied chemical agents on product properties

Abstract

Waste paper (WP) is rich in cellulose, which can be activated to produce porous carbon, bio-oil, and combustible gases. During chemical activation of WP, the use of varied chemical agents not only generates activated carbon of distinct pore structure but also bio-oil/gases of different property. In this study, the activation of WP with varied chemical agents was conducted. The distinct characteristics of activated carbon and also bio-oil/gases were correlated with the different nature of the used chemical agents. The results indicated that H₃PO₄ and ZnCl₂ catalyzed polymerization reactions for producing more bio-oil while less gases owing to their Brønsted and Lewis acidic sites. K₂C₂O₄ showed high activity for cracking/gasification reactions, forming bio-oil with higher abundance of organics with smaller π-conjugated structures. In addition, ZnCl₂ could create a very coarse porous structure with abundant macropores via destroying fiber structure in WP and promoting the growth of graphitic crystals. In comparison, K₂C₂O₄ hindered the aromatization and facilitated the formation of amorphous activated carbon. K₂C₂O₄ and ZnCl₂ were much more effective than H₃PO₄ for creating micropores and mesopores from WP, the derived activated carbon showed superior performances as the electrode of supercapacitor and adsorbent for adsorption of oxytetracycline from aqueous solution. In addition, K₂C₂O₄ as activating agent showed lower environmental impact than ZnCl₂ in terms of energy consumption, environmental pollution and the greenhouse effect.

Keywords: Activated carbon; Activation; Chemical agents; Life cycle assessment; Waste paper.