Valorization of plastics and paper mill sludge into carbon composite and its catalytic performance for acarbon material consisted of the multi-layerzo dye oxidation

Abstract

In this work, polyvinyl chloride (PVC) and paper mill sludge (PMS) were co-pyrolyzed under two environments of N₂ and CO₂. The pyrolysis process was assessed by conducting thermogravimetric analysis (TGA) and monitoring the evolution of gaseous products. The resulting solid composites were characterized using XRD, XPS, BET, and Raman analyzers, and their ability to catalytically activate persulfate (S₂O₈^2-) was tested by conducting methyl orange (MO) degradation experiments. Co-pyrolysis of PVC and PMS at the same mass ratio (1:1) in CO₂ resulted in the highest production of H₂ and CO (0.36 mol % H₂ at 480 °C & 1.53 mol % CO at 700 °C). The characterization results revealed that the composite consisted of Fe₃O₄, highly graphitic carbon, and mesoporous structure. In MO oxidation experiments, the co-pyrolyzed composite actively generated OH and SO₄^- by activating S₂O₈^2- to achieve complete removal of 5 mg L^-1 of MO during 100 min at acidic-neutral pH condition. The composite was also able to complete 3 successive cycles of MO oxidation without deactivation. Consequently, the feasibility of achieving the simultaneous production of energy resources and catalyst via industrial wastes utilization in pyrolytic process was demonstrated.

Keywords: Azo dye degradation; CO(2) utilization; Catalyst; Co-pyrolysis; Persulfate activation; Waste management.