Coked Ni/Al2O3 from the catalytic reforming of volatiles from co-pyrolysis of lignin and polyethylene: preparation, identification and application as a potential adsorbent

Abstract

A novel and eco-friendly C–Ni/Al₂O₃ composite was prepared through Ni/Al₂O₃ coking during the catalytic reforming of volatiles from co-pyrolysis of lignin and polyethylene. The influence of Ni loading (0–20%) in the Ni/Al₂O₃ catalyst and catalytic reforming temperature (500–800 °C) on the characteristics of the C–Ni/Al₂O₃ composite was investigated, involving the analysis of SEM, XRD, TPO and FTIR. Fibrous carbon on the C–Ni/Al₂O₃ composite was produced by the catalyst Ni(10%)/Al₂O₃ at reforming temperatures of 600 and 700 °C, which was oxidized at around 500 °C according to the TPO analysis. The maximum deposition of carbon in the C–Ni(10%)/Al₂O₃ composite was about 10.86%, achieved at a catalytic reforming temperature of 700 °C. Abundant oxygen-containing functional groups were observed on the C–Ni/Al₂O₃ composite through the FTIR analysis, leading to the outstanding adsorption performance for pollutant removal from aqueous systems. The optimal C–Ni/Al₂O₃ composite was selected to investigate the effect of process conditions on the adsorption performance for Pb(II), Cr(VI), rhodamine B (RhB) and methyl orange (MO). The adsorption isotherms for the four mentioned pollutants were well fitted by the Langmuir model and the maximum adsorption amount for Pb(II), Cr(VI), RhB and MO was estimated to be 223.52, 54.90, 290.76 and 95.71 mg g⁻¹, respectively. The results indicated that the as-prepared C–Ni/Al₂O₃ composite had potential for the removal of heavy metal ions and hazardous organic compounds from aqueous systems.