Preparation of activated carbon monolith from waste corrugated cardboard box via catalytic pyrolysis and gasification under CO2 atmosphere for adsorption and solar steam generation

Abstract

Activated carbon monolith (ACM) was prepared from waste corrugated cardboard box (WCCB) via slurrying in seawater (SW) followed by dewatering, molding and heating under CO2 atmosphere. The thermal process was analyzed by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). ACM was characterized by N2-adsorption/desorption, FTIR, Raman spectroscopy and ultraviolet–visible-near infrared (UV–Vis-NIR) spectroscopy. The adsorption behavior of ACM for methylene blue (MB) and its solar steam generation performance were investigated. Results showed alkali and alkaline earth metals (AAEMs) in SW promoted the occurrence of pyrolysis of cellulose in WCCB at lower temperatures but inhibited the formation of organic volatiles, and the activation energy was reduced by 24.53 kJ mol−1. AAEMs catalyzed the formation of more CO during CO2 gasification of WCCB char between 755 and 860 °C, and the activation reaction with higher degree led to the formation of more micro- and mesopores in ACM at 785 °C. The adsorption behavior of ACM for MB fitted Langmuir model with a monolayer adsorption capacity of 174 mg g−1, and ACM in floating state was also effective in adsorption of MB from water. ACM exhibited high optical absorption above 90% within a broadband wavelength, and 66.7% higher water evaporation can be achieved with the assistance of ACM during solar steam generation under the same condition.