Adsorption/desorption characteristics of sludge-based activated carbon and methanol
GONG Xu-jin1, DONG Yu-qi1, LI Wei-guang2
1. School of Energy and Civil Engineering, Harbin University of Commerce, Harbin 150028, China; 2. School of Environment, Harbin Institute of Technology, Harbin 150080, China
Abstract:Interdisciplinary research was conducted between sewage sludge reclamation and adsorption refrigeration. Pore structure regulation was investigated using sewage sludge as the main carbon precursor, and effects of KOH-catalytic carbonization and phosphoric-acid catalytic activation were clarified. And four new types of sludge-based activated carbons (WNC-4/3/2/1) were prepared by innovative procedure. Performances in terms of adsorption/desorption capacities, refrigerating capacities and refrigerating power were conducted, based on WNC-methanol adsorption refrigeration working pair. Results suggested that the impregnation process of KOH and phosphoric acid resulted in increasing of microporous and mesoporous structures, respectively. Especially, total-, micro- and meso-porous volumes of the new carbon WNC-4 researched to 0.6960, 0.1641 and 0.5319cm3/g, respectively, which was prepared by combined catalysis of KOH and phosphoric acid. The correlation analysis between the specific surface area/pore structure distribution and QL* showed that degree of mesoporous volumes have the most significant correlation with methanol adsorption capacity (R2> 0.90). The maximum adsorption capacity (QL*) calculated by Langmuir adsorption isotherm model (R2=0.9939) reached to 552.67±23.83mg/g. The equilibrium adsorption and desorption capacities within 40min obtained by Sokoda-Suzuki equation were (372.94±9.504) and (412.55±8.309) mg/g, respectively. The desorption capacity, refrigerating capacity and power reached to (327.95±10.56)mg/g, (299.55±7.87)kJ/kg and (599.10±8.15) kJ/(kg·h), respectively, under 100℃ of desorption temperature.
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