Abstract
In this study, we demonstrate a means of simultaneously solving two serious environmental issues by reutilization of pulverized waste oyster shells to prepare CaO-based sorbents for CO2 capture. First, waste oyster shell are calcined with poly(methyl methacrylate) (PMMA) nanospheres. Here, a highly surface area and pore volume “three-dimensionally ordered macroporous (3DOM)” structures are formed. After 10 cycles of isothermal carbonation/calcination at 750 °C, the greatest CO2 uptake (0.19 g CO2/g sorbent) is that for the sorbent featuring 70 wt% of PMMA, which is almost three times higher than that (0.07 g CO2/g sorbent) of untreated waste oyster shell. Subsequent experiment is proposed to solve the “sintering effect” during carbonation/regeneration cycles. By fitting experiment results with an exponential decay equation y=exp-kt, it is found as-determined decay constant (k value) decreases with increasing amount of ZrO2 introduced. This suggests that surface CaZrO3 layer enhances the thermal stability against sintering effect. Following life cycle assessment, whose all input values are collected from our experimental results, suggested that the (a) CO2 uptake efficiency must be greater than 20% or sorbents prepared from limestone mining would eventually produce a net positive CO2 emission in first experiment (b) comparison of materials and energy requirements of mineralizing 1 kg CO2 of plasma and oven thermal treatment, a fewer environmental impacts was calculated of oven thermal treatment.