Recycling waste-derived marble powder for CO2 capture

One of the most promising technologies to reduce global emissions of CO2 as a major greenhouse gas is called calcium looping (CaL). Current calcium-oxide-based sorbents used in CaL process either expensive or lose their effectiveness over many cycles. On the other hand, the negative impact of large amounts of waste marble powder generated by cutting and polishing marble on the environment cannot be ignored. With the aim of cleaning up both carbon emissions and waste at the same time, therefore, this study will investigate the application of inexpensive waste marble powder as potential alternative to current commercial calcium-carbonate sorbents for capturing CO2. The marble powder-based sorbents were characterized by SEM-EDS, XRD, TGA, XRF and N-2 sorption analysis. To improve the CO2 capture performance, the waste marble powder was modified with several various acids. The results revealed that an increase in the acid volume has changed the CO2 uptake capacity and stability of sorbents particularly propionic acid (PA) and acetic acid (AA). It was found that the carbonation conversion of modified sorbents with AA-50% and MD PA-50 were 70.2% and 76%, respectively, higher than that of unmodified CaO sorbent after 20 cycles. In terms of CO2 uptake capacity, modified sorbent with PA-50% showed the highest performance of 0.675 g CO2/g sorbent, while, modified sorbent with AA-50% showed improved cyclic stability over multiple cycles (average decay 1.24 mg CO2/cycle) regarding the stability. Therefore, these results indicate that (acid-modified) CaO derived from marble powder is much better sorbent than limestone and can be used as a low cost and environment-friendly sorbent for CO2 capture. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.