Feasible utility of inorganic remains from potable water purification process in chemical looping combustion studied in TG

The objective of the research is to prepare naturally occurring Fe-based materials for use as oxygen carriers and investigate their reactivity in terms of their applicability to energy systems. The inductively coupled plasma optical emission spectrometry test showed that the sediments from potable water purification were largely composed of Fe 2 O 3 (57.8–58.1 %), SiO 2 (25.2–30.7 %), CaO (3.92–8.43 %), and Mn 3 O 4 (0.94–1.39 %). Sediments were examined by cyclic redox experiments in the thermogravimetric analyzer and were compared with reference materials. Gaseous (3 % H 2 ) and solid fuel (hard coal) were tested in terms of chemical looping combustion (CLC). Three cycle tests showed their good reactivity performance. The temperature-depended oxygen transport capacity varied from 4 to 13.9 % by mass. The fairly stable performance was observed during twenty redox cycles. The X-ray powder diffraction patterns after cycling tests showed a stable crystalline phase and confirmed that complete regeneration was achieved, that is contrary to synthetic carriers. Possibly other elements may help to maintain their reactivity and prevented the silicate formation. Scanning electron micrographs of reacted samples showed minor morphology changes. Based on these results, those wastes might be successfully used in a CLC process as efficient and low-cost oxygen carriers.