Fabrication of Lithium Silicate-Based Sorbents from Sediment Treated by Citric Acid with Enhanced Co2 Sorption Property

In this paper, a low-cost and environmental-friendly solution citric acid (C 6 H 8 O 7 ) was used to pretreat the sediment of Dianchi Lake (SDL) to synthesize lithium silicate (Li 4 SiO 4 ) based CO 2 sorbent. The results were compared with that pretreated with strong acid. Moreover, the effects of preparation conditions, adsorption conditions and desorption conditions on the CO 2 adsorption performance of prepared Li 4 SiO 4 were systematically studied. Under optimal conditions, the Li 4 SiO 4 sorbent was successfully synthesized and its CO 2 sorption capacity can reach 31.37 wt%, which is much higher than that synthesized from SDL pretreated with strong acid. It is speculated that the presence of some elements after C 6 H 8 O 7 treatment may promote the adsorption of synthetic Li 4 SiO 4 to CO 2 . In addition, after doping with K 2 CO 3 , the CO 2 uptake increases from the original 12.02 wt% and 22.12 wt% to 23.96 wt% and 32.41 wt% under the 20% and 50% CO 2 partial pressure, respectively. More importantly, after doping K 2 CO 3 , the synthesized Li 4 SiO 4 has a high cyclic stability under the low CO 2 partial pressure