Cement Kiln Dust (CKD), a by-product of the cement industry, was used as the raw material to determine the optimum conditions of Ca extraction, which could ultimately be used for indirect mineral carbonation. CKD was a suitable raw material for mineral carbonation due to its high CaO content (42.7%) and fine particle size (23.08 μm), not requiring a pretreatment such as grinding and pH adjustment. Extractions were conducted by varying the factors such as the solvent type, reaction time, temperature, solid-liquid ratio, solvent concentration, and stirring speed, which could affect the Ca extraction. The solvents used (hydrochloric acid, acetic acid, ammonium chloride, ammonium acetate, and sodium citrate) resulted in high Ca extraction efficiencies, and the resultant Ca extract (except for hydrochloric acid) had sufficiently high pH for the carbonation reaction. The optimum conditions set for extracting Ca from the CKD were: 30 min reaction time, 25°C reaction temperature, 1:10 solid-liquid ratio, 1.74 M solvent concentration, and 250 rpm stirring speed. Under these conditions, Ca extraction efficiencies were very high and depended on the solvent used: hydrochloric acid (94.3%), acetic acid (93.7%), ammonium chloride (86.9%), ammonium acetate (85.3%), and sodium citrate (70%). Calcium carbonate was produced by reacting CO₂ with Ca extracted with ammonium chloride and ammonium acetate.

The purpose of this study was investigating the effects of curcumin on the histological changes and functional recovery following spinal cord injury (SCI) in a rat model. Following either sham operation or SCI, 36 male Sprague–Dawley rats were distributed into three groups: sham group, curcumin-treated group, and vehicle-injected group. Locomotor function was assessed according to the Basso, Beattie, and Bresnahan (BBB) scale in rats who had received daily intraperitoneal injections of 200 mg/kg curcumin or an equivalent volume of vehicle for 7 days following SCI. The injured spinal cord was then examined histologically, including quantification of cavitation. BBB scores were significantly higher in rats receiving curcumin than receiving vehicle (P < 0.05). The cavity volume was significantly reduced in the curcumin group as compared to the control group (P = 0.039). Superoxide dismutase (SOD) activity was significantly elevated in the curcumin group as compared to the vehicle group but was not significantly different from the sham group (P < 0.05, P > 0.05, respectively) at one and two weeks after SCI. Malondialdehyde (MDA) levels were significantly elevated in the vehicle group as compared to the sham group (P < 0.05 at 1 and 2 weeks). MDA activity was significantly reduced in the curcumin group at 2 weeks after SCI when compared to the vehicle group (P = 0.004). The numbers of macrophage were significantly decreased in the curcumin group (P = 0.001). This study demonstrated that curcumin enhances early functional recovery after SCI by diminishing cavitation volume, anti-inflammatory reactions, and antioxidant activity.