Recovering phosphorus (P) from waste streams takes the unique advantage in simultaneously addressing the crisis of eutrophication and the shortage of P resource. A novel calcium decorated sludge carbon (Ca-SC) was developed from dyeing industry wastewater treatment sludge by decorating calcium (Ca) to effectively adsorb phosphorus from solution. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques were used to characterize the Ca-SCs, followed by isotherm and kinetic sorption experiments. A preferred design with CaCO 3 to sludge mass ratio of 1:2 was found to have a sorption capacity of 116.82 mg/g for phosphorus. This work reveals the crucial role of well-dispersed nano-rod calcium on the Ca-SC surface for the sorption of phosphorus. Moreover, the decoration of nano-rod calcium was found to further promote the uptake of phosphorus through the formation of hydroxylapatite (Ca 5 (PO 4 ) 3 (OH)). Thus, the development of decorated Ca-SC for sorption of phosphorus is very important in solving the P pollution and resource loss.
In the chemical looping combustion of chlorine-rich biomass or coal, a trace element, chlorine, will cause serious corrosion of oxygen carriers and heat exchange equipment in boilers. To address this issue, we design Ca- and Ba-decorated oxygen carriers to achieve two goals: on one hand, reducing the concentration of chlorine-containing gases by in situ dechlorination; on the other hand, employing protective materials to preferentially bind with gaseous chlorine to safeguard the active components of the oxygen carriers. Carefully designed experiments are conducted under simplified experimental conditions using 50 ppmv HCl-containing CH4 to evaluate the intrinsic characteristics of oxygen carriers in terms of dechlorination efficiency and reactivity. The results demonstrate that both the reaction performance and the chlorine-resistance performance of Ca–Cu and Ba–Cu composite oxygen carriers are significantly improved. This is because (a) Ca and Ba preferentially form chlorides with HCl, effectively shielding the active Cu component of the oxygen carrier from chlorine poisoning and (b) the specific surface area and pores of Ca/Ba-decorated oxygen carriers are increased, which not only strengthens the heterogeneous reaction between oxygen carrier and combustible gas but also improves the chemical looping combustion performance. The Cl-resistant oxygen carriers, Ca–Cu and Ba–Cu, emerge as promising candidates for the chemical looping combustion of fuels with high chlorine content.
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