Ion-exchange coupled crystallization for the removal of calcium ions from dicyandiamide
- PDF / 19,697,391 Bytes
- 13 Pages / 595 x 842 pts (A4) Page_size
- 21 Downloads / 167 Views
pISSN: 0256-1115 eISSN: 1975-7220
INVITED REVIEW PAPER
INVITED REVIEW PAPER
Ion-exchange coupled crystallization for the removal of calcium ions from dicyandiamide Meiying Huang*,†, Yongsheng Ren**, Demin Jiang*, and Junsheng Qi* *Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservior (Chongqing Three Georges University), Wanzhou 404100, P. R. China **School of Chemistry & Chemical Engineering, Ningxia University, Yinchuan 750021, P. R. China (Received 14 January 2020 • Revised 9 May 2020 • Accepted 11 May 2020) AbstractA new process for ion exchange coupled crystallization is introduced for the removal of calcium ions from dicyandiamide. The effects of different ion-exchange resins, temperature, reaction time, stirring rate, and treatment amount and resin dosage on the removal of calcium ions in dicyandiamide were studied. On this basis, the crystallization process of dicyandiamide was optimized by response surface methodology, together with respective investigations on the effects of cooling rate, stirring rate, seed grain size and seeding time on the removal of calcium ions in dicyandiamide. It was found that the removal efficiency of calcium ion could reach up to 98.12%, during the ion-exchange treatment, and the value increased then fell, with the rise of stirring rate and temperature; the efficiency would improve, with the accumulation of resin dosage; but it would diminish with the increase of treatment amount; and the value would first rise and then remain unchanged when the reaction time was extended. In addition, the best conditions for crystallization are also provided. When the cooling rate is at 0.3 oC/min, the stirring rate 300 rpm, the seed size 60 meshes, and the seeding time 30 minutes, seeds in uniform size with the content of Ca2+ pharmaceutically qualified would be obtained, under the optimum process conditions. Keywords: Ion Exchange, Dicyandiamide, Calcium Ion, Crystallization, Response Surface Methodology
al. used chemical precipitation method to remove calcium ions by water feeding from steam generators, and they applied 50 mg/L sodium phosphate to remove calcium ions from water. By their efforts, the maximum removal efficiency reached 81% [9]. Qin et al. synthesized a calcium ion-selective adsorption zeolite that can effectively remove calcium ions from solution. They found that when the pH is 8, the initial calcium concentration of 800 mg/L, the maximum adsorption capacity of calcium achieved 92.35 mg/ g, after reacting 70 minutes [10]. Nair and Hwang took the lipophilic ester of phosphoric acid (bis-(2-ethylhexyl) hydrogen phosphate) as a carrier to separate calcium ions from the mixed cationic solution in the solvent of n-dodecane which serves as the supporting liquid film. The results showed that the membrane system can be used as a calcium ion detecting electrode under certain conditions [11]. Marsousi et al. utilized liquid-liquid extraction to extract and recover calcium ions in spiral microchannels. It was found that when operating under o
Data Loading...
