Department of Materials, Energy Science and Engineering, Nelson Mandela African Institution of Science and Technology, P.O.BOX 447, Arusha, Tanzania.
Department of Water, Environmental Science and Engineering, Nelson Mandela African Institution of Science and Technology, P.O.BOX 447, Arusha, Tanzania.
J Hazard Mater. 2018 Apr 5;347:95-105. doi: 10.1016/j.jhazmat.2017.12.049. Epub 2017 Dec 24.
Calcium phosphate adsorbents, derived from prawns and crabs shell biomass wastes have been developed using wet chemistry and low temperature treatment. The adsorbents were characterized by X-ray diffractometry and Fourier transform infrared spectroscopy. Batch adsorption test were carried out to investigate their effectiveness in adsorption of fluoride from ground and surface waters. Adsorption capacities were compared with bone char and synthetic hydroxyapatite (CCHA). Results indicate that prawns derived adsorbent (PHA) formed hexagonal structure with phases identifiable with hydroxyapatite while crabs based adsorbent (CHA) formed predominantly monoclinic structure with crystalline phase characteristic of brushite. Vibrational analysis and kinetic studies predicted defluoridation occurred mainly by ion exchange and ion adsorption mechanisms. Defluoridation capacity of the adsorbents was found to be superior compared to bone char and CCHA. CHA was the most effective with efficiencies above 92% and highest capacity of 13.6 mg/g in field water with fluoride concentration of 5-70 mg/L. PHA had highest capacity of 8.5 mg/g which was still better than 2.6 mg/g recorded by CCHA and bone char. Adsorption was best described by pseudo 2nd order kinetics. The findings indicate that crustacean derived calcium phosphate systems have better potential for defluoridation than traditional bone char and synthetic systems.
采用湿化学法和低温处理技术，从虾蟹壳生物质废弃物中开发出了磷酸钙吸附剂。采用 X 射线衍射和傅里叶变换红外光谱对吸附剂进行了表征。进行了批量吸附实验，以研究其从地下水和地表水中吸附氟化物的效果。将吸附容量与骨炭和合成羟磷灰石（CCHA）进行了比较。结果表明，虾衍生的吸附剂（PHA）形成了六方结构，具有羟基磷灰石的可识别相，而蟹基吸附剂（CHA）主要形成单斜结构，具有水合磷酸钙的特征结晶相。振动分析和动力学研究预测脱氟主要通过离子交换和离子吸附机制发生。与骨炭和 CCHA 相比，吸附剂的脱氟能力更高。CHA 的效果最佳，在氟浓度为 5-70mg/L 的田间水中，效率高于 92%，最高容量为 13.6mg/g。PHA 的容量最高，为 8.5mg/g，仍优于 CCHA 和骨炭的 2.6mg/g。吸附最符合拟二级动力学。研究结果表明，与传统的骨炭和合成系统相比，甲壳类动物衍生的磷酸钙系统在脱氟方面具有更好的潜力。
