Journal of Hazardous Materials ( IF 13.6 ) Pub Date : 2017-12-24 , DOI: 10.1016/j.jhazmat.2017.12.049 Agatha W. Wagutu , Revocatus Machunda , Yusufu Abeid Chande Jande
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.
中文翻译:
甲壳动物衍生的磷酸钙系统:在东非大裂谷饮用水除氟中的应用
从虾和蟹壳生物质废物中提取的磷酸钙吸附剂已通过湿化学和低温处理得到了开发。通过X射线衍射和傅里叶变换红外光谱对吸附剂进行表征。进行了批量吸附试验,以研究其吸附地下水和地表水中氟化物的有效性。将吸附能力与骨炭和合成羟基磷灰石(CCHA)进行了比较。结果表明,对虾衍生的吸附剂(PHA)形成了六边形结构,可与羟基磷灰石识别相,而螃蟹基吸附剂(CHA)则主要形成了具有斜晶石结晶相特征的单斜晶结构。振动分析和动力学研究预测脱氟主要是由离子交换和离子吸附机制引起的。发现吸附剂的脱氟能力优于骨炭和CCHA。在含氟浓度为5-70 mg / L的野外水中,CHA效率最高,效率高达92%以上,容量最高,为13.6 mg / g。PHA的最高容量为8.5 mg / g,仍优于CCHA和骨炭记录的2.6 mg / g。吸附最好用伪2描述第二级动力学。研究结果表明,与传统的骨炭和合成系统相比,甲壳类衍生的磷酸钙系统具有更好的除氟潜力。