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Enhanced phosphate removal by thermally pretreated waste oyster shells
Journal of Material Cycles and Waste Management ( IF 2.7 ) Pub Date : 2020-09-16 , DOI: 10.1007/s10163-020-01112-4
Thanh-Tham Tran , Ngoc-Ngan Thi Tran , Shigeru Sugiyama , Jhy-Chern Liu

Waste oyster shells were used to remove phosphate and the effects of thermal pretreatment were studied. Thermal pretreatment under different conditions (400 °C for 0.5 h, 400 °C for 2 h, and 700 °C for 2 h) shifted the isoelectric point (pHIEP) of oyster shells to more alkaline range, while surface area decreased from 3.47 to 0.52 m2/g when pretreated at 700 °C for 2 h. Phosphate adsorption was enhanced when using pretreated oyster shells. Adsorption fitted well with Langmuir isotherm model. Both the maximum monolayer coverage (Q0) and the adsorption constant (b) increased when using oyster shells preheated at 400 °C. The values of Q0 and b increased significantly to 5.332 mg/g and 0.728 L/mg, respectively, at pH 10.59 when using oyster shells preheated at 700 °C for 2 h, which could be attributed to the formation of calcium oxide (CaO) as evidenced by analysis of X-ray photoelectron spectroscopy (XPS). Both adsorption and precipitation processes were involved in the reactions as supported by analysis of loaded oyster shells by XPS, and hydroxyapatite (Ca5(PO4)3(OH)) was formed on surfaces of oyster shells.



中文翻译:

通过热处理的牡蛎废壳增强磷酸盐的去除

使用废牡蛎壳去除磷酸盐,并研究了热预处理的效果。在不同条件下(400°C持续0.5 h,400°C持续2 h和700°C持续2 h)进行热预处理将牡蛎壳的等电点(pH IEP)移至更大的碱性范围,而表面积从3.47减小于700°C预处理2 h时达到0.52 m 2 / g。使用预处理过的牡蛎壳时,磷酸盐的吸附作用增强。吸附非常适合Langmuir等温模型。当使用在400°C下预热的牡蛎壳时,最大单层覆盖率(Q 0)和吸附常数(b)均增加。Q 0b的值当使用在700°C下预热2小时的牡蛎壳时,在pH 10.59时分别显着增加至5.332 mg / g和0.728 L / mg,这可能是由于X的分析所证明的形成了氧化钙(CaO)射线光电子能谱(XPS)。通过XPS分析负载的牡蛎壳,吸附和沉淀过程均参与了反应,并且在牡蛎壳表面形成了羟基磷灰石(Ca 5(PO 43(OH))。

更新日期:2020-09-16
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