牡蛎壳中钙的改性及吸附特性的研究

Study on Modification of Calcium and Adsorbability of Oyster Shells

为提高牡蛎壳的综合利用价值,比较了活化前后牡蛎壳中钙的结构特征和成分变化,分析了其吸附性能,初步研究了对刚果红染料的吸附效果。利用牡蛎壳为原料经活化处理制备出一种新型高效吸附材料,采用原子吸收法测定其总钙含量,利用扫描电镜(SEM)、热重分析仪(TG)、粉末X射线衍射仪(XRD)和傅里叶变换红外光谱(FTIR)分析活化前后牡蛎壳的超微结构、热力学变化、成分变化和红外吸收光谱带。结果表明,牡蛎壳的总钙含量为37.56%,标准差为0.46%;SEM图显示,活化前颗粒粒径不均匀、表面光滑、孔隙少,活化后表面高度复杂,不规则微孔和孔隙增多;TG分析表明,峰温为877.0℃时,失重率达到(43.71±0.73)%;XRD显示,活化前牡蛎壳主要成分是三方晶系方解石型CaCO3,活化后主要是CaO;FTIR显示,牡蛎壳有明显的方解石的特征吸收峰(1421cm-1、876cm-1、713cm-1);当900℃活化2h的牡蛎壳用量为3g/L时,对10mg/L的刚果红溶液的脱色率为(98.13±1.39)%。

With the aim of improving the high value utilization of oyster shells, the structural characteristics and components changes between actived and unactived oyster shells were compared, the theoretical adsorbability of oyster shells were analyzed, and preliminary studies on the their adsorption toward congo red dye were carried out. An efficient adsorption material was prepared from oyster shells. The total calcium content of activated and unactivated oyster shells were tested by atomic absorption spectrometry （AAS）. Meanwhile, their ultrastructure, thermodynamic changes, component changes and infrared spectral characteristics were measured using scanning electron microscopy （SEM）, thermogravimetric analyzer （TG）, X-ray diffraetomer （XRD） and Fourier transform infrared （FTIR） spec- troscopy respectively. The results showed that oyster shells contained 37.56 % calcium content and the standard devia- tion was 0. 46%. SEM observat ions indicated that the unactived oyster shell had a smooth surface, uneven particle and low porosity, while the actived oyster shells had highly convoluted surfaces and a large number of irregular pores. The greatest mass loss （43.71±4-0. 73）% was tested by TG, while the peak temperature was 877. 0℃. XRD showed that the major components of unactivated oyster shells was trigonal calcite CaCO3, while the actived Oyster shells was nearly identical and exhibited peak characteristic of CaO. The characteristic absorption peak of calcite at 1421cm^-1 , 876cm^- 1,713cm^-1 were seen from the FTIR spectrum of oyster shells. The decolorization rate of 3g/L activated oys- ter shell toward 10mg/L congo red dye solution reached （98. 134±1.39）% when the activation of 900℃ for 2h.