改性柚皮吸附剂的制备及其去除水中六价铬效果分析

Preparation of modified pomelo peel absorbent and adsorption of hexavalent chromium in water

【目的】研究改性柚皮吸附剂制备工艺及其对水中六价铬[Cr(Ⅵ)]的去除效果,为实现果皮类废弃物资源化利用提供参考依据。【方法】以柚皮为原料,采用磷酸活化改性并经挤压成型制备柚皮炭基颗粒吸附剂(PP-H3PO4),通过红外光谱(IR)、扫描电镜(SEM)和热重—差热(DSC/TG)检测分析柚皮活化改性前后的组成、结构和性质变化,并考察PP-H3PO4投加量、pH、处理时间和盐浓度等因素对含100 mg/L Cr(Ⅵ)污水去除效果的影响。【结果】正交试验获得柚皮粉最优磷酸改性制备工艺为:柚皮粉与磷酸质量比1∶1.2、活化温度130 ℃、活化时间45 min,所得产物碘值达1036.79 mg/g;经IR、SEM和DSC/TG检测分析证实,改性吸附剂的-OH、-NH2和-C=O活性基团增多,内部孔道更丰富、结构变粗糙。PP-H3PO4对含100 mg/L Cr(Ⅵ)污水处理的最佳条件为:吸附剂投加量3.0 g/L、温度25 ℃、pH 2.0,处理120 min可达吸附平衡,Cr(Ⅵ)去除率在99.50%以上,且0~3.0 mol/L的氯化钠盐物质对Cr(Ⅵ)去除率影响较小。【结论】采用磷酸活化改性并经挤压成型制备的柚皮炭基颗粒吸附剂(PP-H3PO4)对Cr(Ⅵ)有很强的吸附能力,可用于去除污水中Cr(Ⅵ)。

【Objective】The present experiment was conducted to investigate the preparation of modified pomelo peel absorbent and its adsorption effect on wastewater containing hexavalent chromium[Cr(Ⅵ)],in order to provide basis and support for realizing the resource utilization of peel waste.【Method】The composition,structure and properties of pomelo peel carbon-based granular adsorbent(PP-H3PO4)were prepared by phosphoric acid activation modification and extrusion molding with pomelo skin as raw material,and detected by infrared spectroscopy(IR),scanning electron microscope (SEM),thermogravimetric-differential thermal(DSC/TG). The effects of PP-H3PO4 addition,pH value,handling time and salt concentration on the removal effect of water containing 100 mg/L Cr(Ⅵ)were investigated.【Result】The optimum phosphoric acid modification preparation process of pomelo powder was obtained by orthogonal experiment: pomelo powder and phosphoric acid mass ratio was 1∶1.2,the activation temperature was 130 ℃,the activation time was 45 min,the iodine adsorption value of the product was up to 1036.79 mg/g. The test analysis of IR,SEM and DSC/TG confirmed that the -OH,-NH2 and -C=O active groups of modified adsorbent increased,the internal orifice was richer and the structure became rough. The optimal condition for PP-H3PO4 on 100 mg/L wasterwater containing Cr(Ⅵ)was:the adsorbent was added to 3.0 g/L,the temperature was 25 ℃,the pH value was 2.0. 120 min treatment could reach the adsorption balance, Cr(Ⅵ)removal rate was more than 99.50%,and the sodium chloride substance in the 0-3.0 mol/L concentration range had little effect on the removal rate of Cr(Ⅵ).【Conclusion】Pomelo carbon-based granule adsorbent(PP-H3PO4),which is modified by phosphoric acid and prepared by extrusion molding,has a strong adsorption capacity for Cr(Ⅵ)and can be used to remove Cr(Ⅵ)from waste water.