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论文标题:改性沸石应用于废水处理的研究
Studies on Application of Modified Zeolite in Treating Wastewater
论文作者 谢晓凤
论文导师 王京刚,论文学位 硕士,论文专业 环境工程
论文单位 北京化工大学,点击次数 24,论文页数 66页File Size1743k
2003-02-14论文网 http://www./lunwen_714820597/ 沸石;改性剂;六价铬;甲基橙; 吸附
zeolite; HTAB; Cr(Ⅵ);methyl orange; adsorption
沸石是一族具有连通孔道、呈架状构造的含水铝硅酸盐矿物。特殊的晶体化学结构使沸石拥有离子交换、高效选择性吸附、催化等优异性能和环境属性,从而能有效的治理各种污水。首先讨论了沸石吸附剂的改性方法。研究结果表明:用十六烷基三甲基溴化铵(HTAB)改性沸石可增强吸附性能。通过扫描电镜、红外光谱、X射线衍射、热失重和差热分析等进行表征,探讨了沸石的结构和改性机理。实验研究了有机沸石处理含重铬酸根阴离子废水的各种影响因素。结果表明:250C时,在pH=6、有机沸石投加量25g/L条件下,可使水中重铬酸根阴离子的去除率达到98%。实验测得有机沸石对重铬酸根阴离子的饱和吸附量明显高于天然沸石,吸附符合Langmuir和Freundlich吸附等温式。由于大的表面活性剂分子不能进入沸石孔穴内部,表面活性剂分子仅仅在沸石表面的作用点发生作用。有机沸石对重铬酸根阴离子的吸附主要是以表面吸附为主,重铬酸根阴离子由于和表面活性剂形成沉淀被去除。以有机沸石作吸附剂,对水中甲基橙染料进行吸附脱色研究,探讨了影响吸附的因素和吸附机理。结果表明:有机沸石对甲基橙的吸附等温线呈非线性,主要以表面吸附为主。吸附速率大,pH值对脱色效果有较大的影响。随温度升高脱色率下降。在实验条件下可使甲基橙脱色率达99%以上。
Zeolite, a kind of aqueous silicoaluminate mineral with frame structure and numerous connecting holes, possesses excellent properties such as ionexchange, high efficient preferential adsorption, catalysis etc. These properties make it possible to use zeolite in purification of wastewater.This paper deals with the method of modifying natural zeolite and application to waste water treatment. The results showed that zeolite modified by hexadecyltrimethyl-ammonium bromide(HTAB) has higher adsorptive ability. The structure and adsorption mechanism of zeolite were studied by analyses on scanning electron microscopy , differential thermal , X-ray spectroscopy , TG-DTA . The effect of adsorption conditions on adsorption capacity of zeolite modified by HTAB were studied. The experimental results showed that when temperature at 250C, pH of water controlled at 6, the dosage of modified zeolite was 25g/L, the efficiency for organo-zeolite to remove Cr2O72- from water was 98%. The saturated adsorption capacity of organo-zeolite to Cr2O72- in water was larger than that of unmodified zeolite and the adsorption isotherm was accorded with Langmuir and Freundlich isotherm equation. Adsorption mechanism of dichromate on organo-zeolite indicated that since HTAB was too large to enter into the internal portion of the zeolite, sorption of the HTAB only occurred on the zeolite’s external exchange sites. Surface adsorption of organo-zeolite to Cr2O72- is the predominant. The mechanism of anion retention appears to be the formation of an HTAB-anion precipitate on the zeolite surface.The decolorization efficiency of an aqueous solution of methyl orange with organo-zeolite as an adsorbent was studied. Influencing factors and the mechanism of adsorption were investigated in detail. The experimental results showed that the sorption isotherm of organo-zeolite was non-linear, which was the result of methyl orange exterior adsorption into HTAB. The rate of adsorption of dye on the organo-zeolite was high. pH values of solution were the key effect on decolorization. The decoloriation rate will decrease with the increase of temperature. In experiment the efficiency of decolorization was up to 99%.
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