沸石对工业工艺循环用水中无机盐去除的研究

【作者】 张栩；

【导师】 傅柳松；

【作者基本信息】 浙江大学 ， 环境工程， 2002， 硕士

【摘要】 沸石是一族构造中存在着广阔的空洞和孔道的架状铝硅酸盐矿物。沸石可分天然品和合成品两类，目前已知的沸石约有40多种天然沸石和100多种合成沸石，其中斜发沸石、丝光沸石、钙十字沸石、毛沸石等的应用价值较大。沸石晶体细小，具有大量的均匀的微孔，微孔的孔径大多在10nm以下，与一般物质的分子大小相当，硬度为3.5～5，相对密度为1.92～2.8。天然沸石的晶体结构比较特殊，比其它架状骨干的铝硅酸盐矿物存在着更宽阔的空洞和孔道，其中占据着阳离子和水分子。一般认为沸石基本结构是以〔（Si，Al）O₄〕四面体的角顶（氧原子）互相联结形成架状硅铝酸盐骨干的晶体结构，被Na⁺、K⁺等阳离子和水分子所占据，可用化学式（M，N）·O·Al₂O₃·nSiO₂·mH₂O表示，其中M、N表示沸石孔穴中的一价和二价阳离子。 沸石由于以上结构特性而具有分子筛作用、极性吸附作用、催化作用以及离子交换作用等，在化学工业、水处理、动物饲料和鱼类饲养等方面有着广泛的用途，在微电子和气体存储等方面的应用研究也有一些报道。沸石储量丰富，价格低廉，具有很高的经济利用价值。 为节约用水、减少污水排放量、减轻污染程度，近年来世界各国相继研究开发污水再生与回用技术，实现工业应用上工艺用水的封闭循环和零排放。工业工艺用水不断地循环使用，必然会造成水中无机盐的累积，当达到一定浓度时，会对整个工艺和设备产生影响或形成危害，如结垢堵塞管道，腐蚀机械设备，危害原材料，降低系统操作效率，以及影响产品质量等。前人对天然沸石或活化后的沸石去除废水中的pb²⁺、Cr³⁺、Cd²⁺等重金属离子、磷酸盐、N-NH₄⁺、有机污染物的去除等方面都有研究。虽然沸石在废水中的应用研究的很多，但是对其在含多种无机盐的废水中的无机盐的去除并没有具体的研究论述。并且在一些工业如造纸工业，天然沸石可以作为其加工工艺的填料和助剂，而对纸的机械性能无显著变化。因此，用储量丰富、价格低廉的天然沸石粉投入到废水中，降低了循环用水中的无机盐含量，吸附无机盐的沸石可随原料进入造纸工艺，降低了吸附剂再生及吸附物质回收利用的费用，减少二次污染，而对产品无太大影响。 本论文以天然沸石作为吸附剂，研究其对模拟废水中的硫酸盐、硝酸盐、磷酸浙江大学硕十学位论文 沸石对工业工艺循环用水中无机盐去除的研究盐和氯化物等无机盐离子的去除效率及其影响因素，同时研究沸石对废水中＊＊D和氨氮的去除效率，并选用几种富含无机盐的工业废水如造纸工业循环用水、污水处理厂污水和洗衣粉工艺循环用水等，进行实际应用方面的研究。 天然沸石对废水中磷酸盐、硫酸盐、氨氮和 COD都有良好的去除效果，对氯化物和硝酸盐没有明显的去除效果。实验以 100mg／L磷酸盐和 1000mgh。硫酸盐溶液，溶液pHgs，8，以每毫克磷酸根需投加 120～140目沸石0．仍（或每毫克硫酸根需投加沸石0．005克），恒温振荡1小时，可以得出沸石去除溶液中硫酸x和磷酸款的最高效率。吸附无机盐的沸石可以作为造纸填料随原料进人造纸工艺，也可以作为农仆物复混肥、水泥、混凝土和建筑砂浆等的配料和填料进行再利用，无二次污染问题。本研究为沸石在工业废水处理中应用提供了基础依据。更多还原

【Abstract】 Zeolite is a class of mircroporous crystalline aluminosilicates with well-defined channels and cavities, it has rigid anionic framework. There are about 40 kind of natural zeolites and more than 100 kind of synthetic zeolites. Some kind of zeolites have used well in practice, such as Clinoptiloite, Mordenite and Frionite. Zeolite is formed with slim crystal and plentiful well-proportioned tiny cavities that apertures mostly low than lOnm and same as common molecules. The rigidity of zeolite is 3. 5-5 and relative density is 1.92-2.8. The natural zeolies have special structure, they have more expanse channels and cavities than other mircroporous crystalline aluminosilicates. The primary building blocks of the zeoli,tes are the (Si04)4~and (AI04)5" tstrahedra. These terahedra are linked by all their corners to form well-defined channels and cages or cavities of discrete size with no two aluminum atoms sharing the same oxygen. The cations, such as sodium and potassium, and water molecules locate in the cages, cavities and channels of zeolite. The base composition of zeolite can be expressed as (M, N) ?0 ?A1203 ?nSi02 ?mH20: Where M is I valence cation and N is II valence cation.Zeolites are widely used in industry and other fields, used as catalysts and molecular sieves in chemical industry, ion exchangers in treatment water and absorbents in detergent, also can be used in animal nutrition and aquacultural farm, microelectronic and hydrogen storage. Fdch reserves and cheap price make it has high economic value in practice.In order to saving water, reducing sewage drainage and debasing pollution, researchers in different countries concern their works about sewage retexture and reuse, the base water processing in industry is water system closure and zero discharge. But continuous use of waster water make inorganic accumulate reaching high concentration, it will jam the pipeline, erode the machine equipment, damage the raw and processed materials, reduce the system manipulation efficiency and affect the production quality. Environmentalists use natural zeolites and activation zeolites to wipe off heavy metal (for instance lead and chromeand cadmium), phosphate, N-NHT and organic contaminations. There are lots of researches about processing wastewater by natural zeolites, but seldom about inorganic salt processing in wastewater. In some industries, such as paper industries, natural zeolites are used asIVstuffing and aid-solvent in paper making process, and have no special affection to paper mechanical properties. Put zeolites into wastewater can reduce organic salt in circulating water, the zeolites which have adsorbed inorganic salt can be mixed with current material and come into papermak processing, reduce the expenses of sorbent regeneration and adsorbed substance reclaim, and lessen secondary pollution and have little influence on manufacture mass.In this paper, based on natural zeolites as a sorbent, we have researched removal efficiency of sulphate, phosphate, nitrate, chloride, COD and N-NH/, investigated other affect factors, and evaluated the applied value of zeolites. From those, we have got the optimum condition and adsorption mechanism, select some kinds of industrial circulate water which contain rich inorganic salt, such as papermaking process cycle water, wastewater of sewage farm and washing powder process cycle water as our experiment object, then we get the real efficiency and put it into to use.Zeolites have preferably removal efficiency to absorb sulphate, phosphate, nitrate, chloride, COD and N-NRT. This experiment used lOOmg/L phosphate and lOOOmg/L sulphate, pH = 5. 8, put 0.05 gram zeolites per milligram phosphate or 0.005 gram zeolites into per milligram sulphate, surged one hour, and in this condition zeolites absorbed sulphate and phosphate. Zeolites absorbed inorganic salt can come into papermake processing as papermake filling with material, and reuse as wad in cropper fertilizer and architectural cement and beton and grit slurry, lessen secondary pollution.更多还原