| 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. |
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