Clinoptilolite zeolite processing factory price of natural zeolite

 ? Ammonia to form ammonium ion (NH + 4) and free form ammonia (NH3) 2 forms exist in water, mainly from industrial waste (such as wastewater, monosodium glutamate waste water, etc.) as well as municipal sewage, in part from natural waters protein decomposition or under certain conditions nitrite, nitrate nitrogen transformation. NH3 is a colorless gas with a pungent alkaline, extremely dry water soluble, water bodies NH3 toxic effects on aquatic organisms, toxic to fish caused by the amount of 2.1 × 10-2mg / L, on the human body have certain hazards, in vivo synthesis of nitroso compounds may enter, change induced ulcers. ? Currently, the world of water, ammonia have strict control targets. General use of biological nitrification and denitrification technology to achieve ammonia removal of wastewater, but this conventional biological treatment technology is difficult to achieve complete removal of ammonia, it is difficult to make the water to meet drinking water standards. Compared with biological treatment, physico-chemical treatment technology can achieve the depth of removal of ammonia process ammonia, and operating flexibility, high efficiency, low investment, small footprint [3]. Wherein the zeolite ion exchange, because zeolite NH4 + has a strong selective adsorption and popular attention by scholars. ? Structural characteristics 2 zeolite? Zeolite is a form of a porous crystalline aluminosilicate mineral anion-frame-like structure, is more than 30 kinds of zeolite group minerals in general. In more than 40 countries around the world volcaniclastic sedimentary rocks have been found 1000 multiple zeolite origin. Common Major minerals are sodium zeolite, calcium zeolite, analcime, zeolite beam, main zeolite, turbidity, erionite, clinoptilolite, mordenite, etc., how much of their moisture content varies with ambient temperature and humidity changes. Its chemical formula can be expressed as:?? (Na, K) x (Mg, Ca, Sr, Ba ......) y [Alx + ySin- (x + 2y) O2n] mH2O. Wherein, x is the number of alkali metal ions, y is the number of ions of alkaline earth metals, n represents the number of Al-Si ions and, m represents the number of water molecules [4-6]. ? Basic unit of anionic frame structure constituting the zeolite crystal is silicon oxide (SiO4) tetrahedra and aluminum oxide (AlO4) tetrahedron. In this tetrahedron, the center is the silicon (or aluminum) atoms, each silicon (or aluminum) have four oxygen atoms surrounding atoms, each silicon-oxygen tetrahedra in the tetrahedral vertices via oxygen atoms are connected to each other to form The so-called giant molecule. Wherein the aluminoxane tetrahedron valence electrons due to an oxygen atom and has not been, so that the entire alumina tetrahedron with a negative charge, is electrically neutral, near must have a positively charged metal cation (M +) to offset polarity (usually an alkali metal or alkaline earth metal ion). These cations and aluminum silicate combined with relatively weak, with great mobility, easy and water around the cation exchange interactions occur, exchanged zeolite structure is not destroyed. This structure of the zeolite determines that it has ion-exchange. ? Zeolite having open framework structure, 40% to about 50% by volume of the total volume of the crystal of the hole, so that a unique crystal structure having a large number of uniform pores, pore diameter 1nm or less at most. Its uniform molecular size pores and ordinary matter fairly, thus forming a selective adsorption properties of zeolite, namely zeolite pore size can enter the crystal determines the size of the molecules inside the hole, only smaller than the zeolite pore molecules or ions to enter. ? Such crystalline anionic frame structure of the zeolite cations produced specific selection order, which is generated by the electrostatic adsorption by the choice of the structure and effect selection effects together form the molecular sieve. On the one hand, each of which has its own specific zeolite crystal lattice anion and produces its own specific field, each way between the various cations and zeolite framework and its associated electric field interaction is not the same, so that the zeolite with various affinity cation is not the same, resulting in a certain selection effects cation electrostatic attraction; on the other hand, hydrated ionic radius of various cations in water are different, so the degree of difficulty into the zeolite pores of different, resulting in a molecular sieve selection effect . ? Clinoptilolite of selective adsorption coefficient different cations may be selective, ie KaB = (A) znA (Bn) nB / (B) znB (An) nA, wherein (An), (Bn) represents a cation A and B equivalent concentration in the equilibrium solution; (A) z, (B) z A and B represents a cation equivalent on the zeolite portion; nA, nB represents the exchange A and B of the chemical reaction equation mole of A and B number. ? 3 zeolite ion exchange removal of ammonia zeolite has a specific cation exchange order, usually clinoptilolite cation exchange order:? Cs +> Rb +> NH4 +> K +> Na +> Li +> Ba2> Sr3 +> Ca2 +> Mg2 +. Conventional strong acid cation resin selection order for the [7]: Fe3 +> Ca2 +> Mg2 +> K +> NH4 +> Na +> H +> Li +. In particular, the water there is interference cation Ca2 +, Mg2 + present, choose ammonium clinoptilolite off better. ? 3.1 Principle of zeolite NH4 + exchange process can be expressed as: X + Z- + NH4 + → NH4 + Z- + X +, Z represents an anionic aluminosilicate framework, X is an ion exchange. Usually this process [8,9] in the zeolite packed column. After the bed exhausted, usually its regeneration, there will be cheap zeolite-containing powder is added directly to the waste landfill or together as a raw material for cement. ? There are three kinds of method for regenerating a zeolite bed:? (1) chemical regeneration, i.e., treatment with liquid containing a suitable regenerant (H2SO4, HCl, HNO3, NaOH, NaCl) by used clinoptilolite. Chemical regeneration process is actually the inverse of the ion exchange process can be expressed as follows: NH4 + Z- + X + → X + Z- + NH4 +, wherein Z represents an aluminum silicate anion lattice, X is Na or H. ? (2) thermal regeneration, will used zeolite is heated to different temperatures (300 ~ 600 ℃) for regeneration. It has been reported by the hot regenerated zeolite, NH4 + removal capacity has significantly improved. ? (3) biological regeneration, regeneration of the zeolite to achieve by means of denitrifying bacteria. The earliest biological regeneration is equal to 1977 test Semmens proposed actually NaNO3 solution containing denitrifying bacteria rinse zeolite bed, with the replacement of Na + NH4 +, then nitrification denitrifying bacteria. 3.2 Factors? Exchange capacity and adsorption rate are two key indicators of performance evaluation zeolite packed column. Factors affecting the performance of zeolite ion exchange column more, one of the major factors are follows: pH, hydraulic loading, zeolite particle size, water composition, exchange bed height. 3.2.1 pH value? General control pH 4 ~ 8. H + will compete with NH4 + exchange occurs when pH is too low, because the NH4 + diameter 0.286nm [20], H + diameter 0.240nm, both of which can enter the zeolite channels. When the pH is too high, the water mainly exists in the form of NH3. 3.2.2 hydraulic load? Experiments show that for 20 to 80 mesh clinoptilolite exchange column, hydraulic loading of 7.5 ~ 20BV (bed volume) / h, ammonia nitrogen removal rate is unlikely. When the hydraulic load than 20BV / h, the ion exchange column condition deteriorated, significant ammonia loss. In the longer HRT that is smaller inlet flow conditions, both for coarse powdered zeolite or zeolite, ammonia nitrogen removal rate compared with the original high. 3.2.3 zeolite particle? Generally use 20 to 80 mesh zeolite. Small particle size, relatively enriched zeolite, the contact surface is large, the exchange capacity is relatively large, and the finer the particle size, the faster the rate of removal of ammonia. Particle size decreases, the static adsorption capacity will be significantly increased. The smaller the particle size, the exchange dynamics situation better, but the head loss increases, so should not be too small. 3.2.4 Sewage composition? Sewage generated cation-exchange competition section. In a typical municipal sewage cation composition, K + as the main interfering ions, Ca2 +, Mg2 +, Na + less influence with the rise in the concentration of its impact was relatively even increase. Ca2 +, Mg2 +, Na +, K + 4 interfering cations, K + on of NH4 + ion exchange process most obvious inhibition, ammonia nitrogen removal rate can be reduced more than 20%. 3.2.5 exchange bed height? In the same hydraulic loading, switching bed height have a certain impact on the penetration of ammonia. Low bed, the flow rate is small, it may cause uneven water distribution; bed-storey, high velocity, it may result in the loss of ammonia. Meanwhile, the exchange bed height also have an impact on the exchange capacity. ? In addition, pretreatment of the zeolite, influent concentration of ammonia also have an impact on the zeolite ion-exchange properties. After activation zeolite natural zeolite into N, ammonia nitrogen removal rate. When the distribution of the influent concentration of ammonia in the trial in 25 ~ 40mg / L, the water dropped to 1mg / L or less, the best adsorption capacity is 4.5mg (ammonia) / g (zeolite). Found repeatedly pretreated zeolite, can significantly improve the performance of the zeolite. In addition, the exchange of ammonium clinoptilolite total capacity will decrease with lower initial concentration of ammonia. Physical and chemical properties of zeolites 4. Analysis: Analysis Project test data test data analysis project proportion 2.2g / cm3 SiO2 68-70 bulk density of 1.32 g / cm3 AI2O3 13-14 wear rate ≤0.8% Fe2O3 1-1.8 broken rate ≤1.0% CaO 1.8-2.2 porosity ≥48% MgO 0.9-1.4 clay content ≤1.0% K2O 1.6-3.9 Water ≤1.8% NaO 0.6-1.6