Procurement and use of the montmorillonite, users will find the following several aspects:
(1) not all effect of montmorillonite.
We know that the adsorption properties of the montmorillonite interlayer charge with closely related, according to the montmorillonite interlayer charge and montmorillonite can be divided into: Wyoming type (Wyoming) (lower charge montmorillonite, can produce 0.20 ~ 0.35 unit negative half cell layers), cutting type (Cheto) (top charge montmorillonite, can produce 0.45 ~ 0.60 unit negative half cell layers) and type (between) between the three types, and the differences between three types of charge can be three times as much, visible difference to charge the effect will be to make much difference. In addition, the cause of the montmorillonite, crystal shape and types of impurities will affect the adsorption of montmorillonite, dispersion, and many other performance.
Montmorillonite technology research and development personnel, in fact, as early as 2007 with different origin of different charge properties of the toxin montmorillonite samples adsorption experiments, and the minimum bacteriostasis concentration (see table: different provinces montmorillonite the specific adsorption of AFB1 detoxification effect)
The results show that the various types of origin of the montmorillonite on the effects of toxin and bacteria is very significant difference, not montmorillonite interlayer charge and the higher the better adsorption effect, the adsorption of different substances need to choose different properties of montmorillonite, to achieve the best effect.
(2) common montmorillonite and purification of modified montmorillonite is a big difference.
Montmorillonite product core technology in addition to the montmorillonite purification technology, more important is that montmorillonite modification technology. Why to purification and modification of the montmorillonite? Differ as a result the causes of montmorillonite, the montmorillonite content in bentonite different, the amount and type of impurities and harmful components, in order to get higher purity, better quality of montmorillonite, bentonite have to be purified. Also because of various kinds of bentonite properties and impurity, making its purification technology has the unique and unrepeatable, that is, different bentonite ore is only possible with different methods of purification technology and best quality. In addition, we know that montmorillonite on bacteria and toxins have certain adsorption effect, but the effect for different substances difference is also very obvious. In 2009, for example, a study reported that pure montmorillonite on aflatoxin adsorption effect is good but not stable and easy desorption, for corn gibberellic ketene toxins, almost no adsorption after modification can increase at the same time montmorillonite on aflatoxin and corn gibberellic ketene toxin stability of adsorption capacity and adsorption. But because there are dozens of ways to modify, each kind of method of effect is different, so will appear on the market of many kinds of modified montmorillonite.
(3) adsorption force, specific surface area and montmorillonite content cannot explain the using effect.
In the practical application of montmorillonite product, often heard some customers put forward "adsorption?? Surface montmorillonite content? The higher the better?" Wait for a problem. Adsorption is montmorillonite sulfuric acid and better ability of adsorption, adsorption time with methyl blue, its height can only explain the adsorption effect of this kind of material, not as a substitute for the adsorption of aflatoxin, corn gibberellic ketene and evaluation methods of various kinds of bacterial toxins. Also, for different application fields of the specific surface area than out of step with the using effect is also listed. For without the modification of montmorillonite, the content, the higher the better the results. But for the modified montmorillonite, changes by the composition of modified montmorillonite after the adsorption of methylene blue or ability to change, and the content of montmorillonite is the amount of methylene blue adsorption time can be used to calculate, so often there will be the use effect of the modified montmorillonite suspension increased, but the content is falling phenomenon.
(4) montmorillonite product safety is very important.
In the feed and food safety is more and more attention today, montmorillonite as an important feed additive products, the safety of the product itself is also particularly important. The harm of dioxin is well known, a 2005 study, points out that the special nutrition company production of feed additives mildew can take off (modified montmorillonite) of dioxin levels as high as 88.003 ps/g, serious damage to the breeding of animals and human health are prohibited from use.
There are some manufacturers with organic bentonite as raw material to produce mycotoxins adsorbent preparation (organic bentonite bentonite modified by quaternary ammonium salt compound modified montmorillonite with the products), in vitro experiments show that organic modified montmorillonite is helpful to improve its adsorption of ZEN, but animals application test results are inconsistent; At the same time, the application of the organic montmorillonite in aquaculture has great potential safety hazard, modified with organic reagents and residual intermediates in organic reagents are there may be some side effects, if this kind of material is the use of a large amount for a long time, will damage to the breeding animals and human health. The feed industry should pay attention to.
In addition also has attracted much attention in recent years, the harm of cristobalite, in 2013 China pharmacopoeia of montmorillonite on the implementation of the latest API standards have clear limits the cristobalite content of harmful substances, so it is necessary to consider using montmorillonite on livestock products also on relevant indicators.
For this, of montmorillonite, the author to say some superficial analysis, usually we will use the following some performance index to preliminary evaluation of montmorillonite:
(1) montmorillonite purity of the products
At present, the evaluation index of montmorillonite purity are mainly blue uptake, cation exchange capacity, amount of ammonia absorption value, sandstone, and XRD.
Blue uptake: the basic principle of water under the decentralized state of montmorillonite has the ability of adsorption of methylene blue, its adsorption amount was known as the blue uptake, with 100 g sample adsorption of methylene blue mg equivalent number or g said. Methylene blue for monovalent cations in water, can with montmorillonite interlayer ion exchange, the formation of organic montmorillonite is complex. According to the empirical formula of montmorillonite content (%) = blue uptake / 0.442 calculated. Generally the higher the montmorillonite content in bentonite, the greater the blue uptake. Blue uptake, therefore, can be used as a rough evaluation of montmorillonite of a bentonite relative content of one of the main technical indicators.
Cation exchange capacity/ammonia absorption value: between the layers of bentonite has exchangeability cation, cation exchange capacity of bentonite tests, is to identify bentonite ore type and judge the important basis of montmorillonite content. Conventional ammonium chloride - 50% ethanol method is used to test. Ammonia absorption value from GB/T21695-2008 feed grade zeolite powder, basic principle is the same as the test method of cation exchange capacity, high cation exchange test results.
Sand: generally refers to the mineral inside without removal of quartz sand, mica sheet, iron and other coarse impurities, content is too much will affect the product quality. Therefore, sand volume is a rough evaluation of montmorillonite of a bentonite one of the main technical indicators of quality. The test method is to use under the condition of a dispersant, water will be made uniformly dispersed suspension sample, such as coarse grained quartz, mica sheet is not affected by dispersing agent, after a period of time deposit in the bottom of the container, according to the percentage content of sediment calculation of quartz sand. On the market a lot of fake montmorillonite or undesirable businessman with bentonite modified montmorillonite, even claimed product purity 95-99%, by the amount of sand and gravel method can distinguish between similar montmorillonite of fake and shoddy products, but we should pay attention to is that some of the montmorillonite product contains fine impurities, such as clay, christobalite sand quantity can be lower.
XRD spectrum: generally refers to using X ray diffraction to measure some montmorillonite samples of XRD diffraction pattern, according to the diffraction peak position and intensity, contrast JCPDS card retrieval, determine the species and content of montmorillonite is available and montmorillonite product kinds of impurity and cristobalite content of harmful substances.
(2) the granularity of the montmorillonite products
As is known to all, the granularity of montmorillonite product fine dispersion performance and the better the performance of adsorption, and montmorillonite granularity of evaluation methods mainly include: powder particle size, bulk density, water dispersed particle size.
Powder particle size test: divided into dry sieving, microscopy, powder particle size instrument and SEM (scanning electronic microscope) images.
Will heap of density test: test samples at 105 ℃ drying to constant weight, slowly pour in 100 ml measuring cylinder drying scale until 100, in the process of the landslide is a standard with no apparent rose powder, no shock on measuring cylinder for operation, the full scale two barrels of powder in weighing, calculation of bulk density value, expressed in g/ml, the granularity of product fine, the smaller the bulk density. This method can rapid simple comparison of the differences of granularity of different products.
Water dispersed particle size, is spread montmorillonite products in water using laser particle size distribution of particle size test, this method is scientific and intuitive, widely used.
(3) the dispersion suspended
Expansion times and montmorillonite dispersion colloid valence is suspended, the main technical indicators. At the same time, the expansion times and glial price and type of bentonite and montmorillonite content is closely related to the same type of the bentonite, the higher the content of montmorillonite, expansion times and glial price is higher; So the expansion times and glial price appraisal is a type of bentonite and evaluate the quality of bentonite is one of the technical indicators. And times according to different requirements, inflation is divided into acid expansion times, drug times, 5 g and 2 g expansion times.
(4) of heavy metals and toxic ingredients
Montmorillonite heavy metals including lead, cadmium, mercury and arsenic, etc, this kind of material can undertake assessment by atomic absorption spectrophotometry, and the current for pharmaceutical montmorillonite main test method of heavy metals by colorimetric method. Toxic ingredients including stones and dioxins.
(5) adsorption
Evaluation of montmorillonite adsorption performance indicators mainly include: adsorption capacity and adsorption ability of mycotoxin; But the size of the adsorption force can't represent its ability to adsorb mycotoxins.
Adsorption: montmorillonite is per 1 g should be the amount of adsorption of sulfuric acid and ning, general is 0.30 ~ 0.50 g. The index can only reaction of sulfuric acid and montmorillonite better adsorption effect and the content of montmorillonite, the montmorillonite stone magnesium content leads to adsorption force increases.
In vitro and evaluate the adsorption ability of mycotoxin consists of buffer system, feed system, artificial simulation animal gastric intestinal juice and animal test four aspects.
Montmorillonite product performance evaluation index is numerous, the application scope of each are not identical. In fact, different USES of montmorillonite product to use different evaluation index system to evaluate and the best evaluation method is animal breeding test.
SanDing technology research and development team as early as 2006 animals with huazhong agricultural university medical school cooperation on nanometer montmorillonite used in piglets test of diarrhoea, cooperation with south China agricultural university animal academy of sciences in 2007 nanometer montmorillonite instead of zinc oxide affect the performance of weaned piglets production test, and later, and with dozens of breeding to continually evaluate and improve product performance and effect, and in the feed industry, fine and specialty chemicals, animal husbandry and veterinary in hubei, shandong animal husbandry and veterinary, "feed of guangdong", "the veterinarian guide," jilin veterinary ", "veterinary drugs and feed additives", "rural breeding technology", "animal health", "animal husbandry and veterinary today", journal of medicine that the win has been have another year, hunan feed, protect and utilize mineral, animal husbandry and veterinary in zhejiang "pig", "non-metallic", "southern feed" and so on dozens of public journals published more than 100 article related application research, the results of this test is now a multitude of bentonite and some montmorillonite factory widely adopted, contributing to the montmorillonite industry.
Different montmorillonite material, different modification processing technology, different manufacturers is not possible to have the same effect.
