1. Organic modification
MMT organic modification is an organic process of introducing organic modifiers into the MMT crystal layer. Common organic modifiers are quaternary ammonium salts and amine compounds, such as dodecyl trimethyl bromide (DTAB), hexadecyl Cylpyridine (CPB). After modification, the layer spacing of MMT increases, the pores increase, and it has a larger specific surface area than natural MMT, which is conducive to improving the adsorption effect on mycotoxins and heavy metals. MMT has also changed from a single hydrophilicity to both lipophilicity and hydrophilicity. Appropriate modification will also reduce the adsorption rate of MMT to amino acids, vitamins and other nutrients, and increase the desorption rate of nutrients.
2. Inorganic modification
MMT inorganic modification refers to the use of MMT expansion, adsorption and the exchangeability of interlayer cations to introduce water and hydroxyl polymerized metal cations into the interlayer, and then dehydroxylate or dehydrogenate by heating to form a columnar A new substance with a columnar structure of metal oxide clusters. In the inorganic modification of MMT, the choice of modifier is very important, and polynuclear metal cations such as aluminum hydroxide and iron hydroxyl are the most ideal modifiers. The MMT modified by metal cations forms pillars, the interlayer spacing increases, and the adsorption capacity for antibiotics and mycotoxins is enhanced. Studies have shown that inorganically modified MMT also has antibacterial function.
3. Composite modification
The composite modification of MMT refers to the fact that two or more inorganic and organic modified molecules or ions enter the MMT interlayer domain environment, and form a composite pillared MMT through the pillaring effect, which shows synergy and has various special properties. modification method. Organically modified MMT forms flexible pillars between layers, while inorganic modification forms rigid pillars. Composite modified MMT combines the properties of more than two pillars, and has certain advantages over a single pillar. At present, composite modified MMT is widely used in industrial wastewater. Composite modification of MMT with aluminum chloride, lanthanum chloride and cetylpyridine significantly enhanced the removal capacity of benzopyrene and p-chlorophenol in wastewater, and was superior to activated carbon. The inorganic-organic composite MMT prepared by this method can remove up to 97.57% of the orange Ⅱ dye in the leather industry wastewater. MMT was modified with polyhydroxyaluminum and cetyltrimethylammonium, and the adsorption efficiency of modified MMT for arsenic was as high as 99%.