Modification method of Bentonite for drilling mud

　　As we all know, bentonite has good expansibility, adsorption, and can be intercalated or intercalated with many guest substances. Therefore, it is widely used in chemical industry, petroleum, food, transportation, medicine, papermaking, energy, military industry, environmental protection and other industries, also known as "universal material". In order to meet the needs of this industry, especially wastewater treatment, and improve the efficiency of bentonite, it is necessary to modify bentonite. Here are some modification methods of bentonite.
　　Bentonite modification is generally divided into inorganic modification and organic modification. The commonly used modification methods of bentonite are activation modification, modification by adding modifier and sodium modification.
　　The activation modification method is to activate bentonite. The commonly used methods are acidification, roasting, salt activation, microwave activation, reduction, oxidation, etc., among which acidification and roasting are more commonly used. Acidification modification is that after acid treatment of bentonite, Na +, Mg2 +, K +, Ca2 + ions among bentonite layers can be dissolved into soluble salts, which weakens the bond between layers, increases the interlayer spacing, forms porous active substances with microporous grid structure and large specific surface area, and also removes impurities distributed in the structural channel of bentonite and increases its pore volume The diffusion of adsorbate molecules makes the modified bentonite have strong chemical activity and physical adsorption performance.
　　High temperature roasting method mainly caters to the different surface area of bentonite calcined at different temperatures. When the bentonite is heated, it will lose the surface water, adsorb the water and impurities in the pores, reduce the adsorption resistance caused by water film and impurities, and improve its adsorption property.
　　Modification by adding modifiers is a hot spot in this field, which can be divided into organic bentonite, cross-linked bentonite and organic cross-linked bentonite. Organic bentonite is a kind of bentonite prepared by modifying natural bentonite with organic modifier. The common organic modifier of bentonite is quaternary ammonium salt type cationic modifier. Its main mechanism is that the quaternary ammonium salt cation enters the interlayer of bentonite, which not only makes the interlayer distance of organic bentonite larger, but also improves its hydrophobicity, thus enhancing the ability of bentonite to remove organic matters. The cross-linked bentonite has adjustable pore size, uniform distribution and good adsorption. It can be used for the treatment of ionic or non-ionic pollutants in water.
　　The main methods of sodification of Ca bentonite include suspension method, dry mixing method, wet stacking method and wet extrusion method. Sodium carbonate and caustic soda are commonly used. The mechanism is that the cation calcium between montmorillonite layers is exchanged by ion exchange reaction, resulting in the loss of positive charge, which is balanced by the exchangeable cations adsorbed on the outer surface of the crystal and between the crystal layers.
　　In recent years, China has made some achievements in the modification of bentonite. At present, bentonite modified products have been applied to the treatment of organic wastewater containing aromatic compounds, printing and dyeing wastewater, petroleum wastewater, phosphorus wastewater and monosodium glutamate wastewater.