Preparation Technology of Clay Mineral-Metal Composite Bactericidal Material
In the new bactericidal materials prepared based on clay minerals, clay minerals themselves are mainly used as carriers for bactericidal substances (such as metals, metal oxides, organic substances), and their bactericidal ability is still limited. Modified clay minerals prepared by various methods, and composites made of clay minerals and other materials can be used as new bactericidal materials to produce bactericidal effects on various bacteria.
Clay minerals can enhance the bactericidal ability through various modification methods (including thermal modification, acid modification, inorganic modification of metals or metal oxides, organic modification and composite modification, etc.). The surface area increases, the porosity and dispersion of minerals increase, and the overall thermal stability and mechanical strength of the material are improved. The clay minerals used to modify and prepare bactericidal materials are mainly montmorillonite, kaolinite, halloysite, and vermiculite, among which montmorillonite has outstanding cation exchange capacity, large interlayer domain, specific surface area and strong It is widely used because of its adsorption capacity.
Toxic metal ions and metal oxides can be inserted into the clay mineral layer or adsorbed on its surface to prepare a composite bactericidal material. The metal ions used in the research mainly include zinc, copper, and silver (among which silver is widely used), and the metal oxides include titanium oxide, zinc oxide, copper oxide, and ferrous oxide. Clay minerals and metals or metal oxides are mainly modified through interlayer cation exchange or mineral surface adsorption. The bactericidal mechanism of this type of composite bactericidal material is related to the toxicity of metals to cells or the free radicals generated.
Clay minerals loaded with metal ions have the advantages of slow release of metals, prolonging the sterilization time, and improving the stability of sterilization materials. The slow release of metals is related to the bonding ability between hydroxyl groups on the surface of clay minerals and metals. The increased specific surface area and porosity of clay minerals help to disperse nano-metal particles, improve the contact efficiency between nano-metals and bacteria, and improve the bactericidal effect. However, considering the toxicity of metal nanoparticles, their biological toxicity needs to be considered in specific applications. However, due to the slow release of metal ions in clay minerals, metals may continue to accumulate in the body and exhibit toxicity over time.