Write the name and chemical formula of one ore of zinc.
Define : Quaternary ammonium salt.
Answers
Answer:
The chemical compound present in zinc blende is zinc sulphide (sulphide ore) and its chemical formula is ZnS
Quaternary ammonium salts
Quaternary ammonium salts, particularly those containing 12–18 carbon atoms chains, have been widely used as antimicrobial agents in manufacturing antimicrobial textiles [41,42]. These compounds carry a positive charge at N atoms after immersed in water solution and inflict a variety of negative effects on microbes. They adsorb onto phosphate containing cell walls of bacteria through an ionic interaction, penetrate the cell wall, and then attach to the cytoplasmic membrane, thus causing the denaturation of proteins and resulting in leakage of intracellular components and the death of bacteria [43,44]. During inactivation of bacteria, quaternary ammonium groups remain intact and retain their antimicrobial ability as long as the compounds are attached to textiles. However, because of the slow release mechanism, the washing durability of treated fabrics is limited due to the amount of biocides incorporated. Moreover, quaternary ammonium salts have a relatively lower antibacterial efficacy compared with other antibacterial compounds [45,46]. Today, new kinds of quaternary ammonium compounds have been synthesized and successfully treated on textiles.
Organosilicon quaternary salts are a novel type of cationic surfactants with hydrophobic groups containing silicon. In general, this type of surfactant exhibits excellent properties such as low critical micelle concentration (CMC), thermal stability, low temperature flexibility, and chemical inertness. This kind of biocide also has good antimicrobial activity toward gram-positive and gram-negtive bacteria, yeast, fungi, and mold. Dow Corning first synthesized an organosilicon quaternry salt (DC-5700, Figure 9.1). It is a reactive silane that is able to react with many materials such as cotton, glass, or polyester by the hydrolyzed silanol. The treated materials showed antibacterial property after repeated washings [47]. The toxicity experiments with DC-5700 indicated that the median lethal dose is LD50=12.27 g/kg±0.116 g/kg and it cannot be absorbed into body through treated fabrics [48], which shows that this kind of organosilicon quaternary salt is probably a safe antibacterial agent.