Biocide and Algicide

Introduction

Biocides and algicides are the chemical substance that are highly sensitive to some microorganisms and can be added to water in small amounts to achieve anti-microbial performance. They can effectively control the reproduction of bacteria and algae and the growth of muck in water, and have a good muck stripping function and a certain degree of dispersion and penetration. Generally, industrial water has an appropriate temperature, more nutrients and organics, which inevitably promotes the reproduction of microorganisms, leading to water quality deterioration and huge harm of industrial production. At present, the most direct and effective way to control the growth of microorganisms in water system is to add biocide and algicide. Because of their effective and low cost, biocides and algicides are widely used in circulating cooling water system, oil field water, leather, construction, paint and other industries.

Fig. 1. Bacteria and algae thrive in the water.

Classification

According to the bactericidal mechanism, biocide and algicide can be divided into oxidizing biocide and algicide and non-oxidizing biocide and algicide.

• Oxidizing biocide and algicide: Oxidizing biocides and algicides mainly include four categories of (1) chlorine-based product (such as chlorine gas, bleaching powder, chlorine dioxide, dichloro-1,3,5-triazinetrione, trichloroisocyanuric acid and its sodium salt.), (2) bromide-based product (such as hypobromite, bromine chloride and active bromate.), (3) ozone and (4) hydrogen peroxide. Oxidizing biocides and algicides are the first to be used. Their advantages of strong sterilization, low price and wide range of source make them still widely used today. But they also have the disadvantages of poor stability, easy to decompose and prone to corrosion.
• Non-oxidizing biocide and algicide: Non-oxidizing biocides and algicides mainly include (1) quaternary ammonium salt type (such as alkyl dimethyl benzyl ammonium chloride, double alkyl quaternary ammonium salt, double quaternary ammonium salt and poly quaternary ammonium salt), (2) quaternary phosphonium salt type (such as BTPC, TTPC, oxygen alkane modified quaternary phosphonium salt, acetal modified quaternary phosphonium salt and polyether modified quaternary phosphonium salt and others), (3) isothiazolinone, (4) organic aldehyde type (such as glutaraldehyde) and (5) others such as chlorophenols, organic tin compounds, organic sulfur compounds, amine salts, guanidine salts and so on. Non-oxidizing biocides and algicides have greatly improved the shortcomings of toxicity and stability of oxidizing biocides and algicides, and become the mainstream product on the market at present.

Mechanism

The bactericidal mechanisms are different in oxidizing and non-oxidizing biocides and algicides. Generally speaking, oxidizing biocides and algicides can produce the strong oxidizing material such as atomic state oxygen and hypochlorous acid that can kill microorganisms by oxidizing the enzymes that are closely related to metabolism in microorganisms. For example, quaternary amine salts, the oxidizing biocides and algicides, can absorb negatively charged microorganism through hydrophobic combination, electrostatic, hydrogen bond and then aggregate on the cell of microorganism, resulting in chamber resistance effect to inhibit the bacterial growth. The non-oxidizing biocides and algicides like a poison which act on a particular part of microorganisms, thus destroying the cell of the microorganism to achieve the purpose of bactericidal. For instance, organic aldehydes act as non-oxidizing biocide and algicide that can occur the nucleophilic addition reaction between its positively charged carbon and protein or enzyme system of microorganism, so that microorganism loses replication ability to achieve the purpose of sterilization.

Alfa Chemistry can offer various biocides and algicides. If you can't find the desired product in our product catalog, we also offer you with custom synthesis service. Please contact us, if you have any needs.