**5. Chemical antifouling treatments**

The chemical compounds used as antifouling agents in heat exchangers are called biocides. In addition, sequestrants, dispersants, or chelators can be used for other purposes (**Table 1**).

The biocides contain one or more active substances, whose function is to destroy, counteract, neutralize, and impede the action or exert a control of another type on any harmful organism by chemical or biological means. Properly dosed reduce drastically the number and activity of cells and biofilms in water. Due to its toxic nature, inadequate doses can be harmful to the environment and are therefore


**77**

**Table 3.**

Quaternary ammonium chloride

*Biocides used in cooling water [71].*

*Fouling in Heat Exchangers*

Sales de NH4

**Table 2.**

*DOI: http://dx.doi.org/10.5772/intechopen.88079*

*Specific operating conditions of different biocides [67].*

BNP 2-Bromo-2-nitro propane-1,3-diol BNS Beta-bromo-beta-nitrostyrene

DBNPA 2,2-Dibromo-3-nitrile-propiomide DGH Dodecylguanidine hydrochloride Isothiazolone 5-Chloro-2-methyl-4-isothiazolon-3-one

HPMTS Hydroxypropyl methanethiosulfonate

MBT Methylene-bis- (thiocyanate)

Sulfone Bis- (trichloromethyl) -sulfone TBTO Bis- (tri-n-butyl) tin oxide TCMTB 2(Tiocianatometiltio) benzotiazol

Tris-nitro Tris (hydroxymethyl) nitro methane

**Common name Compound**

Glutaraldehyde 1,5-Pentadial

Sodium bromide Sodium bromide

**character**

Cl2 gas No 5–7.5 Algae and bacteria NaClO Anionic 7–8.5 Algae and bacterias Br2 No 5–9 Algae and bacteria

Chlorophenols Anionic 5–8 Algae, bacteria, and fungi

Sulfur organ Anionic 5–7.5 Bacteria and fungi

ClO2 No 6–10 Algae, bacteria, fungi, and sulfate reducing bacteria

<sup>+</sup> Cationic 7–9.5 Algae and bacteria

Brominated organ No 5–8 Algae, bacteria, fungi and sulfate reducing bacteria Isothiazolones No 5–8.5 Algae, bacteria, fungi, and sulfate reducing bacteria Glutaraldehyde No 5–8.5 Algae, bacteria, fungi, and sulfate reducing bacteria

Carbamates Sodium dimethyl dithiocarbamate, ethylene bis dithiocarbamate disodium,

Chlorine Sodium hypochlorite, calcium hypochlorite trichloroisocyanuric acid, sodium dichloroisocyanide and potassium acid dichloroisocyanide

Hydantoin 1-Bromo-3-chloro-5,5-dimethylhydantoin, 1,3 dichloro-5,5 dimethyl hydantoin,

1,3-dichloro-5-ethyl-5-ethylhydantoin

Triacin Dimethyl propyl-n-ethyl-6- (methylthio) triazine diamine

Chloro-4-ethylamino-6-t-butylamino-s-triazine

Didecyl dimethyl ammonium chloride, n-alkyl dimethyl benzyl ammonium chloride, dialkyl dimethyl ammonium chloride poly oxyethylene (dimethyl ammonium), ethylene (dimethylammonium) ethylene dichloride

potassium methyldithiocarbamate

Chlorophenols Sodium pentachlorophenate and sodium trichlorophenate Dazomet Tetrahydro-3,5-dimethyl-1-2-H-1,3,5-thiadiazine-2-thione

disodium cyanodithioimidocarbamate, Potassium N-methyldithiocarbamate,

**pH Optimal activity**

**Biocide Ionic** 

**Table 1.**

*Chemical agents used in the treatment of seawater [56].*
