*3.1.4 Molybdate programs*

Most formulators combine molybdate with zinc, orthophosphate, or phosphonate to reduce the cost of sodium molybdate, which maintains the excellent


**Table 7.**

*The typical formulation of alkaline zinc/organic program.*


#### **Table 8.**

*The typical formulation of Zn/organic program.*


#### **Table 9.**

*The typical pH ranges of these programs.*

corrosion inhibition properties of molybdate. Azole and polymers are also added for this purpose. The relatively high levels of azoles in these formulations are required to make sure that the finished products are strong alkaline. Typically, the reserve of molybdenum in recirculating cooling water for such blended products is on the order of 2–5 ppm. Molybdate has a comparatively low aquatic toxicity, and it is considered as a safe alternative to replace chromate. However, in the United States (partly in response to the possible pressures on the reduction of Mo in wastewater), new formulations have been developed in recent years that perform equally well but with <1.5 ppm Mo.

Two examples of traditional molybdate formulations are shown below. Formulation A is designed for lower hardness makeup waters (i.e., 50–100 ppm or thereabout). Formulation B is designed for higher hardness makeup waters (i.e., 100–200 ppm or thereabout). Both of the formulations are designed to provide excellent corrosion inhibition and deposit control in comfort cooling systems, with a cooling water reserve of about 75–125 ppm. Formulation A will yield ~4.0 ppm Mo, and the operating pH is around 7.5–8.5, while Formulation B will yield ~2.5 ppm Mo with the operation pH of 8.0–9.0 (**Table 10**).

For those closed circuits, which in reality are semi-open systems, good corrosion control has been obtained by changing from a nitrite-based program to a molybdate program and maintaining the Mo reserve of 8–10 ppm.

#### *3.1.5 All organic programs*

These programs have become popular and diverse since the presence of improved DCAs, phosphonates, HPA, and other organic inhibitors. They have been widely available since the mid-1980s. They can successfully operate under a

**163**

**Table 11.**

*An example of the all organic program.*

**Table 10.**

*Two examples of traditional molybdate formulations.*

*Formulation of Corrosion Inhibitors*

involved.

*DOI: http://dx.doi.org/10.5772/intechopen.88533*

oxidizing biocides, such as bromine (**Table 11**).

*3.1.6 Soft and lean water and environmental programs*

variety of operating conditions at high pH level, without the need of acid dosing. It means the operators can increase the cycles of concentration. In addition, this kind of program type is suitable for employing in small industrial and comfort cooling systems, where acid or continual and precise analytical control is not

An example of the all organic program is given below. Typically, this program would be used at the concentration of 75–125 ppm, depending on operating conditions. The pH range is from 7.5 to 9.0, and this formulation is suitable for use with

There are numerous permutations of all organic formulations. Formulations containing 6–12% POCA perform good results at the presence of high chlorides.

Acceptable cooling water programs usually use either lean water, with very low natural hardness, or ion-exchange softened water as a makeup source. In order to minimize the deposits of calcium carbonate, it must require softened water, of which the total hardness (TH) should be <5–10 ppm, to act as the makeup water

**Basic formulation materials Formulation A (%) Formulation B (%)**

NaOH, commercial solution 7 16 MA/EA/VA 6 6 ATMP 4 6 AA/AMPS — 6 TTA, commercial solution 4 4 PEG 2 2 Sodium molybdate solution 25 16 Water 52 44 Total 100 100

**Basic formulation materials All organic formulation (%)**

NaOH, commercial solution 17 POCA 6 HPA 6 MEA 1 HEDP 6 PAA 6 TTA, commercial solution 4 PEG 54 Total 100

Some formulations also incorporate phosphate-polymer constituent.

### *Formulation of Corrosion Inhibitors DOI: http://dx.doi.org/10.5772/intechopen.88533*

*Water Chemistry*

**Table 8.**

**Table 9.**

*The typical formulation of Zn/organic program.*

*The typical pH ranges of these programs.*

corrosion inhibition properties of molybdate. Azole and polymers are also added for this purpose. The relatively high levels of azoles in these formulations are required to make sure that the finished products are strong alkaline. Typically, the reserve of molybdenum in recirculating cooling water for such blended products is on the order of 2–5 ppm. Molybdate has a comparatively low aquatic toxicity, and it is considered as a safe alternative to replace chromate. However, in the United States (partly in response to the possible pressures on the reduction of Mo in wastewater), new formulations have been developed in recent years that perform equally well but

**Basic formulation materials Zn/phosphate organic compound (%)**

H3PO4, commercial acid 10 ZnCl2 5 PBTC 5 AA/AMPS 5 TTA, commercial solution 1 PAA 6 MA/EA/VA 6 Water 62 Total 100

**Programs pH range** Alkaline phosphate 8.0–9.0 Alkaline zinc 7.0–8.0 Zinc/polymer/phosphonate 7.5–8.5 Zinc/phosphate/organic 7.5–9.0

Two examples of traditional molybdate formulations are shown below. Formulation A is designed for lower hardness makeup waters (i.e., 50–100 ppm or thereabout). Formulation B is designed for higher hardness makeup waters (i.e., 100–200 ppm or thereabout). Both of the formulations are designed to provide excellent corrosion inhibition and deposit control in comfort cooling systems, with a cooling water reserve of about 75–125 ppm. Formulation A will yield ~4.0 ppm Mo, and the operating pH is around 7.5–8.5, while Formulation B will yield

For those closed circuits, which in reality are semi-open systems, good corrosion control has been obtained by changing from a nitrite-based program to a molybdate

These programs have become popular and diverse since the presence of improved DCAs, phosphonates, HPA, and other organic inhibitors. They have been widely available since the mid-1980s. They can successfully operate under a

~2.5 ppm Mo with the operation pH of 8.0–9.0 (**Table 10**).

program and maintaining the Mo reserve of 8–10 ppm.

**162**

with <1.5 ppm Mo.

*3.1.5 All organic programs*

variety of operating conditions at high pH level, without the need of acid dosing. It means the operators can increase the cycles of concentration. In addition, this kind of program type is suitable for employing in small industrial and comfort cooling systems, where acid or continual and precise analytical control is not involved.

An example of the all organic program is given below. Typically, this program would be used at the concentration of 75–125 ppm, depending on operating conditions. The pH range is from 7.5 to 9.0, and this formulation is suitable for use with oxidizing biocides, such as bromine (**Table 11**).

There are numerous permutations of all organic formulations. Formulations containing 6–12% POCA perform good results at the presence of high chlorides. Some formulations also incorporate phosphate-polymer constituent.
