WATER TREATMENT
A B
Figure 3 - QCM delta frequency : Utilities A , B & C
C
precipitation was recorded . Table 2 shows the comparison between the treated and untreated experiments with respect to induction time and ∆F change ( amount of deposition ).
Based upon computer modelling and momentary excess calculations , Utility A would be expected to show the greatest amount of deposition and resulting decrease in frequency . This was indeed the case where a negative ∆F of > 250 Hz was observed over the 60-second duration of the test ( Figure 3 ). Utility C would have been expected to show the next greatest drop in frequency followed by Utility B . In fact , C showed a drop of about 140 Hz compared to 190 for B . As mentioned , calcite saturation can be a gauge of the potential for precipitation or driving force .
Utility C shows a calcite saturation of about 140 times versus 94 for A and about 44 for B . As such , it would be expected that the induction time and subsequent measurement of deposition for the untreated blanks would follow this same order . In fact , C showed the longest induction time for the untreated blank , whereas A and B had similar observed induction times . At this point , there is not enough experimental data to suggest why this is the case and propose a mechanism for cause and effect .
Conclusions
Given the current issues with supply of phosphonates , the use of certain polymer treatments in once-through applications seems to be a viable option for utilities . In particular , PEPMA / HPSP shows efficacy when compared to untreated blank and phosphonate-treated samples in three synthetic once-through cooling waters . Further , a QCM proved to be a valuable tool for the evaluation of additives in short holding time applications due to its sensitivity .
The work presented in this paper provides a good start to proving both the use of the PEPMA / HPSP alternative treatment , as well as the use QCM as a laboratory evaluation tool . However , this methodology does not consider many important factors such as surface discontinuities , pre-existing deposition , resulting in increases nucleation sits , or fluid dynamics .
Additional work is also needed to understand causes of deviation from saturation models , correlation to field use of scale inhibitors , the examination of different polymeric additives , the evaluation of the combination of phosphonate and polymerics , and the investigation of additional water chemistries .
This future work will help bolster the methodology and develop data sets to support dosage model development . Despite the limitations of the data and work conducted thus far , the approach demonstrates promise and has led to a commercially successful product in the field . ●
References : 1 : M . Standish , US Patent 11,358,891 B2 , 2022 2 : M . Standish , AWT Annual Convention 2014 , 12-15 3 : C . Garcia , G . Courbin C . Noik & F . Ropital , Corrosion 1999 , 99 , 2-4
Mike Standish
VICE PRESIDENT – WATER ADDITIVES
RADICAL POLYMERS – DIVISION OF MFG CHEMICAL , LLC
k + 1 423 316 9877 J mike . standish @ radicalpolymers . com j www . radicalpolymers . com
26 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981