Sodium Polyphosphate: Versatile Applications in Cement Modification and PVA Recovery

General Description

Sodium polyphosphate shows promising applications in two distinct areas: modifying calcium aluminate cement and recovering polyvinyl alcohol from wastewater. In the context of CAP modification, varying the amount and concentration of mixing solution influences the consumption of monocalcium aluminate and the formation of gibbsite, ultimately enhancing the microstructure of cement products. On the other hand, in PVA recovery, sodium polyphosphate acts as a key flocculating agent alongside salting-out and coagulating agents, resulting in an impressive 96.5% PVA recovery rate. This effective combination facilitates the efficient treatment and reuse of PVA wastewater, showcasing sodium polyphosphate's significant role in environmental sustainability and resource conservation efforts. Overall, these studies highlight the versatile and beneficial properties of sodium polyphosphate in diverse industrial applications.

Figure 1. Sodium polyphosphate

Applications in Modifying Calcium Aluminate Cement

Sodium polyphosphate, a phosphate compound, has been investigated for its application in modifying calcium aluminate cement used in cement production. A study aimed to explore the effects of changing the amount and concentration of mixing solution on the characteristics of calcium aluminate cement modified with sodium polyphosphate. The results indicated that when the amount of mixing solution was increased while keeping the amount of sodium polyphosphate constant, there was an enhanced consumption of monocalcium aluminate compared to gehlenite in the calcium aluminate cement. Additionally, the formation of gibbsite (Al(OH)3), a hydration product, increased in the calcium aluminate cement, leading to a reduction of water in the amorphous gel phase. This suggested that the increased formation of gibbsite and the reduction of water content contributed to the improvement of the microstructure in the cement products. On the other hand, when the amount of mixing solution was increased while maintaining a constant concentration of sodium polyphosphate, there was no observed enhanced consumption of monocalcium aluminate, and no significant formation of gibbsite or other crystalline hydration products were identified. Interestingly, unreacted sodium polyphosphate remained in the system under these conditions. Overall, the findings suggest that the addition of sodium polyphosphate in calcium aluminate cement can have a positive impact on the characteristics of calcium aluminate cement. It can enhance the consumption of certain components, promote the formation of specific hydration products like gibbsite, and potentially contribute to the improvement of the microstructure in the cement products. Further research is needed to optimize the dosage and concentration of sodium polyphosphate for desired cement properties. ¹

Applications in Recovery of Polyvinyl Alcohol Wastewater

Sodium polyphosphate has been utilized in the recovery of polyvinyl alcohol from wastewater using the flocculation method. This study investigates the effectiveness of sodium polyphosphate as a flocculating agent, while sodium sulfate acts as a salting-out agent, and sodium carbonate functions as a coagulating agent. To determine the optimal ratio of these components, an orthogonal experiment is conducted. The absorbency of the polyvinyl alcohol solution is used as a reference index to evaluate the efficiency of the recovery process. The polyvinyl alcohol content is quantified through spectrophotometry, and the structure of the recovered polyvinyl alcohol is analyzed using infrared spectrum analysis. The findings reveal a remarkable polyvinyl alcoholrecovery rate of 96.5%. This indicates that the combination of sodium polyphosphate as a flocculating agent, along with the application of sodium sulfate as a salting-out agent and sodium carbonate as a coagulating agent, effectively facilitates the recovery of PVA from wastewater. In summary, sodium polyphosphate plays a vital role as a flocculating agent in the recovery of polyvinyl alcohol from wastewater using the flocculation method. Together with appropriate salting-out and coagulating agents, sodium polyphosphate enables a high rate of PVA recovery. This research contributes to the advancement of efficient techniques for treating and reusing PVA wastewater, promoting environmental sustainability and resource conservation. ²

Reference

1. Irisawa K, Hajime Kinoshita H, Garcia-Lodeiro I. Influence of mixing solution on characteristics of calcium aluminate cement modified with sodium polyphosphate. Cement and Concrete Research. 2020; 128: 105951.

2. Yue Z, Hui W, Yu MY. Recovery of Polyvinyl Alcohol Wastewater with Sodium Polyphosphate. Advanced Materials Research. 2013; 122(1): 546-549.