Fluorescent-tagged hyper-branched polyester for inhibition of CaSO4 scale and the scale inhibition mechanism

A fluorescent-tagged and carboxyl-terminated hyper-branched waterborne polyester (HBP-AP) was prepared and characterized. Acted as CaSO4 scale inhibitor, its application conditions such as the dosage, Ca2+ concentration and pH value, were investigated to optimize the scale inhibition efficiency. In order to provide some theoretical supports for the scale inhibition mechanism of hyper-branched polymers, the scale inhibition mechanism for CaSO4 was then investigated in detailed. The experimental results showed that the HBP-AP provided an excellent scale inhibiting efficiency for CaSO4, which was as high as 98.8 % at dosage of 15 mg/L, and performed well both at high Ca2+ concentration and extended pH value. Besides, the HBP-APTA showed good solubilizing property and dispersion ability. The XRD, SEM and CLSM have been used to character the CaSO4 scale crystal. Especially, with the help of CLSM technology, it is convenient to observe how the prepared hyper-branched inhibitor affected both the CaSO4 crystal nucleation process and crystal growing process, allowing us to understand the scale inhibition mechanism easily for its leading the scale inhibition process visualization.