In order to improve the scale inhibition efficiency of existing scale inhibitors for industrial water and to reduce the phosphorus pollution of water bodies, a new type of scale inhibitor with a hyper-branched structure has been developed in this study. First, an AB′ type of functional monomer (AMA) was synthesized from maleic anhydride (MAH) and propylene glycol, then copolymerized with monomer B (MAH) through radical polymerization, resulting in a hyper-branched polycarboxylic acid. The synthesis conditions, such as reaction temperature and time, monomer ratio and initiator dosage, have been investigated for obtaining the expected hyper-branched polymer with good scale inhibition performance. The scale inhibition efficiency of the obtained products was determined according to their resistance to the crystallization of calcium sulfate and calcium carbonate under the optimal application conditions. The experimental results show that the hyper-branched polycarboxylic acid provides a scale inhibiting efficiency for CaCO3 and CaSO4 as high as 95.2% and 92.3%, respectively. In addition, XRD analysis showed that the good scale inhibition of the hyper-branched polycarboxylic acid is attributed to its ability to inhibit and destroy the formation of crystals, changing the crystal forms of the calcium scale. This conclusion indicates that the prepared hyper-branched polycarboxylic acid has great application potential in the treatment of industrial water.
Polyaspartic acid (PASP), a well-known green scale inhibitor for industrial water treatment, might be decomposed with prolonged duration, and its anti-scaling performance against CaCO3 and CaSO4 is diminished at a low concentration (<10 mg L−1) and a high temperature. With semi-ethylenediaminetetraacetic acid (EDTA) tetrasodium salt as the mimicking model, novel phosphorus-free PASP-capped 2-aminoethylamino acid (PASP–ED2A) containing side chains bearing multi-functional groups is rationally designed and successfully prepared via the ring-opening reaction of cheap poly(succinimide) under mild reaction conditions with the assistance of readily available 2-aminoethyl amino acid. The static scale inhibition method is used to evaluate the scale inhibition performance of the as-synthesized PASP derivative. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy are utilized to monitor the crystallization process of calcium carbonate and calcium sulfate scales, and density functional theory calculations are conducted to shed light on the relationship between the molecular structure and scale inhibition mechanism of PASP–ED2A. Results show that the as-prepared PASP–ED2A shows better scale inhibition performance for CaCO3 and CaSO4 than PASP with a low concentration, a high temperature, and an extended duration. Particularly, PASP–ED2A with a concentration of 10 mg L−1 exhibits the best scale inhibition performance for CaCO3; its scale inhibition capacity is about two times as much as that of PASP. The reason lies in that the coordination atoms in the molecular structure of PASP–ED2A can chelate with Ca2+ to inhibit the combination of Ca2+ with anions and prevent the generation of CaCO3 and CaSO4 scales. The PASP–ED2A derivative can more efficiently retard the formation and growth of CaCO3 and CaSO4 crystal nuclei and exerts better inhibition performance against CaCO3 and CaSO4 scales than PASP.
Based on the principle of free radical polymerization, a novel scale inhibiting and dispersing copolymer was successfully prepared using the monomers of itaconic acid (IA), 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and tannic acid (TA). The chemical structure, molecular weight and thermal stability of the copolymer were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and thermogravimetric analysis (TGA), respectively. The effects of synthesis and water conditions on the scale inhibition performance of the copolymer were investigated by static scale inhibition method. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to study the microscopic morphology and crystal structure of the scale deposits. When the reaction time was 3.5 h, the reaction temperature was 75 °C, the amount of tannic acid added was 4 g, and the amount of initiator was 5% of the total mass of the monomers, the copolymer had the excellent scale inhibition performance. With the test temperature raised, the basicity of the simulated cooling water increased, and the concentration of CO 3 2− /HCO 3 − enhanced, scale inhibition efficiency of the copolymer decreased. TGA analysis proved that the significant thermal degradation of copolymer occurred at 220 °C, which demonstrated that the copolymer had outstanding temperature resistance. Characterization of the inorganic calcium scale deposits indicated that the copolymer markedly destroyed the surface morphology and crystal structure of the scale deposits. The novel scale inhibiting and dispersing copolymer containing natural tannin prepared in this work will have a bright application prospect in controlling the formation of inorganic calcium scale deposits,which is about to have potential strategic implications for water conservation and energy efficiency.
危险品化学品经营许可证（带存储）