Synergistic scale inhibition of both IA/AMPS copolymer and magnetic field

. The antiscaling rate of both water magnetic device and IA/AMPS copolymer was investigated by using a stationary scale inhibition experimental device, and the result illustrated that there was a synergistic scale inhibition effect between magnetic field and IA/AMPS copolymer. Under the condition the experimental water through the water magnetizer was 120L / h, and the magnetic field strength was 0.7T, the magnetization time of 40 min, the antiscaling rate of both water magnetic device and copolymer IA/AMPS to CaCO 3 increased 11% as compared with that of the copolymer IA/AMPS alone. At this time, the dosage of copolymer IA/AMPS was 6mg/L. And the synergistic antiscaling rate of both water magnetic device and IA/AMPS copolymer to Ca 3 (PO 4 ) 2 increased 25% as compared with that of the copolymer IA/AMPS alone under the same condition except dosage of IA/AMPS copolymer was 20 mg/L.


Introduction
In the industrial circulating water system, it is generally necessary to add scale inhibitors to achieve the effect of scale inhibitors and corrosion inhibitors. Phosphate inhibitors have been widely used due to their good scale inhibitors [1][2]. However, the large-scale use of phosphate scale inhibitors will cause water quality nutrient enrichment, promote a large number of bacteria and algae derivatives, and seriously affect the ecological environment [3]. Itaconic acid belongs to a wide range of biologically fermented products and has received widespread attention [4]. AMPS is a water-soluble monomer containing sulfonic acid groups, which have strong hydrophilicity, can enhance the solubility of copolymer, and can make copolymer scale inhibitor have good inhibition, complexation, adsorption and dispersion of calcium phosphate scale and iron oxide, etc.In addition, the introduction of sulfonic acid groups can enhance the rigidity and thermal stability of the polymer molecular chain, so that the polymer has good temperature resistance [5].
Magnetized water treatment technology has the advantages of simple operation, low operating cost, non-toxic and pollution-free. Magnetized water treatment technology is a very promising scale inhibition technology from both environmental and economic perspectives. But when the treatment method is applied alone, the effect is not ideal.
In this paper, Itaconic acid was copolymerized with 2-acrylamido-2-methylpropanesulfonic acid (AMPS) which contain sulfonic acid group to obtain an IA / AMPS copolymer. Then, a comprehensive physical and chemical treatment method was used to synergize the magnetized water treatment technology with the IA/AMPS copolymer to study its synergistic scale inhibition performance [6]. The purpose is to reduce the amount of IA/AMPS copolymers and develop a new process for the magnetic field-water treatment agents to co-process industrial circulating cooling water with low operating cost.
We made a magnetized treatment equipment by ourselves. The schematic diagram of magnetic water device is shown in Fig. 1. 1.water inlet 2. rare earth permanent magnet 3. water storage tank at inlet4. magnetization gallery 5. water storage tank at exit 6. water outlet

Synthesis of the copolymer IA/AMPS
Typically, a given amount of IA and AMPS were added into a four-necked flask which contained a thermometer and a condenser, and then put some distilled water, isopropanol and ammonium persulfate into the four-necked flask. Then place the flask in a thermostatic water bath with a magnetic stirrer. When the temperature of the liquid reaches our desired value, a certain concentration of hydrogen peroxide and sodium bisulfite solution were added dropwise using two syringe pumps. Make sure that the two agents are added in the same time. And then it reacted at a constant temperature for a period of time. The product was left at room temperature, and when the reactant solution was cooled to room temperature, the solution was discharged. The obtained pale yellow transparent liquid was an aqueous polymer solution.

Scale inhibition rate by static method of IA / AMPS polymer to CaCO3[7]
The experiment used mixed water and non-evaporative concentration to determine the resistance to CaCO 3 (the concentration of calcium ion in the solution was 600mgꞏL -1 , and the concentration of bicarbonate ion was 1200mgꞏL -1 ). 500 mL of the formulation water containing the polymer agent was heated to 80℃, and then the temperature maintained at 80℃ for 10 hours.
Then it was taken out and cooled to room temperature. Titrate with EDTA solution and calculate the calcium ion content in the liquid supernatant after cooling, and do a blank experiment at the same time. The rate of scale inhibition is calculated by equation 1.
Rate of scale inhibition = ) ( The calculation formula of scale prevention rate C 0 represents the mass concentrations of Ca 2+ in the blank water sample after heated. C 1 represents the mass concentrations of Ca 2+ in the water sample with the inhibitor after heated. And C 2 stands for unheated formulated water.

Measurement of the rate of static scale inhibition on Ca3(PO4)2
The experiment used mixed water and non-evaporative concentration to determine the resistance to Ca 3 (PO 4 ) 2 (The concentration of calcium ion in the solution was 250mgꞏL -1 and the concentration of phosphate ion was 150mgꞏL -1 , pH was equal to 9.0 (Adjust with 25gꞏL -1 sodium borate solution)). 500 mL of the formulation water containing the polymer agent was heated to 80℃, and then maintained at 80℃ for 10 hours. Then it was taken out and cooled to room temperature. The PO 4 3content in the supernatant after cooling was measured with a 721 spectrophotometer, and a blank experiment was performed at the same time. The rate of scale inhibition is calculated by equation 2.
Rate of scale inhibition = ) ( .C alculation formula of scale prevention rate C 0 represents the mass concentrations of PO 4 3in the blank water sample after heated. C 1 represents the mass concentrations of PO 4 3in water sample with polymer medicament after heated. And C 2 stands for unheated formulated water.

Scale inhibition of the polymer IA / AMPS under the synergy of the magnetic field
The scale inhibition rate to CaCO 3 and Ca 3 (PO 4 ) 2 of using the copolymer alone and its synergy with water magnetizer at different IA/AMPS copolymer concentrations were investigated when the flow rate of the experimental water through the water magnetizer was 120L/h, and the magnetic field strength was 0.7T, the magnetization time of 40 min. The results are shown in Fig.2. and Fig.3.  2 can show that the antiscaling rate to calcium carbonate when magnetic field and IA / AMPS copolymer work together. When the water flow of the prepared water through the water magnet was 120 L / h, and the magnetic field strength was 0.7 T, the magnetic treatment time of 40 min, and an amount of IA / AMPS copolymer was 6 mg / L, the scale ratio was 11% higher than that of the polymer IA / AMPS alone. From Fig.3, it is shown that the addition of the magnetic field greatly improves the scale inhibition rate. Under the same conditions, the antiscaling rate to Ca 3 (PO 4 ) 2 by passing the water magnetic device and copolymer IA/AMPS together was increased 25% except that the amount of IA / AMPS copolymer was 20 mg / L.

Mechanism analysis
(1) In summary, the above experimental results show that the polymer IA / AMPS has good scale inhibition and dispersion properties. This is because when the IA / AMPS copolymer is dissolved in water, it will ionize and generate negatively charged molecular chains. These negatively charged molecular chains can chelate with calcium ions to form complexes that are soluble in water. Then the complex makes the dissolving ability of the scale-forming compound increase, thereby acting as a scale inhibitor.
(2) The addition of a magnetic field improves the scale inhibition rate to a certain extent. This is because that under normal circumstances, calcium ions and anion ions in water all exist as hydrated ions. However, when the hydrated ions flow through the magnetic field, they will be subject to Lorentz force to make a spiral circular motion, and the positive and negative ions rotate in opposite directions. This situation will destroy the physical hydration layer of the ions, and under sufficient magnetic field strength, the chemical hydration layer of the ions will also be destroyed. In this way, these scaling ions are released from the hydrated state and become "naked" ions. Then the opportunity for direct collision between the released calcium ions and the anions to combine to form a compound increases, thereby forming a large number of compound nuclei and microcrystals. These microcrystals are mainly formed in water, and the particles are finely dispersed and easy to be carried away by the water flow, thereby greatly reducing the chance of scaling on the pipe wall.

Conclusion
The above experiments show that both the copolymer IA/AMPS and the water magnetic device can prevents scaling to calcium carbonate and calcium phosphate. The best conditions for the synergistic effect of the magnetic field and the IA/AMPS copolymer on calcium carbonate scales are the water flow of the prepared water through the water magnet 120 L/h, the magnetic field strength of 0.7 T, the magnetic treatment time of 40 min. When the dosage of the agent was 6mg/L, the antiscaling rate of the water magnetic device and the copolymer to calcium carbonate increased significantly, an increase of 11%. Under the same conditions, when the dosage of the agent was 20mg/L, the scale inhibition rate on calcium phosphate can be increased by 25% when the magnetic field and the agent cooperate.
The magnetization and water treatment agents have a good synergistic scale inhibition effect. The addition of a magnetic field can effectively improve the scale inhibition performance of water treatment agents and has a wide application prospect.