Reverse osmosis scale inhibitor Features
Concentrated water of RO membranes is easy to be polluted by deposition. If on membranes surface there are deposition CaCO3, Ca3 (PO4)2, CaSO4, BaSO4, SrSO4, metal oxide and 1, Function of antiscalant 1.1 Precipitation function of infiltration In system including antiscalant, the precipitated sum of cation and anion is too high than critical precipitated sum excluding antiscalant. 1.2 Dispersion function In system including antiscalant, the precipitated particles are difficult to deposit because of its small diameter. 1.3 Crystallization shape-change effect In system including antiscalant, the precipitated crystallization have shapes of ball, multi-flat and snowflake. Generally, antiscalant adsorption to unfixed-shapecrystallization and cooling fast, so they are different to original crystallization. 1.4 Low limit effect Even if the volume of antiscalant is less than scaling in water, it still effect. 2, Categories and characteristics of antiscalant 2.1 Polyphosphate class Polyphosphate class antiscalant is the earliest used in RO system, in it SHMP and sodium tripolyphosphate are often used. Principal of inhibition is partial electrostatic adsorbs activity point ofcrystallization to slow the creation of crystallization, to make much crystallization in micro crystallization situation for its better solution features. This kind of antiscalant has phosphorus with high concentration, it is easy to solute as negative phosphate and deposition of Ca3(PO4)2. And more, polyphosphate may pollute membranes fast. So when the kind of medicine is used, acid must be added in. This kind of antiscalant is ineffective to CaSO4 . It will be replaced with new antiscalant. 2.2 Organic phosphate class Organic phosphate class was developed in 60s of 20th century and advanced in 70s. Main types of them are HEDP and ATMP. The two kinds of antiscalants have low concentration of phosphate against to polyphosphate and little water solution. But they are affective for scaling of CaCO. Meanwhile, polyphosphate class may inhibit silicon deposition. 2.3 Polymeric Scale Inhibitor For nearly years, polymers class antiscalant without phosphorus or fouling has been used in site, they are acrylic, methyl acrylic, maleate and 2-methylene succinic acid. The kind of antiscalant has the good features of without effect from chlorine and other oxide medicine. But its relative molecular has large effect to inhibition dispersion character. Now the action on researching to the antiscalant is operating on high polymer and other gene. High polymer has multifunction of gene to inhibit various scaling. During nearly years, new type of antiscalant PASP and PESA have been developed , which have strong effect on inhibiting deposition and without pollution to circumstance and better bio degradation. Meanwhile it is the hot topics in the world.
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