The Study of the Green Chemistry of Polyepoxysuccinic Acid as a Reverse Osmosis Scale Inhibitor
|School||Central South University of Forestry Science and Technology|
|Keywords||Green Chemistry Reverse osmosis Antiscalant Polyepoxysuccinate by|
Over the twentieth century, chemistry for mankind to create enormous material wealth and the survival of the revolution, but also to humanity to pay the heavy price of resource depletion and environmental pollution, self-regulating capacity using a chemical process to produce a series of ecological ignore the laws of nature and ecosystems problems. \chemical reactions and chemical process, non-polluting emissions are efforts in the direction of the chemical workers and the pursuit of the goal. In this study, starting from the concept of green chemistry, green scale inhibitor to the currently accepted polyepoxysuccinate by (Polyepoxysuccinic acid PESA) for the object, starting from the green scale inhibitor chemical design and performance study, through experimental and theoretical analysis, PESA synthesis process and reverse osmosis (RO) water treatment for more comprehensive and in-depth research. According to the principles of green chemistry, the study of atom economy, human and environmental friendly PESA synthesis method. Select non-phosphorus nitrogen compound excluding environmentally harmful components of maleic anhydride as the monomer, with the aqueous solution as the reaction medium, without using an organic solvent, in the synthesis process and the use of simple inorganic compounds, with hydrogen peroxide as the oxidant, sodium tungstate as catalyst, solid sodium hydroxide as the initiator, through single factor test and orthogonal design test one step synthesis the PESA process of hydrolysis, epoxidation reaction polymerization conditions were optimized to achieve the target product of high-performance, no-waste minimization of energy consumption and response process. Epoxidation conditions optimized as follows: reaction temperature of 70 ° C; reaction time of 55 minutes; the oxidant H202 (30%) the amount for the 35% of maleic anhydride; catalyst Na2WO4 amount of 2.4% of maleic anhydride. The polymerization reaction conditions as follows: the amount of initiator NaOH 0.34% of maleic anhydride; polymerization temperature 80 ° C; polymerization time 2h; polymerization reaction system pH = 7 ± 0.5. PESA, the synthesis of the above optimal conditions maleic anhydride monomer conversion was 89.1%; purpose of the product in the carboxyl content of 21.45%; CaCO3 scale inhibition rate greater than 96%. HG / T 3823-2006 \Static and dynamic methods to study the effectiveness and feasibility of PESA as Antiscalant. Analog reverse osmosis concentrated water quality in the cation mass concentrations were 40 mg / L, 100 mg / L, 200 mg / L test water added 10m/LPESA, experimental results show that, PESA easily deposited in the reverse osmosis membrane calcium carbonate, sulfuric calcium, barium sulfate, the average strontium sulfate scale inhibition rate can reach 90% or more, with multi-scale inhibition performance. Simulated seawater and city tap water reverse osmosis system, the use of the full cycle of dosing, examine the the PESA dynamic scale inhibition performance, did not exceed 5% after 10 cycles of the experiment, the reverse osmosis membrane water permeability and salt rejection rate of change. Has a good compatibility with commonly used in reverse osmosis pretreatment of the iron salt and aluminum salt coagulant. JSM-6360LV scanning electron microscope scan join the scale inhibitor PESA calcium carbonate scale crystal analysis results show that PESA can make calcium carbonate (CaCO3) lattice distortion, destruction of CaCO3 crystal compact structure of the original rules, which inhibit the formation of CaCO3 scale, combined with PESA can significantly improve slightly soluble salt relative over-saturation, evident PESA scale-forming ions dispersed, complexation, solubilization, the role of lattice distortion and variety of scale. The evaluation method of scale inhibitors pilot study using the conductance method for evaluation of PESA scale inhibition performance relative over-saturation of the insoluble salt conductivity titration analysis evaluating the scale inhibition effect. The comparative test results show that the test results consistent the conductance titration with calcium carbonate deposition, but reproducibility better than calcium carbonate deposition. Compared with the deposition of calcium carbonate, the conductance method to quickly and accurately assess the scale inhibition performance, easy, good reproducibility, etc..