Digestion Of Phosphonate Inhibitors In Circulating Water By Ultraviolet Photooxidation

Organic Phosphorus Scale Inhibitor is an important phosphorus-containing compound that is widely used in circulating cooling water systems to prevent pipeline corrosion caused by fouling of pipelines.However,the organic phosphorus scale inhibitors in circulating water are difficult to directly remove by ordinary biochemical methods.Direct or indirect discharge of industrial wastewater will cause the increase of the phosphorus concentration in the water environment,thus forming eutrophication and other intractable ecological problems.Therefore,under the normal circumstances,the Phosphonates is first converted into inorganic phosphate,and then combined with other processes to remove.Conventional organic phosphine digestion methods include nitric acid-perchloric acid digestion and microwave or ultrasonic digestion.However,such methods have tong-term digestion and are likely to produce secondary pollutants that are harmful to health,and the end point of digestion is not easily determined.And these methods will cause the measurement result error.In order to make up for the deficiencies of the above methods,this experiment used UV-sodium peroxodisulfate digestion,mo lybdenum blue colorimetric spectrophotometric determination of phosphorus in organic phosphorus scale inhibitor,and determined the best experimental parameters of digestion,and discussed the effect of coexisting ions in circulating water.The main conclusions areas follows:(1)The optimal digestion conditions for different concentrations of ATMP,EDTMPA,DTPMPA,and PBTCA were studied.The trend of digestion of four different organic phosphorus scale inhibitors is basically the same.In the same concentration of oxidants,the oxidation effect is the best with sodium persulfate;the relationship between organic phosphorus scale inhibitor digestion and oxidant consumption is slightly different.When using ATMP,the concentration of Na2S2O8 solution was 1.0 g/L,that of EDTMPA was 0.8 g/L,while that of DTPMPA and PBTCA was only 0.6 g/L.The best digestion time of ATMP and EDTMPA was 8 min,however,the digestion of DTPMPA and PBTCA was relatively rapid,and after 6 minutes of illumination time,the dissolution of the solution tended to be stable.The digestion rate is basically not affected by pH and there is no need to adjust the initial pH;the final digestion rate of each organic phosphine scale inhibitor is also slightly different,and the ATMP degradation rate is about 95%,and the degradation rate of EDTMPA ard DTPMPA can reach 97%,white the highest PBTCA is more than 98%.(2)Under the irradiation of 10W ultraviolet lamp at 254 nm,the same oxidant with the same concentration has the best oxidation effect with sodium persulfate;the initial pH value of the solution has almost no effect on the reaction,and no need to adjust the pH;The effect of the amount of oxidant on the reaction was slightly different from that of the 365 nm high-pressure nercury lamp,but the difference was not si~gnificant.The optimum oxidant dosage of the organophosphorus scale inhibitor at the wavelength of 254 nm was 0.8 g/L,however,the organic phosphine samples digested quickly under the shortwave UV,the reaction was complete in 2.5 minutes,the average digestion rate was over 97%,and the digestion effect was stable and good.Taking into account the energy consumption and cost issues,this experiment selected a 254-nm wavelength UV lamp as a digestion device.(3)The detection limit of this method is 0.00179 mg/L.It can be known from the precision test and the standard rec.overy test results that the method has high precision and good test reproducibility.(4)Taking PBTCA as an example,the influence of four main ion in circulating water on the digestion rate was explored.Ca2+、Mg2+and SO4+have almost no effect on the digestion of organophosphorus,and the final digestion effect is good.Chloride ion obviously inhibited the degradation of organic phosphine,and the degradation rate decreased with the increase of chloride ion concentration.In summary,the UV oxidation digestion method used in this experiment is smple,rapid,and accurate.It provides a possibility for the treatment of organic phosphorus in industrial circulating water systems.