An Improvement of Determination Method of Total Phosphorus in Wastewater by Using Rapid Graphite Digestion

Objectives  A rapid graphite digestion device is used for total phosphorus in wastewater pre-treatment.

Methods  Potassium-persulfade was applied to digest phosphorus compounds in water into orthophosphate at 120℃.In acidic condition, phosphorus-molybdenum heteropoly acid was produced by the reaction among orthophosphate, ammonium molybdate and potassium antimony tartrate. Phosphorus-molybdenum heteropoly acid was reduced into blue complex by Vitamin C. The blue complex was determined by using 1cm cuvette under the wavelength of 700 nm.

Results  The correlation coefficient of this method was 0.9997. The detection limits were 0.01mg/L. Returns-ratio varied from 97.0%~102.5%, and RSD was 0.34%.

Conclusions  The improved method was rapid and safe. The accuracy, precision and sensitivity were able to meet the requirement of the related standards.