The refinement and concentration of agricultural antibiotic A in aqueous solution using membrane processes

Abstract

This paper looks at the possibilities of refining and concentrating the agricultural antibiotic A (AAA) in aqueous solution using the membrane processes of millipore filtration, ultrafiltration and reverse osmosis. The effects of relevant factors on separation performance are examined and the main factors affecting refinement and concentration are analysed. The most favourable operating parameters are presented, as well as a suitable separation process. Our experiments show that the results of pretreatment are better when using precipitation of oxalic acid and millipore filtration. Cellulose ester membranes can be used to refine and concentrate AAA aqueous solution. When the feed was treated using ultrafiltration with a flux of about 100 ml/cm 2 h for distilled water, the permeate was transparent and limpid; this is a very effective method ofrefinement. When the product was refined by ultrafiltration and then treated using reverse osmosis membranes, with a salt rejection level of 95% or so for tap water, normalization flux was 0.14, and the colour of the permeate was light red-brown according to analysis of the apparent-colour reaction. The concentration of 800–1000 ml feed which had already been refined by ultrafiltration was more than doubled by reverse osmosis at an operating pressure of between 30 and 55 kg/cm 2, lasting for 10 to 13 h at 15 to 50°C, in equipment with an effective film surface area of 80cm 2. The refractivity of the permeate was 1.0–1.2% and the corresponding solute retention levels were over 93% during the whole concentrating cycle. The results offer a basis for the spreading of membrane processes to some areas of biology.