Abstract
Wastewater of resorcinol production that included acid, m-phenylenediamine, m-aminophenol, resorcinol, and other impurities was generated by m-phenylenediamine hydrolysis. In this paper formaldehyde condensed with organics of wastewater to form oligomeric solid polymer that could be separated by filtration. The oligomeric solid polymer could be used as plasticizer of rubbers. And then the acidity of wastewater was neutralized by adding ammonia water. It was found that other impurity reacted with ammonia and precipitated from the solution in the neutralized process. Methanol and n-butyl ester of wastewater were removed by stripping one third water after forward two steps. Lastly activated carbon was utilized to adsorb trace organics and impurities, and then water was evaporated to product ammonium sulphate. An orthogonal experiment about adsorption temperature, activated carbon quantity, stirring time was arranged to gain optimal activated carbon adsorption operation conditions. The condensed mole ratio of formaldehyde and organics, neutralized pH value, and the activated carbon adsorption conditions were investigated to achieve the minimum impurities, the qualified nitrogen content, and the best color of ammonium sulphate. The final mole ratio of formaldehyde and organics was 4:1 according to the minimum organics residues and the best color of ammonium sulphate product. At the neutralized pH value of 7 - 8, the color and nitrogen content were optimal and the ammonium sulphate had a little impurities. Based on the range analysis results of orthogonal experiment and the color of ammonium sulphate, the minimum impurities and best color of ammonium sulphate were at adsorption temperature of 90 °C, activated carbon quantity of 3 %, the stirring time of 30 min. The evaporated water vapor can be condensed and reused as process water to minimize the wastewater discharge of the production process.
