Screening of Absorbents for Viscose Fiber CS2 Waste Air and Absorption–Desorption Process

Abstract

Screening of absorbents is essential for improving the removal rate of carbon disulfide (CS2) waste air by absorption. In this work, the UNIFAC model in Aspen Plus was utilized to calculate the excess Gibbs function and absorption potential of the binary system of CS2 with various alcohols, ethers, esters, amines, and aromatic hydrocarbons. The results were used to quantitatively compare the efficiency of each solvent for CS2 absorption. The theoretical predictions were then verified by absorption experiments in a packed tower. The results showed that the performance of various solvents to CS2 roughly followed the order of esters < alcohols < amines < heavy aromatics < glycol ethers. Meanwhile, N-methyl-2-pyrrolidone (NMP) is the optimal absorbent for CS2 waste air treatment. Additionally, the process parameters of absorption and desorption of NMP were optimized. The results illustrated that the average mass removal efficiency of CS2 by NMP is 95.2% under following conditions: liquid–gas ratio of 3.75 L·m−3, a temperature of 20 °C, and inlet concentration lower than 10,000 mg·m−3. Under the conditions of 115 °C, 10 kPa, and a desorption time of 45 min, the average desorption rate of CS2 is 99.6%, and the average water content after desorption is 0.39%. Furthermore, the recycled lean liquid can maintain an excellent CS2 purification effect during the recycling process.