| A large amount of wastewater characterized by high concentration of organic substances is discharged as the production of DSD acid, which is an important intermediate in the production of fluorescent whitening agents, direct dyes, and fungicides. The ion exchange technology has shown great selectivity and easy manipulation in the separation process. Through the resin selection experiment, D301R resin showed a better capacity for the removal of those substances in the wastewater. CODCr removal ratio of DSD acid reduction wastewater was over 74.7% at appropriately operating conditions. Effects of time, temperature, pH and the concentration of Na2SO4 on adsorption behavior were investigated. The results indicated that the equilibrium time was about 6h; low temperature and high pH was good for the adsorption. Na2SO4 in the wastewater was a competitive, leading to a negative effect on the adsorption. The results of column dynamic adsorption and regeneration showed that CODCr could be efficiently removed by D301R resin from DSD acid reduction wastewater. Effects like flow rate, pH, and concentration of Na2SO4 had also been discussed in the researches. The increase of the flow rate led to a worse breakthrough curve, the higher the pH, the better the adsorption can be, and the high concentration of Na2SO4 could be a negative factor for its competitive adsorption. The resin was easily regenerated by NaOH stripping, especially with a slow flow rate and high concentration of NaOH, at high temperature. The DSD salt was chosen to study the behavior of the resin adsorption and exchange process. Langmuir-Freundlich isotherm was best to simulate the adsorption among the isotherm models of Langmuir, Freundlich and Langmuir-Freundlich. A first-order adsorption kinetics equation was developed for the process, and relevant parameters were calculated. Furthermore, results showed that the process was controlled by the particle diffusion, i.e. PDC.
|
PDF Full Text Request