剩余污泥对酸性红14染料的吸附特性

Adsorption characteristics of Acid Red 14 by excessive sludge

采用剩余污泥作为低成本吸附剂对偶氮染料酸性红14进行批次吸附试验,发现pH是影响吸附过程的关键因素,低于等电点(pH 3~4)条件下,污泥絮体表面带负电荷,产生的静电吸引作用是平衡吸附量倍增的主要原因。温度升高对吸附过程有一定的促进作用。染料负荷升高,平衡吸附量和平衡质量浓度均升高,染料去除率下降。实际应用中,可根据目标平衡质量浓度或染料去除率,计算最佳染料负荷,从而指导工艺设计。试验条件下,吸附过程符合Freundlich吸附等温线模型(1/n为0.3~0.4)和准二级动力学模型;热力学分析表明该吸附过程属于自发吸热过程。

Excess sludge is used as low-cost adsorbent for the adsorption of azo dye Acid Red 14 in batch tests.It is found that pH is a critical factor affecting adsorption performance.Electrostatic attraction between positive-charged sludge under pH lower than zero charge point(pH 3-4)and negative-charged dye is the main reason of double equilibrium adsorption capacity.The increase of temperature has a certain promotion ef⁃fect on the adsorption process.With dye loading increase,equilibrium adsorption capacity and dye equilibrium concentration increased.The optimal dye loading can be determined based on the target dye equilibrium con⁃centration or dye removal to direct process design for real application.Under the experimental conditions,the adsorption process conforms to the Freundlich adsorption isotherm model(1/n is 0.3-0.4)and the pseudo-sec⁃ond-order kinetic model.Thermodynamic analysis shows that the adsorption process is a spontaneous endo⁃thermic process.