粉煤灰作为吸附剂对提高造纸废水中污染物去除效率研究

Study on Enhancing the Removal Efficiency of Pollutants in Papermaking Wastewater Using Fly Ash as an Adsorbent

关键词:  粉煤灰  造纸废水  污染物  吸附性能

Key Words:fly ash  papermaking wastewater  pollutants  adsorption performance

摘要:本研究探究了粉煤灰对造纸废水中污染物的吸附性能，分析了粉煤灰用量、废水初始COD浓度、吸附时间、pH值和温度等参数对造纸废水污染物吸附性能的影响。结果表明，粉煤灰用量2.0 g/100 mL时，废水中各污染物去除率达较优水平；继续增加用量，废水中各污染物去除效率提升幅度显著降低。废水初始COD_Cr浓度从3 000 mg/L升至4 000 mg/L，COD_Cr和色度去除率分别下降约16.9%、13.8%。pH值=6时最利于吸附，COD_Cr去除率达58.6%，酸性和碱性环境均会降低COD去除效率。温度从20 ℃升至60 ℃，COD_Cr去除率提升约18.9个百分点。动力学分析显示，吸附符合伪二阶模型（R²>0.99），化学吸附占主导。粉煤灰最优吸附条件为：粉煤灰用量2.0 g/100 mL、pH值=6、温度60 ℃、吸附时间240 min。该条件下，COD_Cr、色度、BOD₅和SS去除率分别为73.4%、78.6%、62.7%、55.6%。

Abstract:This study investigated the adsorption performance of fly ash for pollutants in papermaking wastewater and analyzed the effects of various parameters， including the dosage of fly ash， initial COD concentration of the wastewater， adsorption time， pH value， and temperature， on the adsorption of pollutants in papermaking wastewater. The results showed that when the dosage of fly ash was 2.0 g/100 mL， the removal rates of various pollutants in the wastewater reached an optimal level. Further increases in the dosage resulted in a significantly diminished enhancement in the removal efficiency of pollutants. As the initial COD_Cr concentration of the wastewater increased from 3 000 mg/L to 4 000 mg/L， the removal rates of COD_Cr and chromaticity decreased by approximately 16.9% and 13.8%， respectively. The pH value of 6 was the most favorable for adsorption， achieving a COD_Cr removal rate of 58.6%. Both acidic and alkaline environments could reduce the COD removal efficiency. When the temperature increased from 20 ℃ to 60 ℃， the COD_Cr removal rate improved by approximately 18.9 percentage points. Kinetic analysis showed that the adsorption process conformed to the pseudo-second-order model （R²>0.99）， with chemisorption being the dominant mechanism. The optimal adsorption conditions for fly ash were determined as follows： the dosage of fly ash was 2.0 g/100 mL， the pH value was 6， the temperature was 60 ℃， and the adsorption time was 240 min. Under these conditions， the removal rates of COD_Cr， chromaticity， BOD₅， and SS were 73.4%， 78.6%， 62.7%， and 55.6%， respectively.