NaOH改性落叶松锯木屑对活性染料的吸附性能

通过间歇式试验研究NaOH改性落叶松锯木屑对活性染料KN-B、K-2BP和KN-R的吸附脱色性能。结果表明,酸性条件下该改性木屑对3种染料均具有较好的脱色效果。在初始pH值为3时,3种染料的吸附脱色率均表现为随温度升高而逐渐降低,随改性木屑用量的增加而增加的趋势;而随染料初始浓度的增大,表现出先升高后降低的趋势。在初始pH值为3、温度为298 K条件下,3种染料在改性锯木屑上的等温吸附符合Langmuir吸附模型,KN-B、K-2BP和KN-R的最大饱和吸附量分别为22.32、10.47和14.93 mg.g-1,吸附自由能ΔG298 K分别为-12.61、-9.77和-14.45 kJ.mol-1,均为物理性自发吸附过程。试验条件下,KN-R、KN-B和K-2BP的吸附动力学均符合准二级动力学吸附方程,吸附速率常数依次减小。综合等温吸附和吸附动力学研究结果表明,3种染料的脱色效果以KN-R为最好,KN-B次之,K-2BP最差。

Performance of NaOH-Modified Larch Sawdust Adsorbing Reactive Dyes

Through batch experiments,performances of NaOH-modified larch sawdust adsorbing and decoloring Reactive Black 5(KN-B),Reactive Red 24(K-2BP) and Reactive Blue 19(KN-R) were investigated.Results show that in acid conditions,the sawdust could decolor quite well the three dyes in wastewaters.In wastewater,3 in initial pH,adsorption and decoloration rate of the three dyes declined with rising temperature,but rose with application rate of the saw-dust and content of NaCl,and went upwards first and then downwards with rising initial concentration of reactive dyes.Under the conditions of 3 in initial pH and 298 K in temperature,isothermal adsorption of the three dyes on the sawdust fittedthe Langmuir adsorption model quite well.Of the three dyes,KN-B,K-2BP and KN-R,the monolayer sorption capacity Qmax was measured to be 22.32,10.47 and 14.93 mg·g-1,respectively,and the adsorption thermodynamic parameter ΔG298 K,-12.61,-9.77 and-14.45 kJ·mol-1,respectively,demonstrating that the adsorption was a spontaneous physical process.Under the conditions of the experiment,the kinetic adsorption data all fitted the pseudo second-order kinetic adsorption equation.In terms of adsorption rate constant,the three dyes followed an decreasing order:KN-R>KN-B>K-2BP.To sum up the findings regarding isothermal adsorption and kinetic adsorption,it can be conclu-ded that the three reactive dyes follow the same order in decoloring effect as in adsorption rate constants.