Abstract: 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. 

Key words: reactive dye, sawdust, modification, adsorption, decolorization