CMC固定化灭活烟曲霉小球对活性艳蓝KN-R的吸附机理——吸附平衡、动力学和扩散传质过程

Mechanism of biosorption of reactive brilliant blue KN-R by inactive Aspergillus fumigatus immobilized on CMC beads:Equilibrium,kinetics,diffusion and mass transfer

考察了羧甲基纤维素钠(CMC)固定化灭活烟曲霉小球吸附活性艳蓝KN-R的吸附平衡、吸附动力学和扩散传质过程.结果表明:CMC固定化灭活烟曲霉小球对活性艳蓝KN-R的吸附较易进行,吸附等温线能较好地用Langmuir模型和Freundlich模型来描述,而且用Langmuir模型更好,最大单分子层吸附量为66.7mg.g-1.吸附动力学很好地符合准二级动力学模型.小球内部扩散过程用Weber-Morris模型拟合的结果反映小球内部扩散过程是其吸附控制步骤,且染料从小球液相边界层向小球表面的扩散过程亦不能忽略.用外部传质模型MathewsandWeber(M&W)模型和FrusawaandSmith(F&S)模型分别计算得到的外部传质速度的表征值βIS值均小于0.1h-1.初始染料浓度越大,染料从液相到固相的外部传质速度越慢,而在小球内部越易扩散.

Batch studies and thermodynamics of biosorption of reactive brilliant KN-R by inactive Aspergillus fumigatus immobilized on sodium carboxymethylcellulose （CMC） beads were investigated. The results showed that the inactive Aspergillus fumigatus immobilized on CMC beads could effectively decolorize a solution containing 103.4 mg·L^-1 reactive brilliant blue KN-R by biosorption within the equilibrium time, viz. 48 h. The optimal initial pH of the dye solution was 10.5. The biosorption capacity increased with increasing temperature in the range of 10 - 50℃. In the beads dosage range of 1% - 5% （ wt % ）, the biosorption efficiency increased from 54.2% to 94.9% , but the biosorption capacity decreased from 54.7 mg·g^-1 to 19.6 mg·g^-1 after 48 h equilibrium. High salinity in dye solutions had little influence on biosorption capacity. The biosorption capacity decreased only 5.6 mg·g^-1 at the NaC1 concentrations in the range of 0% - 3.0% （wt % ）. The thermodynamics parameters values such as Gibb＇s free energy changes （△G） , enthalpy changes （△H） and entropy changes （△S） over the temperature range of 10 - 50℃ were： AG less than 0, △H 15. 343kJ. mol^-1 and AS 0. 0607 kJ·mol^-1·K^-1 . These values indicate that the biosorption process by inactive A. fumigatus immobilized on CMC beads was spontaneous and endothermic. The dye molecules movements increased slightly in randomness at the solid/liquid interface during the sorption of dye on the biosorbent.