Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montréal, Quebec, Canada.
J Environ Sci (China). 2012;24(5):808-13. doi: 10.1016/s1001-0742(11)60863-2.
The present study describes the use of two commercially available lignins, namely, alkali and organosolv lignin, for the removal of 2,4-dinitroanisole (DNAN), a chemical widely used by the military and the dye industry, from water. Sorption of DNAN on both lignins reached equilibrium within 10 hr and followed pseudo second-order kinetics with sorption being faster with alkali than with organosolv lignin, i.e. k2 10.3 and 0.3 g/(mg x hr), respectively. In a separate study we investigated sorption of DNAN between 10 and 40 degrees C and found that the removal of DNAN by organosolv lignin increased from 0.8 to 7.5 mg/g but reduced slightly from 8.5 to 7.6 mg/g in the case of alkali lignin. Sorption isotherms for either alkali or organosolv lignin best fitted Freundlich equation with enthalpy of formation, deltaH0 equaled to 14 or 80 kJ/mol. To help understand DNAN sorption mechanisms we characterized the two lignins by elemental analysis, BET nitrogen adsorption-desorption and 31P NMR. Variations in elemental compositions between the two lignins indicated that alkali lignin should have more sites (O- and S-containing functionalities) for H-bonding. The BET surface area and calculated total pore volume of alkali lignin were almost 10 times greater than that of organosolv lignin suggesting that alkali lignin should provide more sites for sorption. 31P NMR showed that organosolv lignin contains more phenolic -OH groups than alkali lignin, i.e., 70% and 45%, respectively. The variations in the type of OH groups between the two lignins might have affected the strength of H-bonding between DNAN and the type of lignin used.
本研究描述了两种市售木质素（即碱木质素和有机溶剂木质素）在去除 2,4-二硝基苯甲醚（DNAN）方面的应用。DNAN 在两种木质素上的吸附均在 10 小时内达到平衡，并遵循伪二级动力学，碱木质素的吸附速度比有机溶剂木质素快，即 k2 分别为 10.3 和 0.3 g/(mg x hr)。在另一项研究中，我们研究了 10 至 40 摄氏度之间的 DNAN 吸附，发现有机溶剂木质素对 DNAN 的去除率从 0.8 增加到 7.5 mg/g，但碱木质素的去除率从 8.5 略微降低到 7.6 mg/g。对于碱木质素或有机溶剂木质素，吸附等温线均最好拟合 Freundlich 方程，形成焓，ΔH0 等于 14 或 80 kJ/mol。为了帮助理解 DNAN 吸附机制，我们通过元素分析、BET 氮吸附-解吸和 31P NMR 对两种木质素进行了表征。两种木质素之间的元素组成变化表明，碱木质素应该具有更多的氢键结合位点（含 O 和 S 的官能团）。碱木质素的 BET 比表面积和计算的总孔体积几乎是有机溶剂木质素的 10 倍，这表明碱木质素应该提供更多的吸附位点。31P NMR 表明，有机溶剂木质素比碱木质素含有更多的酚羟基，分别为 70%和 45%。两种木质素之间 OH 基团类型的变化可能会影响 DNAN 与所使用木质素之间氢键的强度。
