以TEMPO为媒介电化学氧化解聚微晶纤维素的研究

对以2,2,6,6-四甲基哌啶氧化物(TEMPO)为媒介阳极电解解聚微晶纤维素(MCC)的条件及效果进行了研究。研究结果表明,60 g/L MCC在(25±5)℃,含有0.2 mol/L Na2CO3-Na HCO3(p H=10.0)和1.5 g/L TEMPO的电解液中,以石墨电极为阳极0.80 V(vs.Ag/Ag Cl)下恒电位电解会在MCC中引入羧基;当引入羧基量达到2.0mmol/g时,55%的MCC解聚为水溶性低聚糖、纳米纤维素、纤维二糖及葡萄糖,继而在150℃水热反应釜中水解处理,MCC的解聚率可达82%;而未经电化学氧化解聚处理的MCC在150℃水热反应釜中水解处理的解聚率不到1%。

Depolymerization of cellulose using a 2,2,6,6-tetra methylpiperidine-1-oxygen radical (TEMPO)-mediated electrochemical oxidation process

The effects of varying the reaction conditions in the depolymerization of microcrystalline cellulose (MCC) through indirect electro oxidization with 2,2,6,6-tetra methylpiperidine-1-oxygen radicals (TEMPO) as mediator have been studied. At (25±5) ℃, 60 g/L MCC in an electrolyte containing 0.2 mol/L Na₂CO₃-NaHCO₃ (pH=10.0) and 1.5 g/L TEMPO was potentiostatically electrolized at 0.80 V (vs. Ag/AgCl) using a graphite anode. The results showed that many carboxyl groups were introduced into MCC, and 55% of MCC was depolymerized into water-soluble oligoes, nano-sized cellulose, cellobiose and glucose when the amount of the introduced carboxyl groups reached 2.0 mmol/g. The depolymerization yield was as high as 82% after subsequent hydrolysis in a hydrothermal kettle, while the yield was less than 1% if MCC was not pretreated by the electrochemical method. 