Biogas production is an important component of an environmentally benign renewable energy strategy. However, the cost-effectiveness of biogas production from biomass is limited by the presence of polymeric structures, which are recalcitrant to digestion by bacteria. Therefore, pretreatments must often be applied prior to anaerobic fermentation to increase yields of biogas. Many physico-chemical pretreatments have a high energy demand and are generally costly. An alternative could be the ignition of a plasma directly in the biomass substrate. The reactive species that are generated by plasma–liquid interactions, such as hydroxyl radicals and hydrogen peroxides, could contribute significantly to the disintegration of cell walls and the breakage of poorly digestible polymers. With respect to economic, processing, and other potential benefits, a microwave instigated and sustained plasma was investigated. A microwave circuit transmitted 2-kW pulses into a recirculated sodium carboxymethyl cellulose solution, which mimicked the rheological properties of biomass. Each microwave pulse had a duration of 12.5 ms and caused the ignition of a discharge after a vapor bubble had formed. Microwaves were absorbed in the process with an efficiency of ∼97%. Slow-motion imaging showed the development of the discharge. The plasma discharges provoked a decrease in the viscosity, probably caused by the shortening of polymer chains of the cellulose derivative. The decrease in viscosity by itself could reduce processing costs and promotes bacterial activity in actual biomass. The results demonstrate the potential of microwave in-liquid plasma discharges for the pretreatment of biomass.

中文翻译：

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用于生物质预处理的微波等离子体放电：羧甲基纤维素钠模型的降解

沼气生产是对环境无害的可再生能源战略的重要组成部分。然而，由生物质生产沼气的成本效益受到聚合物结构的限制，该聚合物结构难以被细菌消化。因此，必须经常在厌氧发酵之前进行预处理，以增加沼气的产量。许多物理化学预处理具有很高的能量需求，并且通常很昂贵。另一种选择是直接在生物质基质中点燃等离子体。由血浆-液体相互作用产生的反应性物质，例如羟基自由基和过氧化氢，可显着促进细胞壁的分解和难消化的聚合物的破裂。关于经济，加工和其他潜在利益，研究了微波激发和持续的等离子体。微波电路将2kW脉冲传输到再循环的羧甲基纤维素钠溶液中，该溶液模仿了生物质的流变特性。每个微波脉冲的持续时间为12.5毫秒，并在形成水蒸气气泡后引发放电。在此过程中，微波被吸收的效率约为97％。慢动作成像显示放电的发展。等离子体放电引起粘度降低，这可能是由于纤维素衍生物的聚合物链缩短引起的。粘度的降低本身可以降低加工成本并促进实际生物质中的细菌活性。结果证明了微波液体中等离子体放电对生物质进行预处理的潜力。