^(60)Co-γ射线辐照预处理聚乳酸改善厌氧发酵性能

Enhancement of anaerobic fermentation performance of polylactic acid by ^(60)Co-γ ray irradiation pretreatment

聚乳酸(PLA)塑料垃圾沼气生产潜力大,但降解速率低,对其进行预处理可以提高其厌氧发酵效率,促进资源化。本文采用^(60)Co-γ射线对聚乳酸塑料杯样品进行辐照预处理,研究吸收剂量为0 kGy、20 kGy、40 kGy和60 kGy的照射下PLA分子结构及可溶性物质含量变化,并通过蛋白酶酶解实验和厌氧发酵产气量的变化研究电离辐照对其厌氧发酵性能的影响。结果表明:PLA样品经^(60)Co-γ射线辐照,PLA样品上清液中乳酸含量在0~60 kGy范围内随吸收剂量增加略微上升,样品的分子结构未发生明显改变,但辐照后其分子量和结晶度明显下降;辐照后样品在酶解过程中乳酸浓度和质量损失较未辐照样品有明显提升,其中吸收剂量为60 kGy的PLA样品在第4天的乳酸浓度达到最大值并比未辐照样品高17.4%,其质量损失随时间增加,在第7天比未辐照样品提升68.7%;辐照后的样品厌氧发酵达到产气平衡的时间明显缩短,总产气量提升3.0%。研究结果表明,γ射线辐照作为PLA塑料的预处理技术具有潜在的应用价值,本研究可为PLA塑料的资源化处置提供理论参考。

Polylactic acid(PLA)plastic waste has significant potential for methane production in anaerobic digestion,but its slow degradation rate hinders efficient fermentation.Pre-treatment of PLA plastic waste can enhance anaerobic fermentation efficiency,promoting resource utilization.PLA plastic cup sample was pre-treated by irradiation with ^(60)Co-γray to study the changes of PLA molecular structure and soluble substance content under the irradiation with absorbed doses of 0,20,40 and 60 kGy.And the effect of ionizing irradiation on the anaerobic fermentation performance of PLA samples was investigated by the proteolytic enzyme enzymatic digestion experiments and the changes of anaerobic fermentation gas production.The results showed that the lactic acid content in the supernatant of PLA samples irradiated by ^(60)Co-γ ray increased slightly with the increase of absorbed dose in the range of 0~60 kGy.The molecular structure of the samples did not change significantly,but their crystallinity and molecular weight decreased significantly.The lactate concentration and mass loss of the irradiated samples increased significantly during the enzymatic digestion process compared to the unirradiated samples.Specifically,The PLA sample with an absorbed dose of 60 kGy reached its maximum lactate concentration on the 4th day,which was 17.4% higher than that of non irradiated samples.The mass loss increased over time,which was 68.7% higher than that of non irradiated samples on the 7th day.The irradiated samples took significantly less time to reach gas production equilibrium in anaerobic fermentation,and the total gas production increased by 3.0%.The results indicate that γ-ray irradiation has potential application as a pretreatment technology for PLA plastics,and this study can provide a theoretical reference for the resourceful disposal of PLA plastics.