Institute for Environment and Energy, Pusan National University, Busan, 46241, South Korea.
Department of Environmental Engineering, Pusan National University, Busan, 46241, South Korea.
J Environ Manage. 2020 Apr 1;259:110089. doi: 10.1016/j.jenvman.2020.110089. Epub 2020 Jan 7.
Microwaves (MW) have great potential for sludge solubilization, and carbon materials can act as good microwave absorbers and heat transfer media because of their high dielectric loss tangent and thermal conductivity. In this study, carbon nanotube-coated MW vessels were developed by preparing a silane-CNT mixture and spray coating. In addition, sludge solubilization by microwave irradiation was performed to evaluate the effects of the CNT-coating at different initial total suspended solid (TSS) concentrations, target temperatures, and MW irradiation times in the uncoated and CNT-coated MW vessels. The sludge solubilization efficiency increased with increasing MW irradiation time and temperature and followed a first-order reaction in both vessels. However, the energy requirement to maintain the temperature was reduced in the CNT-coated MW vessel compared to the uncoated vessel. In addition, the Arrhenius equation revealed the catalytic site in the CNT-coated MW vessel to have a temperature of around 130 °C at an average sludge temperature of 100 °C. The maximum chemical oxygen demand (COD) solubilization and soluble COD (sCOD) increase per MW energy used were 1.64 and 1.67 times higher in the CNT-coated MW vessel than in the uncoated vessel, respectively. The increase in soluble total nitrogen and phosphorus in the CNT-coated MW vessel was attributed to cell wall destruction and intracellular protoplast dissolution, because of the acceleration of the MW thermal effect and high conductivity of CNTs, as well as the MW-induced cell wall and membrane disruption by hot spots on the CNT surface. This suggests that CNTs can be applied to increase the energy efficiency in MW-based pretreatment methods.
微波（MW）在污泥溶解方面具有很大的潜力，而碳材料由于其高介电损耗正切值和热导率，可以作为良好的微波吸收剂和热传递介质。在本研究中，通过制备硅烷-CNT 混合物和喷涂涂层，开发了碳纳米管涂层的 MW 容器。此外，通过微波辐照进行污泥溶解，以评估 CNT 涂层在不同初始总悬浮固体（TSS）浓度、目标温度和 MW 辐照时间下对未涂层和 CNT 涂层 MW 容器的影响。在两种容器中，污泥溶解效率均随 MW 辐照时间和温度的增加而增加，且遵循一级反应动力学。然而，与未涂层 MW 容器相比，在 CNT 涂层 MW 容器中维持温度所需的能量减少。此外，阿累尼乌斯方程表明 CNT 涂层 MW 容器中的催化位在平均污泥温度为 100°C 时的温度约为 130°C。与未涂层 MW 容器相比，CNT 涂层 MW 容器中每单位 MW 能量的最大化学需氧量（COD）溶解和可溶 COD（sCOD）增加分别高 1.64 倍和 1.67 倍。CNT 涂层 MW 容器中可溶性总氮和磷的增加归因于细胞壁破坏和细胞内原生质溶解，这是由于 MW 热效应的加速和 CNTs 的高导电性，以及 CNT 表面热点对细胞壁和膜的 MW 诱导破坏。这表明 CNT 可应用于提高基于 MW 的预处理方法的能源效率。
