混合 HO 进行预处理，然后进行热解，以升级用过的咖啡渣用于燃料生产，并对 HO 预处理的升级水平进行鉴定。
Dual pretreatment of mixing HO followed by torrefaction to upgrade spent coffee grounds for fuel production and upgrade level identification of HO pretreatment.
机构信息
Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan; Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan.
Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan.
出版信息
Environ Res. 2022 Dec;215(Pt 1):114016. doi: 10.1016/j.envres.2022.114016. Epub 2022 Aug 14.
Biochar is a carbon-neutral solid fuel and has emerged as a potential candidate to replace coal. Meanwhile, spent coffee grounds (SCGs) are an abundant and promising biomass waste that could be used for biochar production. This study develops a biochar valorization strategy by mixing SCGs with hydrogen peroxide (HO) at a weight ratio of 1:0.75 to upgrade SCG biochar. In this dual pretreatment method, the HO oxidative ability at a pretreatment temperature of 105 °C contributes to an increase in the higher heating value (HHV) and carbon content of the SCG biochars. The HHV and carbon content of biochar increase by about 6.5% and 7.8%, respectively, when compared to the unpretreated one under the same conditions. Maximized biochar's HHV derived via the Taguchi method is 30.33 MJkg, a 46.9% increase compared to the raw SCG, and a 6.5% increase compared to the unpretreated SCG biochar. The HO concentration is 18% for the maximized HHV. A quantitative identification index of intensity of difference (IOD) is adopted to evaluate the contributive level of HO pretreatment in terms of the HHV and carbon content. IOD increases with increasing HO pretreatment temperature. Before torrefaction, SCGs' IOD pretreated at 50 °C is 1.94%, while that pretreated at 105 °C is 8.06%. This is because, before torrefaction, HO pretreatment sufficiently weakens SCGs' molecular structure, resulting in a higher IOD value. The IOD value of torrefied SCGs (TSCG) pretreated at 105 °C is 10.71%, accounting for a 4.59% increase compared to that pretreated at 50 °C. This implies that TSCG pretreated by HO at 105 °C has better thermal stability. For every 1% increase in IOD of TSCG, the carbon content of the biochar increases 0.726%, and the HHV increases 0.529%. Overall, it is demonstrated that HO is a green and promising pretreatment additive for upgrading SCG biochar's calorific value, and torrefied SCGs can be used as a potential solid fuel to approach carbon neutrality.
生物炭是一种碳中性固体燃料，已成为替代煤炭的潜在候选燃料。同时，废咖啡渣（SCG）是一种丰富且有前途的生物质废物，可用于生产生物炭。本研究通过将 SCG 与过氧化氢（HO）以 1:0.75 的重量比混合来开发一种生物炭增值策略，以升级 SCG 生物炭。在这种双重预处理方法中，预处理温度为 105°C 时的 HO 氧化能力有助于提高 SCG 生物炭的高热值（HHV）和碳含量。与相同条件下未经预处理的生物炭相比，生物炭的 HHV 和碳含量分别增加了约 6.5%和 7.8%。通过田口法得出的最大生物炭 HHV 为 30.33 MJkg，比原始 SCG 提高了 46.9%，比未经预处理的 SCG 生物炭提高了 6.5%。HO 浓度为 18%时，HHV 最大。采用强度差异定量识别指数（IOD）来评估 HO 预处理对 HHV 和碳含量的贡献水平。IOD 随 HO 预处理温度的升高而增加。在热解之前，在 50°C 预处理的 SCG 的 IOD 为 1.94%，而在 105°C 预处理的 SCG 的 IOD 为 8.06%。这是因为在热解之前，HO 预处理充分削弱了 SCG 的分子结构，导致更高的 IOD 值。在 105°C 预处理的热解废咖啡渣（TSCG）的 IOD 值为 10.71%，比在 50°C 预处理的 TSCG 增加了 4.59%。这意味着在 105°C 下用 HO 预处理的 TSCG 具有更好的热稳定性。TSCG 的 IOD 每增加 1%，生物炭的碳含量增加 0.726%，HHV 增加 0.529%。总的来说，结果表明 HO 是一种绿色且有前途的预处理添加剂，可用于提高 SCG 生物炭的热值，而热解废咖啡渣可用作接近碳中和的潜在固体燃料。
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