Heavy metal-loaded almond shell was subjected to pyrolysis to understand the effect of the presence of different heavy metals on its thermal degradation. Pyrolysis behavior of native and metal-loaded samples was studied by thermogravimetric analysis. Similar shapes of thermogravimetric curves indicate that the presence of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and lead (Pb) did not change the main degradation pathways of almond shell. However, the temperature at which the decomposition in each stage takes place at a higher rate and char yield was considerably modified by the presence of Cr and Ni. Then, pyrolysis tests of the almond shell samples were performed in a moving tubular reactor at 700 °C. Gases and volatile organic compounds were collected using Tedlar bags and semivolatile organic compounds were collected using a resin as adsorbent. Significant changes were obtained in the composition of the gaseous fraction as a result of the metal impregnation. The main changes in the composition of the gas were observed for Ni-loaded sample, which presented the highest H₂ and CO yields. Also, the yields of most of the light hydrocarbons decrease in the presence of metal, while the rest remain quite similar. The total PAH yields reached 103 μg/g for nickel-loaded sample (NiAS), 164 μg/g for copper-loaded sample (CuAS), 172 μg/g for lead-loaded sample (PbAS), 245 μg/g for native sample (AS), 248 μg/g for cadmium-loaded sample (CdAS) and 283 μg/g for chromium-loaded sample (CrAS). Nickel is the most effective in the higher aromatic tar reduction, followed by Cu and Pb, whereas the presence of Cd does not affect the total emissions of PAHs. Finally, the carcinogenic potency of the samples was calculated. Native sample and the sample loaded with Cr presented slightly higher values associated to the presence of small amounts of benzo(a)pyrene.

中文翻译：

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装有重金属的杏仁壳热解过程中产生的挥发性和半挥发性排放物

对装有重金属的杏仁壳进行热解，以了解不同重金属的存在对其热降解的影响。通过热重分析研究了天然和金属负载样品的热解行为。热重曲线的相似形状表明，镉（Cd），铬（Cr），铜（Cu），镍（Ni）和铅（Pb）的存在不会改变杏仁壳的主要降解途径。但是，由于Cr和Ni的存在，每个阶段分解的温度都较高，炭的收率大大提高。然后，在移动的管状反应器中于700°C进行杏仁壳样品的热解测试。使用Tedlar袋收集气体和挥发性有机化合物，并使用树脂作为吸附剂收集半挥发性有机化合物。金属浸渍的结果使气态组分的组成发生了显着变化。观察到镍含量最高的样品中气体成分的主要变化₂和CO产率。同样，在金属存在下，大多数轻质烃的收率降低，而其余的仍非常相似。镍负载样品（Ni，Ni）的总PAH产量达到103μg/ gAS），164μg/ g对于铜负载样品（CuAS），含铅样品（Pb）172μg/ gAS），天然样品（AS）245μg/ g，镉样品（Cd）248μg/ gAS）和283μg/ g（铬载样）作为）。镍在较高的芳香族焦油还原中最有效，其次是Cu和Pb，而Cd的存在并不影响PAHs的总排放量。最后，计算出样品的致癌力。天然样品和负载Cr的样品与少量苯并（a）re的存在相关的值略高。