By: Valeria Macias
Figure 1. (a) displays the products retrieved from pyrolysis at 500 ℃. (b) phases of Carbon and Hydrogen after pyrolysis. (c) analysis of oil recovered at 500 ℃.
Polluted Contaminated Soil (PCS) caused by the exposure of crude oil into the environment through oil exploitation can led to adverse results. Oil in soil can halt the growth of soil microbes, plants, and animals. Petroleum also pollutes groundwater, which can cause implications in human health. Another concerning affect is that the petroleum evaporates into the atmosphere. Current techniques are flawed due to their duration as well as the slow rate which air passes through PCS (air permeability). Scientists have found that pyrolysis, the breaking of chemical bonds in organic bonds through high temperatures, could remove contaminants from PCS and even recover oil. In the experiment, 1 artificially made PCS and 2 PCS samples from the environment were tested. The samples were placed in a pyrolysis reactor with temperatures ranging 250-600℃ for 30 minutes to identify the total petroleum hydrocarbons (TPH) removed. PCS at 250℃ removed 69.6% of TPH; PCS at 400℃ removed 99% of TPH; and PCS at 500 ℃ removed all TPH. Additionally, soluble organic material, which can pollute water, was removed higher rates as the temperature increased. The oil recovered was determined to have a better quality for transport and burning/refining processes than regular crude oil. The reusability of the soil after pyrolysis was tested using wheat seeds in unpolluted, PCS with 10% oil, PCS with 20% oil soils. Both PCS samples showed low germination. Afterwards, the PCS samples were remediated by pyrolysis and new seeds were planted. After pyrolysis there was 100% germination. This experiment demonstrated that pyrolysis on PCS is an advantageous technique that saves energy while removing petroleum contaminants, recovering oil, and providing reusable soil for plants.
D.C. Li, W.F. Xu, Y.
Mu, H.Q Yu, H. Jiang, and J. C. Crittenden. 2018. Remediation of petroleum-contaminated soil and simultaneous
recovery of oil by fast pyrolysis. Environmental Science & Technology. doi:
10.1021/acs.est.7b03899
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