Mylapilli S V Prasad, Reddy Sivamohan N
Department of Chemical Engineering, Indian Institute of Technology Roorkee, Uttarakhand, India.
Department of Chemical Engineering, Indian Institute of Technology Roorkee, Uttarakhand, India.
Environ Res. 2022 May 1;207:112191. doi: 10.1016/j.envres.2021.112191. Epub 2021 Oct 9.
Pharmaceutical industrial wastewater is typical wastewater consisting of complex organic compounds with higher concentration, microbial toxicity, strenuous to deteriorate, and environmental threatening. The present work assesses the degradation of recalcitrant acetaminophen (ACM) by a green technology known as supercritical water oxidation (SCWO). Experiments were carried out in a continuous flow SCWO reactor by altering reaction conditions such as temperature 400-600 °C, oxidant coefficient (OC 0 to 3), and Fe(II) catalyst concentration (0.5 and 1 mg L) to study the technical feasibility of highly concentrated ACM. Liquid product analysis indicated the total organic carbon (TOC) removal efficiency could reach up to 99.5% without catalyst at 600 °C and 99.9% with Fe(II) at 500 °C. The addition of Fe not only suppressed the intermediate ring components but also promoted the formation of permanent gases via decarboxylation and reforming reactions. The reaction between Fe(II) and HO in supercritical water is extremely fast, which has a direct impact on the system's operating conditions. The high activity exhibited by Fe(II) catalyst degraded the ACM completely at an operating condition of 500 °C. Maximum H fraction was attained without catalyst at 600 °C, OC 0.5, and with the catalyst at 500 °C, respectively, whereas, CO tends to rise significantly with both temperature and oxidant concentration. The catalytic process is efficient in comparison to the non-catalytic process. A possible reaction pathway was proposed based on the intermediates generated during the degradation.
制药工业废水是典型的废水，由浓度较高、具有微生物毒性、难以降解且对环境有威胁的复杂有机化合物组成。目前的工作评估了一种名为超临界水氧化（SCWO）的绿色技术对难降解的对乙酰氨基酚（ACM）的降解效果。在连续流动的超临界水氧化反应器中进行了实验，通过改变反应条件，如温度400 - 600℃、氧化系数（OC 0至3）和Fe(II)催化剂浓度（0.5和1 mg/L），来研究高浓度ACM的技术可行性。液体产物分析表明，在600℃无催化剂时总有机碳（TOC）去除效率可达99.5%，在500℃添加Fe(II)时可达99.9%。添加Fe不仅抑制了中间环成分，还通过脱羧和重整反应促进了永久性气体的形成。超临界水中Fe(II)与HO之间的反应极快，这对系统的操作条件有直接影响。Fe(II)催化剂在500℃的操作条件下表现出的高活性使ACM完全降解。分别在600℃、OC 0.5时无催化剂以及在500℃有催化剂时达到最大H分数，而CO则随着温度和氧化剂浓度的升高而显著增加。与非催化过程相比，催化过程效率更高。基于降解过程中产生的中间体提出了一条可能的反应途径。
