State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing, 102249, PR China.
State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing, 102249, PR China.
J Environ Manage. 2023 Dec 15;348:119239. doi: 10.1016/j.jenvman.2023.119239. Epub 2023 Oct 10.
The petroleum wastewater (PWW) contains a diverse range of recalcitrant organic contaminants. Of particular concern is the removal of naphthenic acids (NAs) due to the high toxicity and persistence. Persulfate (PS) based oxidation processes have shown promising in treating refractory wastewater, while the high costs of prepared catalysts limited their widespread implementation. This study aims to develop a cost-effective natural pyrite activated PS system for PWW treatment. The removal of NAs by pyrite/PS system was initially investigated. More than 90% of cyclohexanoic acid (CHA), a model NA, was removed in pyrite/PS system (2.0 g/L pyrite, 4.0 mM PS) at initial pH of 3-11. Scavenging experiments revealed that Fe(II) on pyrite surface was the reactive site for PS activation to generate reactive species, including sulfate radical (SO), Fe(IV) and hydroxyl radical (·OH) for CHA degradation. Reactions of Fe(III) with S helped restore Fe(II) and enhance PS activation, resulting in the sustained catalytic activity of pyrites over five cycles. Cl, SO and NO below 10 mM had minimal impact on CHA degradation in pyrite/PS system. However, over 1 mM of HCO inhibited 80% of CHA removal due to the buffer effect to maintain the high solution pH. Removing HCO from real PWW restored the removal of CHA and of total organic carbon (TOC) to over 90% and 71.3% in pyrite/PS system, respectively. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) results indicated that O species including NAs were primarily eliminated through mineralization and oxygen addition. Besides, O-S, NO-S and NO species were the most susceptible to oxidation in PWW, resulting in the increase of the oxidation level (i.e., O/C) from 0.41 to 0.56 after treatment. This study provides valuable insights into the treatment of NAs in real PWW, and potential application of natural minerals in the treatment of industrial wastewater.
石油废水（PWW）含有多种难降解的有机污染物。特别值得关注的是萘酸（NAs）的去除，因为它们毒性高且持久性强。过硫酸盐（PS）基氧化工艺在处理难降解废水方面表现出良好的效果，但预先制备的催化剂成本高，限制了其广泛应用。本研究旨在开发一种经济有效的天然黄铁矿激活过硫酸盐体系来处理 PWW。首先研究了黄铁矿/PS 体系对 NAs 的去除效果。在初始 pH 值为 3-11 的条件下，黄铁矿/PS 体系（2.0 g/L 黄铁矿，4.0 mM PS）中，模型 NAs 环己烷羧酸（CHA）的去除率超过 90%。猝灭实验表明，黄铁矿表面的 Fe(II)是 PS 激活生成活性物质的反应位点，包括硫酸根自由基（SO）、Fe(IV)和羟基自由基（·OH），用于 CHA 的降解。Fe(III)与 S 的反应有助于恢复 Fe(II)并增强 PS 激活，从而使黄铁矿在五个循环中保持持续的催化活性。Cl、SO 和 NO 浓度低于 10 mM 时，对黄铁矿/PS 体系中 CHA 的降解影响很小。但是，HCO 浓度高于 1 mM 时，由于缓冲作用保持溶液 pH 值较高，会抑制 80%的 CHA 去除。从实际 PWW 中去除 HCO 后，CHA 和总有机碳（TOC）的去除率分别恢复到黄铁矿/PS 体系中的 90%和 71.3%以上。傅里叶变换离子回旋共振质谱（FT-ICR MS）结果表明，O 物种（包括 NAs）主要通过矿化和氧加成来消除。此外，在 PWW 中，O-S、NO-S 和 NO 物种最易被氧化，导致处理后氧化水平（即 O/C）从 0.41 增加到 0.56。本研究为实际 PWW 中 NAs 的处理以及天然矿物在工业废水处理中的潜在应用提供了有价值的见解。
