海水法烟气脱硫系统中汞再释放规律及其稳定化研究

赵宏; 雷嗣远; 李成宝; 唐轲; 郭浩; 武伟; 马宝林; 郑晗; 关剑; 徐仁博; 罗通达; 孙路石

doi:10.13226/j.issn.1006-6772.23091601

海水法烟气脱硫系统中汞再释放规律及其稳定化研究

Study on re-emission and stabilization of mercury in seawater flue gas desulfurization wastewater

摘要

摘要: 海水法烟气脱硫（SFGD）系统作为传统石灰石烟气脱硫系统的理想替代品，满足控制燃煤烟气中二氧化硫排放的同时，也可抑制烟气中汞的排放。然而，由于海水的还原性，其汞再排放造成的二次污染一直是全球关注的焦点。通过模拟海水法烟气脱硫废水的曝气过程，研究了pH、系统温度以及 \mathrmSO_3^2- 和Cl⁻浓度等一系列因素对Hg⁰再排放的影响，旨在确定海水法烟气脱硫系统中汞的迁移和转化特性。此外，还考察了4种添加剂，包括沉淀剂（Na₂S-无机硫化物、TMT-15-有机硫化物）和氧化剂（NaClO和Fenton试剂）对Hg⁰再排放的抑制机制。结果表明：S(IV)是促进海水中Hg⁰再释放的主要因素。当\mathrmSO_3^2- 浓度为0.05 mmol/L时，超过54%的Hg²⁺转化为Hg⁰。同时，海水中大量的Cl⁻、较低的温度和较高的pH均能抑制Hg⁰的再释放。4种不同添加剂均能不同程度上抑制Hg⁰再释放，其中Na₂S和TMT-15通过与液相中的Hg²⁺反应生成难溶于水的沉淀和螯合物来有效抑制Hg²⁺的还原，NaClO和Fenton试剂主要利用其强氧化性将还原生成的Hg⁰迅速氧化，使Hg²⁺稳定在液相中，还能通过氧化液相中的还原性离子，抑制Hg²⁺的还原。在最佳添加量下，Na₂S、TMT-15、NaClO和Fenton试剂对Hg⁰释放抑制率分别为78.1%、79.9%、84.8%、94.2%。相较于沉淀剂，氧化剂NaClO和Fenton试剂能有效降低曝气强度，对于实际海水脱硫废水海水法烟气脱硫废水曝气过程具有较好的应用前景。

Abstract: The seawater flue gas desulfurization (SFGD) system, as an ideal alternative to traditional limestone-based systems, effectively controls sulfur dioxide (SO₂) emissions from coal-fired flue gas while also suppressing mercury (Hg) emissions. However, the reductive nature of seawater has led to concerns regarding the re-emission of mercury on a global scale. In this study, the aeration process of SFGD wastewater was simulated to investigate the effects of pH, system temperature, and the concentrations of \mathrmSO_3^2- and Cl⁻ on the re-emission of elemental mercury (Hg⁰). The objective of this study was to elucidate the migration and transformation characteristics of mercury in SFGD systems. Furthermore, the study investigated the suppression mechanisms of four additives: two precipitants (Na₂S, an inorganic sulfide, and TMT-15, an organic sulfide) and two oxidants (NaClO and Fenton reagent). The results demonstrated that S(IV) was the primary factor promoting Hg0 re-emission, with over 54% of Hg²⁺ being reduced to Hg⁰ at an \mathrmSO_3^2- concentration of 0.05 mmol/L. Concurrently, elevated concentrations of Cl⁻, low temperatures, and heightened pH levels exhibited a substantial inhibitory effect on Hg⁰ re-emission. All four additives effectively inhibited Hg⁰ re-emission through different mechanisms. Na₂S and TMT-15 reacted with Hg²⁺ in the liquid phase to form water-insoluble precipitates and chelates, thereby preventing reduction to Hg⁰. NaClO and Fenton reagent suppressed Hg⁰ re-emission by rapidly oxidizing Hg⁰ back to Hg²⁺ and stabilizing it in the liquid phase. They also inhibited Hg²⁺ reduction by oxidizing reductive ions in the solution. At optimal dosages, the suppression efficiencies of Na₂S, TMT-15, NaClO, and Fenton reagent were 78.1%, 79.9%, 84.8%, and 94.2%, respectively. Compared to precipitants, oxidants such as NaClO and Fenton reagent significantly reduced the required aeration intensity, demonstrating excellent potential for application in the aeration processes of SFGD wastewater treatment.

HTML全文

参考文献(31)

施引文献

资源附件(0)