The post-harvest fumigant, sulfuryl fluoride (SO₂F₂), is a >1000-fold more potent greenhouse gas than carbon dioxide and methane. Pilot studies have shown that SO₂F₂ fumes vented from fumigation chambers can be captured and hydrolyzed by hydroxide (OH^–) and hydrogen peroxide (H₂O₂) at pH ∼ 12 in a scrubber, producing SO₄^2– and F^– as waste salts. To reduce the costs and challenges associated with purchasing and mixing these reagents onsite, this study evaluates the electrochemical generation of OH^– and H₂O₂ within spent scrubbing solution, taking advantage of the waste SO₄^2– and F^– as free sources of electrolyte. The study used a gas diffusion electrode constructed from carbon paper coated with carbon black as a catalyst selective for the reduction of O₂ to H₂O₂. Under galvanostatic conditions, the study evaluated the effect of electrochemical conditions, including applied cathodic current density and electrolyte strength. Within an electrolyte containing 200 mM SO₄^2– and 400 mM F^–, comparable to the waste salts generated by a SO₂F₂ scrubbing event, the system produced 250 mM H₂O₂ at pH 12.6 within 4 h with a Faradaic efficiency of 98.8% for O₂ reduction to H₂O₂. In a scrubbing-water sample from lab-scale fumigation, the system generated ∼200 mM H₂O₂ at pH 13.5 within 4 h with a Faradaic efficiency of 75.6%. A comparison of the costs to purchase NaOH and H₂O₂ against the electricity costs for electrochemical treatment indicated that the electrochemical approach could be 38–71% lower, depending on the local cost of electricity.

中文翻译：

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电化学生成氢氧化物和过氧化氢用于硫酰氟熏蒸剂水解


收获后熏蒸剂硫酰氟 (SO ₂ F ₂ ) 是一种比二氧化碳和甲烷强 1000 倍以上的温室气体。试点研究表明，熏蒸室排出的SO ₂ F ₂ 烟雾可被氢氧化物（OH ^– ）和过氧化氢（H O ₂ )，pH ∼ 12，在洗涤器中，产生 SO ₄ ^2– 和 F ^– 作为废盐。为了降低现场购买和混合这些试剂的成本和挑战，本研究评估了废洗涤剂中 OH ^– 和 H ₂ O ₂ 的电化学生成溶液，利用废 SO ₄ ^2– 和 F ^– 作为电解质的免费来源。该研究使用由涂有炭黑的碳纸制成的气体扩散电极作为选择性将 O ₂ 还原为 H ₂ O ₂ 的催化剂。在恒电流条件下，该研究评估了电化学条件的影响，包括施加的阴极电流密度和电解质强度。在含有 200 mM SO ₄ ^2– 和 400 mM F ^– 的电解液中，与 SO ₂ F 产生的废盐相当 ₂ 洗涤事件，系统在 4 小时内产生 250 mM H ₂ O ₂ （pH 12.6），O ₂ O ₂ 。在实验室规模熏蒸的洗涤水样品中，该系统在 4 小时内产生了约 200 mM H ₂ O ₂ （pH 13.5），法拉第效率为 75.6%。 将购买 NaOH 和 H ₂ O ₂ 的成本与电化学处理的电力成本进行比较表明，电化学方法可以降低 38–71%，具体取决于当地成本的电力。