製備電解強酸水及電解次氯酸水與其殺菌效果之探討

Abstract

本研究旨在探討次氯酸水與強酸水之殺菌效果與使用自製的無隔膜電解水生成設備製備電解次氯酸水的最佳操作條件。水中溶入氯化鈉、氯化鉀和氯化鈣等氯系電解質，以石墨為電極，採取無隔膜方式電解可產生次氯酸水；使用以鈦為電極的市售的電解水生成器，兩極之間有隔膜可在陰極與陽極分別產生強鹼水與強酸水。次氯酸水與強酸水為本研究主要探討的主角。 基礎試驗包括探討不同工作電壓、不同極板距離、不同濃度與種類之電解質水溶液在電解下所消耗的電流與所產生強酸水與次氯酸水之酸鹼度、氧化還原電位與溶液溫度隨時間變化的情形,亦探討強酸水及次氯酸水之保存性。 使用自製設備生成1公升次氯酸水的適當操作條件與結果簡列如下：以3克氯化鈉為電解質，極板距離2 cm，固定直流電壓6 V，電解15分鐘的平均電流為0.625 A，總耗電0.0009375度，生成水之酸鹼度為5.92，氧化還原電位為-480 mV，水溫升高0.3℃。 本研究比較此兩種水於生成後及存放多天後於抑制胡蘿蔔黑腐病、香蕉炭疽病及柑橘青黴病病菌孢子發芽之影響。結果顯示pH小於2.7的強酸水在新生成或存放20天後均能對此三種病菌做有效抑制，適用於收穫後清洗；但由於酸鹼度過低，不適合用於灌溉栽培。次氯酸水則無法有效抑制胡蘿蔔黑腐病，但可抑制香蕉炭疽病與柑橘青黴病病菌孢子的滋長且殺菌效果優於強酸水。次氯酸水因酸鹼度適當，或許未來可適用於栽培過程的消毒、殺菌與灌溉，在降低農藥使用量與在有機栽培的應用上應該極具發展潛力。

The purposes of this study are two folds: First, to investigate on the disinfection capabilities of both hi-ClO water and strong acid water generated through electrolysis. Second, to identify the optimum operating condition of the prototype equipment developed for the generation of hi-ClO water. Hi-ClO water can be generated by providing direct current to water dissolved with NaCl, KCl, or CaCl2 when no filter between poles was used. When provided with filter between poles, strong acid water can be generated at the positive pole side. A prototype equipment, using graphite as the poles, was developed to produce hi-ClO water and a commercially available strong acid water generator, using titanium (Ti) as the poles, was used to generate strong acid water to be used in this study. Fundamental studies on various voltages, working currents, distances between poles, concentrations and types of solvents were investigated during electrolysis process to generate hi-ClO and strong acid water. The pH, ORP and water temperature were measured during the electrolyzing process and the preservation of these factors of both water over the long period of time were also investigated. The optimum operating condition and results of the electrolyzing process using NaCl water to generate 1 liter of hi-ClO water are as follow: 3 g of NaCl, 2 cm distance between poles, 6 V, electrolyzed for 15 min. The average working current is 0.625 A and the electricity consumed is 0.0009375 kwhr, the pH of the water is 5.2 and the ORP is -480 mV, temperature increase of the water is 0.3 degree C. The disinfection capabilities of hi-ClO and strong acid water was tested on Xanthomonas campestris pv. campestris of carrot, Colletotrichum musae of banana and Penicillum italiucm of orange. Results showed that the newly generated strong acid water (pH < 2.7) and the same water after 20 days of storage have great disinfection capabilities on above 3 disease causing bacteria and fungi. The strong acid water can be used as the washing/cleaning water to provide better disinfecting capability during the post-harvesting process. However, due to its low pH value, this water can not be used accompanying irrigation/fertigation water. Hi-ClO water was not able to kill soft rod bacteria of carrot. As to other two bacteria, this water shows even better disinfecting performance over strong acid water. The pH of the hi-ClO water is in the range of 6 to 7, which allow us to use it together with the irrigation/fertigation water. The proper range of pH and the disinfection capability enable the hi-ClO water with great potential in reducing the amount of pesticides used in traditional agricultural practices as well as in organic culture.