焦(jiao)亞(ya)(ya)(ya)(ya)(ya)硫(liu)(liu)酸(suan)鈉（Na2S2O5）又(you)叫一縮二亞(ya)(ya)(ya)(ya)(ya)硫(liu)(liu)酸(suan)鈉。系為二分子亞(ya)(ya)(ya)(ya)(ya)（NaHSO3）脫(tuo)去一分子水的產物:焦(jiao)亞(ya)(ya)(ya)(ya)(ya)硫(liu)(liu)酸(suan)鈉溶于(yu)水時，焦(jiao)亞(ya)(ya)(ya)(ya)(ya)硫(liu)(liu)酸(suan)鈉，即形成(cheng)亞(ya)(ya)(ya)(ya)(ya)，所以一切使用亞(ya)(ya)(ya)(ya)(ya)的部門（如食品罐頭、、造紙、制(zhi)糖(tang)、皮(pi)革、有(you)機合成(cheng)、印染(ran)等）都能(neng)使用焦(jiao)亞(ya)(ya)(ya)(ya)(ya)硫(liu)(liu)酸(suan)鈉。焦(jiao)亞(ya)(ya)(ya)(ya)(ya)硫(liu)(liu)酸(suan)鈉較亞(ya)(ya)(ya)(ya)(ya)穩(wen)定（不(bu)易(yi)受空氣氧化(hua)）、吸濕性也較好、更(geng)重要的是(shi)單位(wei)質量的焦(jiao)亞(ya)(ya)(ya)(ya)(ya)硫(liu)(liu)酸(suan)鈉（SO2）含量較高（理(li)論含量約為67.9％而NaHSO3含量為61.5％）并且生產較易(yi)。

焦亞(ya)硫(liu)酸鈉(na)是一種用途十分(fen)廣泛(fan)的化工原(yuan)料。主要分(fen)為工業級跟(gen)食(shi)品(pin)級兩種。

工業級主要(yao)用于(yu)制(zhi)革、織(zhi)物(wu)、有(you)機物(wu)漂白、印染的媒染物(wu)、照相行業還原劑、橡(xiang)膠凝固及及香料(liao)等。

食品級主要用(yong)于食品的保存(cun)、釀造、及飲料用(yong)殺菌防腐(fu)與保鮮劑(ji)。

目(mu)前(qian)國內(nei)以純堿(jian)跟硫(liu)磺為原料(liao)生(sheng)(sheng)(sheng)產(chan)(chan)焦亞(ya)硫(liu)酸(suan)鈉(na)(na)的工藝主要有干法跟濕法兩(liang)種。我(wo)公司生(sheng)(sheng)(sheng)產(chan)(chan)的焦亞(ya)硫(liu)酸(suan)鈉(na)(na)主要是用濕法工藝生(sheng)(sheng)(sheng)產(chan)(chan)。由純堿(jian)的飽和水溶液或者純堿(jian)與酸(suan)式亞(ya)硫(liu)酸(suan)鈉(na)(na)所成(cheng)(cheng)之溶液，焦亞(ya)硫(liu)酸(suan)鈉(na)(na)，通入SO2氣體，即生(sheng)(sheng)(sheng)成(cheng)(cheng)焦亞(ya)硫(liu)酸(suan)鈉(na)(na)結晶，經分離干燥得成(cheng)(cheng)品。

焦(jiao)亞硫酸(suan)鈉作為一種(zhong)(zhong)食(shi)(shi)品添加(jia)劑，被廣泛用(yong)(yong)(yong)(yong)于農產(chan)品加(jia)工中FAO 和 WHO 對亞硫酸(suan)鹽(yan)類(lei)添加(jia)劑的使(shi)(shi)用(yong)(yong)(yong)(yong)范圍(wei)和使(shi)(shi)用(yong)(yong)(yong)(yong)量(liang)(liang)有著嚴格的規定(ding)：SO2每人每日允許(xu)攝(she)入量(liang)(liang)（AD）I 為 0～0.7 mg/kg。中國《食(shi)(shi)品添加(jia)劑使(shi)(shi)用(yong)(yong)(yong)(yong)衛生標準》（GB2760-2007）對亞硫酸(suan)鹽(yan)類(lei)添加(jia)劑的使(shi)(shi)用(yong)(yong)(yong)(yong)范圍(wei)、使(shi)(shi)用(yong)(yong)(yong)(yong)量(liang)(liang)及允許(xu)殘(can)留量(liang)(liang)也有明確規定(ding)：焦(jiao)亞硫酸(suan)鈉用(yong)(yong)(yong)(yong)于蜜餞、餅干、葡萄糖、食(shi)(shi)糖、冰糖、飴糖、糖果、液(ye)體葡萄糖、竹筍、蘑菇(gu)(gu)及蘑菇(gu)(gu)罐頭的不超(chao)過使(shi)(shi)用(yong)(yong)(yong)(yong)量(liang)(liang)為 0.4 g/kg；殘(can)留量(liang)(liang)以SO2計，竹筍、蘑菇(gu)(gu)及蘑菇(gu)(gu)罐頭不得(de)超(chao)過 0.05 g/kg，餅干、食(shi)(shi)糖、粉絲(si)及其他品種(zhong)(zhong)不得(de)超(chao)過 0.1 g/kg。