研究了海藻化工中以氢氧化钙作为钙化剂的新型钙化工艺,使用氢氧化钙+氯化钙作为褐藻酸钠的钙化剂替代传统的单一氯化钙。确定的双钙钙化工艺条件：每升褐藻酸钠胶液（褐藻酸钠质量浓度为2.5 g/L）,添加氯化钙溶液29.0 mL（质量分数为5%）,添加氢氧化钙溶液13.75 mL（质量分数为5%）,复合钙化剂中氯化钙与氢氧化钙物质的量比为1.19∶1。与传统工艺相比,新型钙化工艺褐藻酸钠的产率未有明显变化,得到的褐藻酸钠粘度稍有降低,粘度由275.1 mPa·s降低至241.3 mPa·s;氯化钙使用量降低40%以上,总钙添加量减少19%。双钙钙化工艺实现了对钙化废水的再利用,废水中钙质量浓度经处理由483 mg/L降到20 mg/L左右,电导率由6.84 mS/cm降至4.28 mS/cm;经脱钙处理的钙化废水回用后对产品褐藻酸钠的产率和粘度没有显著影响。新工艺操作简单,不仅有效减少了钙化废水中离子的引入,同时可以实现低成本地脱钙,脱钙后的废水可以作为冲稀水回收利用,减少了水资源的消耗,为海藻化工行业的减排提供了一条新的工艺途径。

A new calcification process in seaweed chemical industry was studied using Ca（OH）₂ as the calcifying agent.A composite of CaCl₂ and Ca（OH）₂ was used as calcifying agent for sodium alginate instead of traditional CaCl₂ .The deter-mined double-calcium calcification process conditions were：per liter of sodium alginate glue（alginate sodium mass concen-tration was 2.5 g/L）,the adding amount of 5%（mass fraction） CaCl₂ solution was 29.0 mL,the adding amount of 5%（mass fraction） Ca（OH）₂ solution was 13.75 mL and the amount-of-substance ratio of CaCl₂ to Ca（OH）₂ in the composite calcify-ing agent was 1.19:1.Compared with the traditional process,the new calcification process did not change the yield of sodium alginate significantly,but decreased the viscosity of the obtained sodium alginate slightly from 275.1 mPa·s to 241.3 mPa·s.The adding amount of CaCl₂ was reduced by more than 40%,and the amount of total calcium ions added was reduced by 19%.The double-calcium calcification process realized the reuse of calcification wastewater,in which the mass concentration of calcium was reduced from 483 mg/L to about 20 mg/L and the electrical conductivity was reduced from 6.84 mS/cm to 4.28 mS/cm after decalcification treatment.The treated calcification wastewater reused as process water did not significantly affect the yield and viscosity of the sodium alginate product.The new process is simple in operation,not only effectively reducing the introduction of ions in the calcification wastewater,but also realizing low-cost decalcification treatment,and the decalcified wastewater would be able to be reused as process water that provides a feasible way to reduce the water consumption in the seaweed chemical industry.