食品级磷酸氢钙中和剂的选择和优化

Selection and optimization of neutralization agent for food grade calcium hydrogen phosphate

简要分析了以肌醇渣为原料制备食品级磷酸氢钙的重要性。对现有工艺中和剂的选择和提纯优化进行了具体分析,最终确定以氯化钙和氢氧化钠为复合中和剂。分别选取活性γ-氧化铝和碱改性活性炭对氯化钙和氢氧化钠进行吸附脱氟实验,探讨了不同吸附条件对其脱氟率的影响。用脱氟精制的复合中和剂中和精磷酸,得到符合GB 1889—2004《食品添加剂:磷酸氢钙》要求的食品级磷酸氢钙,氟质量分数为0.004 8%~0.005 0%。较适宜吸附参数:活性γ-氧化铝对氯化钙的脱氟过程,吸附温度为室温、活性γ-氧化铝用量为20 g、吸附时间为50 min、氯化钙溶液pH=6、氯化钙浓度为2.7 mol/L,最佳脱氟率为93.73%;碱改性活性炭对NaOH的脱氟过程,碱改性活性炭用量为1.0 g、吸附温度为35℃、吸附时间为60 min、氢氧化钠浓度为8.75 mol/L,最佳脱氟率为72.60%。

The importance of using the inositol residue as raw material to prepare food grade calcium hydrogen phosphate was briefly analyzed.In addition,the selection and purification optimization of neutralizer of the current process were analyzed in detai l,and calcium chloride and sodium hydroxide were ultimately confirmed as the compound neutralizer.Then the active y-Al2O3 and the alkali modified activated carbon were selected to carry on the adsorption defluoridation experiments respec- tively.The influences of different adsorption conditions on the defluoridation rate were investigated.Finally,the food grade calcium hydrogen phosphate with fluorine mass fraction of 0.004 8%-0.005 0%,which consistented with the national stand-ard,Food Additive-Calcium Hydrogen Phosphate,GB 1889-2004,was obtained by neutralization reaction between the defluorization refined compound neutralizer and concentrate phosphoric acid.The suitable adsorption parameters were obtained： the better temperature of the active y-Al2 O3 adsorption defluoridation was room tem p e ra tu re ,y -A l2O3 dosage was 20 g,the adsorption time was 50 min,CaCl2 solution pH was 6 ,CaCl2 concentration was 2.7 mol/L,and the best removal rate offluoride was 93.73%;The conditions ofadsorption defluoridation ofalkal i modified activated carbon to NaOH were that alkali activated carbon was 1.0 g,temperature was 35, the adsorption time was 60 min,NaOH concentration was 8.75 mol/L,and the best defluorization rate was 72.60%.