工业废酸中还原性水合二氧化硫的测定与去除

首次采用碘量滴定法对工业废酸中强还原性的水合二氧化硫进行了准确测定,并采用120℃恒温简易蒸馏的方法快速去除了工业废酸中大部分的水合二氧化硫,使废酸中剩余的二氧化硫浓度降低至初始浓度的1/100以下(5.6×10-3 mol/L),达到工业用酸标准,从而变废为宝.不仅解决了相关企业“三废”的排放压力,而且为企业创造了良好的经济和社会效益.     

从尿素废液中回收甲醇

据测定,尿素水份废液中含有甲醇、碘、二氧化硫、碘化钠、醋酸钠以及小量水份等物质。甲醇沸点为64.65℃,我们采用蒸馏法回收甲醇,将蒸馏温度控制在75～80℃时,即可蒸馏出甲醇来,其甲醇含量为99.02%。     

干菜中二氧化硫残留量快速测定方法探究

测定干菜中残留二氧化硫,为深圳瑞利来实业有限公司提供技术支持,以磷酸(1+3)为酸性环境蒸馏干菜,用0.05%碘淀粉吸收液吸收蒸馏出来的二氧化硫,边蒸馏边滴定,同时根据国家相关食品添加剂标准预先设计好相应的吸收液可以通过颜色变化直接判断残留物是否超标,反应速度快,重现性好,回收率高,最低检出限为1 mg/kg,可以用于公司质检部门快速测定含量以及判定是否残留物超标,具有操作简单、快速、对环境污染小、灵敏度高等优点,适用于食品中亚硫酸盐及二氧化硫残留量的测定。     

香菇中二氧化硫检测方法的探索与改进

目前香菇中二氧化硫的检测方法为GB5009.34-2016[1],但在实际工作中发现,由于香菇中存在有挥发性物质,在蒸馏过程中挥发性物质随二氧化硫一起被蒸发出来,从而造成检测结果偏高。本文采用全自动凯氏定氮仪进行蒸馏,由于蒸馏方式与蒸馏时间的改变,使得蒸馏结果更接近真实值,同时对比充氮蒸馏法,发现二者并无区别,说明凯氏定氮法可应用于香菇中二氧化硫的测定。     

四氟硼酸四(乙腈)铜(I)试剂中硼和铜含量的测定

建立了化学试剂四氟硼酸四(乙腈)铜(I)中硼和铜含量的测定方法。比较了电位滴定法测硼、原子吸收分光光度法和碘量电位滴定法测定铜含量所表征该试剂纯度的差异。结果表明,电位滴定法测硼、碘量电位滴定法测定铜两种方法的相对标准偏差均近2%,前者的样品加标平均回收率97.33%后者100.2%,两种方法没有显著差异,但碘量电位滴定法简单易行。     

蒸馏比色法测定食品中二氧化硫不确定度评定

建立蒸馏-比色法检测食品中二氧化硫含量。以《测量不确定度评定与表示》为依据,建立数学模型,分析该测定方法不确定度主要来源。计算出测量过程中的A类、B类不确定度及自由度,进一步合成二氧化硫不确定度。该方法可以作为参考用来评估蒸馏-比色法的不确定度。     

稳定态二氧化氯的测定

用常规法测定成品稳定态二氧化氯的杂质，常有干扰。用蒸馏－滴定法，在H2SO4等酸性溶液中，将ClO2蒸出，吸收于KI溶液中，再用Na2S2O3标准溶液滴定析出的碘，可迅速、方便地测定稳定态二氧化氯。该法NaClO3和NaClO2杂质无干扰。同时对蒸馏时酸的选择、蒸馏时间、吸收液酸度与反应所需时间及方法的重现性进行了比较。     

含碘有机废水中碘回收工艺的研究

研究了含碘有机废液中碘的回收方法,考察了蒸馏方式、氧化剂种类、加入量、氧化反应温度、反应时间、Na2SO3加入量等因素对碘收率的影响。结果表明,最佳蒸馏方式为酸性蒸馏,氧化剂为H2O2,其加入量为理论值的4倍,反应温度为60℃,反应时间为20 min,Na2SO3加入量为理论值的2倍,碘的总收率可达82.1%,纯度为98.5%。     

雄黄矿中砷分析方法研究

对溴酸钾滴定法、高锰酸钾滴定法及碘滴定法测定砷做了可行性对比实验；对快速碘滴定法测定雄黄矿中砷含量做了条件试验和验证试验。实验结果表明，快速碘滴定法准确度和精密度较好，能满足标准分析方法要求，可作为标准分析方法颁布实施。     

脱硝粉煤灰铵含量测定方法的试验研究

通过试验,对粉煤灰中残留铵的萃取方法进行优化,确定蒸馏滴定法中粉煤灰铵溶液的制备参数;同时采用蒸馏滴定法和离子色谱法,对粉煤灰中的铵离子含量进行定量检测,验证粉煤灰中残留铵含量测定方法的重复性和再现性;并且建立了粉煤灰中残留铵含量的测定方法。研究结果表明,蒸馏滴定法中,溶液制备参数和滴定方法,对粉煤灰铵含量的检测结果产生显著影响,可通过规定溶液制备参数和熟练滴定方法提高试验精度。蒸馏滴定法试验结果的重复性和再现性符合精密度要求,可作为粉煤灰中残留铵含量测定的基准方法。离子色谱法测得的结果略低于蒸馏滴定法,可作为代用法。     

碱渣及钙镁多元复混肥农用研究

:针对南方红黄壤 ,将碱渣及用碱渣制造的钙镁多元复混肥 ,施用与于果树 (荔枝 )、四季豆、番茄、番薯进行大田试验。结果表明碱渣对酸性土壤有良好的改良作用 ,对荔枝、四季豆、番茄、番薯等作物均有良好的增产效果。     

Sweet potato amylose and amylopectin with narrower distribution of molar mass and chain length obtained by a repeated retrogradation–hydrolysis procedure

The wide molar mass distribution of native starch creates obstacles in investigating the physicochemical characteristics of starch, such as retrogradation, because samples thought to be the same are actually compounds containing many chains with different molar masses. In this paper, the sweet potato amylose and amylopectin isolated from retrograded starch were treated with the retrogradation–hydrolysis method three times, and their physicochemical changes in this process were determined by absorbance of the starch–iodine complex, light microscopy, and molar mass and chain length distributions. The results showed that repeated retrogradation and hydrolysis caused the molar mass distribution of sweet potato amylose and amylopectin to reduce from 4.2 × 10⁷–205 and 7971–223 to 6.0 × 10⁴–730 and 4533–211 g mol⁻¹, respectively. This retrogradation–hydrolysis cut the chain length distribution of sweet potato amylose from DP 9–35 to DP 3–13, but that of amylopectin remained unchanged. The double helix in sweet potato amylopectin will not form if the percentage of chain length with DP ≥ 4 is less than 25%. Repeated retrogradation and hydrolysis was an appropriate method to obtain amylose or amylopectin with a narrower molar mass distribution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43849.     

Preparation and application of potato flour with low gelatinization degree using flash drying

A novel processing method of potato flour with a low starch gelatinization degree was realized by flash drying technique. Starch gelatinization degree, pasting properties, thermal characteristics, and morphological features between commercial potato flours (commercial potato flake and commercial potato granule) and flash-dried potato flour were analyzed and compared. Results showed that the gelatinization degree of flash-dried potato flour (14.52%) was reduced by nearly 80% than the commercial potato flours (about 95%). Typical viscosity profile, enthalpy value, and morphology features of flash-dried potato flour were retained maximally through an optimized processing of flash drying. The gelatinization temperature and pasting viscosity of flash-dried potato flour were increased significantly than the commercial potato flour. Besides, the intact morphological structure of flash-dried potato flour granules were kept due to the processing of flash drying. By utilizing the low gelatinization degree of flash-dried potato flour, desirable potato noodles were prepared with the ratio of potato flour up to 50%. Textural characteristics and cooking performance such as broken rate and cooking loss of flash-dried potato noodles were superior to these of the commercial potato flours (in the same amount) added noodles.     

过氧化二异丙苯含量测定方法的研究

过氧化二异丙苯(DCP)是强氧化剂,用其强氧化性质将饱和碘化钾溶液中的碘离子还原为碘,在样品中加入碳酸氢钠和浓盐酸,在低温(65℃)条件下使碳酸氢钠和浓盐酸反应生成二氧化碳形成保护气体,防止碘升华与空气中的氧反应而造成测定误差,在酸性条件下以淀粉作指示剂,用硫代硫酸钠标准溶液滴定反应生成的碘,以此方法测定过氧化二异丙苯(DCP)的含量,在实际工作中可操作性较强、精密度和准确度高、方法操作简单且重现性较好、抗干扰能力强,完全能够满足容量分析方法中规定的2个平行测定结果误差不大于0.2%的要求。     

Engineering Properties of Sweet Potato Starch for Industrial Applications by Biotechnological Techniques including Genome Editing

Sweet potato (Ipomoea batatas) is one of the largest food crops in the world. Due to its abundance of starch, sweet potato is a valuable ingredient in food derivatives, dietary supplements, and industrial raw materials. In addition, due to its ability to adapt to a wide range of harsh climate and soil conditions, sweet potato is a crop that copes well with the environmental stresses caused by climate change. However, due to the complexity of the sweet potato genome and the long breeding cycle, our ability to modify sweet potato starch is limited. In this review, we cover the recent development in sweet potato breeding, understanding of starch properties, and the progress in sweet potato genomics. We describe the applicational values of sweet potato starch in food, industrial products, and biofuel, in addition to the effects of starch properties in different industrial applications. We also explore the possibility of manipulating starch properties through biotechnological means, such as the CRISPR/Cas-based genome editing. The ability to target the genome with precision provides new opportunities for reducing breeding time, increasing yield, and optimizing the starch properties of sweet potatoes.     

A study on microwave vacuum dried re-structured lychee (Litchi chinensis Sonn.) mixed with purple sweet potato (Ipomoea batatas) snacks

Lychee high sugar content is the biggest disadvantage in drying processes which limits the production of dried lychee for snacks. Purple sweet potato was blended with lychee to develop new snacks using microwave drying techniques. Optimal ingredients proportion and drying conditions were evaluated in terms of their influences on product's organoleptic properties (crispness and mouth feel) and quality attribute. The results showed that addition of 4% potato starch to paste mixture improved the crispness of dried chips. Also, the optimum ratio between purple sweet potato and lychee to produce desirable snacks was found to be 7:3 (W:W). In case of the drying parameters, the high power density resulted in shorter drying time and chips with improved nutrients. Generally speaking the method employed for the drying operation produced no browning throughout the experiments. Therefore, this research has a good future for industrial application.     

尿素和氨态氮肥中全量氮测定的新方法

提出了一个用气提-自动电位滴定测定尿素和氨态氮肥中全量氮测定的新方法.研究了各种因素对气提和自动电位滴定的影响.实验结果表明,与常规的蒸馏滴定法相比,本法具有八大优点：①节能：节约电能80％以上：②减排：免除了蒸馏时大量冷却水的排放;③降耗：降低了分析试剂的消耗;④增效：分析速度提高了一倍以上;⑤安全：免除了蒸馏法的高温作业;⑥省力：免除了手工滴定之操作劳动;⑦省费：比蒸馏法降低成本4倍以上;⑧准确：免除了手工滴定的观测误差,提高了方法的准确度和精密度.     

不同淀粉的酸解历程及性质研究

将玉米淀粉和马铃薯淀粉分别在35℃条件下用浓度为2 4mol/L的HCl处理不同时间,采用碘量法、X射线衍射(X ray)分析和差热分析(DTA)等对酸解后的淀粉颗粒进行了结构和性能表征。结果表明,马铃薯淀粉的酸解过程可分为3个阶段,酸解速率常数分别为2 78(t<24h),0 94(24h96h)。在比较分析了玉米和马铃薯淀粉酸解前后的一些物理化学性质及结构变化与酸解时间的相互联系后,认为酸首先水解淀粉的无定型区,提高淀粉颗粒结晶度、热稳定性和酶解速率;而后随着酸解时间的延长,淀粉结晶结构遭到侵蚀,热稳定性降低。酸解时间为4d时,玉米淀粉和马铃薯淀粉颗粒的结晶最完美,热稳定性最佳,结晶转变温度分别为87 0℃和93 5℃。     

Extraction of bioethanol from fermented sweet sorghum bagasse by batch distillation

Extraction of bioethanol, a potential alternative to fossil fuel in the transport industry, from sweet sorghum stems [Sorghum bicolor (L.) Moench] using solid-state fermentation (SSF) technology has become a popular research topic worldwide. Because SSF technology can directly convert fermentable sugars into target products without juice squeezing and water input, this method can potentially reduce energy and water consumption. However, ethanol extraction from fermented sweet sorghum bagasse requires further investigation. We used batch solid-state distillation to investigate the optimal operating parameters in a distillation column (diameter, 400 mm) via a single-factor experiment. Results showed that the optimal steam flow rate and loading height were 8-10 kg·h^?1 and 700-1,000 mm, respectively. Under optimal conditions, an energy consumption of 3.82 tons of steam per ton of ethanol and distillate concentration of 60.9% (v/v) were obtained. The pseudo-first-order rate equation was used to describe the distillation kinetics, and good correlations were obtained. Therefore, solid-state distillation can be effectively used to extract ethanol from fermented sweet sorghum bagasse.     

碘-聚乙烯醇在铜精矿测定铜含量中的应用

铜精矿中的存在组分较为复杂、干扰较多,因此在铜精矿铜量测定的过程中,选取合适的分析方法十分重要。碘量法方法成熟,操作简便,在铜精矿化学分析中的应用最为广泛。但由于采用标准法进行滴定时,其专属指示剂——淀粉指示剂与碘会形成大量吸附物,导致体系中的碘与硫代硫酸钠反应不充分且在偏酸性环境中,淀粉易被微生物分解变质,显色迟钝灵敏度下降。这些都将影响滴定终点的判断而造成分析误差。为了有效的避免此类情况的出现,引入聚乙烯醇表面活性剂,将改进型碘量法与标准法进行对比分析,发现新型指示剂消除了传统指示剂存在的干扰和弊端,提高了实验的准确度和精密度,PVA指示剂性能稳定且易于保存,在碘量分析中的表现更加出色。