Simultaneous depolymerization and decolorization of chitosan by ozone treatment

ABSTRACT:  Currently, depolymerization and decolorization of chitosan are achieved by chemical or enzymatic methods, which are time consuming and expensive. Ozone has been shown to be able to degrade macromolecules and remove pigments due to its high oxidation potential. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated. Crawfish chitosan was ozonated in water and acetic acid solution for 0, 5, 10, 15, and 20 min at room temperature with 12 wt% gas. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated by measuring the molecular weight, viscosity, and color of chitosan. The color of ozone-treated chitosan was analyzed using a Minolta spectrophotometer. The degree of deacetylation was determined by a colloid titration method. Molecular weight of ozone-treated chitosan in acetic acid solution decreased appreciably as the ozone treatment duration increased. Ozonation for 20 min reduced the molecular weight of the chitosan by 92% (104 kDa) compared to the untreated chitosan (1333 kDa) with a decrease in viscosity of the chitosan solution. Ozonation for 5 min markedly increased the whiteness of chitosan with a molecular weight of 432 kDa; however, further ozonation resulted in development of yellowness. In the case of the ozonation in water, there were no significant differences in the molecular weight and color between ozone-treated chitosans. This study showed that ozone can be used to modify molecular weight and remove pigments of chitosan without chemical use in a shorter time and with less cost.     

白腐菌处理漂白废水工艺及脱色机理探讨

本文设计了一种适合于白腐菌ｐｈａｎｅｒｏｃｈａｅｔｅ ｃｈｒｙｓｏｓｐｏｒｉｕｍ 处理漂白废水的活性炭———化学纤维固定膜反应器,对漂白废水的脱色率达６０ ％ ～９０ ％ ,ＣＯＤｃｒ 去除率在５０ ％ 以上。本文还探讨了菌膜生长的营养条件和废水组成对处理效果的影响。最后通过用Ｈ２Ｏ２ 对废水进行的脱色处理,验证了白腐菌脱色类似于Ｈ２Ｏ２ 的作用。     

扑热息痛废水治理技术初步研究

通过实验,比较了处理扑热息痛废水的两种工艺流程,认为混凝加兼氧－好氧生物接触氧化法加氧化脱色工艺流程是合理可行的,确定了混凝类型和合理投加量以及操作条件,处理后出水指标ＣＯＤｃｒ、ＢＯＤ５、色度达到国家污水综合排放标准的二级标准。     

一色齿毛菌对直接大红4BS染料的脱色

为避免染料废水处理造成二次污染,采用生物法对直接染料进行脱色处理,通过观察接种一色齿毛菌后染料固体培养基颜色的变化,评价一色齿毛菌对5种直接染料的脱色效果;利用单因素和正交试验对一色齿毛菌脱色直接大红4BS的条件进行优化,得到优化条件:葡萄糖质量浓度为20 g/L,硝酸铵质量浓度为1 g/L,硫酸镁浓度为1.5 mmol/L,每50 mL反应体系接菌量为2片(直径为1 cm)。结果表明:一色齿毛菌对5种直接染料均有脱色能力,其中对直接大红4BS染料的脱色更为彻底;在优化条件下,一色齿毛菌对直接大红4BS脱色13 d时的脱色率达92.00%, 与优化前的脱色率相比提高了50.82%。     

超声强化过氧化氢-维生素C体系糖汁脱色的研究

研究超声强化过氧化氢-维生素C复合脱色剂体系对糖汁脱色的规律,考察了超声功率、复合脱色剂用量、超声温度和时间对糖汁脱色率的影响。试验结果表明:超声空化强化过氧化氢-维生素C对糖汁具有良好的脱色效果,当处理糖汁量为100 mL,超声功率为260 W,过氧化氢与维生素C的用量均为1.6 mL,空化温度为70℃,超声时间为6 min时,脱色率达到53.4%。通过正交试验分析,得到各个因素对糖汁脱色率影响的主次关系为:超声功率>复合脱色剂用量>超声时间>空化温度。     

胭脂萝卜籽油精炼与理化性质分析

以冷榨的胭脂萝卜籽毛油为原料,分别考察了不同因素对水化脱胶、碱炼脱酸、吸附脱色与加热真空脱臭等过程精炼效果的影响,并对油脂的理化性质进行了分析。结果表明:水化脱胶的条件为温度75℃、磷酸添加量0.4%、加水量5%,脱胶率为90.1%;碱炼脱酸的参数为碱炼初温40℃、碱液浓度16 °Bé、超碱量0.3%,脱酸率为93.7%;活性白土为脱色吸附剂,在添加量0.3%、温度80℃、时间50 min时,脱色率为83.5%;在170℃下加热真空脱臭1.5 h得到无气味的精炼油;精炼油的折光指数1.468±0.001、碘值(98.5±0.6)g/100 g、酸值0.28 mg KOH·g-1等各项指标均符合二级菜籽油和萝卜籽油标准。     

Pycnoporus sp. SYBC-L3漆酶催化偶氮染料脱色

为考察 Pycnoporus sp. SYBC-L3漆酶Lac-L对偶氮染料的脱色、解毒效果,探究最佳的脱色反应条件,采用单因素分析方法研究了不同的反应条件对Lac-L催化3种偶氮染料（AR1、RB5、RV5R）脱色的影响,得到最佳处理条件,并通过比较被漆酶降解前后的染料对小麦和水稻发芽率及根、芽生长的影响,分析其毒性变化。结果表明：在以HBT为介体、反应温度50 ℃、pH分别为4.0（AR1,RV5R）和5.0（RB5）、漆酶用量1 U/mL、染料初始质量浓度分别为30 mg/L（AR1）和50 mg/L（RB5、RV5R）条件下,漆酶对3种偶氮染料的脱色效率最高,AR1和RV5R几乎完全降解,脱色率达到96.1%和97.8%,而RB5也有83.8%的脱色率。植物毒理实验表明,3种偶氮染料经漆酶降解后对小麦和水稻发芽率没有影响,对胚芽和根生长的抑制作用也有所降低。     

Regeneration of a spent bleaching earth and its reuse in the refining of an edible oil

A spent bleaching earth from an edible oil refinery has been regenerated by thermal processing followed by washing with a solution of hydrochloric acid. Optimal regeneration conditions have been controlled by decolorization tests of a degummed and neutralized crude edible oil. Optimal values (temperature: 500 °C, carbonization time: 1 h, HCl concentration: 1 M ) gave a material as efficient as a virgin bleaching earth. The percentage uptake of chlorophyll derivatives and β‐carotenoids calculated at 410 and 460 nm, are respectively 92.8 and 95% for an oil processed by the regenerated spent bleaching earth, against 77.4 and 92.7% for the same oil processed by a commercial virgin bleaching earth. The results obtained after decolorization of an edible oil with a regenerated spent bleaching earth indicate that during the process, the resultant oil did not undergo any changes in the iodine value, the free fatty acid content and the saponification value. © 2000 Society of Chemical Industry     

复合型絮凝剂对印染废水的脱色性能研究

研究了由聚合铝铁和助凝剂复合形成的絮凝剂对分散染料和涂料的脱色性能,分析比较了助凝剂用量、废水pH值及絮凝剂的稳定性等因素对絮凝脱色效果和废水沉降速率的影响.结果表明,同其他絮凝剂相比,复合型絮凝剂对分散染料和涂料具有更好和更快的絮凝效果,且投入量少.     

Multistage treatment of high strength dye wastewater by coagulation and ozonation

Two types of wastewaters from the dye manufacturing process were treated by multistage chemical coagulation combined with ozonation. By using the coagulant iron(II) chloride and a commercial coagulant aid, the majority of COD was removed in advance of ozonation, a similar repeated treatment cycle was performed after settlement of the coagulant in each cycle. Results showed that the optimum concentrations to be used were 2·5% (v/v) iron(II) chloride and 35 mg dm⁻³ coagulant aid. The decolorization efficiency was >99% and the COD elimination was >90%. The multistage combined chemical coagulation ozonation treatment was found to be superior to the single-stage treatment. © 1998 SCI.