甲壳素的改性及其对Cr(Ⅵ)吸附性能的研究

通过对甲壳素的改性,探讨了时间、pH、温度、Cr(Ⅵ)浓度和吸附剂与废水质量比等因素对甲壳素衍生物吸附Cr(Ⅵ)的影响.结果表明,改性后的甲壳素具有较强的螯合和吸附作用.吸附效率随着吸附时间的延长而增大;在酸性溶液中,吸附量较高,去除效率较大.但酸性过高时,壳聚糖在溶液中会发生显著的酸溶现象,不利于吸附Cr(Ⅵ),pH控制在2～4,温度控制在30℃有利于吸附;当[Cr(Ⅵ)]≤10 mg/L时,可用N-羧甲基化壳聚糖进行吸附处理;而当原液中[Cr(Ⅵ)]≤20 mg/L时,可用西佛碱进行吸附处理效果较好;N-羧甲基化壳聚糖与废水的质量比为1.4×10-3、西佛碱与废水的质量比为1.2×10-3效果最佳,且2种吸附剂吸附Cr(Ⅵ)的物理化学过程符合Langmuir吸附等温线.     

蒙脱石负载壳聚糖对酸性大红3R染料的吸附研究

为探究蒙脱石负载壳聚糖复合吸附剂对废水中酸性大红3R染料的去除效果,通过改变壳聚糖和蒙脱石的混合比、吸附剂的吸附时间、吸附剂用量、酸性大红3R染料溶液浓度和pH值等实验条件,从多环境因子角度研究蒙脱石负载壳聚糖对于酸性大红3R染料的吸附除去效果。实验结果表明:在壳聚糖/蒙脱石比为0.08 g/g,搅拌时间为45 min,加入壳聚糖/蒙脱石质量为1.33 g/L,溶液pH值为5～6时,复合吸附剂对酸性大红3R染料的吸附效果最好,吸附率可达99.6%以上。用二级动力学方程来描述蒙脱石负载壳聚糖对酸性大红3R的吸附比较适宜,室温条件下复合吸附剂对酸性大红3R的吸附热力学符合Langmuir和Freundlich方程。     

高岭土改性壳聚糖对废水中铜离子吸附效果

利用高岭土与壳聚糖2种天然材料,通过高岭土来改性壳聚糖,用于处理废水中重金属铜。实验结果表明:在铜离子初始浓度为0.2mg/L,壳聚糖与高岭土的配比为0.1,搅拌吸附反应时间为30min,吸附剂质量浓度为1.2g/L,溶液pH值为6时,对铜离子的去除效果最佳。与单一材料相比较,制备的高岭土改性壳聚糖对铜离子的去除能力强,且用量少。     

壳聚糖对Cd2+和Pb2+的吸附作用

为开发新型吸附剂,降低重金属对水体的污染,研究了壳聚糖对Cd²⁺和Pb²⁺的吸附条件,探讨了pH、温度、反应时间、壳聚糖添加量和金属离子初始浓度等因素对壳聚糖吸附性能的影响。结果表明,pH 7~8和pH 5~6条件下壳聚糖对Cd²⁺和Pb²⁺的吸附能力最强;低温有利于壳聚糖的吸附;在8 h时壳聚糖对Cd²⁺的吸附容量达到最大,而对Pb²⁺的吸附在实验时间内是随着吸附时间的延长而增大;随着壳聚糖添加量的增加,其对Cd²⁺和Pb²⁺的吸附能力也增强;初始金属离子浓度的变化对Cd²⁺的影响不大,而在高的金属浓度下对Pb²⁺的吸附率显著降低。壳聚糖对Cd²⁺、Pb²⁺的吸附动力学和热力学分别符合Lagergren方程二级吸附模型和Langmuir吸附方程。研究表明,壳聚糖对不同金属离子的吸附能力不同,在单一金属溶液中,壳聚糖对Cd²⁺的吸附能力要强于对Pb²⁺的吸附能力。系统地研究了壳聚糖对Cd²⁺和Pb²⁺的吸附条件及性能,为壳聚糖作为重金属吸附剂的应用提供理论依据。     

壳聚糖负载纳米Fe_2O_3树脂脱除鱼露中的亚硝酸盐

鱼露是传统水产发酵调味品,味道鲜美,但是其中过量的亚硝酸盐影响鱼露的食用安全。实验选用以生物基材料壳聚糖制备的壳聚糖负载纳米Fe_2O_3树脂(NFCR)为吸附剂,研究了该材料吸附鱼露中亚硝酸盐的可能性及对鱼露品质的影响。研究表明,壳聚糖负载纳米Fe_2O_3树脂在pH为4~6、温度为25℃、反应时间为8 h和物料比为1:200时,对鱼露中NO_2~-的吸附效果最佳。树脂静态脱除鱼露中的NO_2~-时,提高澄清度,但色泽稍有降低,对鱼露的理化性质以及常量元素、氨基酸的含量无明显影响;对常量元素如Ca、Na、K、Mg和P等几乎无影响,对微量元素如Fe、Zn、Mn和Cu等有一定量的减少,鱼露中一些有害的金属元素如Pb、Cd、Al和Ni等均有明显的降低趋势。本研究探讨了应用壳聚糖负载纳米Fe_2O_3树脂处理鱼露中亚硝酸盐的可能性,为应用树脂脱除液体类物料中有害成分提供参考。     

3种填料对集装箱循环水养殖废水处理的初步研究

为探讨聚丙烯塑料发泡材料(EPP)、悬浮球填料和海绵填料对集装箱循环水养殖废水中细菌吸附性能的差异,以及3种填料挂膜启动和挂膜成熟后对氨氮(NH_4~+-N)、亚硝酸盐氮(NO_2~--N)和硝酸盐氮(NO_3~--N)的净水效果,以集装箱循环水养殖废水为研究对象,采用自然挂膜的方式进行了为期3个月的试验,并对相关指标进行测定。结果显示:EPP填料对养殖废水中细菌的吸附能力最好,另外两种填料对细菌的吸附能力次之并且差异不显著(P0.05);3种填料自然挂膜成熟的时间分别为21 d、26 d和30 d;各填料挂膜成熟后处理高浓度NH_4~+-N养殖废水时,NH_4~+-N浓度与NO_2~--N浓度之间的关系可以用多项式y=ax~2+bx+c进行拟合,NH_4~+-N浓度与NO_3~--N浓度之间的关系可以用对数式y=aln(x)+b进行拟合。研究表明:EPP填料、悬浮球填料和海绵填料均可作为生物填料用于集装箱循环水养殖系统。     

镍、铜对海带生长及生理指标的影响

为了研究金属离子铜、镍对海带生长及相关生理指标变化的影响,对不同浓度金属离子进行7d的海带室内养殖实验。对其生长情况、金属离子吸附、可溶性糖、蛋白含量、总抗氧化能力、超氧化物歧化酶活性进行测定。结果表明,海带对Cu2+的敏感度高于Ni 2+,在Cu2+的作用下,海带的生长受到明显的抑制作用,出现厚度变薄、甚至腐烂等症状。低浓度的Ni 2+能促进海带可溶性糖的合成,当达到一定浓度时则抑制,Ni 2+对实验藻海带蛋白含量无明显影响。而在对两种金属离子的吸附方面,海带对Cu2+的吸附量远大于对Ni 2+的吸附量。     

中华鳖养殖废水多级综合处理效果研究

为研究养殖废水的生态处理方法,采用化学沉淀(聚丙烯酰胺)、物理过滤(多孔沸石)、生物吸附(美人蕉等)等方法对中华鳖养殖废水进行逐级综合处理,试验结果:养殖废水的化学需氧量(COD)、氨氮(NH+4-N)、总氮(TN)和总磷(TP)的去除率分别达到95%、86.34%、86.9%和82.17%,水体溶氧量(DO)上升到4.95 mg/L,多级综合废水处理系统表现出良好的碳、氮、磷同步脱除性能。结果表明,多级综合废水处理系统可以对温室甲鱼养殖废水进行有效的净化处理。     

羊栖菜干藻作为生物吸附剂用于去除电镀废水中的重金属

藻类作为一种生物吸附剂用于去除水溶液中单种重金属离子,具有较好的效果,但对共存的多种金属离子去除则相对复杂。本实验利用碱预处理后的羊栖菜藻粉作为海藻吸附剂,研究了不同环境条件对其去除电镀废水中重金属离子[Zn（Ⅱ）、Cu（Ⅱ）、Cr（VI）和Ni（Ⅱ）]的影响,并通过电镜观察和红外光谱分析其对重金属离子的吸附机理。结果发现,pH 2时Cr（VI）去除率最高,在pH 6~9时,Cu（Ⅱ）、Zn（Ⅱ）和Ni（Ⅱ）的去除率较高。海藻吸附剂在低剂量（2~4 g/L）投加时,4种重金属的去除率均有不同程度的增加,大于4 g/L时,去除率不再增加。Zn（Ⅱ）和Ni（Ⅱ）的吸附在25 min左右达到平衡,Cr（VI）和Cu（Ⅱ）稍慢;温度对海藻吸附剂去除Cu（Ⅱ）、Zn（Ⅱ）、Cr（VI）和Ni（Ⅱ）的影响并不明显。Langmuir模型能更好地描述海藻吸附剂对4种重金属离子的吸附行为,表明它们属于单分子层吸附,海藻吸附剂对Cr（VI）和Ni（Ⅱ）的最大吸附容量明显高于Cu（Ⅱ）和Zn（Ⅱ）。准二级吸附动力学方程能更好地描述吸附过程,说明吸附方式以化学吸附为主。吸附前后海藻吸附剂的红外光谱分析表明,对重金属的生物吸附主要与羧基有关。研究表明,海藻吸附剂对电镀废水中Cu（Ⅱ）、Zn（Ⅱ）、Cr（VI）和Ni（Ⅱ）都具有一定的去除效果。     

美国研究蟹壳几丁质的另一种用途

美国科瓦利斯俄勒岗大学化学工程师研究蟹壳另一种用途,从废水里回收重金属。研究人员利用几丁质,这原为蟹壳的主要成分,来吸附废水里的重金属。他们研制了一种方法使壳聚糖产生无数个细孔,这些细孔很稳定,比片状的壳聚糖细孔数要多     

甲壳胺和N－亚甲基甲壳胺对贻贝酶解液中氨基酸吸附性研究

报道了甲壳胺（ｃｈｉｔｏｓａｎ）及Ｎ－亚甲基甲壳胺（Ｎ－ｍｅｔｈｙｌｅｎｅｃｈｉｔｏｓａｎ）对贻贝酶解液中各种氨基酸吸附情况。在一定ｐＨ（６．０）及浓度（９４５ｍｇ／ｋｇ）下：（１）甲壳胺对贻贝酶解液中各种氨基酸均有吸附，其中，对Ｔｙｒ，Ｐｈｅ，Ｈｉｓ，Ａｒｇ，Ａｓｐ及Ｇｉｕ的吸附率较高；（２）Ｎ－亚甲基甲壳胺对贻贝酶解液中Ｈｉｓ，Ａｒｇ，Ｔｙｒ，Ｉｌｅｕ，Ｍｅｔ及Ｌｙｓ吸附率较高：（３）甲壳胺和Ｎ－亚甲基甲壳胺对贻贝酶解液中总氨基酸的吸附率分别为１２．９４％和１１．７０％。     

Optimization of chitosan flocculation for phytoplankton removal in shrimp culture ponds

The removal of phytoplankton cells from aquaculture systems generally results in the reduction of nitrogenous waste and improves water quality. With this study, the effects of chitosan concentration, environmental condition and pH adjustment on flocculation of phytoplankton in marine shrimp (Litopenaeus vannamei) culture tanks were investigated. The remaining phytoplankton and suspended solids in the system were indicators for evaluating the efficiency of chitosan on flocculation. The results indicate that the flocculation efficiency of chitosan was highest (>85%) and remained fairly constant at a chitosan concentration of 40–80 mg L^?1 and a pH range of 7–9 after chitosan addition. With this novel technique including 40 mg L^?1 chitosan addition, pH adjustment to 6.5 and then to 8.5, high efficiency and consistency of flocculation were achieved. This technique could also be applied with various water alkalinity up to 400 mg CaCO₃ L^?1. The experiment for phytoplankton removal by chitosan flocculation in the recirculating aquaculture system showed that flocculation efficiency remained constant even though flocculation was repeated several times.     

Optimization of chitosan flocculation for phytoplankton removal in shrimp culture ponds

The removal of phytoplankton cells from aquaculture systems generally results in the reduction of nitrogenous waste and improves water quality. With this study, the effects of chitosan concentration, environmental condition and pH adjustment on flocculation of phytoplankton in marine shrimp (Litopenaeus vannamei) culture tanks were investigated. The remaining phytoplankton and suspended solids in the system were indicators for evaluating the efficiency of chitosan on flocculation. The results indicate that the flocculation efficiency of chitosan was highest (>85%) and remained fairly constant at a chitosan concentration of 40–80 mg L⁻¹ and a pH range of 7–9 after chitosan addition. With this novel technique including 40 mg L⁻¹ chitosan addition, pH adjustment to 6.5 and then to 8.5, high efficiency and consistency of flocculation were achieved. This technique could also be applied with various water alkalinity up to 400 mg CaCO₃ L⁻¹. The experiment for phytoplankton removal by chitosan flocculation in the recirculating aquaculture system showed that flocculation efficiency remained constant even though flocculation was repeated several times.     

Application of dietary supplements (synbiotics and probiotics in combination with plant products and β‐glucans) in aquaculture

This review addresses the dietary supplements, synbiotics and probiotics in combination with plant products or yeast/β‐glucans in aquaculture. The potential applications of synbiotics have a relatively short history in aquaculture, but have generated interest because of numerous benefits reported in endothermic animals. Since the first study was published by (Aquaculture Science in 2009) the concept has been used in aquaculture to reveal effects on growth performance, gut microbiota, gut histology, immune parameters, haematological and biochemical parameters as well as increased disease resistance. However, a limited number of probiotic bacteria (mainly Bacillus and Enterococcus) and prebiotics (mannan oligosaccharides, fructooligosaccharides, short‐chain fructooligosaccharides, galactooligosaccharides, arabinoxylan–oligosaccharides, isomaltooligosaccharide, chitosan oligosaccharide and inulin) have been used. Additionally, some studies have used plant products or yeast/β‐glucans in combination with probiotics, and these studies suggested that these dietary supplements promote growth performance and boost some immune parameters. The present review identifies evaluations of gut microbiota and gut morphology, and mucosal immune response as significant gaps in existing knowledge and suggests issues that merit further investigations to conclude the potential of dietary supplements in aquaculture.     

饲料源Cu(Ⅱ)在生物絮团水产养殖系统中的积累及其对氨氧化的影响

为提高生物絮团技术的安全性,试验探究硝化型生物絮团水产养殖系统中饲料源铜Cu(Ⅱ)的积累情况和Cu(Ⅱ)对生物絮团氨氧化的影响.通过对生物絮团养殖系统中的水体铜Cu(Ⅱ)和絮团中Cu(Ⅱ)含量进行测定.结果显示:养殖系统中水体Cu(Ⅱ)含量随着饲料投喂而不断上升,在投喂91 d后达到(18.34±0.77)μg/L,絮...     

Preparation and characterization of water-soluble chitosan produced by Maillard reaction

ABSTRACT:   The objective of this research was to improve the solubility of chitosan by Maillard reaction with 1% chitosan and 2% reducing sugar (glucose or glucosamine) dissolved in 0.2 M acetic acid, which was adjusted to pH 6.0, and incubated at either 50°C or 70°C for 1–7 days. The physicochemical and rheological properties of the chitosan–saccharide derivatives were also investigated. Results indicated that the solubility of modified chitosan derivatives was significantly greater than that of native chitosan. The solubility of chitosan–glucosamine was higher than that of chitosan–glucose, and the chitosan–glucosamine derivative remained soluble at pH 10. The degree of deacetylation of the derivatives decreased with increasing reaction time. Rheological investigation revealed that the apparent viscosity of the water-soluble chitosan derivatives in aqueous solution depended upon system conditions such as pH, ionic strength, and solution temperature. The measured apparent viscosity decreased as all system conditions increased. As calculated by the Arrhenius equation, the activation energy ( E _a ) of the derivatives in aqueous solution generally decreased with increasing the extent of Maillard reaction with respect to the reducing sugars used.     

Chitosan as a wall material for a microencapsulated delivery system for Macrobrachium rosenbergii (de Man) larvae

Chitosan has been widely accepted as a wall material for preparing microcapsules of various purposes in human medicine. The possibility of using chitosan as a wall material for microencapsulating nutrients and drugs for aquaculture purposes, specifically to Macrobrachium rosenbergii larvae was evaluated in this study. Two types of chitosan-coated microcapsules were prepared using either acetone (MEC-A) or NaOH (MEC-N) as the cross-linking agents. They were compared with a microbound diet relative to total leaching of nutrients and free amino acids (FAA). Among the microcapsules, MEC-N showed the lowest level of total leaching of nutrients (23.3%) during 5 h of immersion in seawater and released 65% FAA after 60 min. During laboratory trials, 75% larvae had accepted the MEC-N capsule. The results of the study suggest that chitosan can be used as a wall material for preparing microcapsules to deliver drugs and nutrients to M. rosenbergii larvae.     

玻璃钢水槽内大黄鱼养殖环境噪声测量与分析

利用水下声音测量系统,分别记录了开放式圆形玻璃钢水槽内养殖环境噪声和大黄鱼(Larimichthys crocea)摄食过程声音,并进行声压级(sound pressure levels,SPL)计算和频谱特征分析。结果表明:(1)养殖环境噪声SPL约为110.27 d B(d B re:1μPa),包括主频率峰值为100 Hz的养殖工作设备与水槽内壁的低频共振噪声、1 250 Hz的表层水体气泡噪声、1 600~2 500 Hz的曝气石、增氧机、空气压缩机工作噪声;(2)增氧机和曝气关闭时,大黄鱼摄食过程声音SPL约为92.65 d B,高于背景噪声SPL,主要为游泳声音70~500Hz、吞食产生的水体表面搅动与气泡破裂的声音1 000~2 000 Hz、咀嚼颗粒饵料声音2 000~4 500 Hz;(3)增氧机和曝气开启时,背景噪声SPL略高于摄食声音约17.62 d B,且摄食声音无法区别于背景噪声,但并未影响鱼类摄食行为。     

Occurrence of heavy metals in the sediments of Uranouchi Inlet,Kochi prefecture,Japan

The present status of contamination by heavy metals, and the impact of cage culture on sediments at the Uranouchi Inlet, Kochi Prefecture, Japan, were investigated from two stations influenced by intensive aquaculture and a control station, during May–July 2006. The moisture content of the sediments at the aquaculture stations was over 65%, and the organic matter was always over 100 mg/g dry wt. In contrast, the highest moisture content and organic matter at the control station was 45.5% and 62.9 mg/g dry wt, respectively. Concentrations of zinc (Zn) (178 ± 4.8 mg/kg dry wt) and copper (Cu) (125 ± 1.2 mg/kg dry wt) were highest at the aquaculture stations. Lead (Pb) was highest (50.7 ± 0.77 mg/kg dry wt) at the aquaculture station though it was as high as 33.2 ± 0.77 mg/kg dry wt at the control station. One-way ANOVA showed that the differences in concentrations of Zn and Cu in sediments from the aquaculture and control stations were highly significant (P = 0.01), whereas Pb showed no such trend. Occurrence of a large fraction of labile Zn (56.1%) and Cu (40.3%) in these sediments warrants attention. Although factors other than metals may explain the distribution observed, the information presented here may be useful in predicting long-term effects of heavy metal contamination from aquaculture in the marine environment.