改性竹炭脱除贝类酶解液中的重金属镉

以蚶子贝肉酶解液为材料,利用聚天冬氨酸(PAsp)改性的竹炭吸附脱除酶解液中的重金属镉。考察了pH、脱除时间、竹炭投加量和温度对酶解液中镉脱除率的影响,并在单因素试验基础上通过响应面法确定了镉的最佳脱除条件。当pH为5.0、反应时间为25min、竹炭投加量(10m L酶解液)为0.26g,重金属镉的脱除率可达96.59%。研究表明,PAsp改性竹炭能显著提高吸附重金属的效率和能力,可用于脱除蚶子贝肉酶解液中的镉。     

改性稻壳脱除贝类酶解液中的重金属镉

用聚天冬氨酸(PASP)改性碳化稻壳作为吸附剂脱除贝类酶解液中的镉。通过单因素试验研究了pH、脱除时间、稻壳投加量和温度对镉脱除率的影响。使用响应面分析法获得了镉的最佳脱除条件:pH为4. 5,脱除时间为50 min,稻壳投加量为0. 30g。在此条件下镉的理论脱除率可达到94. 39%。实验测得贝类酶解液试样中镉的脱除率为92. 04%(94. 38%。研究表明,PASP改性碳化稻壳能显著提高吸附镉的效率和能力,可用于脱除贝类酶解液中的重金属镉。     

大孔树脂脱除中药水煎液中铅、镉和铜的研究

为探讨D001、D113和D7513种大孔树脂对葛根、毛冬青、乌药和苦参4种中药水煎液中模拟超标的铅、铜和镉离子的脱除效果,将中药水提取液经浓硝酸消化后,采用原子吸收光谱法测定了中药水煎液经大孔树脂处理前后铅、铜和镉的质量浓度变化。结果表明,4种中药水煎液经3种大孔树脂处理后,铅、铜和镉含量都普遍降低。可认为D001、D113与D751都能够显著脱除4种中药水提取液中的铅、铜和镉,尤其对镉的脱除效果最好,对铜的脱除效果相对较差,但脱除率都在58.9%以上;大孔螯合树脂D751的脱除效果最好。     

聚丙二醇-硫酸铵双水相萃取银杏黄酮

研究了银杏叶黄酮在聚丙二醇(PPG)400-(NH_4)_2SO_4双水相体系中的分配情况。探讨了单因素p H、PPG400质量分数、(NH_4)_2SO_4质量分数、料液比、温度、萃取时间对萃取率(Y%)和分配系数(K)的影响,并通过正交试验进一步优化双水相萃取条件。结果表明,各个因素对Y%和K影响为PPG400质量分数pH(NH_4)_2SO_4质量分数萃取时间萃取温度料液比。最佳萃取条件为p H 6、PPG400质量分数25%、(NH_4)_2SO_4质量分数15%、料液比1∶15、萃取温度40℃、萃取时间60min,黄酮萃取率达到98%以上。PPG400-(NH_4)_2SO_4双水相体系对银杏叶黄酮有较好的萃取效果。     

顺序注射-氢化物发生-原子荧光光谱法测定马氏珠母贝中镉的含量

镉是对人体有害的重金属元素之一,是慢性蓄积性毒物,对肾脏、骨骼、肺、肝、神经系统以及血液系统均可产生毒性,并且具有致癌、致畸和致突变的作用[1]。随着现代工业化的迅猛发展,海洋环境特别是贝类的生长环境受到重金属的污染日益严重。而贝类是具有很强富集能力的滤食性底栖生物,使到其体内重金属镉含量极易超标[2]。马氏珠母贝又名合浦珠母贝,是我国南方海水珍珠养殖的主要品种,主要分布在广东、广西和海南三省。其贝肉是一     

离子交换法提取磷矿硝解液中稀土元素的影响因素研究

实验研究了001*7阳离子交换树脂对贵州省织金县含稀土磷矿的硝酸溶解液中稀土元素的提取情况,并采用正交实验法对EDTA的浓度、EDTA的p H、交换时间、淋洗时间等因素对提取稀土元素的影响进行研究。实验结果表明:正交实验条件下吸附率:最低31.3%,最高84.48%;淋洗率:最低31.58%,最高51.06%;最优实验条件为:酸解液p H=0.9,淋洗剂p H=10,EDTA浓度为0.04,交换时间为70 min,淋洗时间为40 min;最优条件下的吸附率35.53%(一次吸附),淋洗率82.56%(一次淋洗)。     

中空纤维分散液膜富集稀土元素

采用2-乙基己基膦酸单-2-乙基己基酯(HEHEHP)-正庚烷为萃取剂,盐酸为反萃取剂,中空纤维膜作支撑膜,研究中空纤维分散液膜技术富集稀土镱(Yb~(3+))离子。考察了体系物性:反萃分散相中反萃剂浓度、萃取剂浓度、萃取剂与反萃剂体积比、料液相p H值、稀土离子浓度;流体流动状态:反萃分散相与料液相流速变化等因素对富集稀土离子的影响。中空纤维分散液膜富集Yb~(3+)的最佳条件为:萃取剂浓度为0.25 mol/L,反萃取剂HCl浓度为4.00 mol/L,萃取剂与反萃剂体积比为10∶40,料液相p H=2.80,稀土离子浓度为0.025 mol/L。反萃分散相体积流量和料液相体积流量较小时,萃取率随流量的增加呈现逐渐增大的趋势。若两相体积流量过大,反萃过程进行不完全,萃取率反而下降。研究结果表明,中空纤维分散液膜技术可实现稀土离子的有效富集。     

NH_4HCO_3沉淀分离还原反萃余液中的稀土与锌工艺研究

在还原萃取分离铕的反萃余液中加入NH_4Cl,用固体NH_4HCO_3与稀土反应生成碳酸稀土沉淀,而Zn与NH_4Cl形成配合物存在于母液中,实现反萃余液中稀土和锌的分离。考察了料液中NH_4Cl,RECl_3,Zn Cl_2浓度、沉淀终点p H和沉淀反应温度这些因素对碳酸稀土中Zn O含量的影响。实验结果表明:在料液中NH_4Cl浓度4 mol·L~(-1),RECl_3浓度0.34 mol·L~(-1),Zn Cl_2浓度不大于0.62 mol·L~(-1),反应温度50℃,沉淀终点p H为6.5条件下,得到的碳酸稀土中Zn O含量小于0.005%。     

改性木质素磺酸钠水凝胶对镉离子的吸附研究

研究了改性木质素磺酸钠水凝胶对水溶液中镉离子的吸附性能,考察了吸附时间、溶液p H值、温度及镉离子初始浓度对吸附的影响。实验结果表明,改性木质素磺酸钠水凝胶对镉离子的平衡吸附量随着温度的上升而增加;p H值小于7时,镉离子的平衡吸附量随着p H值的增加而增大;p H值等于7时,镉离子的平衡吸附量最大。在室温下,p H值为7的水溶液中,该水凝胶对镉离子的平衡吸附量随着镉离子浓度的增加而增大,最大可达到225.2mg/g;吸附过程满足准二级动力学方程,并能较好地符合Langmuir等温吸附模型。     

萃取液浓度对火焰原子吸收光谱法测定日用陶瓷铅、镉溶出量的影响研究

采用火焰原子吸收光谱法测定日用陶瓷的铅、镉溶出量和标准曲线,通过对不同浓度的萃取液及其稀释液在各自相应的标准曲线条件下进行重金属溶出量检测,运用单因素多水平方差分析法(F检验)验证结果数据的显著性差异水平,并依据Lambert-Beer定律研究差异形成原因.推导在置信度为95%的条件下,当样品中铅的质量浓度低于80.00 mg/L、镉的质量浓度低于1.000 mg/L时,原始样液与其稀释液的测定结果间无显著性差异.当样液中铅的质量浓度高于100.00 mg/L、镉的质量浓度高于1.000 mg/L时,原始样液与其稀释液测定结果之间的显著性差异程度将随重金属元素浓度升高而加大.     

Quantitative analysis of iron-containing protein myoglobin in different foodstuffs by liquid chromatography coupled to high-resolution inductively coupled plasma mass spectrometry

Quantitative determination was made of the iron-containing protein myoglobin in a range of different foods, including meat, processed meat, fish, and shellfish, by liquid chromatography coupled to a double-focusing sector field inductively coupled plasma mass spectrometry (ICP-MS). The concentration of myoglobin determined in the samples ranged from 0 to 6.5 mg/kg, and the analytical precision (coefficient of variation) for the analysis of 8 replicate raw steak extracts was 2.1%. By using a double-focusing ICP-MS instrument, direct on-line detection of the most abundant iron isotope 56Fe was possible without interference from a major polyatomic interference (40Ar16O). Separation of myoglobin from other iron-containing compounds was facilitated by use of a gel filtration column (TSK Gel G2000SW) and Tris buffer (pH 7.2). The chromatographic column was coupled directly to the nebulizer of the ICP-MS instrument by a short piece of PEEK tubing. To ensure sufficient quality control throughout the study, a raw beefsteak sample was developed as an in-house reference material. The concentration of the heme-iron-containing protein myoglobin in this sample was determined by the developed method and independently by a conventional spectrophotometric method. The agreement between the 2 analytical techniques was very good. The detection limit (3 times the signal/noise ratio for a blank) of the reported method for myoglobin was 0.85 ng Fe/L.     

聚天冬氨酸与木质素磺酸钠复配物对碳酸钙阻垢性能的研究

通过静态阻垢法研究了国产聚天冬氨酸(PASP)、木质素磺酸钠(SLS)添加量对碳酸钙的阻垢性能.结果表明:PASP在5.0mg/L时阻垢率接近100%,SLS达300mg/L以上时阻垢率趋于平缓,浓度为600mg/L时,其阻垢率仍不足70%.PASP与SLS复合配方及在不同影响因素条件下阻垢性能的研究表明:复合配方(PASP 2.0mg/L SLS 5.0mg/L)的阻垢率接近100%,且适用于高钙、高pH值、高温的水系统中,并可在水系统中长时间停留.     

Biosorption of Cadmium by Phanerochaete Chrysosporium

The biosorption properties of cadmium(Ⅱ) by pre-treated biomass of Phanerochaete chrysosporium in the form of pellet were investigated. It was found that formaldehyde cross-linking and subsequent alkaline treatment could significantly improve the adsorption capacity of the biomass compared to other sorts of treatments, such as calcium chloride treatment, HCl treatment and,acetone treatment. Biosorption capacity of cadmium was examined as a function of physical and chemical factors including the pH of the metal solution pellet size, temperature and biomass concentration. The cadmium removal efficiency was strongly affected by pH. The maximal adsorption occurred around pH4.5. The pellet size also had a marked influence on the cadmium removal efficiency and the optimum size was the diameter range of 1.5-2.0 mm. The effect of biosorption temperature on cadmium uptake was inconspicuous between 25℃ and 35℃, but there was a notable decrease in cadmium uptake when the temperature reached 40℃. The cadmium removal efficiency increased as the biomass concentration when the initial cadmium ion concentration was 10 mg/L. When the biomass concentration was 2 g/L,the removal efficiency was 99.56%. However, the augment of the. removal efficiency was not obvious when the biomass concentration was more than 2 g/L. On the optimum conditions mentioned above,cadmium concentration could be reduced from 10 ppm down to 0.04 ppm that was below the Chinese National Waste Water Integrated Discharge Standard. In the biosotption process, most of the metal uptake happened during a short period immediately after the adsorption process started. It was observed that the biomass pellets had already adsorbed 83.36% of the total amount of cadmium finally adsorbed within the initial 10 minutes. The cadmium uptake rate decreased gradually afterwards. Sorption equilibrium could almost be established in 12 hours. This indicated that biosorption might consist of two processes:a fast surface binding process opcurring first and a slow membrane diffusion process taking place subsequently.     

A mussel tissue certified reference material for multiple phycotoxins. Part 1: design and preparation

The development of multi-analyte methods for lipophilic shellfish toxins based on liquid chromatography–mass spectrometry permits rapid screening and analysis of samples for a wide variety of toxins in a single run. Validated methods and appropriate certified reference materials (CRMs) are required to ensure accuracy of results. CRMs are essential for accurate instrument calibration, for assessing the complete analytical method from sample extraction to data analysis and for verifying trueness. However, CRMs have hitherto only been available for single toxin groups. Production of a CRM containing six major toxin groups was achieved through an international collaboration. Preparation of this material, CRM-FDMT1, drew on information from earlier studies as well as improved methods for isolation of toxins, handling bulk tissues and production of reference materials. Previous investigations of stabilisation techniques indicated freeze-drying to be a suitable procedure for preparation of shellfish toxin reference materials and applicable to a wide range of toxins. CRM-FDMT1 was initially prepared as a bulk wet tissue homogenate containing domoic acid, okadaic acid, dinophysistoxins, azaspiracids, pectenotoxin-2, yessotoxin and 13-desmethylspirolide C. The homogenate was then freeze-dried, milled and bottled in aliquots suitable for distribution and analysis. The moisture content and particle size distribution were measured, and determined to be appropriate. A preliminary toxin analysis of the final material showed a comprehensive toxin profile.     

Performance of Pleurotus ostreatus Mushrooms and Spent Substrate for the Biosorption of Cd(II) From Aqueous Solution

The capacities of Pleurotus ostreatus mushroom and spent substrate were evaluated for the biosorption of cadmium (II) from aqueous solution in order to select the most efficient material for bioremediation. The optimum sorption conditions were optimized, including the pH of the aqueous solution, contact time, biomass dosage, initial metal concentration, and temperature. The sorption of cadmium on both biosorbents was also evaluated by several kinetic, equilibrium, and thermodynamic models. The possible heavy metal biosorption mechanisms were evaluated through point of zero charge (pH_pzc), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX). Based on the results of column studies, the effectiveness of the P. ostreatus spent substrate was confirmed as a biosorbent for Cd(II) removal from aqueous solutions.     

Micellar-enhanced ultrafiltration of cadmium ions with anionic–nonionic surfactants

Micellar-enhanced ultrafiltration (MEUF), a surfactant-based separation process, is promising in removing multivalent metal ions from aqueous solutions. The micellar-enhanced ultrafiltration of cadmium from aqueous solution was studied in systems of anionic surfactant and mixed anionic/nonionic surfactants. The micelle sizes and zeta potentials were investigated by dynamic light scattering measurements. The effects of feed surfactant concentration, cadmium concentration and the molar ratio of nonionic surfactants to sodium dodecyl sulfate (SDS) on the cadmium removal efficiency, the rejection of SDS and nonionic surfactants and the permeate flux were investigated. The rejection efficiencies of cadmium in the MEUF operation were enhanced with higher SDS concentration and moderate Cd concentration. When SDS concentration was fixed at 3 mM, the optimal ranges of the molar ratios of nonionic surfactants to SDS for the removal of cadmium were 0.4–0.7 for Brij 35 and 0.5–0.7 for Triton X-100, respectively. With the addition of nonionic surfactants, the SDS dosage and the SDS concentration in the permeate were reduced efficiently.     

Determination of Cadmium and Lead in Human Teeth Samples Using Dispersive Liquid‐liquid Microextraction and Graphite Furnace Atomic Absorption Spectrometry

A new method for the determination of cadmium and lead in human teeth was developed based on dispersive liquid‐liquid microextraction preconcentration and graphite furnace atomic absorption spectrometry determination. In the proposed approach, O,O‐diethyldithiophosphate (DDTP) was used as a chelating agent, and carbon tetrachloride and methanol were selected as extraction and dispersive solvents. Some factors influencing the extraction efficiency of cadmium and lead and their subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent and extraction time, were studied and optimized. Under the optimum conditions, the enrichment factor of 116 and 68 for cadmium and lead were achieved. The detection limit for cadmium and lead was 5.6 and 45 ng L^?1, and the relative standard deviation (R.S.D) was 4.5% and 3.8% (n = 7, c = 1.0 ng mL^?1), respectively. Verification of the accuracy of the method was carried out by analysis of a standard reference material (NIST 1486, bone meal). The method was successfully applied to the determination of trace amount of cadmium and lead in human teeth samples with satisfactory results.     

Effect of operating parameters on selective separation of heavy metals from binary mixtures via polymer enhanced ultrafiltration

Performance of continuous polymer enhanced ultrafiltration (PEUF) method was investigated for removal of mercury and cadmium from binary mixtures. This method includes the addition of polyethyleneimine (PEI) as a water soluble polymer to bind the metals, which was followed by ultrafiltration operation performed on both laboratory and pilot scale systems. The influence of various operating parameters such as temperature, metal/polymer ratio, presence of calcium ions and pH on retention of metals and permeate flux was investigated. To investigate the possibility of selective separation of mercury and cadmium, experiments were conducted for binary solutions at different pH and loading ratios. It was seen that the retention of mercury decreased and permeate flux increased when the temperature increased. The increased pH and decreased metal/polymer ratio, loading (L), resulted in higher retention of both metals. Shapes of retention vs. pH or L curves were very similar for both metals. Retentions stay almost constant at a value very close to unity until a critical L or pH value was reached, then, R decreases almost linearly with L or pH. However, retention of cadmium was affected more than that of mercury as the pH decreased and L increased. This leads to the selective separation of mercury and cadmium. At low pH values (about 5) and at high L values (about 0.3), mercury was removed by ultrafiltration operation while almost all cadmium passed through the membrane. At pH 5.5 and cadmium/polymer ratio about 0.35 and mercury/polymer ratio about 0.39, the highest separation factor was obtained as 49.     

Removal of Cobalt Ions from Aqueous Solution by Adsorption onto Cross-Linked Calcium Alginate Beads

The removal of cobalt ions from dilute aqueous solutions using cross linked calcium alginate beads as the adsorbent is reported in this article. The influence of various experimental parameters such as pH, initial metal ion concentration, contact time and solid to liquid ratio were studied. The adsorption data were applied to Langmuir and Freundlich isotherm equations and various static parameters were calculated. It was observed that the uptake of cobalt ions was found to increase with time and that maximum adsorption was obtained within the first 60 minutes of the process. These results indicate that the cross linked calcium alginate beads have potential for removing cobalt ions from industrial waste water.