淀粉改性重金属螯合絮凝剂ISXA的制备及性能研究

将具有螯合功能的黄原酸基和酰胺基接枝到交联淀粉分子结构中,制备了高分子重金属螯合絮凝剂ISXA。通过单因素试验和正交试验获得了ISXA的最佳制备条件为:淀粉交联阶段,环氧氯丙烷与淀粉质量比为1.2∶10,反应温度为40℃,p H值为10;黄原酸化阶段,CS2与淀粉质量比为6.3∶10,反应温度为35℃,p H值为11;丙烯酰胺(AM)接枝阶段,AM与淀粉质量比为1.5∶10,反应温度为45℃,p H值为5。经FTIR、元素分析,ISXA具有黄原酸基及酰胺基结构。对Cu2+的螯合絮凝试验结果表明,ISXA在在弱酸性下有很好的捕集沉淀效果,p H值为6时,对于Cu2+质量浓度分别为5、20和50 mg/L的溶液,ISXA的投加量分别为24、90及200mg/L,Cu2+去除率可达99%。絮体颗粒密实,在不同p H值下沉降性能良好。黄原酸基中的硫原子与Cu2+发生配位反应而形成ISXA-Cu螯合沉淀物,吸附架桥和网扫卷捕是ISXA絮凝反应的主要机理。     

Water adsorption in metal–organic frameworks with open‐metal sites

H₂O adsorptions inside porous materials, including silica zeolites, zeolite imidazolate frameworks, and metal–organic frameworks (MOFs) using molecular simulations with different water models are investigated. Due to the existence of coordinately unsaturated metal sites, the predicted adsorption properties in M‐MOF‐74 (M = Mg, Ni, Co, Zn) and Cu‐BTC are found to be greatly sensitive to the adopted H₂O models. Surprisingly, the analysis of the orientations of H₂O minimum energy configuration in these materials show that three‐site H₂O models predict an unusual perpendicular angle of H₂O plane with respect to the Metal‐O₄ plane, whereas those models with more than three sites give a more parallel angle that is in better agreement with the one obtained from density functional theory (DFT) calculations. In addition, the use of these commonly used models estimates the binding energies with the values lower than the ones computed by DFT ranging from 15 to 40%. To correct adsorption energies, simple approach to adjust metal‐O(H₂O) sigma parameters to reproduce the DFT‐calculated binding energies is used. With the refined parameters, the computed water isotherms inside Mg‐MOF‐74 and Cu‐BTC are in reasonable agreement with experimental data, and provide significant improvement compared to the predictions made by the original models. Further, a detailed inspection on the water configurations at higher‐pressure region was also made, and observed that there is an interesting two‐layer water network formed using three‐ and four‐site models. © 2014 American Institute of Chemical Engineers AIChE J, 61: 677–687, 2015     

淀粉/二氧化硅微球对水中重金属离子的吸附性能

利用土豆淀粉、玉米淀粉、正硅酸乙酯为原料,氨水为催化剂,通过溶胶-凝胶法制备了淀粉/二氧化硅复合微球,研究了该复合微球对水中铅离子的吸附性能。结果表明,在弱碱性条件下,淀粉/二氧化硅复合微球对水中铅离子表现出良好的吸附性能,其对铅离子的吸附行为符合Langmuir模型和Freundlich模型,对铅离子的饱和吸附量为31.34 mg/g。动力学研究表明,淀粉/二氧化硅复合微球对铅离子的吸附符合拟二级动力学模型,在淀粉/二氧化硅复合微球的活性点上的化学反应为吸附控制步骤。     

Dynamic adsorption behaviors between Cu2+ ion and water‐insoluble amphoteric starch in aqueous solutions

Dynamic adsorption behavior between Cu²⁺ ion and water‐insoluble amphoteric starch was investigated. The sorption process occurs in two stages: external mass transport occurs in the early stage and intraparticle diffusion occurs in the long‐term stage. The diffusion rate of Cu²⁺ ion in both stages is concentration dependent. In the external mass‐transport process, the diffusion coefficient (D₁) increases with increasing initial concentration in the low‐ (1 × 10^?3‐4 × 10^?3M) and high‐concentration regions (6 × 10^?3‐10 × 10^?3M). The values of adsorption activation energy (k_d1) in the low‐ and high‐concentration regions are 15.46–24.67 and ?1.80 to ?11.57 kJ/mol, respectively. In the intraparticle diffusion process, the diffusion coefficient (D₂) increases with increasing initial concentration in the low‐concentration region (1 × 10^?3‐2 × 10^?3M) and decreases with increasing initial concentration in the high‐concentration region (4 × 10^?3‐10 × 10^?3M). The k_d2 values in the low‐ and high‐concentration regions are 9.96–15.30 and ?15.53 to ?10.71 kJ/mol, respectively. These results indicate that the diffusion process is endothermic in the low‐concentration region and is exothermic in the high‐concentration region for both stages. The external mass‐transport process is more concentration dependent than the intraparticle diffusion process in the high‐concentration region, and the dependence of concentration for both processes is about equal in the low‐concentration region. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2849–2855, 2001     

Saccharification of modified starch to maltose in a semi-continuous counter-current chromatographic reactor–separator (SCCR–S)

Combined bioreaction and separation has been successfully carried out in a Simulated Counter-Current Chromatographic Reactor–Separator (SCCR–S) system for the saccharification of modified starch to maltose and dextrin. The effects of the operating parameters (switch time, eluent flowrate, feed concentration and enzyme activity) on the performance of the SCCR–S system were investigated. By using an eluent of dilute enzyme solution, starch conversions of up to 60% were achieved using lower amounts of enzyme than the theoretical amount required by a conventional bioreactor to produce the same amount of maltose over the same time period. Comparing the SCCR–S system with a continuous rotating annular chromatograph (CRAC) for the saccharification of modified starch showed that the SCCR–S system required only 34·6–47·3% of the amount of enzyme required by the CRAC, system.     

电镀废水中重金属处理技术研究现状与发展

电镀废水中大量的高浓度重金属离子,对生态环境和人类健康造成了极大的危害。本文全面综述了电镀废水中重金属离子的危害、重金属离子种类和各种方法的原理、优缺点和发展趋势。可以为电镀废水中重金属离子工程治理、科学研究提供一定的参考。     

水质分析中重金属检测技术

水是人类和生物生存的不可或缺的基础之一,同时水也是现代产业运行的基本载体之一。随着我国经济的不断发展和物质生活水平不断的提高,用水量也在不断的提高,但是,我国用水是属于粗放型的运用,绝大部分水源并没有得到高效的利用,水资源往往被污染的很严重进而成为污染水质。这和我国建设成为现代化富强美丽的发达国家的初衷相违背。随着工农业的高速发展,我国经济不断腾飞,但同时也由于过度粗放型开发造成了一系列负面效应。基于此类情况,加快对重金属的检测分析是保证我国能够完好的执行监督和治理水污染的基础,同时也是改善水质的重中之重。根据国内外水质重金属检测技术的分析应用进行系统的阐述和分析,为今后水质污染和重金属的检测提供强有力的数据支持和理论支撑。     

多羟基结构态亚铁处理含重金属废水的应用

结构态亚铁是一种具有高活性结构的亚铁化合物,具有比表面积大、还原性强等优点,被广泛应用于研究处理重金属废水和有机废水.然而,目前结构态亚铁处理含高浓度重金属的实际工业废水的重金属去除效果、作用条件、处理工艺还缺乏深入探究.文中选取3种具有代表性的实际工业废水,探究结构态亚铁对废水中重金属的去除效果,设计能够满足排放要求...     

微波消解-电感耦合等离子体质谱法测试烟用香精及料液中6项重金属

采用硝酸-过氧化氢消解体系,微波消解烟用香精及料液,后采用电感耦合等离子体质谱仪对铅、镉、铬、镍、砷、汞进行测试。该方法各元素相对标准偏差1.3%～8.5%,检出限0.091～0.305 ug/L,加标回收率82.4%～103.5%。该方法简单、快速、灵敏性、准确度好,适用于烟用香精及料液中6种痕量重金属元素的定量分析。     

The selectivity and activity determining roles of carbonaceous species and metal–metal oxide interface in metal-catalyzed hydrogenation and isomerization reactions

The activity and/or selectivity determining roles of carbonaceous deposits of various kinds and metal–metal oxide interfaces are described in metal-catalyzed hydrogenation and isomerization reactions. The catalysts used were silica-supported Pt, Pd, Rh, Ni and Cu, while a wide range of probe molecules (cyclopropane, 1,1-dimethylcyclopropane, propylcyclobutane, methyloxirane, 2-methyl-2-butene, cyclohexene) were tested, in most cases, in the presence of H₂ or D₂. The properties of catalytic surfaces were studied by infrared spectroscopy and kinetic methods in static or flow reactors. Six treatment or reaction types were applied for learning about surface transformations during or after the reaction. Carbonaceous deposits of various kinds were identified and their reaction influencing properties are analyzed. Metal–metal oxide interfaces are found to be crucial in the hydrogenative ring opening of methyloxirane and the roles of the metal and the metal oxide are elucidated as well.     

土壤重金属含量变化预测模式在环境影响评价中的应用

以广西某铅锌冶炼企业厂区周边土壤中的重金属为研究对象,采用土壤重金属累积模式预测由大气沉降至土壤中的重金属年变化趋势。根据预测结果,锌、铅最大累积贡献值点在项目投产20年后均满足《土壤环境质量标准》(GB15618-1995)二级标准的要求。     

Adsorption of Heavy Metals from Aqueous Solutions onto Activated Carbon in Single Cu and Ni Systems and in Binary Cu–Ni,Cu–Cd and Cu–Zn Systems

Single copper and nickel adsorption from aqueous solutions onto a granular activated carbon is reported. Metal removals increase on raising pH and temperature, and decrease on raising the initial metal concentration at constant carbon dose. The adsorption processes are modelled using the surface complex formation (SCF) Triple Layer Model (TLM) with an overall surface bidentate species. A dependence of the SCF constant on pH, initial molar metal/carbon ratio and temperature is observed, and a correlation for log K_ads is determined. The SCF model successfully predicts copper and nickel removals in single metal solutions. Adsorption in the binary metal systems copper–nickel, copper–cadmium and copper–zinc is also reported, showing competitive adsorption effects. © 1997 SCI.     

Synthesis and characterization of cellulose ion exchanger. II. Pilot scale and utilization in dye–heavy metal removal

Cotton fabric was converted into an ion exchanger by grafting it with (1) glycidyl methacrylate (GMA), followed by aminization with ethylene diamine; (2) dimethylaminoethyl methacrylate (DMAEMA), followed by quaternization; and (3) acrylic acid (AA). Grafting was carried out on a pilot scale using a thiocarbonate–H₂O₂ redox system. The so-obtained cotton graft copolymers were monitored for their ability to remove different dyes as well as heavy metals from aqueous solutions. It was found that the magnitude of dye exhaustion was as follows. For direct and reactive dyes the percentage of exhaustion follows the order of aminized GMA > quaternarized DMAEMA > DMAEMA, whereas for acid dye the percentage of exhaustion follows the order of quaternarized DMAEMA > DMAEMA > aminized GMA. On the other hand poly(AA)–cotton copolymer is very effective at removal of the basic dye. With respect to heavy metal ions removal, the copolymers show the following order: AA > aminized GMA > quaternarized DMAEMA > DMAEMA. While dichromate removal follows the order of quaternarized DMAEMA > DMAEMA > aminized GMA. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2151–2157, 1998     

Mass transport process for the adsorption of Cr(VI) onto water‐insoluble cationic starch synthetic polymers in aqueous systems

Dynamic adsorption behaviors between Cr(VI) ion and water‐insoluble amphoteric starches was investigated. It was found that the HCrO ion predominates over the initial pH ∼ 2–4, the CrO ion predominates over the initial pH ∼ 10–12, and both ions coexist over the initial pH ∼ 6–8. The sorption process occurs in two stages: the external mass transport process occurs in the early stage and the intraparticle diffusion process occurs in the long‐term stage. The diffusion coefficient of the early stage (D₁) is larger than that of the long‐term stage (D₂) for the initial pH 4 and pH 10. The diffusion rate of HCrO ion is faster than that of CrO ion for both processes. The D₁ and D₂ values are ∼ 1.38 × 10⁻⁷–10.1 × 10⁻⁷ and ∼ 0.41 × 10⁻⁷–1.60 × 10⁻⁷ cm² s⁻¹, respectively. The ion diffusion rate in both processes is concentration dependent and decreases with increasing initial concentration. The diffusion rate of HCrO ion is more concentration dependent than that of CrO ion for the external mass transport process. In the intraparticle diffusion process, the concentration dependence of the diffusion rate of HCrO and CrO ions is about the same. The external mass transport and intraparticle diffusion processes are endothermic and exothermic, respectively, for the initial pH 4 and pH 10. The k_d values of the external mass transport and intraparticle diffusion processes are ∼ 15.20–30.45 and ∼ −3.53 to −12.67 kJ mol⁻¹, respectively. The diffusion rate of HCrO ion is more temperature dependent than that of CrO ion for both processes. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2409–2418, 1999     

ICP-AES法测定PVC塑钢门窗中的重金属元素

采用微波消解制样技术,用电感耦合等离子体发射光谱(ICP-AES)法测定聚氯乙烯(PVC)塑钢门窗中的Pb、Zn、Ti、Cu等重金属元素含量,确定了实验的最佳测定条件。结果表明:方法的检出限为0.01840～1.034μg/mL,回收率为94.23%～103.5%,相对标准偏差在4.6%以内。该方法灵敏度高、准确、快速,可满足PVC塑钢门窗中金属元素的常规测定。     

Evidence of strong metal–oxide interactions in promoted Rh/SiO2 on CO hydrogenation: Analysis at the site level using SSITKA

It has been suggested that the behavior of Group VIII metal catalysts supported on transition metal oxides can be significantly affected by pretreatment conditions due to strong metal–oxide interactions (SMOI). However, the origins for the SMOI effect are still in debate. In this research, SMOI of Rh and vanadium oxide (as a promoter) supported on SiO₂ were studied at the site level for the first time, which provides an insight into the modification of surface properties after high temperature reduction. H₂ chemisorption, Fischer–Tropsch synthesis (FTS), and SSITKA (steady-state isotopic transient kinetic analysis) were used to probe the SMOI effects. The catalytic properties of the catalysts for CO hydrogenation were investigated using a differential fixed bed reactor at 230 °C and 1.8 atm, while for SSITKA, a reaction temperature of 280 °C and an excess of H₂ was used to maximize methane production. The addition of V to Rh/SiO₂ suppresses H₂ chemisorption, and high reduction temperature further decreases H₂ chemisorption on Rh/V/SiO₂ but has little effect on Rh/SiO₂. As reduction temperature increases, the activity for CO hydrogenation on Rh/SiO₂ remains essentially unchanged, but the activity of Rh/V/SiO₂ decreases significantly. SSITKA shows that the concentration of surface reaction intermediates decreases on Rh/V/SiO₂ as the reduction temperature increases, but the activities of the reaction sites increase. The results suggest that Rh being covered by VO_x species is probably the main reason for the decreased overall activity induced by high reduction temperature, but more active sites appear to be formed probably at the Rh–VO_x interface.     

ICP-MS法测定硬聚氯乙烯管材和管件中重金属的研究

采用感应耦合等离子体质谱(ICP-MS)法，对硬聚氯乙烯(PVC-U)饮水管材和管件中痕量重金属元素铅、镉、锡、汞进行了分析.研究了影响测量的各种因素，确定了实验的最佳测定条件。结果表明该方法的检出限为：Pb，0.0028μg/L；Cd，0.0025μg/L；Sn，0.0052μg/；Hg，0.0033μg/L；回收率为96.04％～97.20％，相对标准偏差(RSD)小于2.53％。该方法应用于硬聚氯乙烯饮水管材和管件中痕量铅、镉、锡、汞的测定，简便、快速、准确。     

磷酸锌中重金属对双组分聚氨酯防腐涂料性能的影响

以不同重金属含量的磷酸锌为原料制备双组分聚氨酯防腐涂料,运用傅里叶变换红外光谱仪（FTIR）研究了重金属对双组分聚氨酯防腐涂料固化速率的影响,利用盐雾性能研究了重金属含量对双组分聚氨酯涂料防腐性能的影响。结果表明,磷酸锌中的重金属含量越高,其制备的聚氨酯涂料固化速度越快,耐盐雾性能越差,耐冲击性能越差。     

Organic reagents for removing heavy metals from a 10-34-0 (N-P2O5-K2O) grade fertilizer solution and wet-process phosphoric acid

Fertilizer solutions and wet-process phosphoric acid (WPA) contain heavy metal impurities such as cadmium, zinc, lead, copper, manganese, and chromium. Trisodium trithiocyanuric acid (TMT-15), sodium trithiocarbonate (5% Na₂CS₃), and sodium polythiocarbonate (Thio-Red II) were evaluated as precipitating agents for heavy metals in a 10-34-0 (N-P₂O₅-K₂O) grade fertilizer solution and WPA. A water-insoluble starch xanthate was also evaluated as an adsorbent for the heavy metals in 10-34-0 (N-P₂O₅-K₂O) and WPA. Arsenic (24–99+%), cadmium (36–97+%), copper (98+%), mercury (96+%), lead (83–88+%), and zinc (8–83+%) precipitated from 10-34-0 (N-P₂O₅-K₂O) upon the addition of each organic reagent, while levels of manganese and chromium were unaffected. Mercury (97+%), lead (75+%), cadmium (11–38%), copper (99+%), and chromium (3–35%) precipitated from WPA upon the addition of 5% Na₂CS₃ and Thio-Red II, while precipitation of manganese and zinc was negligible. The water-insoluble starch xanthate adsorbed mercury (96+%), copper (38–98+%), and lead (24–75%) from 10-34-0 (N-P₂O₅-K₂O) and WPA while adsorption of arsenic, cadmium, manganese, chromium, and zinc was negligible.