采用纳米技术开发耐火材料

介绍了采用尖端的纳米技术．探索开发出了耐火材料后代——纳米耐火材料，即以纳米颗粒为核心，由耐火材料颗粒、结合剂等构成纳米结构基质。极少量的纳米结构基质的理化性能成为决定整个耐火材料性能的重要因素，不仅能吸收和缓和因热冲击造成的急剧热膨胀和收缩，而且能防止热应力不均匀分布在耐火材料内部。从而提高了耐火材料的耐剥落性、耐蚀性和抗氧化性等性能。     

纳滤去除水环境中硝酸盐的机理及影响因素

综述了纳滤技术去除水环境中硝酸盐的研究现状。详细介绍了纳滤膜去除硝酸盐的机理(包含道南效应、介电效应和空间位阻效应)并介绍了其截留机理的形成原理。重点介绍了纳滤膜在截留硝酸盐过程中的影响因素(纳滤膜本身性质、压力、温度、盐浓度、pH和磁场等)并详细分析了纳滤膜截留硝酸盐过程中的各个影响因素形成的原因。最后,对纳滤膜的截留机理和影响因素进行了总结。     

纳米材料和纳米技术(续Ⅲ)

<正> 著名诺贝尔奖获得者Feyneman在20世纪60年代曾预言:如果我们对物体微小规模上的排列加以某种控制的话,我们就能使物体得到大量异乎寻常的特性,就会看到材料的性能产生的丰富变化。他所说的材料正是现在所谓的“纳米材料”。我国著名科学家钱学森院士曾说过:“纳米左右和纳米以下的结构将是下一阶段科学技术发展的特     

负载型纳米Fe/Ni材料同步去除水中硝酸盐/磷酸盐

水体的富营养化主要与硝酸盐和磷酸盐有关,但目前的处理方法大多只对其中一种污染物有去除效果。制备的负载型Fe/Ni双金属复合材料(DOW 3N-Fe/Ni)能实现NO_3~-和PO_4~(3-)的同步去除。当NO_3~--N为20 mg/L,PO_4~(3-)-P为1 mg/L时,NO_3~-和PO_4~(3-)的去除率分别可达70%和99%。探讨了DOW 3N-Fe/Ni同步去除NO_3~-和PO_4~(3-)的机理,铁镍金属在还原NO_3~-的过程中被氧化为金属离子或金属氧化物及氢氧化物,并通过Lewis酸碱理论、静电作用及吸附作用去除PO_4~(3-),实现NO_3~-和PO_4~(3-)的同步去除。     

GAC-UF一体化净水柱去除水中硝酸盐氮的研究

在硝酸盐氮浓度5～25 mg/L,pH值在5. 5～8. 5,进水流量75～150 mL/min,颗粒活性炭厚度在100～150 mm的变化条件下,考察了GAC-UF一体化净水柱对水中硝酸盐氮去除的效果,以及活性炭和超滤的协同去除效果。结果表明,随着活性炭厚度、硝酸盐氮浓度的增大,硝酸盐氮的去除率增加;在流量75 mL/min时,pH值为5. 5和8时,硝酸盐氮去除率分别可达25. 21%,23. 01%。协同实验表明,超滤对硝酸盐氮的去除率仅为3. 97%,而活性炭的去除率为14. 55%,但一体化净水柱的去除率达到23. 01%,表明颗粒活性炭和超滤具有协同作用。该装置对硝酸盐氮浓度不超过饮用水标准1. 25倍的原水,经处理后,可达到饮用水标准。     

硝酸盐去除途径浅析

目前研究发现的硝酸盐去除途径包括反硝化、同化作用、异化硝酸盐还原为铵、硫细菌氧化脱氮、厌氧氨氧化和铁细菌化能自养脱氮。硝酸盐负荷超标的淡水系统中,影响这些途径的因素是什么,现有的认识仍然不完整,需要进一步深入研究。     

化学法高效去除废水中硝酸盐的研究

研究利用一种化学脱氮方法，去除废水中高浓度的硝酸盐。其原理为金属物质还原废水中的硝酸盐生成亚硝酸盐，再利用酰胺类物质与亚硝酸盐反应生成氮气。试验表明，用锌和氨基磺酸两种物质与之反应生成氮气，达到去除硝酸盐的目的。结果表明，在停留时间为1．5～2h，反应pH为l及锌与氨基磺酸达到最佳投入比例时，使含硝酸氮的质量浓度为35l～488mg/L的废水达到96％的去除率。     

纳米技术及其在化工行业中应用

纳米技术是兴起的一种全新的技术，也是未来应用最广的技术。简要地概述了纳米材料在各个领域的应用，重点介绍在化工行业中的应用，并指出纳米材料的应用前景。     

生物炭负载纳米零价铁去除硝酸盐作用的研究

为探究生物炭负载纳米零价铁（nZVI/BC）去除水中硝酸盐的机制及其影响因素,采用小麦秸秆为载体制备吸附材料。通过XRD和SEM的表征分析知：铁被成功的负载在生物炭表面,生物炭作为载体分散了纳米零价铁颗粒,并减少了它们的团聚。吸附材料对硝酸盐去除效果的实验研究表明：负载纳米零价铁的小麦秸秆生物炭对硝酸盐的去除效果可达到100%,nZVI/BC氮气选择性为21%;铁炭比（w）为1:2时硝酸盐的去除效果最佳;在偏酸性条件下,氨氮选择性更高,对硝酸盐的去除效果更好;硝酸盐和氨氮去除率会随着硝酸盐初始浓度的升高而逐渐下降。     

SiO_2/CS交联复合吸附剂的制备

研究了对二氧化硅加入壳聚糖(CS)、硅烷,进行改性、冷冻干燥制备气凝胶复合吸附剂,探索对Fe⁽²⁺⁾的吸附特性。吸附等温线符合Langmiur吸附模型,其最大吸附量333.3 mg/g,吸附常数0.75 L/mg。吸附动力学符合二级动力学方程,吸附速率常数1.056 10 g/(mg·min),吸附容量125 mg/g。交联剂和冷冻干燥处理,提高了SiO_2/CS吸附剂的吸附性能。     

Solvent impregnated resins for MTBE removal from aqueous environments

MTBE removal from groundwater is difficult. State-of-the-art processes such as air stripping or adsorption can have significant drawbacks, like high energy consumption, low capacity and low selectivity. This is why the alternative technology of solvent impregnated resins is investigated. The extractant used is 3-iodophenol diluted with propylbenzene. From solids screening and impregnation experiments macroporous polypropylene (MPP) particles appear as a suitable solid support. The MTBE capacity of impregnated MPP is lower than that of a carbonaceous resin, but the selectivity of the SIR between MTBE and humic acid is significantly higher. Solvent impregnated resin (SIR) regeneration can be easily achieved with hot gas.     

改性沸石材料去除水中硝酸盐研究进展

系统总结了改性沸石材料去除水中硝酸盐的主要机理,重点介绍了不同表面活性剂和金属改性沸石材料对硝酸盐的吸附性能和影响因素,进一步分析了改性沸石材料的再生效果,并对改性沸石材料去除硝酸盐的未来发展进行了展望。     

Virus removal from aqueous environments with polyelectrolyte coatings on a polypropylene fleece

The adsorption of viruses from aqueous solution is frequently performed to detect viruses. Charged filtration materials capture viruses via electrostatic interactions, but lack the specificity of biological virus-binding substances like heparin. Herein, we present three methods to immobilize heparin-mimicking, virus-binding polymers to a filter material. Two mussel-inspired approaches are used, based on dopamine or mussel-inspired dendritic polyglycerol, and post-functionalized with a block-copolymer consisting of linear polyglycerol sulfate and amino groups as anchor (lPGS-b-NH₂). As third method, a polymer coating based on lPGS with benzophenone anchor groups is tested (lPGS-b-BPh). All three methods yield dense and stable coatings. A positively charged dye serves as a tool to quantitatively analyze the sulfate content on coated fleece. Especially lPGS-b-BPh is shown to be a dense polymer brush coating with about 0.1 polymer chains per nm². Proteins adsorb to the lPGS coated materials depending on their charge, as shown for lysozyme and human serum albumin. Finally, herpes simplex virus type 1 (HSV-1) and severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) can be removed from solution upon incubation with coated fleece materials by about 90% and 45%, respectively. In summary, the presented techniques may be a useful tool to collect viruses from aqueous environments.     

Adsorption performance of amine functionalized cellulose grafted epichlorohydrin for the removal of nitrate from aqueous solutions

Cellulose grafted epichlorohydrin (Cell-g-E) copolymer was synthesized and functionalization carried out using polyethylenimine (Cell-g-E/PEI). Characterization studies using FTIR, XRD and TGA, confirmed the grafting and functionalization process. Batch adsorption reaction was carried out for removal/recovery of nitrate ions and maximum adsorption capacity was obtained at pH 4.5. Kinetic studies explained pseudo-second-order as the best fit. Isotherm studies conducted at different temperatures revealed applicability of Freundlich isotherm model. Comparative studies proved effectiveness of Cell-g-E/PEI to other reported adsorbents. The adsorption process was spontaneous and exothermic. Batch adsorption/desorption studies for over six cycles showed the repeatability and regeneration capability of the adsorbent.     

Adsorptive removal of nitrate and phosphate anions from aqueous solutions using functionalised SBA‐15: Effects of the organic functional group

Adsorption of nitrate and monovalent phosphate anions from aqueous solutions on mono, di‐ and tri‐ammonium‐functionalised mesoporous SBA‐15 silica was investigated. The adsorbents were prepared via a post‐synthesis grafting method, using either 3‐aminopropyltrimethoxysilane (N‐silane) or [1‐(2‐aminoethyl)‐3‐aminopropyl]trimethoxysilane (NN‐silane) or 1‐[3‐(trimethoxysilyl)‐propyl]‐diethylenetriamine (NNN‐silane), followed by acidification in HCl solution to convert the attached surface amino groups to positively charged ammonium moieties. The nominal loading of amino moieties on the SBA‐15 surface was varied from 5% to 20% as organoalkoxysilane/silica molar ratio. The adsorption experiments were conducted batchwise at room temperature. Results showed that adsorption capacity increased with increasing the concentration of monoammonium groups on the SBA‐15 adsorbent. Nitrate adsorption capacity increased from 0.34 to 0.66 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent while phosphate adsorption capacity increased from 0.34 to 0.63 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent when the molar ratio organoalkoxysilane/silica was varied from 5% to 20%, respectively. Also, for the same organoalkoxysilane/silica molar ratio of 10%, the adsorption capacity increased with the increase of the number of protonated amines in the functional groups. Therefore, maximum adsorption capacities of 0.80, 1.16 and 1.38 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent and 0.72, 0.82 and 1.17 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent were obtained using mono‐, di‐ and triammonium functionalised SBA‐15 adsorbents, respectively. © 2011 Canadian Society for Chemical Engineering     

Study on the phosphate removal from aqueous solution using modified fly ash

In this work the fly ash was modified by sulfuric acid for the removal of phosphate. It was found that modification of fly ash could significantly enhance the phosphate immobilization ability of the fly ash. The specific surface area of the fly ash increased from 8.8 to 32.5 m²/g after treated with sulfuric acid. The modification of the fly ash also resulted in the mobilization of acid-soluble metal ions due to partial or complete dissolution of the metals under the acidic conditions. Both adsorption and precipitation contributed to the removal of phosphate by the modified fly ash but precipitation was a major mechanism of phosphate removal. The experimental results showed that adsorption of phosphate by the modified fly ash was rapid, the removal percentage of phosphate could reach maximum in 5 min. In the range of 5–9, pH did not significantly affect the removal of phosphate and the removal percentage of phosphate increased with the increase of adsorbent dosage. The adsorption of phosphate by the modified fly ash could be described well by Langmuir isotherm equation, the Langmuir constant Q₀ was 9.15 mg g⁻¹. The XRD patterns and the SEM images of modified fly ash after sorption revealed that CaHPO₄·2H₂O was formed in the removal of phosphate. In addition, phosphate also formed precipitate with aluminum and iron.     

高效去除水溶液中重金属离子的氧化石墨烯基材料的综述

综述了氧化石墨烯(graphene oxide,GO)基纳米材料对水溶液中各种重金属离子的优异去除能力的最新研究成果。重点论述了吸附剂的合成,吸附过程特征及相互作用机理,概述了各种环境条件的影响。综述旨在为设计和制造GO基纳米材料提供有用的信息,以消除环境污染管理中废水中的重金属离子。此外,简要概述,并提出了这一鼓舞人心的领域所面临的挑战和前景。     

Accelerated removal of nitrate from aqueous solution by utilizing polyacrylic anion exchange resin with magnetic separation performance

In order to quickly remove nitrate from aqueous solution, a magnetic strong base quaternary ammonium anion exchange resin (MAER) has been successfully designed and synthesized. The physicochemical properties of the MAER as well as its adsorption ones for nitrate removal were investigated in detail. A series of batch experiments were carried out to evaluate the effects of several factors on removal efficiency of nitrate, such as retention time, resin amount and initial nitrate concentration. Compared to the commercial Purolite A300 and D213, the equilibrium time for the adsorption process using MAER was only around 20 min, which is significantly less than that of two ones mentioned. Furthermore, the kinetic process of nitrate sorption on MAER could be well described by both pseudo-first-order and pseudo-second-order models. In addition, the results of batch experiments can be better fitted by the Langmuir and Freundlich adsorption isotherm models. Most importantly, the effects of competing ions on nitrate removal followed the order as: SO₄²⁻ > Cl⁻ > HCO₃⁻. These results are of significance in guiding the development of novel resins with the rapid nitrate removal rate from aqueous solution, which would improve efficiency and save energy greatly.     

Heavy metal ions removal from wastewater using electrocoagulation processes: A comprehensive review

A vast number of publications have investigated the application of electrocoagulation (EC) process in heavy metal ions removal from wastewaters. Most of these studies were simple lab-scale using synthetic wastewater with the absence of holistic and systematic approach to consider the process complexity. This comprehensive review considers the fundamental aspects of EC processes such as mechanisms, kinetic models, and isotherm models used by different researchers. Furthermore, the impact of the main design and process operational parameters on the removal efficiency is discussed and analyzed. Many concluding remarks and perspectives are stated to give insights for possible future investigations.