反渗透膜对水中硼酸脱除性能的实验研究

采用实验室小型反渗透装置,对影响反渗透膜除硼效率的各种因素进行了实验研究.结果表明:苦咸水淡化反渗透膜在通常条件下对硼酸的脱除率仅为30％～45％.反渗透对硼酸的脱除率随进水pH的增大而提高,但不受进水硼浓度的影响;反渗透操作压力的提高也可以增大硼酸脱除率,但元件回收率的增大则会降低脱除率.在各种因素中,增大pH可以显著提高硼酸脱除率,是改善反渗透除硼性能的有效途径.     

国产纳滤膜淡化高氟苦咸水基础研究

实验选取两种国产纳滤膜NF2A和NF3A进行纳滤膜淡化高氟苦咸水的基础研究,考察操作压力、温度、进水pH、进水氟浓度、总含盐量(TDS)及运行时间对纳滤膜分离性能的影响,并测定膜的Zeta电位,同时简单比较两种膜.研究结果表明,两种纳滤膜处理高氟苦咸水的理想操作条件为:压力1.0～1.5 MPa,温度20℃,进水pH=6.5左右,在此条件下NF3A纳滤膜的脱盐率为79％,脱氟率为90％,产水通量为53 L/(m2·h),NF2A纳滤膜的脱盐率分别为73％,73％和71L/(m2·h),此外,随进水氟浓度和总含盐量的增大,纳滤膜的脱氟和脱盐率降低,同时得出两种膜在长期运行72 h内膜性能基本保持稳定,最后测得NF3A和NF2A的Zeta电位分别为-22和-18 mV.这项研究为国产纳滤膜处理高氟苦咸水的实际应用提供了技术数据,有利于国产纳滤膜的发展和完善.     

纳滤膜在北京阿苏卫填埋场渗滤液改扩建工程中的应用

在阿苏卫垃圾卫生填埋场渗滤液改扩建工程中,以膜生物反应器(MBR)的出水为研究对象,考察了在一定的pH、进水流量、操作压力下纳滤膜对CODcr、NH3-N和电导率的去除情况.结果表明:在设备初期运行阶段,在pH为7、操作压力为0.5 MPa时,纳滤膜对CODcr的去除率达75%;对NH3-N的去除率较低,出水的NH3-N值略低于进水;对电导率的平均去除率达55%.此外,还分析了纳滤膜的运行性能以及与原有反渗透处理工艺联合使用等问题.     

γ-Al2O3多孔膜的分离性能

通过改变操作压力、流速、浓度、温度、pH考察以MgSO4·7H2O为溶质,用H3PO4调节溶液pH,用溶胶凝胶法自制的管式γ-Al2O3纳米孔膜的性能.结果发现,操作压力对膜通量和截留率的影响显著,当压力由0.1 MPa升至0.3 MPa时,膜的渗透通量提高了75%,截留率提高了80%;同时温度及pH对也分别对渗透通量和截留率有较为显著的影响,特别是当pH从5.5降至3时,截留率提高了61%,认为酸性环境下有利于该膜对金属阳离子的脱除.     

纳滤膜脱盐及其在海水软化中的应用

采用卷式纳滤膜进行了MgSO4、K2SO4、MgCl2等5种物质的脱盐性能研究,考察了进料操作压力和浓度对表现截留率和膜通量的影响,在此基础上研究了操作压力对海水脱盐性能的影响.实验表明,纳滤膜性能稳定,能除去海水中90％以上的SO42-以及50％以上的Mg2+和Ca2+,大幅度降低了海水的硬度,可解决传统上海水淡化过程中易结垢离子对膜的污染问题;纳滤膜软化海水可以降低海水淡化后期处理的成本和能耗;采用纳滤膜软化海水在技术上是可行的.     

膜法海水吸收烟气中二氧化碳的试验研究

采用自制聚丙烯中空纤维膜接触器,以海水作为吸收剂,对模拟烟气中CO2进行吸收试验研究,主要考察烟气流量、CO2浓度、海水流量、海水pH值及膜填充率对CO2脱除率及膜接触器传质性能的影响.研究结果表明:(1)提高烟气流量或CO2浓度能提高膜接触器对CO2的处理量,导致脱碳率下降;(2)提高海水流量能明显提高脱碳率和传质速率;(3)提高海水pH可增大海水对CO2的吸收能力,直接决定了海水对CO2的吸收机制;(4)增大膜接触器填充率所对应的脱碳率并非最高,有效气液接触面积是影响脱碳率和过程传质的重要因素.     

运行条件对家用型净水机中反渗透膜性能的影响

研究了进水pH值、原水回收率、膜前压力、进水盐浓度、进水水温、进水余氯浓度等运行条件对家用净水机中反渗透膜性能的影响.家用净水机适宜的运行条件为:pH值在6～8,原水回收率为15%～50%,膜前压力维持在0.4～0.6 MPa,进水温度保持在15～30℃.     

海水预处理一体化混凝-微滤工艺

针对渤海近岸海水浊度高、有机物和悬浮固体含量大等特点,开发了一体化混凝-微滤工艺对海水进行预处理.系统较长时间运行表明,出水水质好,能满足海水反渗透进水的要求.对污染的膜进行系统清洗后,膜通量基本可恢复至新膜水平;膜表面沉积物中Ca2 、Mg2 等的化合物含量较高;NaOCl溶液可有效洗脱膜表面UV254所代表的腐殖质类天然有机物.     

海水淡化膜集成系统的发展现状及优势分析

以海水淡化膜集成系统的构建为核心,分析反渗透海水淡化的优势和存在的问题;综合评价膜法预处理-反渗透、反渗透-正渗透、反渗透-压力延迟渗透等几种典型的膜法集成系统;提出利用膜法集成技术进一步降低海水淡化能耗与实现零排放的基本思路与原理.同时,详细介绍海水淡化膜法集成系统在海水淡化过程中海水预处理、盐差发电、浓盐水再利用等方面的具体应用进展,为低能耗零排放的海水淡化膜集成系统的构建提供指导与借鉴.     

海水淡化过程中硼的现场快速测定

针对传统的甲亚胺-H分光光度法,通过优化乙酸盐缓冲液pH缩短显色反应的时间,建立同一校准曲线下,快速测定海水和淡化产水中硼浓度的分析方法.方法中,当静置时间达20 min时,显色即可完全.通过实验确定,该分析方法不受海水高盐基体效应的影响.硼的浓度范围在0.10～2.0μg/mL之间时,校准曲线的线性系数达0.9999...     

CVD法生产硼纤维过程中BCl3的回收再利用的研究

用氯气一硼纤维生产过程回收尾气ＢＣｌ３中的丁硼烷（Ｂ４Ｈ１０）进行反应,实现了硼纤维生产过程中ＢＣｌ３的循环利用。     

碳化硼的氧化特性研究

研究了碳化硼在４００－８００℃空气中烧结时的氧化特性，采用ＸＲＤ、ＳＥＭ对氧化后的碳化硼的相结构和表面形貌进行分析。观察。结果表明，碳化硼有６００℃左右开始氧化，氧化后部分生成玻璃态的Ｂ２Ｏ３，氧化过程为热激活过程，激活能Ｑ＝１７．１７ｋＪ／ｍｏｌ。     

硼及其硼化物的应用现状与研究进展

硼及其硼化物在现代工业中有着广阔的应用前景.分析了我国硼矿资源的分布和特点,着重阐述了硼及其硼化合物综合利用的途径及现状,总结了硼及其硼化合物在冶金工业、陶瓷工业、永磁材料、超导材料、晶须材料、稀土材料等领域的应用情况,并对今后的发展趋势进行了探讨.     

Recent progress in boron nanomaterials

Abstract

Various types of zero, one, and two-dimensional boron nanomaterials such as nanoclusters, nanowires, nanotubes, nanobelts, nanoribbons, nanosheets, and monolayer crystalline sheets named borophene have been experimentally synthesized and identified in the last 20 years. Owing to their low dimensionality, boron nanomaterials have different bonding configurations from those of three-dimensional bulk boron crystals composed of icosahedra or icosahedral fragments. The resulting intriguing physical and chemical properties of boron nanomaterials are fascinating from the viewpoint of material science. Moreover, the wide variety of boron nanomaterials themselves could be the building blocks for combining with other existing nanomaterials, molecules, atoms, and/or ions to design and create materials with new functionalities and properties. Here, the progress of the boron nanomaterials is reviewed and perspectives and future directions are described.     

碳化硼的氧化特性研究

本文研究了碳化硼在400～800℃空气中烧结时的氧化特性．采用XRD、SEM对氧化后的碳化硼的相结构和表面形貌进行分析、观察．结果表明：碳化硼在600℃左右开始氧化,氧化后部分生成玻璃态的B₂O₃,氧化过程为热激活过程,激活能Q=17．17kJ／mol．     

Mechanism of nucleation and growth of cubic boron nitride thin films

The mechanism and the crystallography of the nucleation and growth of cubic boron nitride (c-BN) films deposited on 100-oriented silicon substrate by RF bias sputtering have been studied by means of cross-sectional high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Both methods provide experimental information showing no sp²-bonded BN layer formation in the subsurface region of c-BN phase. This is clear evidence for layer-by-layer homoepitaxial growth of cubic boron nitride without graphitic monolayers in the near-surface region of the film. The turbostratic boron nitride (t-BN) consists of thin sub-layers, 0.5–2 nm thick, growing in such a way that a sub-layer normal is almost parallel to the growth direction. t-BN also comprises a large volume fraction of the grain boundaries with high interface energies. The present result and the finding by Shtansky et al. [Acta Mater. 48, 3745 (2000)], who showed that an individual sub-layer consists of parallel lamellae in both the hexagonal (h-BN) and rhombohedral (r-BN) configurations, demonstrate that high intrinsic stress in the films is due to the complex structure of sp²-bonded BN. The crystallography of c-BN films indicates heteroepitaxial nucleation of cubic phase on the graphitic BN structural precursor. The present results are consistent with stress-induced c-BN formation.     

Mechanism of nucleation and growth of cubic boron nitride thin films

The mechanism and the crystallography of the nucleation and growth of cubic boron nitride (c-BN) films deposited on 〈100〉-oriented silicon substrate by RF bias sputtering have been studied by means of cross-sectional high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Both methods provide experimental information showing no sp²-bonded BN layer formation in the subsurface region of c-BN phase. This is clear evidence for layer-by-layer homoepitaxial growth of cubic boron nitride without graphitic monolayers in the near-surface region of the film. The turbostratic boron nitride (t-BN) consists of thin sub-layers, 0.5–2 nm thick, growing in such a way that a sub-layer normal is almost parallel to the growth direction. t-BN also comprises a large volume fraction of the grain boundaries with high interface energies. The present result and the finding by Shtansky et al. [Acta Mater. 48, 3745 (2000)], who showed that an individual sub-layer consists of parallel lamellae in both the hexagonal +h-BN) and rhombohedral (r-BN) configurations, demonstrate that high intrinsic stress in the films is due to the complex structure of sp²-bonded BN. The crystallography of c-BN films indicates heteroepitaxial nucleation of cubic phase on the graphitic BN structural precursor. The present results are consistent with stress-induced c-BN formation.     

固相反应法合成碳化硼纳米粉体

以六方氮化硼和炭黑(或石墨)为原料, 采用固相反应法合成了碳化硼粉体. 碳源、反应气氛和温度对粉体合成产生重要影响. 以炭黑为碳源, 在1900℃真空下保温5 h, 得到了平均粒径约为100 nm的碳化硼纳米粉体. 与商业粉体相比, 合成的粉体具有较好的烧结活性. 在2000℃/30 MPa/1 h条件下烧结, 样品的相对密度达到97.9%(商业粉体样品为93.1%), 这可归结于合成的粉体具有细小的粒径、低的氧含量和一定程度的孪晶结构.     

高能球磨制备TiB2/TiC纳米复合粉体

研究了通过高能球磨制备TiB2/TiC纳米复合粉体的反应过程和机理,对粉体的显微结构进行了表征。实验结果表明,采用金属Ti和B4C为原料,在球磨过程中,TiC先于TiB2形成。球磨5h后Ti与B4C反应生成TiB2和TiC,在随后的长时间高能球磨过程中TiB2和TiC两相保持稳定。球磨30h后,直径约8nm的TiC纳米粒子分布在100-200nm的TiB2粒子中,形成均匀分布的纳米TiB2/TiC复合粉体。