硼酸的生产应用现状及市场前景

介绍了当前硼酸的生产概况和应用现状,并结合实际提出了今后的发展前景。各国硼矿资源各有特点,其生产硼酸的方法也不尽相同,但以酸法为主。硼酸在玻璃工业、陶瓷、机械、电子、医药、农业、国防及现代科学技术领域有着广泛应用。未来世界硼工业将向集约化、规模化、精细化方向发展。高附加值的硼精细化工产品、新型含硼材料,专用(医药、试剂、照相、反应堆)级别的高纯或无水硼酸将有更为广阔的发展。     

中空介孔氧化硅纳米颗粒的制备及应用进展

集空腔与介孔结构于一体的中空介孔氧化硅纳米材料(HMSNs)因其高比表面积、可调孔径、低密度和高渗透等特性,而在诸多领域展现了极大的潜在应用前景。该文对中空-介孔氧化硅纳米颗粒的主要制备方法及其优缺点进行了概述,着重阐述了硬核模板法、液体界面组装法和界面重组与转换法的研究进展;同时,介绍了中空介孔氧化硅纳米颗粒在生物医药、催化和光学领域方面的应用。最后,对其制备和应用目前存在的挑战以及后续突破方向进行了分析和展望。     

中空介孔氧化硅纳米颗粒的制备及应用进展

集空腔与介孔结构于一体的中空介孔氧化硅纳米颗粒因其高比表面积、可调孔径、低密度和高渗透等特性,而在诸多领域展现了极大的潜在应用前景。本文对中空-介孔氧化硅纳米颗粒的主要制备方法及其优缺点进行了概述,着重阐述了硬核模板法、液体界面组装法和界面重组与转换法;同时介绍了中空介孔氧化硅纳米颗粒在生物医药、催化和光学领域的应用情况。最后,对其制备和应用存在的挑战和研究方向进行了分析和展望。     

油酸辅助水热合成纳米钛酸锶的性能调控与表征

采用油酸辅助一步水热法,以廉价易得的锐钛矿型TiO2为钛源、Sr(OH)2?8H2O为锶源合成SrTiO3纳米颗粒,通过XRD, TEM和SEM研究了SrTiO3纳米颗粒的形貌,考察了反应时间、Sr/Ti摩尔比和油酸浓度对SrTiO3纳米颗粒性能的影响,以所制SrTiO3为催化剂降解亚甲基蓝考察其光催化性能。结果表明,钙钛矿型立方相SrTiO3纳米颗粒具有均匀的尺寸和规则的形貌。实验范围内,随反应时间和Sr/Ti摩尔比增加,SrTiO3纳米粒子的晶粒尺寸呈增加趋势;随油酸浓度增加,SrTiO3颗粒粒度呈下降趋势。添加油酸可调控制备出具有规则形貌的钙钛矿型立方相结构的SrTiO3纳米颗粒;Sr/Ti摩尔比为0.75时,产品纯度高、结晶度好。油酸、反应时间和Sr/Ti摩尔比对SrTiO3纳米粒子微观结构的影响可分别用颗粒间作用力、奥斯特瓦尔德熟化和晶体成核理论解释。     

Design parameters of boric acid production process from colemanite ore in the presence of propionic acid

In this study, three different boric acid production process alternatives which can be performed in the presence of propionic acid and/or calcium propionate were evaluated. The process in which calcium propionate is the recycling component was selected as the best alternative and modeled. Some of the design parameters were determined for the selected process. These parameters are solubility change of boric acid in the presence of calcium propionate at 25 °C, 35 °C and 75 °C, precipitation risk of calcium borate components in concentrated boric acid solutions containing calcium propionate, and the effect of calcium propionate on the solution pH with respect to free sulfuric acid concentration. According to the determined parameters, principal reactions occurred in the process, and other process parameters obtained by industrial practice, mass balances were conducted and all flow rates were calculated. In the process, calcium propionate concentration in production liquor must be kept lower than 3% and the reaction must be carried out without any free sulfuric acid in order to perform the process according to the model.     

Removal of boric acid,monoborate and boron complexes with polyols by reverse osmosis membranes

The effects of reverse osmosis (RO) membrane type on the rejection efficiency of boric acid, monoborate and boron complexes with d-mannitol, sodium d-gluconate and N-methyl d-glucamine was revealed. The membranes examined included: XLE, TW-30, BW-30 and SW-30, supplied by DOW™ FILMTEC™. The mass transport coefficients: permeability and reflection coefficient were determined for each species in boric acid–polyol aqueous system. The influence of the membrane type upon these coefficients was evaluated and quantitative, comparative analysis of the efficacy of boron rejection at varying permeate flux, the feedwater boron content, the alcohol/boron molar ratio and the pH was conducted. It was found that boron rejection in the above systems was determined by the extent of boric acid transport, even when boric acid constituted only a minor component of the feedwater. At high permeate flux the effectiveness in boric acid rejection decreased in the following descending membrane order: SW-30 > BW-30 > TW-30 > XLE. The results presented here enable the selection of the best membrane, the most suitable operating conditions for boron separation by RO in the presence or absence of polyols, and for quantitative prediction of the efficiency of boron removal with various RO membranes.     

Adsorption and release of biocides with mesoporous silica nanoparticles

In this proof-of-concept study, an agricultural biocide (imidacloprid) was effectively loaded into the mesoporous silica nanoparticles (MSNs) with different pore sizes, morphologies and mesoporous structures for termite control. This resulted in nanoparticles with a large surface area, tunable pore diameter and small particle size, which are ideal carriers for adsorption and controlled release of imidacloprid. The effect of pore size, surface area and mesoporous structure on uptake and release of imidacloprid was systematically studied. It was found that the adsorption amount and release profile of imidacloprid were dependent on the type of mesoporous structure and surface area of particles. Specifically, MCM-48 type mesoporous silica nanoparticles with a three dimensional (3D) open network structure and high surface area displayed the highest adsorption capacity compared to other types of silica nanoparticles. Release of imidacloprid from these nanoparticles was found to be controlled over 48 hours. Finally, in vivo laboratory testing on termite control proved the efficacy of these nanoparticles as delivery carriers for biopesticides. We believe that the present study will contribute to the design of more effective controlled and targeted delivery for other biomolecules.     

Preparation of mesoporous silica nanoparticles with controlled pore size,particle diameter,morphology, and structure by two-step process of chlorosilane residue

In this study, mesoporous silica nanoparticles (MSNs) were successfully prepared in two steps using chlorosilane residue. First, chlorosilane residue was subjected to alcoholysis with n-propanol to synthesize tetrapropoxysilane (TPOS), followed by the synthesis of MSNs using TPOS as silicon source. Alcoholysis experiment was designed and optimized using orthogonal experimental method. In addition, effects of four factors (i.e., molar ratio of n-propanol to chlorosilane residue; feed rate of n-propanol; reaction temperature; and molar ratio of n-hexane to chlorosilane residue) on the yield of TPOS were investigated. The optimum alcoholysis conditions were determined. Yield of TPOS was 56% under the optimum alcoholysis conditions. Results obtained from single factor analysis of variance revealed that molar ratio of n-propanol to chlorosilane residue was the most significant factor affecting TPOS yield. Next, a series of spherical MSNs with dendritic structure and irregular mesoporous/microporous silica nanoparticles with non-dendritic structure were successfully synthesized via precise regulation of various experimental parameters in emulsion systems. In this regard, the adjustment of n-hexanol/1,3,5-triisopropylbenzene (TIPB) molar ratio or n-octane/n-hexanol/TIPB molar ratio was found to be effective for achieving controllable regulation of morphology (spherical or irregular); structure (dendritic or non-dendritic); pore size (mesoporous (4.6–9.2?nm) or microporous (1.6–1.7?nm)); and particle diameter (60–134?nm) of silica nanoparticles. However, the adjustment of n-octane/TIPB molar ratio marginally affected spherical morphology, dendritic structure, and pore size (4.0–4.6?nm) of synthesized MSNs, with considerable effect on particle diameter (61–151?nm). In addition, as-synthesized MSNs exhibited large specific surface area (708–857?m²/g) and large pore volume (1.5–3.6 cm³/g).     

Mechanism for the hydrolysis resistance of aluminum nitride powder modified by boric acid

Aluminum nitride (AlN) ceramics are becoming cutting-edge materials for electronic information and communication. However, raw AlN hydrolyzed rapidly, and the high storage costs of this material prevent widespread application. In this study, raw AlN was modified by boric acid (H₃BO₃) at 30 °C to enhance hydrolysis resistance. Transmission electron microscope (TEM), X-ray diffraction (XRD), the magic angle spinning nuclear magnetic resonance (²⁷Al-MAS-NMR and ¹¹B-MAS-NMR), and the fourier transform infrared spectrometer (FTIR) were used to characterize the powder before and after treatment, and the mechanism of hydrolysis resistance was determined. Modification with 0.1 M boric acid did not change the crystal phase of the AlN particles. The modified powder did not hydrolyse at 90% humidity and 70° Celsius. In the presence of boric acid, a network structure of B–O–B linkages ([BO_n], n = 3 or 4) formed that was connected to the AlN core via chemical bonds of B–N–Al and B–O–Al. The protective 6 – 10 nm-thick layer that formed on the surface of the AlN crystal, prevented attack by water molecules and hindered the hydrolysis of aluminium nitride. This study provides an alternative means of preparing anti-hydrolysis AlN powders.     

不同粒度纳米碳酸钙的可控制备

不同粒度的纳米碳酸钙具有不同的特性和应用范围,目前不同粒度纳米碳酸钙的可控制备方法还未见报道。以氯化钙、碳酸铵为原料,以乙醇、柠檬酸和焦磷酸钠为分散剂,采用复分解法研究了不同制备条件对纳米碳酸钙粒径的影响规律,在此基础上制备出平均粒径为17~71 nm的碳酸钙,并对其进行了表征。实验结果表明,所制备的纳米碳酸钙均为球霰石型,纯度很高,而且形貌近似球形。制备条件对纳米碳酸钙的粒径有显著的影响：随着反应温度升高,纳米碳酸钙的粒径减小;随着氯化钙滴加时间的增加,纳米碳酸钙的粒径增大;随着反应物浓度的提高,纳米碳酸钙的粒径先减小后增大;当分散剂为柠檬酸和焦磷酸钠的混合溶液时所得纳米碳酸钙的粒径最小,当分散剂为乙醇和焦磷酸钠的混合溶液时所得纳米碳酸钙的粒径最大。利用这些影响规律通过控制制备条件可以实现所需粒径纳米碳酸钙的可控制备。     

A green process for the synthesis of controllable mesoporous silica materials

The synthesis, characterization, and application of mesoporous silicas have attracted a lot of attention for over two decades, which stems from their fascinating structures, formation mechanisms and prospects of their applications. Various methods have been developed for the synthesis of these silicas with a tunable pore diameter and a narrow pore size distribution. In this paper, mesoporous silica materials with controllable pore diameters (3-9 nm), narrow pore size distributions, high surface area (>700 m² g⁻¹) and pore volume (>1 cm³ g⁻¹) were prepared by a green template, amphiphilic dendritic polyamidoamine. The resulting silica materials were characterized by ¹H, ¹³C NMR spectroscopy; thermogravimetic analysis; nitrogen adsorption; transmission electron microscope. It was shown that the template could be completely removed and recycled from the silica in an environmentally friendly way by means of a simple water extraction. Furthermore, it was shown that the pore diameter of these materials could be controlled by dendritic polyamidoamine with different generations and functional groups. Meanwhile, the porous framework showed strong thermal stability. Thus, a new environmentally friendly pathway for the controllable synthesis of this fascinating silicas has been proposed.     

介孔中空二氧化硅及硅基微球制备研究进展

介孔中空材料有特定孔道结构,具有中空、密度小、比表面积大的特点,因而具有较好的渗透性、吸附性、筛分分子能力和光学性能,成为具有广泛应用前景的热点研究材料。详细地介绍了国内外新型功能材料介孔中空二氧化硅及硅基微球主要制备方法,包括表面沉积法、层层组装法、原子转移自由基聚合法、喷雾法、微乳液法。同时介绍了合成的介孔、中空二氧化硅和硅基微球的形貌特点及应用。指出不同方法、不同制备条件对材料的形貌、孔径大小、孔形状及材料晶形有很大影响,条件温和、步骤简单、环境友好的制备方法是发展趋势。     

Sulfonic acid-functionalized mesoporous silica catalyst with different morphology for biodiesel production

Sulfonic acid functionalized mesoporous silica based solid acid catalysts with different morphology were designed and fabricated. The synthesized materials were characterized by various physicochemical and spectroscopic techniques like scanning electron microscope-energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area, thermogravimetric analysis and n-butylamine acidity. The shape of catalysts particles plays an important role in its activity. The sulfonic acid functionalized mesoporous silica catalysts of spherical shape and the cube shape were assessed for catalytic activity in biodiesel production. The catalytic biodiesel production reaction over the catalysts were studied by esterification of free fatty acid, oleic acid with methanol. The effect of various reaction parameters such as catalyst concentration, acid/alcohol molar ratio, catalyst amount, reaction temperature and reaction time on catalytic activity were investigated to optimize the conditions for maximum conversion. It was sulfonated cubic shape mesoporous silica which exhibited better activity as compared to the spherical shape silica catalysts. Additionally, the catalyst was regenerated and reused up to three cycles without any significant loss in activity. The present catalysts exhibit superior performance in biodiesel production and it can be used for the several biodiesel feedstock’s that are rich in free fatty acids.     

硝酸分解钠硼解石制备硼酸的工艺研究

以玻利维亚钠硼解石矿为原料,采用硝酸酸解硼矿制备硼酸。考察了钠硼解石的洗矿和酸解工艺,结果表明：在洗矿工艺中,控制液固体积质量比为6 mL/g和洗矿时间为20~30 min,氯离子的脱除率达到92.17%;在酸解工艺中,控制硝酸用量为理论用量的90%、液固质量比为5、反应温度为60 ℃和反应时间为40~60 min,硼的浸出率达到98%以上。在上述工艺条件下进行硼酸母液循环研究,结果显示,随着循环次数的增加,虽然母液中的硝酸钙和硝酸钠不断积累,其质量浓度不断增加,但硼酸的质量浓度保持稳定。合适的循环次数有利于硼的回收和母液中硝酸盐浓度的提高,使母液可以用于生产硝酸钠和碳酸钙等附加值高的副产品。     

Effect of boric acid on the porosity of clay and diatomite monoliths

Porous silica ceramics were obtained at low forming pressure (40–80 MPa) and low sintering temperature (850–1300 °C) for 4 h in air. Boric acid was used as a low-cost additive, in the amount of 2 wt%. Relatively high porosities of nearly 40% and 65% are obtained for the samples of clay and diatomite pressed at 40 MPa, and sintered at 1000 °C, respectively. The samples sintered at 1150 °C and 1300 °C have the average pore size diameters in the range of macroporous for clay 0.2–10 μm and for diatomite 0.2–5 μm. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and mercury porosimetry measurements were employed to characterize of the obtained samples. Measurements of densities and open porosities by immersion technique were used, according to the Archimedes principle. The relations between mechanical characteristics of the samples formed by using different pressures and sintered at different temperature, were discussed.     

Superhydrophilic coatings with enhanced transmittance fabricated from solid and mesoporous silica nanoparticles

Superhydrophilic coatings with high transmittance were fabricated from solid and mesoporous silica nanoparticles (NPs) via layer-by-layer assembly followed by calcination. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 96.1%, while that of the glass substrate was 91%. The time for a droplet to spread flat (water contact angle lower than 5°) is <1?s. Scanning and transmission electron microscopies were used to observe the morphology and structure of both NPs and coating surfaces. Transmission spectra and their changes after calcination were characterized by UV–vis spectrophotometry. The surface wettability was studied using a contact angle/interface system.     

不同粒度八棱柱形纳米铜的制备研究

纳米铜具有优异的导电、催化、润滑、抗菌等性能,而这些性能和应用范围均与其形貌和粒度有关。八棱柱形纳米铜很有可能具有一些特殊的性能和用途,而关于不同粒度八棱柱形纳米铜的制备研究还未见报道。采用水热法,以二水合氯化铜（CuCl₂·2H₂O）为铜源,以十八胺（ODA）为还原剂,研究了八棱柱形纳米铜的制备。考察了反应物浓度、反应温度、反应时间等条件对纳米铜的八棱柱形貌及尺寸的影响。讨论了八棱柱形纳米铜的形成机理。结果表明,八棱柱形纳米铜的制备是相当困难的,只有采用具有形貌和粒度控制作用的还原剂十八胺,并严格控制实验条件,才能制备出不同粒度的八棱柱形纳米铜。制备八棱柱形纳米铜的最佳条件：十八胺与氯化铜的浓度比为（2~3）∶1,反应温度为180 ℃,反应时间为48 h。八棱柱形纳米铜的形成机理可归因于十八胺对纳米铜{100}晶面的选择性吸附。八棱柱形纳米铜的粒度随着十八胺浓度的增加而增大,通过控制十八胺的浓度可实现不同粒度八棱柱形纳米铜的可控制备,并且发现十八胺具有还原、形貌控制和粒度控制三重作用。这些结果可为制备八棱柱形其他金属纳米材料提供重要参考。     

Synthesis of spherical mesoporous silica nanoparticles with nanometer-size controllable pores and outer diameters

Spherical mesoporous silica particles with tunable pore size and tunable outer particle diameter in the nanometer range were successfully prepared in a water/oil phase using organic templates method. This method involves the simultaneous hydrolytic condensation of tetraorthosilicate to form silica and polymerization of styrene into polystyrene. An amino acid catalyst, octane hydrophobic-supporting reaction component, and cetyltrimethylammonium bromide surfactant were used in the preparation process. The final step in the method involved removal of the organic components by calcinations, yielding the mesoporous silica particles. Interestingly, unlike common mesoporous materials, the particle with controllable pore size (4–15 nm) and particle diameter (20–80 nm) were produced using the method described herein. The ability to control pore size was drastically altered by the styrene concentration. The outer diameter was mostly controlled by varying the concentration of the hydrophobic molecules. Relatively large organic molecules (i.e. Rhodamine B) were well-absorbed in the prepared sample. Furthermore, the prepared mesoporous silica particles may be used efficiently in various applications, including electronic devices, sensors, pharmaceuticals, and environmentally sensitive pursuits, due to its excellent adsorption properties.     

A simple room temperature synthesis of mesoporous silica nanoparticles for drug storage and pressure pulsed delivery

Mesoporous silica nanoparticles (MSN) have been synthesized at room temperature under assistance of n-hexane by using tetraethyl orthosilicate (TEOS) as a silica source and cetyltrimethylammonium bromide (CTAB) as a structure directing agent. Powder X-ray diffraction studies showed that the quantity of n-hexane added into the solution was critical for the ordering of the final mesostructures. The particle size of MSN was between 200 and 400 nm, which is suitable for endocytosis by human cells. The drug loading capability of MSN prepared through this route was measured and the influence of the pulsed pressure drop on drug delivery was studied. This study showed that the delivery rate of ibuprofen in a simulated body fluid solution increased dramatically under the pulsed pressure drop.     

A facile route to a silica monolith with ordered mesopores and tunable through pores by using hydrophilic urea formaldehyde resin as a template

In this paper, bi-continuous silica monolith with highly ordered mesopores and tunable through pores (macropores or macro channels) has been successfully synthesized through nanocasting method. The starting urea formaldehyde (UF) resin, which is hydrophilic and contains adjustable through pores in micrometer scale, was for the first time used as a hard template in nanocasting. The silica replica has the same macroscopic morphology and macropore structure as the starting UF resin template, indicating that the macropores in silica monolith could also be adjusted. More interestingly, long-range ordered domains with highly ordered mesopores of hexagonal arrays existed in the frameworks of the silica monolith.