Ascorbic acid as a dispersant for concentrated alumina nanopowder suspensions

The stabilization of concentrated nanopowder suspensions is crucial for many industrial applications. Yet, controlling the suspension viscosity is challenging for nanopowder suspension systems. In this study, we examined the adsorption of l-ascorbic acid (Vitamin C) on alumina surfaces and the related reduction in viscosity of the suspensions. Interactions between the ascorbic acid and the alumina surface were investigated by in situ ATR-FTIR and zeta potential measurements. It was shown that ascorbic acid forms complexes with the alumina surface through ligand exchange mechanisms. The optimum concentration of ascorbic acid for minimum suspension viscosity was determined. The maximum achievable solids content could be increased to around 0.35 by the addition of only 1.0 wt.% of dry powder ascorbic acid. Because ascorbic acid is easy to use, inexpensive, and a non-toxic organic additive, it has great potential to be used as a dispersant in a variety of industrial applications, from dilute to concentrated systems of intermediates or products.     

Nuclease treatment of broken bacterial suspensions for removal of highly polymerised nucleic acids

The use of nucleases for depolymerisation of nucleic acids in suspensions of disrupted bacterial cells has been shown to result in a reduction in the viscosity and an increase in the volume of supernatant recoverable after centrifugation. Precipitation of protein from nuclease treated suspensions, followed by dialysis of the protein precipitate, resulted in removal of most of the nucleotide material from the protein solution.     

Slip casting of highly concentrated ZnO suspensions: Rheological studies,two-step sintering and resistivity measurements

The paper presents research on elaboration of well dispersed and stable aqueous suspensions of ZnO fine powder. Within the work the influence of the type and concentration (0.2 wt% - 1.2 wt%) of selected dispersing agents (i.a. poly(acrylic acid)-based polyelectrolyte and tetramethylammonium hydroxide), solid loading (30 - 50 vol%) and milling time (1–3 h) on the rheological properties of the slurries was investigated. Two-step sintering (970/920 °C, 2 h) was applied to sinter the green bodies obtained by slip casting.The lowest viscosity of ZnO suspensions was obtained for the addition of 0.4 wt% of poly(acrylic acid)-based polyelectrolyte (PAA) and TMAH. ZnO suspension containing PAA had negative zeta potential in the whole pH range. The highest solid loading obtained in the study was 50 vol%. The applied two-step sintering allowed to obtain samples of high density (above 96% of TD) and homogeneous microstructure of average grain size of 640 nm. ZnO sintered bodies were characterized by different electric properties at the core part and outer part of the sample which was caused by the differences in concentration of oxygen vacancies.     

Utilisation of bipolar electrodialysis for recovery of galacturonic acid

Galacturonic acid is an acidifying agent and can be utilized in the food industry. It can be recovered from the hydrolysate of various pectins by electrodialysis. In this work bipolar electrodialysis was applied to separated and concentrated galacturonic acid and finally a crystallised product was obtained.     

Materials based on highly concentrated ceramic binding suspensions (HCBS). Evaluation of methods for molding bauxite ceramic concretes

The processes of molding and vibromolding of laboratory samples and large-sized nested blocks for intermediate ladles are studied using bauxite mixtures of the same composition. The ceramic concretes obtained exhibit comparable porosity and strength characteristics, namely, substantial starting strength, significant strengthening upon low-temperature heat treatment, and insignificant shrinkage in service. An effect of substantial grinding of the bauxite filler in the structure of the mold is found even under conditions of a relatively low (25 MPa) molding pressure for nested-block molding on a friction press. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 11–14, May, 1997.     

The engineering rheology of liquid explosives as highly concentrated emulsions

Rheological properties of liquid explosives are summarized and discussed in this paper. Liquid explosives are highly concentrated emulsions by their physical nature. During the internal phase, it is an aqueous supersaturated solution of mainly ammonium nitrate which is a useful component of a multi-component system, and at the continuous phase it is a solution of emulsifier in hydrocarbon oils. Liquid explosives demonstrate a complex set of properties characteristic for highly concentrated emulsions, such as visco-plasticity, existence of the yield stress, thixotropy (or time-dependent behavior), non-Newtonian flow at stresses exceeding the yield stress. Rheological properties depend on the concentration of internal phase, size of droplets, and the nature of the used surfactant. Stability of these materials is determined mainly by the tendency of an aqueous solution to crystallization at prolonged storage, though shearing does not influence on phase separation. Wall slip is absent in flow of liquid emulsions through tubes. Therefore, it allows us to make reliable predictions on the output vs. pressure dependence for real technological practice.     

含苯类有机物的高浓度硫酸废水的固态化处理方法

探讨了用重质碳酸钙粉对含苯类有机物的高浓度硫酸废水进行固态化处理的工艺条件,例如重质碳酸钙粉与废水反应生成灰色固体物质的用量、灰色固体物质煅烧的温度、时间以及废水中硫酸浓度不同时所需重质碳酸钙粉的用量。固态化处理方法不仅工艺简单、操作简便,而且处理过程无废水和有害废气排放,不导致二次污染,具有广阔的应用前景。     

高浓度臭氧用于污水处理的研究

在综述了在国内外有关臭氧产生和应用的文献基础上，结合作者的研究成果，从臭氧产生的机理出发，阐述了获得高浓度臭氧的技术关键，以期提高臭氧的产生和浓度，使得臭氧氧化技术在污水处理领域中得到更为广泛的应用。     

高浓度难降解有机废水处理技术

综述了现有的各种处理方法，包括化学氧化法，溶剂萃取法，吸附法，焚烧法，光催化法，生化处理法等，对各种方法的优缺点进行了比较，重点评价了超声处理新工艺，针对高浓度难降解有机废水化处理的关键问题，对超声波机理和有机物生物可降解性的主要影响因素进行了分析，在此基础上，提出超声波预处理与生物处理相结合的新方法，并以碱法草浆与靛蓝染料废水的实例说明该法的可行性。     

高效螯合剂葡庚糖酸的合成及其用途

葡庚糖酸是一种高效的糖酸螯合荆,具有广泛的用途,可用于微量元素肥料螯合剂.对葡庚糖酸的合成及性质进行研究,并介绍葡庚糖酸的一些用途.     

Polymeric particles with conjugated polymer: Layer on its surface as effective adsorbents of amino acids

In the present paper composite polymeric particles with polypyrrole (PPy) shell have been examined as reservoirs for uptake of amino acids. The particle morphology can be designed in a way that polypyrrole load on the particle surface as well as the PPy shell thickness can be varied easily by control of the pyrrole polymerization conditions, such as monomer concentration and choice of different oxidants. Three different oxidants have been used for the preparation of PPy outer-layers, namely FeCl₃, Na₂S₂O₈, and H₃PMo₁₂O₄₀, which give the possibility to incorporate different anions into PPy structure. l- and d-alanine uptake in the presence of obtained particles has been tested as a function of particle concentration and PPy amount on the particle surface. It has been found that composite particles can adsorb quite high amounts of alanine and even show certain enantioselectivity. The uptake efficiency and selectivity depend strongly on the properties of the PPy layer, such as chemical structure (oxidized or overoxidized state) and the nature of the dopant anion.     

Materials based on highly concentrated ceramic binding suspensions (HCBS). Study and comparative evaluation of methods for molding silica ceramic concretes

The processes of molding via vibrocompression (p=0.3 MPa) and static compression (p up to 500 MPa) are studied as applied to the technology of silica ceramic concretes based on a quartz HCBS and a mixture with a 5% addition of clay. The minimum values of the semifinished-product porosity for the aforementioned methods of molding are 11.5–12 and 15–16%, respectively. In static compression, for comparable compositions and moisture content the same porosity values are attained for mixtures with a clay addition at pressures 3–4-fold lower than those required for mixtures without clay.     

Acrylic acid/allyloxy polyethylene glycol copolymer with methoxysilicon end groups as a highly effective dispersant for nano-SiO2 aqueous system

In order to improve the dispersity and stability of nano-SiO₂ aqueous system with high solid content, acrylic acid/allyloxy polyethylene glycol copolymer dispersants with methoxysilicon end groups (KH590-AA_x-APEG_y) were synthesized by photopolymerization. After adding KH590-AA_x-APEG_y into the nano-SiO₂ aqueous system, the viscosity, the curing time, the particle size, and the zeta potential of these systems were respectively measured. The results showed that introducing polyethylene glycol chain into the dispersant was beneficial to better exerting its electrostatic repulsion and steric hindrance effects and further improving the dispersibility of the nano-SiO₂ aqueous system. Moreover, the dispersion stability of SiO₂ nanoparticles in water was closely related to the composition, the molecular weight, and the addition amount of KH590-AA_x-APEG_y and the solid content. When the molecular weight of KH590-AA_x-APEG_y was 3200 g mol⁻¹ and its addition amount was 0.1 wt %, the nano-SiO₂ aqueous system with 20 wt % solid content showed the best dispersity and stability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48617.     

高浓度切削液废水酸析-混凝破乳试验研究

针对某机械制造厂机械加工过程中产生的高浓度切削液废水进行破乳预处理试验,比较8种絮凝剂的混凝破乳效果,研究了投加助凝剂聚丙烯酰胺(PAM)以及调节p H对混凝破乳的影响,通过正交试验,综合技术可行性,优选出最佳破乳条件。结果表明,聚合氯化铝(PAC)为最佳絮凝剂;废水加浓硫酸酸析,p H降至6后,PAC投加量为6 g/L,PAM投加量为0.1 g/L,混合快搅5 min,絮凝慢搅5 min,静沉30 min后,废水COD去除率可达61.2%。     

Urotropine as a highly effective and versatile promoter for atom transfer radical polymerization

Atom transfer radical polymerization (ATRP) is a transition metal complex‐catalyzed controlled/‘living’ radical process. Recently, there has been a lot of interest focused on decreasing the catalyst loading and reducing the cost of post‐polymerization purification for ATRP. In this work, urotropine was found to significantly enhance the ATRP of methyl acrylate (MA), methyl methacrylate (MMA) and styrene (St) catalyzed by CuBr/N,N,N′,N′,N″‐pentamethyldiethylenetriamine (PMDETA) and CuBr/tris(2‐(dimethylamino)ethylamine) (Me₆TREN). With the addition of 25 times the amount of urotropine relative to CuBr, well‐controlled polymerizations of MA, MMA and St were obtained at catalyst‐to‐initiator ratios of 0.01, 0.05 and 0.05, respectively, producing the corresponding polymers with molecular weights close to theoretical values and low polydispersities. The catalyst concentration could even be reduced to ppm level at a catalyst‐to‐initiator ratio as low as 0.001 in the polymerization of MA. These results indicate that urotropine is a very effective and versatile promoter for both CuBr/PMDETA and CuBr/Me₆TREN. In the presence of urotropine, the catalyst loading could be reduced by as much as 1000 times. As PMDETA is one of the cheapest ATRP ligands, the combination of urotropine with CuBr/PMDETA could substantially reduce the catalyst loading and the cost of post‐polymerization purification at the industrial scale and thus is promising for potential industrial applications. © 2014 Society of Chemical Industry     

板式浓硫酸冷却器的应用

在硫酸装置扩能时 (由 2 0 kt/ a改为 4 0 kt/ a) ,选用板式浓硫酸冷却器 (32 m2 )代替原铸铁排管冷却器。使用中发现管路直径偏小 ( 10 8m m) ,水质差结垢严重 ,硫酸泵扬量选择偏小等问题。提出改进措施     

焦化厂高浓度氨氮废水的治理研究

焦化废水成分复杂,氨氮浓度高,生物难降解有机物含量高,水质、水量变化较大,而传统的活性污泥法生物处理工艺对COD和NH3-N的去除效果不够理想,难以使出水达到排放标准,给环境和人体带来危害。介绍了焦化废水经生化处理和深度处理的过程。     

高浓度活性污泥法处理染料废水的实验研究

介绍了高浓度活性污泥法处理染料废水的现场实验.探讨了该法在不同污泥CODCr负荷下对染料废水的CODCr、酚、色度等几个关键污染因子的去除率及其污泥性状,从而优选出最佳的污泥CODCr负荷区间为0.30～0.50 kg/(kg·d).在此区间内CODCr的去除率可达85%以上,出水酚质量浓度＜0.50 mg/L,出水色度＜150倍.     

A highly regioselective synthesis of δ-lactones from meadowfoam fatty acids

Meadowfoam fatty acids, when treated with mineral acid catalysts in the presence of polar nonparticipating solvents, undergo a facile ring closure to form δ-lactones. Perchloric and sulfuric acids catalyze the cyclization at concentrations of 0.6–13 mole equivalents, both neat and in the presence of solvent. Under constant acid concentrations, methylene chloride was found to increase the rate of reaction, the regioselectivity for the formation of δ-lactone, and the overall yield. In the absence of solvent, increased acid concentration improved the yield of lactone but reduced regioselectivity for the δ-isomer. Solvent polarity plays a significant role in the regioselectivity of the cyclization for δ-lactone, with solvents of higher dielectric strength providing larger δ/γ ratios (38:1) and higher yields up to 92%.