燃煤锅炉烟气中Na2SO4生成的化学动力学研究

准东煤燃烧过程中Na₂SO₄的形成会造成锅炉受热面沾污、尾部SCR催化剂失活等问题。烟气中Na₂SO₄形成及转化规律的研究对于预测和控制燃煤烟气中Na₂SO₄的形成有重要意义。发展了烟气中Na/Cl/S/O/H化学动力学模型,研究了烟气中Na₂SO₄的生成过程及转化机理,考察了含氧量、温度、SO₂浓度、H₂O浓度等因素对Na₂SO₄生成的影响。动力学计算结果表明,模型预测结果与实验数据吻合较好,验证了模型的准确性。烟气中的高氧气含量有利于Na₂SO₄的生成。高温加快化学反应的同时,抑制了Na₂SO₄的生成。SO₂和H₂O的影响效果受温度影响较大。反应路径分析表明,Na₂SO₄的生成路径有两个：一是依赖于SO₂直接氧化（NaCl→NaSO₃Cl→NaHSO₄→Na₂SO₄）,二是依赖于SO₂间接氧化（NaCl→NaO₂→NaSO₄→NaHSO₄→Na₂SO₄）。敏感性分析结果表明,Na₂SO₄的生成主要对系统中生成或消耗自由基的反应更为敏感。     

煤化工烟道气毒性成分对Chlorella pyrenoidosa生长和细胞成分的影响

探究煤化工烟道气中毒性成分对微藻的影响是利用微藻固定煤化工烟道气CO₂实现减排的关键。本文利用不同浓度的NaHS、Na₂SO₃和NH₃·H₂O培养Chlorella pyrenoidosa（C. pyrenoidosa），以探究煤化工烟道气主要毒性成分H₂S、SO₂和NH₃气体水溶物的毒性。实验结果表明：NaHS、Na₂SO₃和NH₃·H₂O浓度分别低于1mmol/(L·d)、40mmol/(L·d)和7mmol/(L·d)时对C. pyrenoidosa生长无抑制作用，而且Na₂SO₃[＜40mmol/(L·d)]会显著促进 C. pyrenoidosa的生长；NaHS 添加4mmol/(L·d)时会在生长初期抑制C. pyrenoidosa的生长，NH₃·H₂O添加35mmol/(L·d)则会直接造成藻细胞的破碎死亡。与对照组相比，NaHS和Na₂SO₃浓度分别低于1mmol/(L·d)、10mmol/(L·d)时对C. pyrenoidosa的细胞成分无影响；NaHS添加4mmol/(L·d)使藻蛋白含量提高7.13%；Na₂SO₃添加40mmol/(L·d)使藻蛋白降低13.45%，总糖含量提高42.90%；NH₃·H₂O的添加会使藻蛋白含量降低，总糖含量提高。微藻生物质整体蛋白质含量较高，可作为蛋白饲料来源。研究结果表明，C. pyrenoidosa对煤化工烟道气中的主要毒性气体有较好的耐受性，利用煤化工烟道气培养微藻具有可行性。     

Na2SO4掺杂含MgO铝酸钙熟料的结构表征及浸出性能

使用分析纯MgO、CaCO₃、SiO₂、Al₂O₃与Na₂SO₄在1350℃保温1 h合成了掺杂Na₂SO₄的含MgO铝酸钙熟料,在Na₂CO₃溶液体系下研究了其氧化铝浸出性能,通过XRD等分析手段对其晶体结构和自粉化性能进行了研究。结果表明,Na₂SO₄可以显著提升铝酸钙熟料的浸出性能,Na₂SO₄掺杂量由0%提高到4%,熟料的氧化铝浸出率由61.89%提高到92.01%,继续添加Na₂SO₄,浸出性能趋于稳定。由XRD结果可知,Na₂SO₄促使20CaO·13Al₂O₃·3MgO·3SiO₂（Q相）发生分解并使其转变为12CaO·7Al₂O₃（C₁₂A₇）。Na⁺进入C₁₂A₇晶格引起晶格畸变,从而提高C₁₂A₇的氧化铝浸出性能。Na₂SO₄的加入降低了熟料的自粉化性能,Na₂SO₄掺杂量由0%提高到6%,熟料的自粉率由97.46%下降到85.34%,当Na₂SO₄掺杂量达到10%后,熟料自粉率仅为36.3%。     

高浓盐水Na2SO4和NaCl结晶盐的冷法分离研究

以NaCl和Na₂SO₄高浓盐水为原料，考察冷却结晶和冷冻浓缩过程对Na₂SO₄和NaCl结晶盐的分离。通过考察不同结晶温度下结晶盐的冷却结晶析出过程，可以得到纯度较高的Na₂SO₄结晶盐，说明可以采用冷却结晶方式，利用溶解度随温度变化差异分离Na₂SO₄。通过对冷冻浓缩过程的研究，表明当温度低于-9.9℃时，剩余浓缩液中主要为NaCl，对应NaCl结晶盐纯度可达到95%。通过深度浓缩NaCl浓盐水，可将NaCl浓缩至～27 wt%的浓度，产水中NaCl浓度不大于1 wt%，可经进一步处理后回用。因此，通过结合冷却结晶和冷冻浓缩过程，可以实现Na₂SO₄和NaCl结晶盐的冷法分离。     

碱液对提取褐煤黄腐酸的影响

为提高褐煤资源的附加值,探索了NaOH,KOH,LiOH,Na₂CO₃,NH₃·H₂O,Na₂SO₃,NaHCO₃,Na₄P₂O₇对萃取褐煤黄腐酸结构的影响。采用碱溶酸析法提取褐煤黄腐酸,以不同弱碱性溶剂为萃取剂再经硫酸酸析,通过容量法测定黄腐酸的纯度,并对提取的褐煤黄腐酸进行光谱表征。结果表明：不同碱液提取褐煤黄腐酸的产率不同,但质量浓度相近,其中LiOH提取黄腐酸的产率(质量分数)最高(5.12%);不同碱液提取褐煤黄腐酸的官能团种类相同,但含量不同,Na₂CO₃提取的褐煤黄腐酸羰基结构最少,NaHCO₃做萃取剂时提取的褐煤黄腐酸的芳香度较高、羟基结构较多;不同碱液提取褐煤黄腐酸的E₄/E₆值明显不同,相对分子质量差距较大,Na₄P     

常见钠盐的高温挥发特性及热解机理

选取有机废液中常见的钠盐(氯化钠、碳酸钠、硫酸钠、甲酸钠、乙酸钠、草酸钠)，通过热重分析仪，在25~1400℃考察其高温挥发特性。基于Gibbs自由能最小原理，对NaCl、Na₂CO₃及Na₂SO₄的挥发特性进行热力学计算。结果表明，在N₂气氛中，NaCl在达到熔点后以气态NaCl及气态Na₂Cl₂的形式释放，Na₂SO₄升温至885℃分解生成Na₂O，同时Na₂O分解，并以Na单质形式释放。而有机羧酸钠盐在600℃之前均热解为Na₂CO₃，继续升高温度则分解为Na₂O，同样最后以气态Na单质的形式释放。在空气气氛中，由于O₂的存在，抑制了Na₂O的分解反应，致使Na₂CO₃分解速率小于N₂气氛。     

基于数字图像处理的盐溶液过饱和比与结晶压力测量方法

溶液过饱和比和结晶压力是研究多孔材料结晶破坏效应的主要参数，但目前没有很好的手段直接测量溶液过饱和比。观察溶液结晶现象发现，溶液结晶前后图像灰度会发生明显变化，因此本文提出一种基于数字图像处理(DIP)技术的盐结晶过饱和比和结晶压力的测量方法。该方法以图像为基础，得出灰度值与溶液浓度的关系，运用MATLAB软件绘出溶液过饱和比和结晶压力分布图。以Na₂SO₄溶液和NaCl溶液的结晶行为为例，得到Na₂SO₄溶液与NaCl溶液结晶的初始过饱和比在1.1～1.3,进一步计算了Na₂SO₄和NaCl的结晶压力理论值。Na₂SO₄和NaCl结晶破坏效应的差异与二者不同的结晶行为有关，Na₂SO₄晶体的蠕变生长行为导致其更具破坏性。     

分子模拟和光谱法研究华法林与人血清白蛋白的结合机制

华法林(WF)是临床常用口服抗凝药物,有关它与人血清白蛋白(HSA)结合位点处的热点残基、作用力类型以及对HSA构象影响报道较少。通过在模拟人体生理条件下,利用分子模拟、内源荧光光谱、三维荧光光谱和同步荧光光谱,研究了WF与HSA之间作用机理。WF能使HSA构象发生改变,导致Tyr残基微环境极性降低、Trp残基周围亲水性增强。WF能有效猝灭HSA内源荧光,猝灭机制属静态猝灭,通过Lineweaver-Burk方程求得两者间结合常数(K_A)为3.55×10⁵L/mol(310 K)、结合位点数(n)约为1。Van′t Hoff定律计算得到的热力学参数(ΔH=169.56 kJ/mol和ΔS=653.23 J/(mol·K)),说明WF与HSA之间的主要作用力为疏水作用力。根据F9rster′s能量转移定律确定,WF与HSA结合距离为2.87 nm。WF通过氢键和疏水作用力与HSA的亚域ⅡA中氨基酸残基进行作用,WF周围4.0?区域还存在ⅠB、ⅡB、ⅢA亚结构域的30个氨基酸残基。     

高盐废水中硫酸铵和硫酸钠的分质结晶工艺研究

处理高盐废水并回收其中的盐资源是许多生产企业废水综合治理的难题。采用等温溶解平衡法测定了10、15、60、80℃下Na₂SO₄-(NH₄)₂SO₄-H₂O的液固相平衡数据，基于相平衡数据划分了结晶区域。根据高盐废水的组成和液固相平衡数据，提出了分质结晶分离(NH₄)₂SO₄和Na₂SO₄的工艺路线，设计了结晶过程工艺参数并进行了实验验证。结果表明，废水经3步结晶回收得到的(NH₄)₂SO₄纯度达到了99.2%、Na₂SO₄纯度达到了98.9%，满足GB/T 535—2020《肥料级硫酸铵》和GB/T 6009—2014《工业无水硫酸钠》的纯度指标要求。该研究可为高盐废水中(NH₄)₂SO_...     

熔盐种类对熔盐法合成镁橄榄石的影响

以分析纯MgO和SiO₂为原料,分别以分析纯NaCl、Na₂CO₃、NaCl-Na₂CO₃和Na₂SO₄为熔盐介质,采用熔盐法在1 100℃保温3 h合成镁橄榄石,并对合成镁橄榄石进行了XRD、SEM、EDS、Jade分析。结果表明：以Na₂CO₃或NaCl-Na₂CO₃为熔盐介质合成的镁橄榄石纯度很低,因为Na₂CO₃与MgO和SiO₂反应生成了大量的Na₂MgSiO₄。以NaCl为熔盐介质合成的镁橄榄石纯度非常高。以Na₂SO₄为熔盐介质合成的镁橄榄石纯度较高,有少量MgSiO₃生成。分析认为,在NaCl熔盐中合成镁橄榄石的机制为“模板生长”,在Na₂     

硫酸钠/氧化硅复合定形相变材料的溶胶凝胶法制备和表征简

A sodium sulfate （NaeSO4）/silica （SiO2） composite was prepared as a shape-stabilized solid-liquid phase change material by a sol-gel procedure using Na2SiO3 as the silica source. Na2SO4 in the composite acts as a latent heat storage substance for solid-liquid phase change, while SiO2 acts as a support material to provide structural strength and prevent leakage of melted NazSO4. The microstructure and composition of the prepared composite were characterized by the N2 adsorption, transmission electron microscope （TEM）, scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FTIR） and X-ray diffraction. The results show that the prepared Na2SOJSiO2 composite is a nanostructured hybrid of NazSO4 and SiO2 without new substances produced during the phase change. The macroscopic shape of the NazSO4/SiO2 composite after the melting and freezing cycles does not change and there is no leakage of Na2SO4. Determined by differential scanning calorimeter （DSC） analysis, the values of phase change latent heat of melting and freezing of the prepared NazSO4/SiO2 （50%, by mass） composite are 82.3 kJ.kg i and 83.7 kJ.kg-1, and temperatures of melting and freezing are 886.0 ℃ and 880.6 ℃, respectively. Furthermore, the Na2SOJSiO2 composite maintains good thermal energy storage and release ability even after 100 cycles of melting and freezing. The satisfactory thermal storage performance renders this composite a versatile tool for high-temperature thermal energy storage.     

Effect of different additives on the phase separation behavior and thermodynamics of p-tert-alkylphenoxy poly (oxyethylene) ether in absence and presence of drug

Cloud point(CP) determinations of 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol(TX-100(nonionic surfactant)) was carried out in aqueous as well as in the attendance of drug(ceftriaxone sodium trihydrate(CFT))/(CFT + different inorganic salts) and discussed thoroughly. Nonionic surfactants are employed extensively in different formulations. In aqueous solution, the values of CP of TX-100 are obtained to increase by means of enhancing of their concentration in the solution. The CP values of TX-100 solutions were found to decrease in the presence of drug and their values decrease more with rising concentrations of the drug. The values of CP of CFT and TX-100 mixtures were found to further decrease in the attendance of inorganic salts in comparison to their absence. The effect of different sodium salts in decreasing CP values of TX-100 was achieved in the following order: NaCO_3 Na_2SO_4 Na Cl. However, in the case of potassium and ammonium salts, the decreasing order obtained is K_2SO_4 KCO_3 KCl and(NH4)2 SO_4 Na_2CO_3 NH_4Cl respectively. Various thermodynamic parameters for example standard free energy(ΔG_c~Θ), standard enthalpy(ΔH_c~Θ) as well as standard entropy(Δ Sc?)changes of phase separation were also evaluated and discussed in detail on the basis of their behavior.     

Hot-corrosion of silicon carbide in combustion gases at temperatures above the dew point of salts

To evaluate the performance of SiC to operating environments expected in future ceramic gas turbines, SiC samples were exposed in a low velocity burner rig at temperatures above the dew point of sodium sulphate (Na₂SO₄). Under these conditions, the corrosion behaviour should be independent of the sulphur content of the fuel, if Na₂SO_4(g) is not involved in the corrosion process. At 1000°C, SiC degradation was dependent on the sulphur levels in the fuel and the rates were controlled by the properties of the glassy corrosion products. Although there was an effect of P_SO3 on a_Na2O at 1300°C, the formation of an inner crystalline silica layer protected the material in both combustion gases so that the effect of p_SO3 on corrosion was concealed. These results indicate that Na₂SO_4(g) is involved in the corrosion process at temperatures above the dew point, contrary to what might be predicted from thermodynamic considerations. The role of sodium on enhancing the rate of corrosion is discussed.     

Chemical activation of blended cements made with lime and natural pozzolans

This paper deals with the chemical activation of lime-pozzolan cement (LPC), which consists of 80% natural pozzolan and 20% hydrated lime (by mass). Results show that the addition of 4% Na₂SO₄ can significantly improve the early strength of this cement. The presence of 4% flake calcium chloride (CaCl₂.2H₂O) is not helpful to early strength, but can increase the later strength substantially. CaSO₄.O.5H₂O and NaCl do not demonstrate an obvious effect on the strength development of the cement. Combination of activators, such as CaCl₂.2H₂O+Na₂SO₄ or Na₂SO₄+NaCl does not improve the activation effect; pastes with 2% Na₂SO₄+2% NaCl show lower strength than the pastes with 2% Na₂SO₄ alone.     

Phase equilibria for salt-induced lysozyme precipitation: Effect of salt concentration and pH

The salt-induced precipitation of lysozyme from aqueous solutions was studied at 25 °C and various pH values by cloud-point investigations, precipitation experiments (analysing the compositions of the coexisting phases) and microscopic investigations of the precipitates. Sodium sulphate as well as ammonium sulphate were used to induce the precipitation. The experimental results are discussed and used to develop a scheme of the phase equilibrium in water-rich aqueous solutions of lysozyme and either Na₂SO₄ or (NH₄)₂SO₄.     

PRECIPITATION IN THE Mg+2-Na+-SO3-2-SO4-2 AQUEOUS SYSTEM

Spontaneous precipitation in the aqueous system Mg₊₂-Na₊-SO₃^-2-SO₄^-2 affected by mixing solutions of MgSO₄ and Na₂SO₃, together was studied for temperature varying from 40 to 80°C and for pH from 5,5 to 9. The initial composition of a precipitating system was 0·67 and 1·17 mol of MgSO₃ and Na₂SO₄ per liter and 0·82 mol of MgSO₃ and Na₂SO₄ together with 0·83 mol of MgSO₄ per liter, respectively. Depending on the prevailing reaction conditions, solid phase consisting of MgSO₃ 6H₂O, MgSO₃ 3H₂O, Mg₂NaOH(SO₃)₂ H₂O or their mixture is formed. Each solid phase forms crystals of typical size and shape. The precipitation diagrams drawn in the temperature and pH coordinates for three different initial composition of the studied system are presented.     

模拟城市垃圾焚烧中硫化合物对重金属Cd迁移分布的影响

The effect of sulfur compounds （including sulfur, sulfide, sulfite and sulfate）, initial concentration of heavy metal and operating conditions on Cd emission in municipal solid waste （MSW） incineration were investi-gated using a simulated tubular furnace and simulated MSW spiked with Cd. The concentration of Cd was meas-ured by inductively coupled plasma-atomic emission spectrometry （ICP-AES） after digesting the samples including bottom ash, fly ash and flue gas according to related USEPA methods. The results show that S and Na2S tend to in- crease Cd partitioning in bottom ash, whereas Na2SO3 and Na2SO4 tend to reduce Cd partitioning in bottom ash. The effect of sulfur compounds on Cd partitioning in bottom ash was in the sequence of Na2S〉S〉Na2SO3〉 Na2SO4. chemical equilibrium analysis is also performed to determine the effect of sorbents on Cd adsorption. The calculations show that S presents strong affinity for Cd and restrains Cd adsorption by SiO2, whereas when temperature rises to between 830℃ and 1030℃, Cd adsorption efficiency of SiO2 is over 80% and the efficiency of Al2O3 is up to 85%.     

Fabrication of anti-fouling polyamide nanofiltration membrane by incorporating streptomycin as a novel co-monomer

Polyamide (PA) thin-film composite (TFC) nanofiltration (NF) membrane has extremely broad application prospects in separation of monovalent/divalent inorganic salts mixed solution. However, membrane fouling is the main obstacle to the application of PA, TFC and NF membrane. Streptomycin (SM) is a hydrophilic antibiotic containing a large number of hydroxyl and amino groups. In this work, the NF membrane was prepared via interfacial polymerization (IP) between trimesoyl chloride (TMC) in the organicphaseand SM/piperazine (PIP) mixture in theaqueousphase. The NF membrane structure and performance were characterized in detail. The results showed that SM successfully participated in the IP. The negative charge and hydrophilicity of membrane surface were improved. The prepared membrane exhibited good anti-adhesion and anti-bacterial performance. Additionally, when the SM concentration was 2%, the prepared membrane exhibited the optimal permselectivity. The water permeance was 89.4 L·m^-2·h^-1·MPa^-1. The rejection of NaCl and Na₂SO₄ were 17.17% and 97.84%, respectively. The NaCl/Na₂SO₄ separation factor of the SM2-PIP/TMC membrane in 1000 mg·L^-1 NaCl and 1000 mg·L^-1 Na₂SO₄ mixed solution was 40, which was 3.3 times that of PIP/TMC membrane. It indicated that SM2-PIP/TMC demonstrated excellent monovalent/divalent salts separation performance. This work provided an easy and effective approach to preparing anti-fouling NF membrane while possessing superior monovalent/divalent salts separation performance.