高镁铝合金在喷射成形过程中显微组织的变化

研究了高镁铝合金在喷射成形过程中显微组织的变化。沉积态高镁铝合金基体呈全部等轴晶组织并存在少量显微孔洞是沉积态组织的主要特征。分析了等轴晶组织和显微孔洞在喷射成形中生成的机制。     

酸性条件下剩余污泥中Ca2＋和Mg2＋溶出对磷回收的影响

为了在酸性条件下实现剩余污泥中磷的高效回收,对pH=3时剩余污泥水解酸化过程中氨氮、正磷酸盐和钙镁离子的溶出现象以及磷回收进行了研究分析。结果表明：当pH=3时,所溶出的氨氮、镁离子和钙离子与磷酸盐的摩尔比均大于1,能满足采用鸟粪石沉淀法或者羟磷灰石沉淀法回收磷的要求;但所溶出的钙镁离子的摩尔比大于1,会对鸟粪石沉淀法回收磷的顺利进行有较大影响;有无外加镁剂对磷回收率影响不大。采用改型后的镁型强酸性阳离子交换树脂进行离子交换可以得到较高纯度的鸟粪石沉淀产品,通过XRD检测其纯度为95％以上。     

两相UASB反应器处理含高浓度硫酸盐黑液

两相UASB反应器处理含高浓度硫酸盐黑液,酸化相为8.87L的普通升流式反应器,甲烷相为28.75L的UASB反应器,系统温度(35±1)℃。当酸化相进水COD为(6.771～11.057)g/L,SO42-为(5.648～8.669)g/L,pH值为5.5时,整个系统COD去除率平均值为74.42%;系统对负荷的冲击有较强的耐受能力。     

火焰原子吸收法测定地表水中钾钠钙镁的方法改进

用空气—乙炔火焰原子吸收测定地表水中钾钠钙镁时,将测钾钠用的消电离剂和测钙镁用的释放剂配成混合溶液,加入待测试样中,便可连续测定其中的钾钠钙镁。与现在常用的火焰原子吸收方法测得的结果一致,精密度和准确度符合规范要求,且方法简单快速。     

海洋硫酸盐还原菌群处理烟气脱硫废水

针对高盐硫酸根废水的特性,从海底沉积物中富集得到1个硫酸盐还原菌菌群SRB-2,并研究了盐度、温度、pH值、碳源、硫酸根浓度和铁形态对其活性的影响.结果表明,SRB-2为嗜盐中温硫酸盐还原菌群, 可以利用乙醇及乳酸为单一碳源,最佳生长温度为30～40℃,最佳生长pH值为7.4～8.3,SRB-2菌群能够在硫酸根浓度为5 200 mg/L或盐度为60　g/L的条件下正常生长,还原铁粉对该菌群还原硫酸根的能力具有加强作用,而二价铁离子则抑制细菌活性.扫描电子显微镜及光学显微镜对菌体形态研究发现,在反应器填料表面,该菌群中有大量短竿状及螺旋状细菌黏附,而在底部,主要为表面覆盖大量黑色粘稠物质,由短竿状细菌组成,推测其可能是菌种SRB-2-64（GenBank 序列号：EU167911）的堆积.     

Effects of seed aerosols on the growth of secondary organic aerosols from the photooxidation of toluene

Hydroxyl radical （.OH）-initiated photooxidation reaction of toluene was carried out in a self-made smog chamber. Four individual seed aerosols such as ammonium sulfate, ammonium nitrate, sodium silicate and calcium chloride, were introduced into the chamber to assess their influence on the growth of secondary organic aerosols （SOA）. It was found that the low concentration of seed aerosols might lead to high concentration of SOA particles. Seed aerosols would promote rates of SOA formation at the start of the reaction and inhibit its formation rate with prolonging the reaction time. In the case of ca. 9000 pt/cm^3 seed aerosol load, the addition of sodium silicate induced a same effect on the SOA formation as ammonium nitrate. The influence of the four individual seed aerosols on the generation of SOA decreased in the order of calcium chloride〉sodium silicate and ammonium nitrate〉ammonium sulfate.     

硫酸根对有机废水厌氧生物处理的影响

利用连续流上流式厌氧污泥床在控制和不控制H_2S浓度两种情况下,考察SO_4~(2-)对有机物厌氧生物处理的影响。试验表明,硫酸根本身对厌氧处理没有毒害作用,它对厌氧处理过程的破坏主要是其还原产物H_2S造成的。在用Fe~(2+)控制H_2S的情况下,硫酸根的存在和浓度大小对出水TOC、TOC去除率、产气量、气化率无不利影响,但会使气体中甲烷含量及甲烷产率逐渐减小而二氧化碳含量及二氧化碳产率逐渐增大,     

氧化镁基生物质炭高效去除水体中磷的特性

利用花生壳为前驱体,在高温限氧条件下,将氧化镁(MgO)负载于生物质炭(BC)表面制备出氧化镁基生物质炭(MgOBC)复合材料.系统研究了MgO-BC对水体中P的吸附特性,并探讨了溶液pH值、接触时间、竞争离子等因素对P的吸附效果的影响.结果表明,P的最佳吸附初始pH为7~9,过酸过碱的环境均不利于P的吸附;P的吸附过程可在540 min内达到平衡,且动力学曲线较好地符合伪一级和伪二级动力学模型,拟合系数可达97.3%和99.0%;当Cl~-、HCO_3~-、NO_3~-等共存离子的量浓度达到P的10倍时,MgO-BC对P仍具有较强的吸附能力;P的吸附过程较好地符合Langmuir等温模型,拟合系数达99%,理论最大吸附容量为138.07 mg·g~(-1),远高于其它未经改性或改性的生物质炭和几种典型P吸附剂的吸附容量.此外,吸附P后的复合材料可作为肥料施入土壤,可有效实现P的再利用.综上所述,该MgO-BC复合材料在净化实际P污染水体中有着广阔的应用前景.     

Thermal decomposition mechanism of 65% lysine sulfate powder and its thermal stability based on thermal analysis

Lysine is widely used in the fields of food, medicine and feed, which generally appears in the form of lysine sulfate or lysine hydrochloride dust because of the high instability of the free L-lysine. The L-lysine Sulfate is in high risk of decomposition, spontaneous ignition and even the dust explosion, because the control temperature in its production process is high up to 90 °C. Thus, the thermal behaviors and its thermal stability of 65% lysine sulfate are experimentally explored in Air and Nitrogen using the simultaneous TG-DSC measurements. Results show: (1) the decomposition of 65% lysine sulfate can be divided into three stages both in the atmospheres of air and nitrogen, and most of the weight loss occurred in the first two stages, which are related with the decarboxylation and deamination process. (2) The effects of atmosphere on the decomposition of 65% lysine sulfate mainly occur at the third stage. In this stage, the weight loss in nitrogen is only 14.2%, which is much lower than that in air (34.3%), which is related to the oxidative degradation at high temperature. Besides, the active energy is slightly increased in nitrogen compared to that in air. (3) The initial temperatures of the decomposition of the 65% lysine sulfate are 145 °C and 155 °C, for the air and nitrogen atmosphere, respectively, which are much lower than that (260 °C) of the pure lysine.     

Study of the influence of melamine polyphosphate and aluminum hydroxide on the flame propagation and explosion overpressure of aluminum magnesium alloy dust

When aluminum magnesium alloy dust floats in the air, a certain ignition energy can easily cause an accidental explosion. To prevent and control the occurrence of accidental explosions and reduce the severity of accidents, it is necessary to carry out research on the explosion suppression of aluminum magnesium alloy dust. This paper uses a vertical glass tube experimental device and a 20 L spherical explosive experimental device to carry out experimental studies on the suppression of the flame propagation and explosion overpressure of aluminum magnesium alloy dust with melamine polyphosphate (MPP) and Al(OH)₃. With increasing MPP and Al(OH)₃ concentrations, the flame brightness darkened, the flame velocity and propagation distance gradually decreased, and P_max and (dp/dt)_max decreased significantly. When the amount of MPP added reached 60%, the flame propagation distance decreased to 188 mm, which is a decrease of 68%, and the explosion overpressure decreased to 0.014 MPa, effectively suppressing the explosion of aluminum magnesium alloy dust. The experimental results showed that MPP was more effective than Al(OH)₃ in inhibiting the flame propagation and explosion overpressure of the aluminum magnesium alloy dust. Finally, the inhibitory mechanisms of the MPP and Al(OH)₃ were further investigated. The MPP and Al(OH)₃ endothermic decomposition produced an inert gas, diluted the oxygen concentration and trapped active radicals to terminate the combustion chain reaction.