Time-Resolved Dynamics of Struvite Crystallization: Insights from the Macroscopic to Molecular Scale

The crystallization of magnesium ammonium phosphate hexahydrate (struvite) often occurs under conditions of fluid flow, yet the dynamics of struvite growth under these relevant environments has not been previously reported. In this study, we use a microfluidic device to evaluate the anisotropic growth of struvite crystals at variable flow rates and solution supersaturation. We show that bulk crystallization under quiescent conditions yields irreproducible data owing to the propensity of struvite to adopt defects in its crystal lattice, as well as fluctuations in pH that markedly impact crystal growth rates. Studies in microfluidic channels allow for time-resolved analysis of seeded growth along all three principle crystallographic directions and under highly controlled environments. After having first identified flow rates that differentiate diffusion and reaction limited growth regimes, we operated solely in the latter regime to extract the kinetic rates of struvite growth along the [100], [010], and [001] directions. In situ atomic force microscopy was used to obtain molecular level details of surface growth mechanisms. Our findings reveal a classical pathway of crystallization by monomer addition with the expected transition from growth by screw dislocations at low supersaturation to that of two-dimensional layer generation and spreading at high supersaturation. Collectively, these studies present a platform for assessing struvite crystallization under flow conditions and demonstrate how this approach is superior to measurements under quiescent conditions.     

Removal of Heavy Metals from Plating Wastewater by Crystallization/Precipitation of Gypsum

A high surface area was created during nucleation and crystal growth of gypsum by mixing calcium and sulfate ions, causing adsorption of heavy metals on the colloids of gypsum and capsulation in the subsequent precipitation process. In addition to the effect of surface area, zeta potential and surface pH of the gypsum colloids, ionic strength of solution, as well as solubility and particle size of the metal hydroxide influenced the extent of uptake of heavy metals from wastewater.     

液膜萃取法回收磷酸体系中的微量镧

通过斜率分析法研究了P204和TOPO从磷酸体系中液液萃取微量镧的反应机制和热力学,推测出一种可能的反应历程和萃合物结构,得到萃取反应式和反应的平衡常数K=104.502,焓变ΔH=-13.02 kJ.mol-1,自由能ΔG=-25.686 kJ.mol-1,熵变ΔS=0.0425kJ.(mol.K)-1。在液液萃取反应机制研究的基础上,采用液膜萃取法进行磷酸体系中微量镧的富集回收研究,考察了载体P204(2%～10%w/w)和TOPO(1%～10%w/w)、表面活性剂磺化聚丁二烯LYF(1%～10%w/w)、内萃取剂HCl(1～5 mol.L-1)和水乳体积比A/O(2:1～7:1)对液膜萃取收率及稳定性的影响。在最优条件下,可回收94.10%～95.94%的镧,并且膜溶胀率为8%～17%,破损率为0.45%～1.93%,能够维持较好的液膜稳定性。研究结果对磷酸中的微量稀土镧回收利用具有一定的参考价值。     

Recovery of Phosphate from Steel Manufacture Slag by Sulfuric Acid Treatment

The sulfuric acid treatment on steel manufacture slag (SMS) was performed to recover P resource. P element in SMS was successfully removed. Final products were a solid of CaSO 4 /SiO 2 and a solution containing PO 4 3 m , Fe, Al, Mg, and Mn.     

磷酸铵镁法回收稀土分离废水中镁及氨氮的研究

磷酸铵镁法是一种有效的回收氨氮、磷和镁的方法。本文通过热力学计算,分析了反应过程及pH值对磷酸铵镁生成的影响规律。根据理论分析结果,进行了pH值、磷源、加料方式等因素对氨氮、磷去除率的影响实验。结果表明:以Na3PO4为磷源,通过向氮磷混合液中加入含镁废水,并控制反应液pH值为9时,氮磷镁去除率均可达98%以上,得到沉淀物经X衍射分析为六水磷酸铵镁。     

镁铝二元水滑石的焙烧产物对染料废水酸性红88的吸附

研究了镁铝水滑石的焙烧产物(LDO)对阴离子染料废水酸性红88(AR88)的吸附特征。分别考察了染料的初始浓度、吸附剂投加量、初始pH值、反应温度和竞争离子等因素的影响,并用XRD、红外光谱对水滑石以及吸附前后的LDO进行了表征。实验结果表明：LDO对高浓度的AR88具有良好的去除效果,在15 ℃、pH=10～11下,1.0 g·L^-1的LDO对浓度为2 000 mg·L^-1的AR88的去除率可高达99.95%,吸附容量为1 999.0 mg·g^-1。经4次回收重复利用的LDO对AR88的去除率仍为90%以上。     

Separation of Emulsified Oil from Oily Wastewater by Functionalized Multiwalled Carbon Nanotubes

Rapid separation of emulsified oil from oily wastewater is one of the most serious challenges faced in the petroleum industry. In this study, a rapid and efficient demulsifier, functionalized multiwalled carbon nanotubes (F-MWCNTs), was prepared and used to separate the emulsified oil from oily wastewater. Demulsification test showed that the oil removal efficiency could attain as high as 99.8% at an optimal condition within a few minutes. The micro-morphology of the oil–water mixture before and after demulsification was observed using a polarizing microscope. It was found that the fine oil droplets experienced a rapid coalescence to form oil phase floating on the water surface. Mechanism of the demulsification process was discussed. The introduction of the functional groups (such as ?OH and ?COOH) on the surfaces of F-MWCNTs enable them good amphiphilicity and therefore easily arriving at the oil/water interface to destroy the interfacial protective film mainly composed of asphaltenes and resins. The findings in this work showed that the F-MWCNT is an efficient nanomaterial to remove emulsified oil from the oily wastewater and might have wide application prospects in the petroleum industry.     

Recovery of Acid and Alkaline from Industrial Saline Wastewater by Bipolar Membrane Electrodialysis under High-Chemical Oxygen Demand Concentration

Actual high saline wastewater containing concentrated organics and sodium chloride is a bioenergy and renewable resource. This study compared two different bipolar membrane electrodialysis membranes from two companies’ stacks to recover HCl and NaOH from sodium chloride solution and actual chemical wastewater. The results demonstrated that the electrolysis rates were around 1.5 kg/m²h, the HCl and NaOH production rates were about 0.9 kg/m²h, energy consumption was in the range of 1.05–1.27 kWh/kg, and the economic benefits were above 1 yuan/h in BMED systems. From analyzing the performance of seven different BMED membrane stacks, the B2 stack was chosen for electrolyzing actual high salt wastewater to observe the effect of chemical oxygen demand on BMED systems, where electrolytic salt performance, HCl-NaOH alkali production rates, and energy consumption show linear dependence on time for 5000 mg/L chemical oxygen demand wastewater. It illustrated chemical oxygen demand can enhance energy consumption and reduce electrolytic salt performance and the acid and alkali production rates, due to improving the membrane area resistance. In this study, the effect of high COD saline wastewater on the performance of a BMED membrane stack was clarified and the mechanism was analyzed for its practical application in treating chemical high salt wastewater.     

Removal of Naphthol Green B from Aqueous Solution by Calcined Layered Double Hydroxides:Adsorption Property and Mechanism Studies

The adsorption of naphthol green B (NGB) by Mg/Al‐LDO (layered double oxides) with a Mg/Al molar ratio of 3:1 was investigated in a batch mode. Our study indicates that the maximum capacity of NGB adsorption at equilibrium is 193.4 mg and the percentage of absorption is 96.7%, with an adsorbent dose of 1.0 g/L under the following condition: 200 mg/L NGB concentration, temperature 298 K, pH 10.0 and an equilibrium time of 80 min. Langmuir and Freundlich adsorption models were used for fitting the isotherms, and the thermodynamic parameters have been calculated, which showed that the adsorption process was spontaneous and exothermic in nature. In the light of so called "memory effect", the Mg/Al‐LDO was found to recover their original layered structure after adsorption, and part of NGB ions intercalated into the interlayer of LDH (layered double hydroxides), which has been supported by XRD and FTIR. In addition, the competitive anions for adsorption and the regeneration of Mg/Al‐LDO have also been investigated.     

高效液相色谱法测定化妆品中的维生素C及其衍生物

建立了化妆品中维生素C及其3种衍生物(抗坏血酸葡糖苷(AA-2G)、抗坏血酸磷酸酯镁(AA-2P)、抗坏血酸乙基醚(Only VCE))的高效液相色谱分析方法。化妆水、水乳液等含油脂较少的样品先采用30 mL 0.02 mol/L磷酸二氢钾溶液(pH 3.0)直接提取,然后定容至50 mL;面膏等含油脂较高及凝胶类、啫喱类的样品先加入1.0 mL二氯甲烷分散均匀后再加25 mL 0.02 mol/L磷酸二氢钾溶液(pH 3.0)提取。提取液在12000 r/min下离心后用0.22 μm滤膜过滤。样品分析采用YMC-Triart C18色谱柱,以0.02 mol/L磷酸二氢钾溶液(pH 3.0)和甲醇溶液为流动相,梯度洗脱,流速为1.0 mL/min,柱温为25 ℃,使用二极管阵列检测器(DAD)检测,检测波长为250 nm,外标法定量。结果显示:4种化合物在其线性范围内线性关系良好,相关系数(r²)均大于0.9999;方法的定量限(以信噪比为10计)为0.04~0.08 g/kg;添加水平为0.25~5.0 g/kg时的回收率为95.6%~101.0%,相对标准偏差为0.62%~3.0%。该方法前处理简单、回收率高、精密度好,适用于化妆品中维生素C及其衍生物的测定。     

Recovery of fortified (2 ppb) EPA method 525.1 analytes from Chesapeake Bay water via solid phase deposition followed by supercritical fluid elution

Application of solid phase deposition/supercitical fluid (SPD/SF) elution to real, brackish water samples, obtained from the Chesapeake Bay, has been investigated. The fortified (2ppb) brackish water samples contained suspended sediment, dissolved organic matter and salt. The sediment made post-deposition drying of the SPE disk difficult and the residual water interfered with analyte recovery. Attempts to dry the disk included increasing the vacuum drying time, use of a higher percent of modifier, and desiccation. The best results were obtained by first drying the disk for 10 min under a stream of nitrogen, followed by overnight desiccation, and finally, SF elution. The SF method required a 3 step, 42 min extraction which reduced organic solvent use by 60% compared to traditional elution. All but five analytes met EPA criteria when fresh desiccant was used to dry the disk; four of the unacceptable recoveries were presumably due to plasticizer contamination.     

硅铝比对完全液相法制备的一步法二甲醚合成催化剂反应性能的影响

采用完全液相法制备了不同Si/Al摩尔比的浆状一步法二甲醚合成催化荆,在搅拌式反应釜中对其催化性能进行了评价.通过XRD,NH3-TPD-MS,H2-TPR和XPS等方法表征了催化剂的体相结构和表面性质.结果表明,完全液相法制备的CuZnSiAl催化剂在反应前其活性组分Cu主要以低价态存在,Cu晶粒大小是影响其活性的主...     

UPLC-MS/MS结合多探针底物方法研究刺五加叶中黄酮苷类成分对CYP450活性的影响

利用超高效液相色谱-串联质谱联用(UPLC-MS/MS)的多反应监测(MRM)技术结合多探针底物方法, 研究了刺五加叶中的主要黄酮苷类化合物槲皮苷、金丝桃苷及芦丁对肝细胞色素P450酶(CYP450)亚型CYP1A2, CYP2C, CYP2E1, CYP2D和CYP3A活性的影响. 结果表明, 3种化合物对各CYP亚型酶均有抑制作用, 其中金丝桃苷和槲皮苷对CYP1A2催化的非那西丁的O-脱乙基反应抑制的IC₅₀值分别为46.53和49.75 μmol/L, 金丝桃苷和芦丁对CYP2E1催化的氯唑沙宗的6-羟基化反应抑制的IC₅₀值分别为99.87和86.36 μmol/L. 机理性抑制实验结果表明, 3种化合物对2种亚型酶的抑制作用是随着预孵时间延长而增强的机理性抑制.     

High quality drug screening by capillary electrophoresis: A review

High quality assays are needed in drug discovery to reduce the high attrition rate of lead compounds during primary screening. Capillary electrophoresis (CE) represents a versatile micro-separation technique for resolution of enzyme-catalyzed reactions, including substrate(s), product(s), cofactor(s) and their stereoisomers, which is needed for reliable characterization of biomolecular interactions in free solution. This review article provides a critical overview of new advances in CE for drug screening over the past five years involving biologically relevant enzymes of therapeutic interest, including transferases, hydrolases, oxidoreductases, and isomerases. The basic principles and major configurations in CE, as well as data processing methods needed for rigorous characterization of enzyme inhibition are described. New developments in functional screening of small molecules that modulate the activity of disease-related enzymes are also discussed. Although inhibition is a widely measured response in most enzyme assays, other important outcomes of ligand interactions on protein structure/function that impact the therapeutic potential of a drug will also be highlighted, such as enzyme stabilization, activation and/or catalytic uncoupling. CE offers a selective platform for drug screening that reduces false-positives while also enabling the analysis of low amounts of complex sample mixtures with minimal sample handling.