Single and combined deactivating effect of alkali metals and HCl on commercial SCR catalysts

Two commercial SCR catalysts, with a nominal W content of about 9 wt.% and a V nominal content of 0.55 and 1.8 wt.%, respectively, were contacted with different amounts of Na and K and with HCl vapours in order to simulate poisoning by species more specifically contained in exhaust gases from MSW combustion. Catalysts were characterised using XRD analysis, SEM/EDX analysis, BET and pore size distribution measurements, NH₃ TPD, TG analysis. Poisoning agents do not cause loss of surface area nor pore occlusion. A significant loss of surface acidity was observed upon alkali metals poisoning whereas a decreasing of vanadium content was observed for the more concentrated catalysts upon HCl poisoning. Catalysts deactivation is proportional to the number of acid sites neutralised by alkali metals adsorbing ammonia in the temperature range typical of SCR process. HCl promotes the formation of new acid sites showing a lower activity compared to the original one.     

Preparation,characterization and in vitro drug release properties of polytrimethylene carbonate/polyadipic anhydride blend microspheres

Polyadipic anhydride (PAA), an aliphatic polyanhydride, and polytrimethylene carbonate (PTMC), an aliphatic polycarbonate, were synthesized via ring opening polymerization of oxepan‐2,7‐dione and melt‐condensation of trimethylene carbonate (1,3 dioxan‐2‐one), respectively. PTMC–PAA blend microspheres containing different ratios of buprenorphine HCl (2, 5, and 10%) were prepared by an oil‐in‐oil emulsion solvent removal method. Microspheres with different ratios of PTMC–PAA (85/15, 70/30, and 55/45) containing 5% buprenorphine HCl were prepared. Microspheres were spherical with visible cracks and pores on the surface. The average particle size of microspheres was around 200 μm for all microspheres. Drug loading efficiency of PTMC–PAA microspheres (85/15, 70/30, and 55/45) was 97.2, 95.2, and 70.2%, respectively. With the increase in the PTMC ratio, the melting point and the enthalpy of melting were both decreased. The mechanism for drug release from PTMC–PAA blend microspheres were generally a combination of drug diffusion through polymers and biodegradation of the polymers. In first three days, the release from microspheres followed zero order kinetics and was dependent on the PAA content. After three days the drug release from microspheres followed first order kinetics. In conclusion it was demonstrated that buprenorphine HCl release from microspheres could be successfully controlled by using different ratios of PTMC–PAA blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2377–2383, 2006     

The inhibitive effect of poly(p‐toluidine) on corrosion of iron in 1M HCL solutions

In recent years, polymer amines have been recognized as an excellent corrosion inhibitors for iron in acid solutions. In this work, the inhibitive effect of p‐toluidine and poly(p‐toluidine) on corrosion of iron in 1M HCl has been studied by the electrochemical methods such as impedance, linear polarization, Tafel polarization techniques. The effectiveness of poly(p‐toluidine) was found to be high in comparison with that of monomer. The results showed that p‐toluidine and poly(p‐toluidine) suppressed both cathodic and anodic processes of iron dissolution in 1M HCl. The inhibition efficiency of both p‐toluidine and poly(p‐toluidine) were found to increase with the inhibitor concentrations. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

浅谈电厂凝汽器应用化学清洗的优点

叙述了凝汽器铜管化学清洗的优点和在清洗过程中必须注意的几个问题，并且用实例进一步说明化学清洗还能够有效防止凝汽器铜管的腐蚀     

聚四氟乙烯在烃化器上的应用

应用四氟衬里技术，成功地解决AlCl3液相法制乙苯存在的HCI对烃化器的腐蚀。     

Corrosion of Three Commercial Steels Under ZnCl2 –KCl Deposits in a Reducing Atmosphere Containing HCl and H2S at 400–500°C

The corrosion of three commercial steels in a reducing atmosphere containing HCl plus H₂S in the presence of ZnCl₂–KCl deposits has been investigated at 400–500°C and compared with the corrosion of the same materials in a similar gas mixture free from H₂S. The presence of H₂S in the gas accelerated the corrosion of the three commercial steels beneath ZnCl₂–KCl deposits. All materials suffered from severe corrosion with partial detachment and spalling of the external scales. Degradation of the steels resulted from the penetration of chlorine-containing species through the scale formed initially down to the metal matrix, because chorine-rich species were detected close to the alloy/scale interface. Although the corrosion resistance generally increased with increasing Cr content, even the high-Cr stainless steel SS304 is still unable to provide good corrosion resistance against the ZnCl₂–KCl deposits in the presence of H₂S due to the bad adherence of the scales to the alloy. The mechanisms of attack are discussed on the basis of thermodynamic considerations and of the active-oxidation model.     

Low Temperature Dechlorination of Densified Refuse Derived Fuel in Pyrolysis

Study on behavior of chlorine contained in oval-shaped densified refuse derived fuel (d-RDF) prepared from municipal solid waste in pyrolysis was carried out by means of temperature-programmed electrical furnace, and the gas evolving from pyrolysis was investigated by FFIR. De-HC1 rate was calculated by determining the emission fraction of HC1 in the flue gas and the fraction of C1 left in the pyrolysis residue. The results show that C1 in the d-RDF releases primarily in the form of HC1 during the pyrolysis, and the initial releasing temperature of HC1 enhances with the increase of heating rate. Meanwhile, the higher the end temperature of pyrolysis, the more the C1 released. De-HCl rate is about 70% when the end temperature of pyrolysis is around 600℃. Besides, mechanism of C1 release is discussed.     

~(13)C,~(15)N_3-盐酸氨基脲合成方法的优化

采用13C,15N2双标记尿素和15N2标记水合肼为原料,经回流反应一步合成13C,15N3-盐酸氨基脲。通过单因素考察和正交实验对13C,15N3-盐酸氨基脲的合成工艺进行优化,得到最优反应条件为:15N2-水合肼与13C,15N2-尿素的进料摩尔比为1.4∶1,加热温度为135℃,反应时间为4.5 h。采用此优化合成条件单步合成反应收率90%,13C,15N3-盐酸氨基脲纯度≥98%,13C丰度≥97%,15N丰度≥99%。结果显示,该方法具有反应周期短,产物收率高,后处理简便易行等优点。     

Innovation of novel ‘Tab in Tab’ system for release modulation of milnacipran HCl: optimization,formulation and in vitro investigations

The study was aimed toward development of modified release oral drug delivery system for highly water soluble drug, Milnacipran HCl (MH). Novel Tablet in Tablet system (TITs) comprising immediate and extended release dose of MH in different parts was fabricated. The outer shell was composed of admixture of MH, lactose and novel herbal disintegrant obtained from seeds of Lepidium sativum. In the inner core, MH was matrixed with blend of hydrophilic (Benecel^®) and hydrophobic (Compritol^®) polymers. 3² full factorial design and an artificial neuron network (ANN) were employed for correlating effect of independent variables on dependent variables. The TITs were characterized for pharmacopoeial specifications, in vitro drug release, SEM, drug release kinetics and FTIR study. The release pattern of MH from batch A10 containing 25.17% w/w Benecel^® and 8.21% w/w of Compritol^® exhibited drug release pattern close proximal to the ideal theoretical profile (t_50% = 5.92?h, t_75% = 11.9?h, t_90% = 18.11 h). The phenomenon of drug release was further explained by concept of percolation and the role of Benecel^® and Compritol^® in drug release retardation was studied. The normalized error obtained from ANN was less, compared with the multiple regression analysis, and exhibits the higher accuracy in prediction. The results of short-term stability study revealed stable chataracteristics of TITs. SEM study of TITs at different dissolution time points confirmed both diffusion and erosion mechanisms to be operative during drug release from the batch A10. Novel TITs can be a succesful once a day delivery system for highly water soluble drugs.     

Mucoadhesive liposomes as ocular delivery system: physical,microbiological, and in vivo assessment

Background: Mucoadhesive drug delivery is a promising strategy to overcome ocular biopharmaceutical constraints. Objective and methods: Ciprofloxacin HCl-loaded reverse phase evaporation liposomes were coated with different concentrations and molecular weights of mucoadhesive biocompatible chitosan polymer to form chitosomes. This colloidal mucoadhesive system was evaluated in vitro and in vivo with respect to deliver the antibiotic to ocular surface. Results and conclusion: The results obtained pointed out that liposome coating process resulted in entrapment efficiency reduction and higher chitosan concentration, and molecular weight showed a more pronounced effect. No morphological differences between coated and uncoated liposomes were observed. Diffusion was the drug release mechanism from chitosomes. Concerning rheological behavior, pseudoplastic flow was characteristic to the prepared chitosomal dispersions. In addition, chitosan coating improved the ocular permeation of ciprofloxacin HCl. Microbiologically; this formulated system enhanced antimicrobial activity of ciprofloxacin HCl against both Gram-positive and Gram-negative bacteria. Moreover, this mucoadhesive system was able to inhibit the growth of Pseudomonas aeruginosa in rabbits' eyes for 24 hours when compared to the marketed preparation. In vivo bacterial conjunctivitis model elucidated that symptoms were controlled by the prolonged release formulation such as that done by the marketed product.