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The molecular weight of polytetramethylene glycol (PTMG) prepared from tetrahydrofu-ran (THF) by using cocatalysts of BF3-etherate and epichlorohydrin (ECH) in the presence of butylene glycol(BG) increased sharply with the polymer conversion, but at yields higher than 80% but could be exactly controlled by the molar ratio of BG to BF3. The polyether obtained possessed around 70 mol% primaly hydrcxyl end-groups and a hydroxyl end-group functionality of two. The content of ECH derived units in each polymer chain containing 18.2 or 33.8THF derived units is around 1.60 or 2.16 respectively. 相似文献
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LaPO4纳米微粒的制备及表征 总被引:5,自引:0,他引:5
Surface-modified LaPO4 nanoparticales were synthesized in the mixture solvent of water-ethanol with the surface modification age of dialkylphosphate. The conditions of synthesis and characterization were discussed. The results indicated that nanoparticle core of LaPO4 and surface-modified layer were formed. The surface-modified nanoparticles of LaPO4 can be dispersed in organic solvent and has better lubricating properties. 相似文献
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纳米TiO2膜用于光催化氧化测定化学需氧量的研究 总被引:4,自引:0,他引:4
A photocatalytic oxidation method for determination of chemical oxygen demand (COD) using nano-TiO2 film, based on the use of a nano-TiO2-Ce(SO4)2 system and electrochemical detection, was proposed. The technique was originated from the direct determination of the Ce(Ⅲ) concentration change resulting from photocatalytic oxidation of organic compounds. Ce(Ⅲ), which was produced by photocatalytic reduction of Ce(SO4)2, could be measured at a multi-walled carbon nanotubes (MWNT) chemically modified electrode (CME). The COD values by this method were calculated from the differential pulse voltammetry (DPV) current of Ce(Ⅲ) at the CME. Under the optimal operation conditions, the detection limit of 0.5 mg·L^-1 COD with the linear range of 1-600 mg·L^-1 was achieved. This method was also applied to determination of various COD of ground water and wastewater samples. The resuits were in good agreement with those from the conventional COD methods, i.e., permanganate and dichromate ones. 相似文献