Effect of PVC on low-polar isobutylene polymerization in the presence of BCl3

Summary The low-polar polymerization of isobutylene (IB) in the presence of BCI₃ was carried out in CH₂Cl₂ ([IB]=7 mol/l) at -78, -20 and +20°C in the presence of vinyl chloride/2-chloropropene (VC/2CP) copolymer, representing PVC resin enriched in structures with chlorine atoms bonded to the tertiary carbons. The polymerization products consist of mixtures of polyisobutylenes (PIB) and grafted VC/2CP-g-PIB copolymer. Attention was focused on evaluation of the extent of the grafting reaction. VC/2CP-g-PIB was analyzed by GPC, ¹H-NMR and ¹³C-NMR spectroscopies and elemental analysis. The results obtained indicate that the rate of polymerization of IB decreases with increasing temperature but that the grafting efficiency increases. The experiments demonstrated that the VC/2CP copolymer induces strong grafting, compared with PVC, and that it might therefore be assumed that the C-Cl bonds with chlorine atoms bound to tertiary carbons directly initiate the polymerization of IB. The effect of the C-Cl bonds is discussed in terms of their catalytic and initiation activities.     

Effect of PVC on low-polar isobutylene polymerization in the presence of BCl3

Summary The isobutylene polymerizations in the presence of BCl₃ were carried out in dichloromethane ([M]=7 mol/l) at-20°C in the presence and absence of PVC. The products of polymerizations in the absence of PVC are oligoisobutylenes with a narrow molecular weight distribution ; their structure was analyzed by ¹H-NMR spectroscopy. In addition to the signals assigned to known unsaturated terminal structures [ 4.62 and 4.82-CH₂C(CH₃)=CH₂, 5.12-CH=C(CH₃)₂], a new intense signal was found at 5.09 ppm and assigned to the structure-CH=C(CH₃)CH₂CH₃. A mixture of isobutylene homopolymers and PVC grafted with isobutylene (approx. 9.5% wt. isobutylene grafted) is formed in the presence of PVC.     

Living carbocationic polymerization of isobutylene by tert-amyl alcohol/BCl3/1-methyl-2-pyrrolidinone initiating system

1-Methyl-2-pyrrolidinone has been investigated, for the first time, as an efficient electronpair donor in conjunction with tert-amyl alcohol and BCl₃ in CH₂Cl₂ diluent at ?40°C for the living polymerization of isobutylene. The use of this new monofunctional initiator -trans fer (minifer) system has led to the synthesis of low molecular weight, living (near-monodisperse) polyisobutylenes carrying “ethyl” head group and “tert-chloro” end group (asymmetric telechelic polyisobutylenes). The nature of these groups was confirmed by ¹H-NMR spectroscopy. The living nature of the α-ethyl-ω-(tert-chloro)polyisobutylenes has been demonstrated by a linear plot, passing through the origin, of number-average molecular weight (M?_n) vs. the amount of polymer formed (W_p) and a horizontal N (number of polyisobutylene molecules) vs. W_p plot. These results are further substantiated by gel permeation chromatography data of these polymers, and the molecular weight distributions of these polymers are narrow (low M?_w/M?_n = 1.1–1.2). The initiating efficiencies (I_eff) are close to 100% with this system. Dehydrochlorination of the prepolymer has yielded an isopropylidene (exo-olefin) end group. Structure of the end group in the resulting polymer, α-ethyl-ω-(isopropenyl)polyisobutylene, was confirmed by FTIR spectroscopy.     

Living polymerization of isobutylene initiated byp-dicumyl chloride/BCl3/n-Bu4NX systems

Summary The 1,4-di-(2-chloro-2-propyl)-benzene (pDCC)/BCl₃/IB system was investigated in the presence and absence ofn-Bu₄NX. The presence ofn-Bu₄NX (X=Cl or I) changes the mechanism increasing the living character of the polymerization of isobutylene in both cases. Whenn-Bu₄NCl is added, BCl₄ ^– is formed and as a common ion in excess it shifts the dissociation equilibrium toward the non-dissociated species. In the case of the addition ofn-Bu₄NI, an exchange reaction between the gegenions, i.e., BCl₄ ^– and BCl₃I^– has been recognised and a possible reaction mechanism is given.     

Investigation of 1,3,5-tris(2-metoxypropane)benzene/BCl3 initiated living isobutylene polymerization by C13 and B11 NMR spectroscopy

Summary The living carbocationic polymerization of isobutylene initiated by 1,3,5-tris(2-methoxypropane) benzene (TriCumOMe)/BCl₃ system was investigated by C¹³ and B¹¹ NMR spectroscopy. The reaction between the TriCumOMe and BCl₃ at-30°C in CH₂Cl₂ after 15 mins reaction time resulted in 1,3,5-tris(2-chloropropane) benzene (TriCumCl) and methyl-dichloroboronite (BCl₂OMe). The same system in the presence of isobutylene yielded three-arm star, chlorine terminated telechelic polyisobutylene and BCl₂OMe. No counterions, i.e., BCl₃OMe, BCl ₄ , or neutral boron complexes, e.g., TriCumOMe, 3BCl₃ could be detected. The simultaneous measurement of static permittivity (direct monitoring method) showed different reaction rate patterns in the case of AMI method, and when the TriCumOMe+BCl₃ mixture was aged and the polymerization was started by isobutylene.     

Enhanced Bactericidal Effect of O3/H2O2 Followed by Cl2

With the appearance of chlorine resistant microorganisms such as Cryptosporidium parvum and Giardia lamblia in drinking water, significant attention has been drawn to the sequential application of multiple disinfectants including ozone, chlorine dioxide, and UV as a primary disinfectant. However, few studies have reported about the inactivation behavior of ozone-based AOP (advanced oxidation process) or its sequential application combined with other disinfectants. This is especially important since ozone itself experiences difficulty in the inactivation of these pathogens, especially at low temperatures: This study investigates the enhanced inactivation of Bacillus subtilis spores by the presence of an OH radical in the O₃/H₂O₂ system and the synergistically enhanced inactivation in the application of the O₃/H₂O₂ system followed by Cl₂. The results suggest that the O₃/H₂O₂ process can be considered as one of the viable alternatives when O₃ alone does not satisfy the disinfection requirement.     

废水阴离子化学组分对O3/H2O2降解TNT功效的影响

结合实际三硝基甲苯(TNT)废水的水质状况,选择HCO3-、NO3、HCOO、MnO4、SO42-及C1-等为代表性污染组分,以TNT去除率及反应速率常数为评价指标,开展了阴离子对O3/H2O2降解TNT功效影响的实验研究.结果表明,废水中阴离子对O3/H2O2降解TNT功效的影响,与离子种类及浓度的关系密切,HCO3-、HCOO、MnO4-等对O3/H2O2降解TNT具有抑制作用,且随浓度的增加而加强,抑制作用能力HCOO＞HCO3-＞MnO4-,而NO3、SO42-及Cl-等对O3/H2O2降解TNT作用功效几乎没有影响HCOO-、HCO3-可能影响O3/H2O2体系中·OH的形成,MnO4-既影响·OH的形成又影响其寿命,使O3/H2O2降解TNT的功效降低.     

The Effect of CO2 and H2O on the Kinetics of NO Reduction by CH4 Over Sr-Promoted La2O3

The influence of CO₂ and H₂O on the activity of 4% Sr-La₂O₃ mimics that observed with pure La₂O₃, and a reversible inhibition of the rate is observed. CO₂ causes a greater effect, with decreases in rate of about 65% with O₂ present and 90% in its absence, while with H₂O in the feed, the rate decreased around 35-40% with O₂ present or absent. The influence of these two reaction products on kinetic behavior can be described by assuming competitive adsorption on the surface, incorporating adsorbed CO₂ and H₂O in the site balance, and using rate expressions previously proposed for this reaction over Sr-promoted La₂O₃. In the absence of O₂, the rate expression is $$r_{N_2 } = \frac{{k'P_{{\text{NO}}} P_{{\text{CH}}_{\text{4}} } }}{{{\text{(1 + }}K_{{\text{NO}}} P_{{\text{NO}}} {\text{ + }}K_{{\text{CH}}_{\text{4}} } P_{{\text{CH}}_{\text{4}} } {\text{ + }}K_{{\text{CO}}_{\text{2}} } P_{{\text{CO}}_{\text{2}} } {\text{ + }}K_{{\text{H}}_{\text{2}} {\text{O}}} P_{{\text{H}}_{\text{2}} {\text{O}}} {\text{)}}^{\text{2}} }},$$ which yields a good fit to the experimental data and gives optimized equilibrium adsorption constants that demonstrate thermodynamic consistency. With O₂ in the feed, nondifferential changes in reactant concentrations through the reactor bed were accounted for by assuming integral reactor behavior and simultaneously considering both CH₄ combustion and CH₄ reduction of NO, which provided the following rate law for total CH₄ disappearance: $$(r_{{\text{CH}}_{\text{4}} } )_{\text{T}} = \frac{{k'_{{\text{com}}} P_{{\text{CH}}_{\text{4}} } P_{{\text{O}}_{\text{2}} }^{{\text{0}}{\text{.5}}} + k'_{{\text{NO}}} P_{{\text{NO}}} P_{{\text{CH}}_{\text{4}} } P_{{\text{O}}_{\text{2}} }^{{\text{0}}{\text{.5}}} }}{{{\text{(1 + }}K_{{\text{NO}}} P_{{\text{NO}}} {\text{ + }}K_{{\text{CH}}_{\text{4}} } P_{{\text{CH}}_{\text{4}} } {\text{ + }}K_{{\text{O}}_{\text{2}} }^{{\text{0}}{\text{.5}}} P_{{\text{O}}_{\text{2}} }^{{\text{0}}{\text{.5}}} {\text{ + }}K_{{\text{CO}}_{\text{2}} } P_{{\text{CO}}_{\text{2}} } {\text{ + }}K_{{\text{H}}_{\text{2}} {\text{O}}} P_{{\text{H}}_{\text{2}} {\text{O}}} {\text{)}}^{\text{2}} }}.$$ The second term of this expression represents N₂ formation, and it again fit the experimental data well. The fitting constants in the denominator, which correspond to equilibrium adsorption constants, were not only thermodynamically consistent but also provided entropies and enthalpies of adsorption that were similar to values obtained with other La₂O₃-based catalysts. Apparent activation energies typically ranged from 23 to 28 kcal/mol with O₂ absent and 31-36 kcal/mol with O₂ in the feed. With CO₂ in the feed, but no O₂, the activation energy for the formation of a methyl group via interaction of CH₄ with adsorbed NO was determined to be 35 kcal/mol.     

TNT的O3/H2O2降解规律

利用自制装置,采用连续投加O3、H2O2的方式,研究了O。／H：O：对废水中TNT的降解规律。结果表明,与Oa作用相比,O3／H2O2工艺可显著提高TNT的降解率,还可避免中间产物的形成与积累;在试验研究条件下,H2O2：O3的最优摩尔比为1,最佳初始pH值在11左右,利用缓冲溶液可维持反应体系pH值的稳定,但不利于O3／H2O2功效的发挥,反应适合在常温下进行,尽量避开40℃左右;动力学特征分析表明,O／H2O2降解TNT偏离伪一级反应动力学规律。     

废水溶液化学组分对O3/H2O2降解TNT的影响

O3/H2O2作用功效是通过羟基自由基(.OH)反应实现的。水溶液的化学组分可能影响.OH的形成或寿命,即影响O3/H2O2作用功效。然而,目前研究多集中于单一化学组分,对多组分体系的研究鲜见报道。该文以三硝基甲苯(TNT)废水为例,选择HCO3-、HCOO-、Cu2+及A l3+等化学组分,以TNT去除率及反应速率常数的改变为评价指标,研究了废水溶液化学组分对O3/H2O2降解TNT功效影响的联合作用。结果表明,(1)废水溶液化学组分对O3/H2O2降解TNT功效的影响因组分种类而异,HCO3-、HCOO-、Cu2+对O3/H2O2作用功效具有抑制作用,A l3+具有促进作用;(2)不同组分间可以不同的联合作用方式影响O3/H2O2的作用功效,如HCO3-与HCOO-之间为协同作用,Cu2+与HCOO-之间为独立作用,A l3+与HCOO-之间可近似认为是相加作用。     

BCl_3–C_3H_6–H_2体系的热力学相图研究(英文)

利用 FactSage software 软件计算了 BCl3–C3H6–H2体系的热力学相图,分析了反应气体分压、系统总压以及沉积温度对热力学相图中固相产物种类、分布区域及面积的影响规律与作用机制。结果表明:(1)系统总压是影响相图中固相产物种类、分布区域及其面积的最主要因素。随系统总压升高,固相产物由简到繁,相图内 B 单质区域的面积增加,B+B4C 及 B4C+C 区域面积减小,B4C 区域面积变化不明显,各区域明显右移;相图内气态区域面积增加。(2)反应气体分压影响相图中固相产物的元素含量。随 C3H6分压增加,固相产物由 B 含量高的产物向 C 含量高的产物转变,即由B单质或 B+B4C 向 B4C+C 转变。(3)在 800～1 200 ℃,沉积温度对相图中产物种类及分布的作用不明显,沉积过程不受热力学控制。     

Supported BF3 catalyst on crystalline polyolefins; carbocationic polymerization of isobutylene

Summary This paper describes a new supported Lewis acid catalyst which involves BF₃ species chemically bonded to the crystalline polyolefins, such as polypropylene and poly(1-butene). The supported catalysts are active in the carbocationic polymerization of isobutylene and are recovered and reused for many reaction cycles without significantly losing their activity. Several advantages, such as chemical and physical stabilities of the substrate, convenient implantation to load high concentration of catalyst to the substrate and high catalyst reactivity, have been observed. In addition, polyisobutylene obtained in this process has high terminal unsaturation.     

Degradation Effect and Mechanism of Dinitrotoluene Wastewater by Magnetic Nano-Fe3O4/H2O2 Fenton-like

The characteristics and influencing factors for dinitrotoluene degradation by nano-Fe₃O₄-H₂O₂ were studied, and the nano-scale Fe₃O₄ catalyst was prepared by the coprecipitation method, with dinitrotoluene wastewater as the degradation object. The results showed that the catalytic reaction system within the pH value range of 1 to 9 could effectively degrade dinitrotoluene, and the optimal pH value was 3; with the increase of catalyst dosage, the degradation efficiency and the catalytic reaction rate of dinitrotoluene grew as well. The optimal catalyst dosage was 1.0 g/L when the H₂O₂ dosage was within the range of 0 to 0.8 mL/L; the degradation efficiency and reaction rate grew with the increase of H₂O₂ dosage. With further increase of H₂O₂ dosage, degradation efficiency and reaction rate decreased; under the best conditions with the H₂O₂ dosage of 0.8 mL/L, the catalyst concentration of 1 g/L and the pH value of 3 at room temperature (25 °C), the degradation rate of the 100-mg/L dinitrotoluene in 120 min reached 97.6%. Through the use of the probe compounds n-butyl alcohol and benzoquinone, it was proved that the oxidation activity species in the nano-Fe₃O₄-H₂O₂ catalytic system were mainly hydroxyl radical (?OH) and superoxide radicals (HO2 ?), based on which, the reaction mechanism was hypothesized.     

Modeling of polymerization reactions. I. The cationic polymerization of isobutylene by aluminum organic compounds

This paper describes the development of a mathematical model for the polymerization of isobutylene initiated with Et₂AlCl + Cl₂. Previous experiments have shown that this polymerization is “kinetically living”. A computer analysis based on our mathematical model permits the calculation of the theoretical conversion–time curves, the molecular weight averages, and polydispersity. The good agreement between experimental and theoretical results suggests that the reaction mechanism proposed and the mathematical model derived are quite correct.     

Bactericidal Effectiveness of O3, O3/H2O2 and O3/TiO2 on Clostridium perfringens

The purpose of this research is to evaluate the bactericidal capacity of different Advanced Oxidation Treatments (AOTs) based on ozone: ozone, ozone/hydrogen peroxide and ozone/titanium dioxide on a wild strain of Clostridium perfringens, a fecal bacterial indicator in drinking water. The dose of ozone consumed ranges from 0.6 mg L^?1 min^?1 to 5.13 mg L^?1 min^?1 depending on the process and on the sample. In the treatments combined with O₃, H₂O₂ dose utilized is 0.04 mM and TiO₂ dose, 1 g L^?1. In order to evaluate the influence of natural organic matter and suspension solids over the disinfection rate, treatments are performed with two types of water – natural water from Ebro River (Zaragoza, Spain) and NaCl solution 0.9%. To achieve 4 log units of inactivation, 3.6 mg O₃ L^?1 is necessary in O₃ treatment, 4.25 mg O₃ L^?1 in O₃/TiO₂ system and 2.7 mg O₃ L^?1 in O₃/H₂O₂ after processing the natural water. In NaCl solution, to get the same inactivation, 0.42 mg O₃ L^?1 is necessary in O₃ treatment, 1.15 mg O₃ L^?1 in O₃/TiO₂ system and 0.06 mg O₃ L^?1 in O₃/H₂O₂ process. Even though the three treatments studied have a high bactericidal activity due to the number of surviving bacteria decreases to non-detectable levels, O₃/H₂O₂ is the most effective system for eliminating C. perfringens cells in a lower contact time, followed by O₃ and finally O₃/TiO₂ system.     

O3/H2O2协同氧化法预处理石化废水的实验研究

采用O3/H2O2法对含高浓度酚的石化废水进行了实验研究,对单独O3法和O3/H2O2法的处理效果进行了比较。结果表明:O3/H2O2法的处理效果优于单独O3法;在pH为10,反应时间为40 min,O3流量为4 g/h,H2O2投加量为30 mmol/L条件下,废水中的挥发酚和COD的去除率分别达到96.79%和76.78%,B/C由原来的0.067提高到0.380。     

A cost-effective process for highly reactive polyisobutylenes via cationic polymerization coinitiated by AlCl3

The initiating system consisting of AlCl₃ with dialkyl ether such as di-n-butyl ether or diisopropyl ether has been successfully developed for providing a cost-effective process of synthesis of highly reactive polyisobutylenes (HRPIBs) with large proportion of exo-olefin end groups up to 93 mol% at temperatures ranging from −20 to +20 °C. The above dialkyl ethers played very important roles in promoting the directly rapid β-proton elimination from -CH₃ of the growing chain ends to create exo-olefin end groups and decreasing or even suppressing the carbenium ion rearrangements to form the double bond isomers. Very importantly, the highly reactive PIBs with 80-92 mol% of exo-olefin end groups, having low M_ns of 1300-2300 g mol⁻¹ and monomodal molecular weight distribution (M_w/M_n = 1.7-2.0) could be achieved at 0-20 °C. These results are comparable to those of commercial HRPIBs produced industrially by the best BF₃-based initiating system at far below 0 °C.     

Decomposition of Carboxylic Acids in Water by O3, O3/H2O2, and O3/Catalyst

This paper studies the decomposition of formic, oxalic and maleic acids by O₃, O₃/catalyst, and O₃/H₂O₂. The catalytic effect of Co²⁺, Ni²⁺, Cu²⁺, Mn²⁺, Zn²⁺, Cr³⁺, and Fe²⁺ ions is investigated. The results showed that—Co²⁺ and Mn²⁺ have the highest catalytic activity for the decomposition of oxalic acid while the catalytic effect of the studied ions is insignificant on the rate of decomposition of formic acid. Maleic acid decomposes by ozone into formic acid and glyoxylic acid, which subsequently oxidizes to oxalic acid. Though the studied ions have no effect on the decomposition of maleic acid, they have a significant effect on the produced oxalic and glyoxylic acids. In the presence of Cu²⁺ ions glyoxylic acid is mainly transformed into formic acid and traces of oxalic acid. In such case, a complete decomposition of maleic acid and its degradation products is achieved within 45 min. The results also show that combining H₂O₂ with O₃ results in an increase in the rate of decomposition of oxalic acid. However, O₃/H₂O₂ system is less active than O₃/Co²⁺ or O₃/Mn²⁺.     

Carbocationic polymerization of isobutylene by using supported Lewis acid catalyst on polypropylene

Summary This paper describes a new class of supported Lewis acid catalysts which are based on partially crystalline polypropylene. The Lewis acid, such as EtAlCl₂, is chemically bonded to the side chain of polypropylene and serves as catalyst for the cationic polymerization of isobutylene. This type supported catalyst can be easily recovered and reused for many reaction cycles without significant loss of its reactivity. The unique features of the structure of polypropylene offers the catalyst with high surface area and good mobility which account for the high catalytic activity. In addition, polypropylene is chemically and physically stable during the processes.