New Preparation and Purification Methods for Metallo-Supramolecular Block Copolymers

The bis-complex formation of two terpyridine-modified polymers using microwave assisted reaction conditions was investigated in detail. In order to construct a heteroleptic block copolymer polystyrene, which was prepared by nitroxide-mediated radical polymerization (NMRP), and a commercial available poly(ethylene oxide) were used. These studies include the influence of temperature, reaction time, concentration and the use of different solvent mixtures on complexation. The conversion was determined by GPC measurements. The amphiphilic metallo-supramolecular block copolymers were investigated towards their formation of micellar aggregates in water. Other characterization techniques include ¹H-NMR, UV/vis spectroscopy, dynamic light scattering (DLS), atomic force spectroscopy (AFM) and transmission electron microscopy (TEM) techniques. This paper is dedicated to Professor Ian Manners for his scientific contributions to inorganic and organometallic polymers.     

Effect of calcination conditions on the species formed and the reduction behavior of the cobalt–magnesia catalysts

The structural characteristics and the reduction behavior of the Co/MgO catalysts were investigated using temperature‐programmed reduction (TPR) and X‐ray diffraction (XRD). The variables investigated included the preparation method and the heat treatment conditions (calcination temperature and time). Depending on these factors, one, two or three of the following Co‐containing species, Co₃O₄, MgCo₂O₄ and (Co, Mg)O (solid solution of CoO and MgO) were identified. The extent of solid solution formation increased as the calcination temperature and calcination time increased. A much lower calcination temperature was needed to form a solid solution in the impregnated catalysts than in the physically mixed ones. The formation of a solid solution rendered the catalyst less reducible. Finally, the decomposition of CH₄, as a probe reaction, was performed and it was found that the amount of carbon deposited decreased with increasing extent of solid solution formation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Poly(styrene-alt-maleic anhydride)-4-aminophenol conjugate: synthesis and antibacterial activity

Poly(styrene-alt-maleic anhydride) (SMA) may be conveniently used as an intermediate in preparing functional polymers since active agents containing amino or hydroxy groups can be linked to it via ring-opening reaction. In this study, SMA was reacted with 4-aminophenol (AP) to obtain SMA–AP conjugate. The glass transition temperature (218 °C) of the polymer was higher than that of SMA (202 °C) due to intermolecular hydrogen bonding. The polymer underwent thermal degradation in two steps where the initial weight loss began to occur at about 230 °C due to the formation of acid anhydride bonds with loss of water. SMA-AP exhibited bactericidal activity against E. coli and S. aureus, but it did not show any inhibition zone against the bacteria cells. No free AP was detected from the polymer incubated under similar conditions. Therefore, it was concluded that SMA–AP may be a bactericidal material by itself and its bactericidal activity may last for a fairly long period of time under neutral conditions.     

Catalysts based in cerium oxide for wet oxidation of acrylic acid in the prevention of environmental risks

Acrylic acid is a refractory compound for the non-catalytic wet oxidation (WO) process and can seriously damage the environment when released in industrial effluents. Oxidation of acrylic acid by catalytic wet oxidation (CWO) was studied in slurry conditions in a high-pressure batch reactor at 200 °C and 15 bar of oxygen partial pressure. Several solid cerium-based catalysts prepared in our laboratory were used (Ag/Ce, Co/Ce, Mn/Ce, CeO, MnO) and evaluated in terms of activity, selectivity and stability. Mn/Ce shows the higher activity in 2 h with 97.7% reduction of total organic carbon (TOC) followed by: MnO(95.5%)>Ag/Ce(85.0%)>Co/Ce(65.1%)>CeO(61.2%). Attempts were also carried out to analyze the influence of different Mn/Ce molar ratios. High percentages of Mn lead to practically total organic carbon concentration (TOC) abatements while low ratios lead to the formation of non-oxidizable compounds. Acrylic acid was readily degraded by all the catalysts pointing out the high importance of using a catalytic process. pH was an indicator of the reaction pathway and acetic acid was found as the major reaction intermediate compound; however it is completely oxidized after 2 h with exception for Co/Ce, CeO and MnO. Carbon adsorption and leaching of metals were poorly found for Mn/Ce indicating high stability. The catalyst microstructure after the reaction was analyzed and formation of whiskers of β-MnO₂ (or less probably MnOOH) were observed at the catalyst surface. Therefore, Mn/Ce revealed to be a promising catalyst for the treatment of effluents containing acrylic acid; nevertheless, its commercialization depends on further research.     

Influence of an annealing treatment on the solid‐state grafting of styrene onto spherical isotactic polypropylene granules

The main place of solid‐state graft polymerization in polypropylene (PP) granules has been believed to be the amorphous region of PP. In this work, the solid‐phase morphology of nascent spherical PP (N‐PP) granules was found to be markedly changed by an annealing treatment. The crystallinity of PP granules was almost doubled after annealing at 150°C for 12 h, whereas the porosity of the granules was unchanged. Solid‐state grafting polymerizations of styrene initiated by tert‐butyl perbenzoate in both N‐PP and annealed polypropylene (A‐PP) granules were compared under different reaction conditions. The formation of gel in the product could be completely depressed at a low concentration of the initiator when A‐PP granules were used as the matrix and graft‐polymerized at 120°C. Both the introduction of styrene and the annealing treatment of the PP granules led to a depression of polymer degradation in the process of the grafting reaction. However, using A‐PP as the matrix caused an increase in the grafting degree at a relatively high concentration of the initiator. A reduction in the amorphous phase in the PP granules was thought to be the main reason for the effects of the annealing treatment on the structure of the graft polymerization products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cerium(IV)-mediated electrochemical oxidation process for destruction of organic pollutants in a batch and a continuous flow reactor

The mediated electrochemical oxidation (MEO) process with Ce(IV) and nitric acid as the oxidizing medium was employed for the destruction of various model organic pollutants in batch and continuous organic feeding modes. A near complete destruction was observed for all the model organic pollutants studied. The effects of organic concentration, temperature, concentration of Ce(IV), concentration of nitric acid and feeding time on the organic destruction efficiency were investigated. Under the experimental conditions of 80 °C and 0.95 M Ce(IV) in 3 M nitric acid, nearly 90% destruction was achieved based on CO₂ production and 95% based on TOC and COD nearly for all the organic compounds studied in batch organic addition. In the case of continuous organic addition with in situ electroregeneration of Ce(IV) by the electrochemical cell a good destruction efficiency was obtained. For long term organic feeding (120 min) the destruction efficiency was found to be 85% based on CO₂ evolution and 98–99% based on TOC and COD analyses. A model was proposed for calculating the CO₂ formation constant during the continuous process of organic addition. The model predicted a steady state CO₂ evolution pattern for the destruction process during continuous organic feeding. The experimental results obtained confirmed the predicted trends for the destruction process. The changes in enthalpy, entropy, activation energy and free energy for EDTA degradation were found to be 26.7 kJ/mol, −230 J/(mol·K), 29.7 kJ/mol, and 118 kJ/mol respectively.     

Organometallic polymers. V. Synthesis and properties of metallocene-modified polymers

The reaction of metallocenes with solutions of polydienes and halogenated polymers, under Friedel-Crafts conditions, has now been applied to the surface modification of solid polymer films. The reaction of ferrocene with chlorinated polyethylene films appears to proceed by a fast substitution step followed by a slower diffusion-controlled step. The stress–strain curves of surface-modified films, as well as of solution-cast polymetallocene films, have been examined by means of a bursting-strength apparatus. The weathering behavior of metallocene-modified polymers has been studied in both natural and accelerated conditions. Studies on the effect of ageing on composition and properties by spectrophotometric and mechanical measurements indicate that the photooxidative resistance of polymers is improved significantly by metallocene modification. Additionally, modified films have been found to be effective as clear shields for the protection of vulnerable substrates against photodegradation. The observed darkening of the irradiated films could be due to a thermal reaction between metallocene and photolytically generated macroperoxides.     

Radical polymerization of acrylamide initiated by ceric ammonium nitrate-methionine redox initiator system

The polymerization of acrylamide, initiated by a cerium (IV) [Ce(IV)] ammonium nitrate-methionine redox initiator system, was carried out in an aqueous solution at different reaction conditions. The dependence of molecular weight and polymerization yield on the concentration of Ce(IV), polymerization time, and temperature was determined. The molecular weight distributions (MWD) of the resulting polymers were examined using the HPLC method. Based on the HPLC results, optimum reaction conditions were determined that provided an opportunity to obtain a polymer that had a narrow MWD. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1643–1648, 1997     

On the Optical Activity of Poly(l-lactic acid) (PLLA) Oligomers and Polymer: Detection of Multiple Cotton Effect on Thin PLLA Solid Film Loaded with Two Dyes

Optical rotatory dispersion (ORD) is a beautiful analytical technique for the study of chiral molecules and polymers. In this study, ORD was applied successfully to follow the degree of polycondensation of l-(+)-lactic acid toward the formation of poly(lactic acid) oligomers (PLAO) and high molecular weight poly(l-lactic acid) (PLLA) in a simple esterification reaction equipment. PLLA is a biodegradable polymer obtainable from renewable raw materials. The racemization of the intrinsically isotactic PLLA through thermal treatment can be easily followed through the use of ORD spectroscopy. Organic or molecular electronics is a hot topic dealing with the combination of π-conjugated organic compounds and polymers with specific properties (e.g., chirality) which can be exploited to construct optoelectronic devices, such as organic light-emitting diodes (OLEDs), organic photovoltaic (OPV) high efficiency cells, switchable chirality devices, organic field-effect transistors (OFETs), and so on. ORD spectroscopy was applied to study either the gigantic optical rotation of PLLA films, as well as to detect successfully the excitonic coupling, occurring in thin solid PLLA green film loaded with a combination of two dyes: SY96 (a pyrazolone dye) and PB16 (the metal-free phthalocyanine pigment). The latter compound PLLA loaded with SY96 and PB16 shows a really gigantic optical activity in addition to typical ORD signal due to exciton coupling and may be considered as a simple and easily accessible model composite of a chiral polymer matrix combined with π-conjugated dyes for molecular electronics studies.     

Photoreactor design and CFD modelling of a UV/H2O2 process for distillery wastewater treatment

A pseudo‐kinetic model for the treatment of a distillery wastewater by the ultraviolet irradiation and hydrogen peroxide process in a continuous tubular photoreactor is developed. There is a scarcity of information on modelling of organic degradation rates based on chemical oxygen demand (COD) and total organic carbon (TOC) in advanced oxidation technologies (AOTs). In this study, the COD and TOC are used as surrogate parameters to design a photoreactor instead of individual concentrations of species. The rate constants for the reaction between COD and TOC with hydroxyl radicals were determined to be 4.9 × 10⁹ and 5.0 × 10⁶ M^?1 s^?1, respectively. A laminar flow model was simulated to estimate the velocity and residence time of the medium in a cylindrical photoreactor. The model was validated by the experimental data published in the open literature for different concentrations of H₂O₂ (1, 10, and 100 mM), COD (589, 709, and 850 mg O₂ L^?1), and TOC (190, 200, and 192 mg C L^?1). The optimal value of the inlet hydrogen peroxide concentration was predicted to be 400 mg L^?1. Axial and radial concentration distributions of species in the photoreactor were also obtained. At different photoreactor radii (from 50 to 200 mm), the values of radial local volumetric rate of energy absorption (LVREA) were estimated. It was found that a higher LVREA was achieved in the photoreactor space at smaller radii. © 2011 Canadian Society for Chemical Engineering     

Fourier‐transform infrared spectroscopic study of plasticization effects on the photodegradation of poly(fluorostyrene) isomers films

The photodegradation of poly(fluorostyrene) isomers with different amounts of phthalate and terephthalate plasticizers has been investigated with the aid of Fourier‐transform infrared spectroscopy. Photo irradiation was carried out with light from a Hydrogen‐Xenon lamp at 265 nm and 293 K. As irradiation time increased, changes occurred in the structure of the polymers due to the destruction of polymeric chains and the formation of new photo products during the degradation. The photo products caused shifts, an increase or decrease of the polymer vibrational frequencies, as well as changes in numerous infrared band intensities. The increase in the intensities of the analyzed ranges is attributed to the formation of carbonyl, hydroxyl, and aliphatic ketones and to the increase in the number of polyene structures that resulted from hydrogen abstraction during photodegradation reactions. The analysis of the Fourier‐transform infrared spectra of the irradiated and nonirradiated samples showed a noticeable formation of a new broad band centered at (1,727 cm^?1, C=O), assigned to the growth of aliphatic ketones formerly from the reaction of reactive alkoxy radicals. Its intensity was found to increase with the increase in irradiation time and also with the increase in the amount of added terephthalate and phthalates plasticizer, indicating an increase in the efficiency of the photo degradation process. Trends of photostability of these isomers were found such that poly(para‐fluorostyrene) > poly(meta‐fluorostyrene) > poly(ortho‐fluorostyrene). The photodegradation process for these plasticized isomers was found to increase by the increase in the bulkiness of the plasticizer molecule . J. VINYL ADDIT. TECHNOL., 24:75–83, 2018. © 2015 Society of Plastics Engineers     

Different photodegradation processes of PVC with different average degrees of polymerization

The influence of ultraviolet (UV)‐irradiation on the photodegradation mechanism of different average degrees of polymerization (DP ) of poly(vinyl) chloride (PVC) with UV‐irradiation time was investigated by viscosity‐average molecular weight determination, UV‐vis spectroscopy, Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), contact angle measurement, and scanning electron microscopy (SEM). PVC films with different DP (800, 1000, 1300, 3000) were prepared by solution casting. It was carried out exposing specimens to a xenon‐arc light source with a spectral irradiance of 0.68 W/(m² ·nm) at 63°C. It was found that the photodegradation mechanism of the lower DP of PVC (DP = 1000) was different from the higher DP of PVC (DP = 3000). This was because the lower DP of PVC was a homopolymer, while the higher DP of PVC was often produced by copolymerizing with a certain quantity of crosslinking agent (e.g., DAP and DAM). UV‐vis and FTIR spectroscopy studies provided some results concerning the structure of the irradiated PVC, and the carbonyl index and C? Cl index were induced to study the process of PVC photodegradation with different DP . TGA showed that the degradation temperatures of different weight loss increased with the irradiation time. The surface morphology of the irradiated polymer films with different DP was observed by contact angle measurement and SEM. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

反应条件对玉米秸秆水热液化产物分布及特性的影响

利用间歇式生物质水热液化反应釜,通过正交试验设计考察不同反应条件对玉米秸秆水热液化(HTL)的影响,过程参数包括反应温度(250～350℃),反应时间(0～60 min)和含固量(5％～15％).从元素组成、官能团分布、主要化学成分以及结构形貌等对玉米秸秆水热液化产物的特性进行了分析.研究结果表明:玉米秸秆水热液化的较...     

Low-Temperature Dilute Acid Hydrolysis of Oil Palm Frond

Oil palm frond (OPF) fiber, a lignocellulosic waste from the palm oil industry, contains high cellulose and hemicellulose content, thus it is a potential feedstock for simple sugars production. This paper describes the two-stage hydrolysis process focusing on the use of low-temperature dilute acid hydrolysis to convert the hemicellulose in OPF fiber to simple sugars (xylose, arabinose, and glucose). The objective of the present study was to evaluate the effect of operating conditions of dilute sulfuric acid hydrolysis undertaken in a 1 L self-built batch reactor on xylose production from OPF fiber. The reaction conditions were temperatures (100–140°C), acid concentrations (2–6%), and reaction times (30–240 min). The mass ratio of solid/liquid was kept at 1:30. Analysis of the three main sugars glucose, xylose, and arabinose were determined using high-pressure liquid chromatography. The optimum reaction temperature, reaction time, and acid concentration were found to be 120°C, 120 min, and 2% acid, respectively. Based on the potential amount of xylose (10.8 mg/mL), 94% conversion (10.15 mg/mL) was obtained under the optimum conditions with small amount of furfural (0.016 mg/mL). To enhance the effectiveness of dilute acid hydrolysis, the hydrolysis of OPF fiber was also performed using ultrasonic-pretreated OPF fiber. The effects of ultrasonic parameters power (40–80%) and ultrasonication times (20–60 min) were determined on sugar yields under optimum hydrolysis conditions (2% acid sulfuric, 120°C and 120 min). However, the use of ultrasonication was found to have detrimental effect on the yield of simple sugars due to the 10-fold increase in the formation of furfural.     

Fenton试剂对垃圾渗滤液中腐殖质的氧化/混凝作用

采用Fenton试剂处理反渗透浓缩垃圾渗滤液,通过COD,TOC,UV254以及COD/TOC等表征手段考察氧化/混凝作用对COD和腐殖质去除效果的影响。结果表明,Fenton试剂对浓缩渗滤液中腐殖质去除（11.9 % ~ 89.5 %）高于总COD去除（9.6 % ~ 75.2 %）;渗滤液中腐殖质降解和COD去除具有较好的相关性。混凝作用（CODcoag,HScoag）受氧化作用（CODoxid,HSoxid）的影响并与之相反,氧化作用越大,混凝作用越小。(COD/TOC)oxid变化表明,在[H₂O₂]>80 mmol.L^-1,pH=2.0~4.0, [Fe ²⁺ ]=40~160 mmol.L^-1,反应时间2 h的实验条件下,渗滤液中有完全氧化过程发生,同时(COD/TOC)coag的变化说明经混凝作用去除的有机物氧化态高于其它实验区间。     

Behaviour of natural organic mater during ultrasonic irradiation

Ultrasonic irradiation has been one of the advanced oxidation methods for natural organic matter (NOM) removal. Its application simplicity and no production of toxic by-products make the system attractive. It has been shown that high power ultrasound produces strong cavitation in aqueous solution causing shock wave and reactive free radicals by the violent collapse of the cavitation bubble. These effects should contribute to the physical disruption and inactivation of microbial structures as well as to the decomposition of toxic chemicals in the water. The objective of this research was to investigate the effectiveness of low frequency – high power sonication for NOM removal (measured by both means of UV₂₅₄ absorbance and TOC) as well as controlling DBPs formation by varying irradiation time, light intensity, NOM concentration. Temperature, pH, conductivity, redox potential, and turbidity were monitored to evaluate the experimental study. The results indicate a strong capacity of sonication for NOM removal. The preliminary experiments showed that NOM removal is influenced by the intensity and time of sonication. Ultrasound, applied under such conditions, may be a realistic possibility for large-scale treatment; however, further studies should be performed to evaluate its effectiveness on different water sources.     

Photooxidative degradation of carboxylated poly(vinyl chloride)

Thin films of poly(vinyl chloride), PVC, and carboxylated poly(vinyl chloride), C-PVC, containing 1.8% of carboxyl groups were exposed to high energy ultraviolet radiation (λ = 254 nm) in laboratory conditions. The photochemical reactions in irradiated samples were studied by FTIR and UV–Vis spectroscopy, gel permeation chromatography and gravimetric estimation of insoluble gel. It was found that photodegradation and photocrosslinking in C-PVC is accelerated, whereas photodehydrochlorination is retarded comparing to these processes in PVC. Photooxidation investigated on the base of reaction leading to formation of hydroxyl groups is also more efficient in modified PVC. However, the total amount of carbonyl groups is much lower in UV-irradiated C-PVC than that in PVC. It indicates that competitive reactions (destruction of carboxyl groups and formation of new carbonyls) occur simultaneously in C-PVC chains. The influence of carbonyl groups on photochemical processes can be explained by an efficient Norrish I and II reactions as well as by energy transfer from absorbing species to weak chemical bonds.     

Poly(vinylpyrrolidone) as a tool: aqueous dispersion of nanodiamonds by wrapping in the solid state

Among carbon‐based nanomaterials such as fullerenes, carbon nanotubes and nanodiamonds, the latter are good candidates as prospective materials in the future due to their potential physical, chemical and biological properties. Thus, nanodiamonds were wrapped with biocompatible polymers in the solid state. The dispersibility of the polymer‐wrapped nanodiamonds in water was investigated with respect to reaction time and mass ratio of the polymers during the wrapping process. The dispersibility of the materials was monitored using UV spectroscopy, and the size distribution of the polymer‐wrapped nanodiamonds was analyzed using high‐resolution transmission electron microscopy and dynamic light scattering measurements. In addition, molecular modeling calculations were performed. Finally, the best dispersion for the polymer‐wrapped nanodiamonds in water was found for a reaction time of 120 min. Copyright © 2012 Society of Chemical Industry     

Tannin antioxidant characteristics in leather versus leather light stability: Models

The variation of leather color as a function of aging time on prolonged irradiation with UV light of the leather produced by tanning with different polyflavonoid and hydrolyzable vegetable tannins is reported. A predictive model and two equations for the variation of leather color as a function of UV‐irradiation time and as a function of the different vegetable tannins used was also established. This technique appears to describe well the overall phenomenon of oxidation and color change in situ observable in vegetable‐tanned leathers. The variation of leather color as a function of aging time on prolonged irradiation with UV light of the leather produced based on different vegetable tannins was found to be composed of two main effects: The first one of these is the darkening reaction of the leather. This is due to the formation of quinones on the phenolic structure of the vegetable tannin. The second one is the leather‐lightening reaction due to the photodegradation of the system. These two phases were equated and correlated with the radical uptake reaction and radical stabilization/decay reaction observed by ESR for UV‐irradiation of pure tannin in the solid form and of the leather produced using the same. Thus, correlation among the antioxidant capability of tannins in the solid form, their antioxidant capability once included in the leather, and the color variation (darkening and lightening) of leather by colorimetry was established. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1030–1040, 2004     

强化混凝处理碎煤加压气化废水生化水中有机物的实验研究

碎煤加压气化废水生化出水分别用混凝剂PAC和PFC进行强化混凝处理,考察出水有机物（TOC）的去除率.结果表明,采用强化混凝工艺可有效降低水中的有机物,随着混凝剂加药量的增大,有机物的去除率升高,并且使用PFC的效果要优于使用PAC的效果.PAC和PFC分别对应不同的最优混凝水力条件,采用PFC的最优混凝水力条件为混合转速100 r/min,混合时间3 min,反应转速60 r/min,反应时间30 min;采用PAC的最优混凝水力条件为混合转速100 r/min,混合时间0.5 min,反应转速60 r/min,反应时间30 min.