Degradation Of Acrylonitrile Research Articles

Fluorine promoted and silica supported TiO2 for photocatalytic decomposition of acrylonitrile under simulant solar light irradiation

Abstract The F doped TiO2/SiO2 composition oxides were prepared by sol–gel method using HF solution as fluorine source. The prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), ultraviolet–visible absorption spectroscopy (UV–Vis), photoluminescence spectroscopy (PL), Fourier transform infrared spectroscopy (FT-IR) and ammonia adsorption and temperature-programmed desorption (NH3-TPD). The photocatalytic activities of the powders for acrylonitrile degradation have been inspected. The results show that the presence of SiO2 as a support for TiO2 loading benefits the formation of the nanoparticles with a large surface. In situ IR and NH3-TPD investigation shows that the higher photocatalytic activity for F doped samples is attributed to the increase of number and strength of surface acid sites. The highest photcatalytic activity for acrylonitrile degradation is obtained for a sample calcined at 450 °C with molar ratio (HF to Ti) of 1.1 and 36% TiO2 loading. The degradation ratio of acrylonitrile can reach to 66% under simulant solar light for 6 min, indicating the effectiveness of photocatalytic degradation acrylonitrile using F doped TiO2/SiO2 composite oxide.

Synchrotron-based FTIR microspectroscopy for the mapping of photo-oxidation and additives in acrylonitrile–butadiene–styrene model samples and historical objects

Synchrotron-based Fourier transform infrared micro-spectroscopy (SR-μFTIR) was used to map photo-oxidative degradation of acrylonitrile–butadiene–styrene (ABS) and to investigate the presence and the migration of additives in historical samples from important Italian design objects. High resolution (3×3μm2) molecular maps were obtained by FTIR microspectroscopy in transmission mode, using a new method for the preparation of polymer thin sections. The depth of photo-oxidation in samples was evaluated and accompanied by the formation of ketones, aldehydes, esters, and unsaturated carbonyl compounds. This study demonstrates selective surface oxidation and a probable passivation of material against further degradation. In polymer fragments from design objects made of ABS from the 1960s, UV-stabilizers were detected and mapped, and microscopic inclusions of proteinaceous material were identified and mapped for the first time.

Optimization of photocatalytic process parameters for the degradation of acrylonitrile using Box Behnken Design

The present study involves the photocatalytic degradation of aqueous solution of acrylonitrile (ACN) which was carried out in a batch reactor under UV light. The degradation efficiency was evaluated with ZnO as a photocatalyst and hydrogen peroxide as an oxidant for a period of 5 h. The variables examined in this study included ZnO dose (0.5–3.0 g/L), pH (2–12), and H2O2 concentration (2.5–10 m mol/L). The rate of degradation was studied in terms of changes in concentration of the pollutant using spectrophotometry. The optimal values of operational parameters leading to degradation of ACN were obtained using Box Behnken design (BBD) under response surface methodology (RSM). The optimum conditions were found to be ZnO dose of 1.48 g/L; pH 7.0 and hydrogen peroxide (H2O2) concentration of 4.22 m mol/L. Under optimum condition, the degradation efficiency of ACN was found to be 89.6%. Optimization of photocatalytic process parameters for the degradation of ACN by BBD under RSM effectively copes with interaction between optimizing variables and its prediction agreed well with the experimental result.

Kinetic analysis of nonisothermal degradation of acrylonitrile–butadiene/ethylene–propylene–diene rubber blends reinforced with carbon black filler

AbstractThe nonisothermal degradation process of acrylonitrile–butadiene/ethylene–propylene–diene rubber blends reinforced with carbon black filler was investigated with thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG), using the different calculation procedures. Using different isoconversional methods, it was found that the degradation of the 50 phr loaded carbon black in NBR/EPDM (80/20) blend represents the complex process, where exists the conversion region with a constant value of the apparent activation energy (Ea). It was found that the degradation process of the carbon black‐loaded polymer blend under nitrogen atmosphere, can be described by the three‐(D3) dimensional diffusion mechanism. Good agreement was observed between the experimental and calculated differential (rate) conversion curves, for the investigated degradation process. It was established that the considered polymer blend which have high contents of the carbon black (50 phr carbon black), shows very strong self‐protective behavior (i.e., in the formation of a protective barrier). POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Thermal degradation of acrylonitrile–butadiene–styrene (ABS) containing flame retardants using a fluidized bed reactor: The effects of Ca-based additives on halogen removal

In this study, the thermal degradation of a waste fraction of acrylonitrile–butadiene–styrene containing brominated flame retardants was performed to reduce halogen content in the pyrolysis oil. Thermal degradation was completed using Ca-based additives (calcium oxide, calcium hydroxide and oyster shells) in a bench-scale pyrolysis plant equipped with a fluidized bed reactor and char separation system. Pyrolysis was carried out in a temperature range of 430–510°C. In the absence of any additive, the oil yield amounted to about 77wt.%. With the additives, the oil yield was markedly reduced to within a range of 45–64wt.%. The principle compounds in the oils were toluene, ethylbenzene, styrene, cumene, α-methylstyrene, phenol and heteroatom-containing compounds. When Ca(OH)2 was applied, total bromine and chlorine contents in the oil decreased to 0.05 and 0.04wt.%, respectively. In addition, Ca(OH)2 reduced the antimony content in the oil to below 0.001ppm. Most of the halogens and antimony in the feed material were present in the char obtained after pyrolysis.

Gas-phase photocatalytic oxidation of acrylonitrile

Photocatalytic oxidation (PCO) of acrylonitrile (AN) on titanium dioxide in the gaseous phase was studied. AN readily undergoes photocatalytic degradation in a gas-solid system by using TiO(2) Degussa P25. The AN PCO volatile products, visible in the infrared spectra, included nitrogen dioxide, nitrous oxide, carbon dioxide, water, hydrogen cyanide and carbon monoxide. Longer contact time resulted in deeper oxidation of AN with decreasing hydrogen cyanide and increasing nitrogen dioxide content. The effect of temperature increasing from 60 to 130 degrees C was observed to be slightly negative in terms of AN degradation rate. However, the effect of increased temperature was noticeable in terms of the character and yields of the PCO products: HCN peaks diminished with growing peaks of NO(2).

The impact of acrylonitrile and bioaugmentation on the biodegradation activity and bacterial community structure of a topsoil

The analysis of the bacterial community within the soil using DGGE showed acrylonitrile (ACN) could lead to the selection of significantly similar communities. Moreover, Rhodococcus sp. AJ270 was successfully established in the soil community. High GC G+-bacteria also responded positively to ACN addition. Bioaugmentation or carbon addition had no impact on the rate or degree of ACN degradation. ACN could be readily degraded by the soil bacteria, however, the community structure was significantly affected by its addition as well as by the addition of carbon or Rhodococcus sp. AJ270. The bioaugmentation of the soil with this strain was successful, in that the organism became established within the community. ACN addition to a soil produces statistically significant changes in the bacterial community.

Degradation of acrylonitrile–ammonium itaconate copolymers

AbstractAcrylonitrile–ammonium itaconate copolymers were prepared by H2O/dimethyl formamide suspension polymerization technique. Differential scanning calorimetry results of the degradation of acrylonitrile–ammonium itaconate copolymers in air are presented. The apparent activation energy of degradation of the copolymer was calculated using the Kissinger method. Effects of copolymerization conditions on the apparent activation energy of copolymer were studied. Increasing the dimethyl formamide concentration in the solvent mixture leads to a rapid increase in the degradation apparent activation energy of acrylonitrile–ammonium itaconate copolymer. The value of the degradation apparent activation energy of the copolymer synthesized in dimethyl formamide solvent increases up to 168.3 kJ mol−1. The apparent activation energy decreases quickly along with an increase in ammonium itaconate concentration, and this change becomes less prominent as the weight ratio of ammonium itaconate/acrylonitrile goes beyond 6/94, ΔEa = 89.4 ± 2.0 kJ mol−1. The apparent activation energy shows a trend of increase with increasing copolymerization temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1708–1711, 2005

Kinetic study of the degradation of acrylonitrile–acrylamide copolymers

AbstractDifferential scanning calorimetry was used to investigate the degradation of acrylonitrile–acrylamide copolymers in air. The apparent activation energy of degradation of the copolymers was calculated with the Kissinger method. The effects of the copolymerization conditions on the apparent activation energy of the copolymers were studied. Increasing the dimethylformamide concentration in the solvent mixture led to a rapid increase in the apparent activation energy of degradation of the acrylonitrile–acrylamide copolymers. The apparent activation energy decreased quickly as the comonomer acrylamide concentration increased, and this change became less prominent as the acrylamide/acrylonitrile weight ratio increased beyond 5/95. The apparent activation energy increased as the copolymerization temperature increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1017–1020, 2005

The individual and cumulative effect of brominated flame retardant and polyvinylchloride (PVC) on thermal degradation of acrylonitrile–butadiene–styrene (ABS) copolymer

Acrylonitrile–butadiene–styrene (ABS) copolymers without and with a polybrominated epoxy type flame retardant were thermally degraded at 450 °C alone (10 g) and mixed with polyvinylchloride (PVC) (8 g/2 g). Gaseous and liquid products of degradation were analysed by various gas chromatographic methods (GC with TCD, FID, AED, MSD) in order to determine the individual and cumulative effect of bromine and chlorine on the quality and quantity of degradation compounds. It was found that nitrogen, chlorine, bromine and oxygen are present as organic compounds in liquid products, their quantity depends on the pyrolysed polymer or polymer mixture. Bromophenol and dibromophenols were the main brominated compounds that come from the flame retardant. 1-Chloroethylbenzene was the main chlorine compound observed in liquid products. It was also determined that interactions appear at high temperatures during decomposition between the flame retardant, PVC and the ABS copolymer.

Thermal analysis of an acrylonitrile–butadiene–styrene/SWNT composite

Thermogravimetric analysis and differential thermal analysis were used to study the thermal degradation of acrylonitrile–butadiene–styrene/single-walled carbon nanotube composites under static air and nitrogen. For the dynamic analysis, two-step degradation was observed. Low concentrations of SWNTs (0.5 wt.%) tend to destabilize the first degradation step of ABS but reinforce it at the second step degradation. Further addition of SWNT, destabilizes the whole system by lowering both degradation peak temperatures. The activation energies of isothermal degradation were evaluated by using Freeman's model. Under both static air and nitrogen, the activation energy was lowered by the SWNTs. DSC analysis showed that the introduction of SWNTs increases the glass transition temperature of the composites and low concentration of SWNTs act as nucleating agents to the crystallization of ABS.

Thermal degradation of acrylonitrile–butadiene–styrene (ABS) blends

This work investigates the accelerated thermal degradation of acrylonitrile–butadiene–styrene (ABS) due to aging at elevated temperatures (>80 °C). The impact resistance is shown to decrease dramatically beyond a critical aging time at 120 °C and this reduction strongly depends on surface property modifications during aging. Visual examination of specimen cross-sections after aging, verifies that (dis)colouration is limited to a surface layer, which is characteristic of degradation where oxygen diffusion into the bulk is limited. Degradation is supported by chemiluminescence assessment, which shows a rapid depletion of residual stabiliser within this layer as compared to the bulk polymer. Micro-indentation measurements also indicate that degradation causes an increase in Young's modulus at the specimen surface, which in turn promotes brittle failure. It is proposed that a critical depth of degradation (approximately 0.08 mm) forms on the surface of ABS due to aging. Applied loading initiates microcracks in this degraded layer, which propagate rapidly, causing bulk failure. Absorbance bands from Fourier transform infra-red spectroscopy indicate that surface degradation proceeds by chain scission and cross-linking in the polybutadiene (PB) phase of aged ABS specimens. Cross-linking is also supported by positron annihilation lifetime spectroscopy, which shows a decrease in free volume sites at the surface of aged specimens. Dynamic mechanical thermal analysis also supports the occurrence of cross-linking, as shown by an increase in the glass transition temperature of the PB phase after aging. Although degradation in the styrene–acrylonitrile (SAN) phase is less significant to the reduction in overall mechanical properties of ABS compared to the PB phase, an assessment of SAN copolymer indicates that heat aging decreases impact resistance. The contribution of SAN to the overall mechanical properties of ABS is also reflected by aging ABS specimens at temperatures just below the glass transition of the SAN phase (∼112 °C). The mechanism of thermal degradation is shown to be non-Arrhenius and governed by diffusion-limited oxidation. The long-term impact strength of ABS at ambient temperature is extrapolated from short-term data at elevated temperatures. As temperature and aging time influence degradation, it is proposed that at ambient service temperatures (40 °C), the degradation mechanism differs to that at elevated temperatures, and comprises both surface and bulk polymer degradation effects.

Catalytic Degradation of Acrylonitrile−Butadiene−Styrene into Fuel Oil 1. The Effect of Iron Oxides on the Distribution of Nitrogen-Containing Compounds

The thermal and catalytic degradation of acrylonitrile−butadiene−styrene copolymer (ABS) was performed at 400 °C in static nitrogen atmosphere, by semibatch operation. γ-Fe2O3, an Fe3O4−C composite, and α-FeOOH were used as catalysts, in two contact modes: either mixed with the polymer or in contact with the volatile degradation products of ABS. All iron oxides decrease the concentration of nitrogen (N) in ABS degradation oil. Reactions in a flow-type reactor with 4-phenylbutyronitrile as model N-containing compound show that α-FeOOH is active at low temperatures (250−300 °C) in converting heavy N-containing compounds into light aliphatic nitriles. XRD analysis proved that during reaction α-FeOOH was transformed into Fe3O4 in several steps, with α-Fe2O3 as intermediary compound.

Catalytic Degradation of Acrylonitrile−Butadiene−Styrene into Fuel Oil 2. Changes in the Structure and Catalytic Activity of Iron Oxides

The changes in the structure and catalytic activity of three iron oxides (α-FeOOH, γ-Fe2O3, and an Fe3O4−C composite) were studied by temperature-programmed desorption/degradation (TPD) and XRD analysis. Thermal desorption analysis was performed for the fresh iron oxide catalysts. Thermal degradation experiments were performed for 4-phenylbutyronitrile as nitrogen-containing model compound adsorbed over α-FeOOH, fresh or prepared by heating at 280, 350, and 400 °C. TPD was also performed for acrylonitrile−butadiene−styrene copolymer (ABS) mixed with α-FeOOH. XRD analysis was performed after each TPD experiment. Catalytic degradation of 4-phenylbutyronitrile over α-FeOOH leads to formation of light aliphatic nitriles and styrene derivatives. Increasing the temperature, α-FeOOH catalyst gradually changes its composition and crystalline structure, with decreasing the catalytic activity. The changes are accompanied by elimination of water and oxygen and can be schematically represented as follows: α-FeOOH → α-Fe2O3 → Fe3O4. Iron oxide catalysts act mainly on the primary products of ABS thermal degradation, but they can also degrade the chain end or branched styrene units in the polymer.

Thermal degradation of acrylonitrile–butadiene–styrene terpolymer in bean oil

Thermal degradation of acrylonitrile–butadiene–styrene terpolymer (ABS) in bean oil has been carried out in the temperature 350 and 370°C. The degradation products have been investigated by means of gel permeation chromatography (GPC) and fourier transform infra-red spectrometry (FTIR). With the presence of bean oil, ABS thermally degrades into asphalt-like degradation residue, which is soluble in common organic solvent such as tetrahydrofuran (THF), instead of monomer and oligomers that are usually generated in direct pyrolysis of ABS. Moreover, for the system of ABS/bean oil the cross-linking reaction of ABS with bean oil takes place and forms a polymer network before the decomposition of ABS. Between the two reaction stages, the polymerization or oligomerization of sequence of adjacent nitrile groups occurs. The thermal degradation of ABS in bean oil was believed to be a radical process, which is dependent on the reaction condition, especially the concentration of bean oil, reaction temperature and time.

Effects of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile in aerobic submerged biofilter

The effects of coexistence-of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile (AN) in an aerobic submerged biofilter were investigated on the basis of kinetic and ecological studies. The experimental results show that the acclimation of microbial film to AN was promoted by a higher microbial concentration in the biofilter and by the coexistence of glucose and peptone in the influent. It was clarified that the upper limit of AN loading to the biofilter for the ultimate degradation, i.e., complete mineralization, of the influent AN was about 2.0-2.2 kg/m3. d. In addition, a new microbial quinone profile method was applied for the analysis of the microbial community change in the biofilter. The change in quinone profiles of the microbial film during the acclimation to AN suggested that Brevibacterium sp., Pseudomonas aeruginosa and Corynebacterium sp. could contribute to the degradation of AN in the aerobic biofilter.

Analysis of microbial acclimation to refractory chemicals in wastewater using respiratory quinone profiles

The effects of initial microbial concentration and the coexistence of biodegradable substrates on the acclimation of microbes to acrylonitrile (AN) was investigated in an aerobic submerged biofilter using respiratory quinone profiles. The acclimation of microbes to AN was accelerated by increased initial microbial concentrations in the biofilter and by the coexistence of glucose and peptone in the influent. The change in quinone profiles of microbial films during the course of acclimation suggested that Brevibacterium sp., Pseudomonas aeruginosa and Corynebacterium sp. contributed to the degradation of AN in the aerobic biofilter.

Analysis of microbial acclimation to refractory chemicals in wastewater using respiratory quinone profiles

The effects of initial microbial concentration and the coexistence of biodegradable substrates on the acclimation of microbes to acrylonitrile (AN) was investigated in an aerobic submerged biofilter using respiratory quinone profiles. The acclimation of microbes to AN was accelerated by increased initial microbial concentrations in the biofilter and by the coexistence of glucose and peptone in the influent. The change m quinone profiles of microbial films during the course of acclimation suggested that Brevibacterium sp., Pseiulomonas aeruginosa and Corynebacterium sp. contributed to the degradation of AN in the aerobic biofilter.

Effects of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile in aerobic submerged biofilter

The effects of coexistence-of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile (AN) in an aerobic submerged biofilter were investigated on the basis of kinetic and ecological studies. The experimental results show that the acclimation of microbial film to AN was promoted by a higher microbial concentration in the biofilter and by the coexistence of glucose and peptone in the influent. It was clarified that the upper limit of AN loading to the biofilter for the ultimate degradation, i.e., complete mineralization, of the influent AN was about 2.0–2.2 kg/m3. d. In addition, a new microbial quinone profile method was applied for the analysis of the microbial community change in the biofilter. The change in quinone profiles of the microbial film during the acclimation to AN suggested that Brevibacterium sp., Pseudomonas aeruginosa and Corynebacterium sp. could contribute to the degradation of AN in the aerobic biofilter.

The thermo–oxidative degradation of acrylonitrile–butadiene–styrene copolymers during processing as studied by chemiluminescence

AbstractThe glow curve obtained upon processing acrylonitrile–butadiene–styrene copolymers (ABS), through various machines, reaches a peak at 180°C. The proper assignment of that peak has required the study of the chemiluminescence (CL) shown by related polymers such as: polybutadiene (PB), styrene–acrylonitrile copolymer (SAN), and polyacrylonitrile (PAN). Three hydroperoxide types associated with the structural units, that is, 1, 2, and cis‐ and trans‐1,4, exhibiting CL peaks at 180, 240, and 340°C, respectively, have been identified in the PB sample. The activation energy (Ea), recorded for the hydroperoxides thermal decomposition, was 15.0 ± 1.0, 17.85 ± 0.9, 20.7 ± 0.8 kcal/mol. PAN shows a CL peak at 180°C. Its occurance is related to the color developed during the thermal treatment. That PAN peak has been attributed to the hydroperoxides generated on the acrylonitrile units neighboring the azomethinic structures. The corresponding Ea is 23.3 ± 1.0 kcal/mol. The same peak (having an identical position and Ea) has been identified with processed ABS and SAN copolymers. As is evident by CL studies, the processing induced oxidation mainly occurs within the SAN phase of the ABS copolymers, though it was also noted within 1,2 units of the PB phase.