Phosphorus speciation analysis of fatty-acid-based feedstocks and fast pyrolysis biocrudes via gel permeation chromatography inductively coupled plasma high-resolution mass spectrometry

Renewable feedstocks, such as lignocelulosic fast pyrolysis oils and both vegetable oil and animal fats, are becoming a viable alternative to petroleum for producing high-quality renewable transportation fuels. However, the presence of phosphorus-containing compounds, mainly from phospholipids, in these renewable feedstocks is known to poison and deactivate hydrotreating catalysts during fuel production. In this work, gel permeation chromatography (GPC) combined with inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) was used to analyze feedstocks including unprocessed soybean oil, animal fat, and pyrolysis oils from red oak and milorganite to identify phosphorus species. The results have shown the presence of a wide range of different phosphorous compounds among all the samples analysed in this work. The GPC-ICP-HRMS analyses of a vegetable oil and two animal fats have shown different fingerprints based on the molecular weight of each of the samples, highlighting the structural differences among their corresponding phosphorus-containing compounds. While the presence of low-molecular-weight species, such as phospholipids, was expected, several high-molecular-weight species (MW > 10 000 Da) have been found, suggesting that high-molecular-weight micelles or liposomes might have been formed due to the high concentration of phospholipids in these samples. Results obtained through the hydroxylation of a mix of phospholipids (asolectin) and its posterior GPC-ICP-HRMS agree with this hypothesis. With respect to the lignocellulosic catalytic fast pyrolysis oil samples, the GPC-ICP-HRMS results obtained suggest that either aggregation or polymerization reactions might have occurred during the pyrolysis process, yielding phosphorus-containing compounds with an approximate molecular weight above 91 000 kDa. In addition, an aggregation phenomenom has been observed for those phosphorus species present within the fast pyrolysis oils after being stored for 3 months, especially for those pyrolysis oils contaning pre-processed feedstocks, such as milorganite.

Renewable feedstocks, such as lignocelulosic fast pyrolysis oils and both vegetable oil and animal fats, are becoming a viable alternative to petroleum for producing high-quality renewable transportation fuels.     

Ex situ catalytic fast pyrolysis of soy sauce residue with HZSM-5 for co-production of aromatic hydrocarbons and supercapacitor materials

A promising approach is proposed for the efficient conversion of soy sauce residue (SSR) into aromatic hydrocarbons and a supercapacitor electrode material by ex situ catalytic fast pyrolysis (CFP) technology with HZSM-5. The thermal decomposition behaviors of SSR were first investigated via thermogravimetry (TG) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analyses. The ex situ CFP of SSR was conducted to elucidate the aromatic hydrocarbons production under different pyrolysis temperatures and HZSM-5-to-SSR (HZ-to-SSR) ratios using both Py-GC/MS and lab-scale instruments. The results indicated that the aromatic hydrocarbons reached the maximal yields of 22.20 wt% from Py-GC/MS with an HZ-to-SSR ratio of 11 at 650 °C, and 17.61 wt% from the lab-scale device with an HZ-to-SSR ratio of 2, respectively. The as-obtained yield of aromatic hydrocarbons was far higher than those obtained from typical lignocellulosic biomass materials, confirming that SSR is a promising material for aromatics production. The pyrolytic solid product collected with this method was further activated by KOH to synthesize N-doped activated carbon (NAC) for supercapacitors. The physicochemical analysis showed that NAC possessed N-incorporated hierarchical pores, and exhibited a promising capacitance of 274.5 F g⁻¹ at 1 A g⁻¹.

A new method to co-produce aromatic hydrocarbons and a supercapacitor material from the catalytic fast pyrolysis of soy sauce residue has been developed.     

Effect of polymer molecular weight on J51 based organic solar cells

Very recently, organic solar cells (OSCs) have achieved outstanding scientific results with a power conversion efficiency (PCE) of over 16%. However, it is rarely reported on how molecular weight (M_n) of polymer donors affects the solar cell performances. In this work, the wide bandgap polymer donor J51 with different M_n from 8 to 36 kDa were synthesized and used for fabrication of J51:PC₇₁BM devices. It was found that the PCEs were gradually on the increase with the increased molecular weight of J51 donor. This work demonstrated the relationship between devices performance and polymer molecular weight, which enriched the OSCs research content. It provides valuable reference information that optimal molecular weight of polymer donors should be limited in what is considered the applicable range.

Very recently, organic solar cells (OSCs) have achieved outstanding scientific results with a power conversion efficiency (PCE) of over 16%.     

The influences of electronic effect and isomerization of salalen titanium(iv) complexes on ethylene polymerization in the presence of methylaluminoxane

Herein, two salalen titanium(iv) complexes were synthesized and characterized. These complexes coexisted as two isomers in certain conditions and underwent isomerization, as evidenced by ¹H NMR spectroscopy. Furthermore, the molar ratio of the two isomers ranged from 100 : 15 at 30 °C to 100 : 34 at 120 °C, driven by thermal energy, based on variable temperature ¹H NMR characterization. Both complexes were employed as catalysts for ethylene polymerization in the presence of methylaluminoxane (MAO). The influence of the electronic effects of different substituent groups at the ortho position of the phenolate on ethylene polymerization behaviors, molecular weight and molecular weight distributions of the resulting polyethylene was investigated. The fluorinated salalen titanium(iv) complex revealed relatively high catalytic activity and thermal stability owing to the electron-withdrawing inductive effect. Moreover, disentangled linear polyethylene with ultrahigh molecular weight (M_w up to 3000 kDa) and narrow molecular weight distribution (M_w/M_n ∼ 2) was obtained in the polymerization temperature range of 30 °C to 50 °C.

Herein, two salalen titanium(iv) complexes were synthesized and characterized. Both complexes were used as catalysts for the polymerization of ethylene in the presence of methylaluminoxane (MAO), and disentangled ultrahigh molecular weight polyethylene was obtained.     

Synthesis of new polyesters by acyclic diene metathesis polymerization of bio-based α,ω-dienes prepared from eugenol and castor oil (undecenoate)

Synthesis of new polyesters by acyclic diene metathesis (ADMET) polymerization of α,ω-diene, 4-allyl-2-methoxyphenyl 10-undecenoate (M1), prepared from bio-renewable eugenol and castor oil (undecenoate), have been demonstrated. Ruthenium-carbene (called second generation Grubbs) catalyst afforded polymers with unimodal molecular weight distributions (M_n = 12 700, M_w/M_n = 1.85). The polymerization in the presence of a triarm cross-linker, 5-formylbenzene-1,2,3-triyl tris(undec-10-enoate), also afforded polymers with certain uniform network structures.

Synthesis of high molecular weight polymers by acyclic diene metathesis (ADMET) polymerization of α,ω-diene prepared from bio-renewable eugenol and castor oil (undecenoate) has been demonstrated.     

Controlled degradation of low-fouling poly(oligo(ethylene glycol)methyl ether methacrylate) hydrogels

Degradable low-fouling hydrogels are ideal vehicles for drug and cell delivery. For each application, hydrogel degradation rate must be re-optimized for maximum therapeutic benefit. We developed a method to rapidly and predictably tune degradation rates of low-fouling poly(oligo(ethylene glycol)methyl ether methacrylate) (P(EG)_xMA) hydrogels by modifying two interdependent variables: (1) base-catalysed crosslink degradation kinetics, dependent on crosslinker electronics (electron withdrawing groups (EWGs)); and, (2) polymer hydration, dependent on the molecular weight (M_W) of poly(ethylene glycol) (PEG) pendant groups. By controlling PEG M_W and EWG strength, P(EG)_xMA hydrogels were tuned to degrade over 6 to 52 d. A 6-member P(EG)_xMA copolymer library yielded slow and fast degrading low-fouling hydrogels suitable for short- and long-term delivery applications. The degradation mechanism was also applied to RGD-functionalized poly(carboxybetaine methacrylamide) (PCBMAA) hydrogels to achieve slow (∼50 d) and fast (∼13 d) degrading low-fouling, bioactive hydrogels.

To tune degradation rates of low-fouling hydrogels, a 6-member P(EG)_xMA copolymer library with different electronics and hydration levels was developed.     

Chemical characterization of Cassia fistula polysaccharide (CFP) and its potential application as a prebiotic in synbiotic preparation

Prebiotics are non-digestible food ingredients that are selectively fermented by probiotics. The aim of this study was to investigate the chemical properties of a polysaccharide extracted from Cassia fistula mature fruit pulp and to evaluate its effects on probiotic strains: L. casei, L. rhamnosus, E. coli Nissle 1917 (EcN), and E. faecalis. These strains were compared for their growth behavior in culture media supplemented with different Cassia fistula polysaccharide (CFP) concentrations. The molecular weight of CFP was approximately 8.707 × 10⁵ Da. The recovered polysaccharide contained a low percentage of crude protein (4.4%). Aspartic acid, glutamic acid, and proline were the most abundant amino acids. Glucose and mannose were the predominant sugars followed by arabinose and rhamnose. L. casei grew faster at high CFP concentrations (2%) compared with the lower concentrations of CFP. The highest values for the prebiotic index and prebiotic activity score were observed for L. casei treated with 2% CFP, and it may be considered a prebiotic due to its high resistance against α-amylase and acidic conditions. CFP provides two ways to adjust nitric oxide (NO) synthesis in macrophages. Finally, the use of 1.5 and 2% CFP for cultured milk production significantly shortened the fermentation period from 210 min to 180 min and 150 min, respectively.

CFP may be a prebiotic due to its high resistance against α-amylase and acid. CFP provides two ways to adjust nitric oxide synthesis in macrophages. We show the use of CFP in the production of synbiotic yogurt with favorable physical and chemical characteristics.     

Preparation of environmentally friendly acrylic pressure-sensitive adhesives by bulk photopolymerization and their performance

Polyacrylic pressure-sensitive adhesives (PSAs) based on butyl acrylate (BA), 2-hydroxyethyl acrylate (HEA), and acrylic acid (AA) were prepared by a bulk polymerization process triggered by a radical photoinitiator under UV irradiation and UV-crosslinking. 1,6-Hexanediol diacrylate (HDDA) with difunctional groups was introduced into the PSAs to modify semi-interpenetrating network structures. The effect of HDDA content on the pressure-sensitive performance was comprehensively tested. The viscosity of the prepolymer was measured by a rotational viscometer. Prepolymers obtained by a photoinduced process and UV crosslinking process were confirmed via Fourier transform infrared spectroscopy (FTIR). All double bonds participated in the copolymerization without any remaining monomers, which reflected the concept of green environmental protection. Gel content in the crosslinked portion was examined by Soxhlet extraction, whilst the soluble molecular weight of PSAs was characterized by gel permeation chromatography (GPC). The viscoelastic properties of polymer films were determined by dynamic mechanical analysis (DMA). The T_g value and storage modulus (G′) of the PSAs were enhanced with the addition of HDDA. Moreover, three fundamental adhesive properties, i.e. loop tack force, peel force and shear strength of PSAs, were measured. The results showed that UV crosslinking technology achieved a good balance of the three forces with excellent pressure-sensitive properties.

Polyacrylic pressure-sensitive adhesives based on butyl acrylate, 2-hydroxyethyl acrylate, and acrylic acid were prepared by a bulk polymerization process triggered by a radical photoinitiator under UV irradiation and UV-crosslinking.     

One-pot synthesis of end-functionalised soluble star-shaped polymers by living ring-opening metathesis polymerisation using a molybdenum-alkylidene catalyst

Precise synthesis of soluble star-shaped polymers has been achieved by adopting living ring-opening metathesis polymerisation (ROMP) using a molybdenum-alkylidene catalyst with sequential addition of norbornene and cross-linking agent; the method provides efficient one-pot synthesis of high molecular weight end-functionalised star-shaped polymers (M_n = >1.37 × 10⁵) with more arms (branching) with rather low PDI values (M_w/M_n = 1.17–1.37) under the optimised conditions.

Precise synthesis of star-shaped polymers has been achieved by living ROMP using a molybdenum catalyst with sequential addition of norbornene and cross-linker.     

Comparative study on the pyrolysis behavior and pyrolysate characteristics of Fushun oil shale during anhydrous pyrolysis and sub/supercritical water pyrolysis

Injected steam can be converted to the sub/supercritical state during the in situ exploitation of oil shale. Thus, the pyrolysis behavior and pyrolysate characteristic of Fushun oil shale during anhydrous pyrolysis and sub/supercritical water pyrolysis were fully compared. The results revealed that the discharged oil yields from sub/supercritical water pyrolysis were 5.44 and 14.33 times that from anhydrous pyrolysis at 360 °C and 450 °C, which was due to the extraction and driving effect of sub/supercritical water. Also, sub/supercritical water could facilitate the discharge and migration of shale oil from the pores and channels. The H₂ and CO₂ yields in sub/supercritical water pyrolysis were higher than that in anhydrous pyrolysis, resulting from the water–gas shift reaction. The component of shale oil was dominated by saturated hydrocarbons in anhydrous pyrolysis, which accounted for 50–65%. In contrast, a large amount of asphaltenes and resins was formed during pyrolysis in sub/supercritical water due to the solvent effect and weak thermal cracking. The shale oil from anhydrous pyrolysis was lighter than that from sub/supercritical water pyrolysis. Sub/supercritical water reduced the geochemical characteristic indices and lowered the hydrocarbon generation potential and maturity of solid residuals, which can be attributed to the fact that more organic matter was depolymerized and released. The pyrolysate characteristic of oil shale in sub/supercritical water pyrolysis was controlled by multiple mechanisms, including solvent and driving effect, chemical hydrogen-donation and acid–base catalysis.

Sub/supercritical water can directly extract oil and gas from oil shale due to the solvent and driving effects. Also, they can be considered as an acid–base catalyst, which can catalyze some reactions such as hydrolysis, addition and rearrangement.     

Synthesis of butadiene/isoprene–styrene di-block copolymer with high cis-1,4 unit content based on a neodymium phosphate ester

A novel two-step synthesis strategy based on a liquid neodymium phosphate ester (Nd(P₅₀₇)₃) catalyst was used to synthesize diene-styrene di-block copolymers with high cis-1,4 unit content, such as butadiene–styrene (PB-b-PS), isoprene–styrene (PI-b-PS), and so on. The strategy not only makes full use of the high cis-1,4 stereo-selectivity of the rare earth catalyst to conjugated dienes, but also adjusts the electron cloud density of the catalytic active center by introducing triphenyl phosphine (PPh₃). Thus, the catalytic activity of the neodymium-based catalyst center toward styrene has been largely improved, and a series of PB/PI-b-PSs with high cis-1,4 unit content (98.3 and 98.1% respectively), narrow molecular weight distribution and controllable block ratio were successfully synthesized. Herein, molecular weight (M_n), molecular weight distribution (M_w/M_n) and microstructure of the block polymers were characterized using SEC-MALLS, FT-IR, ¹H NMR, ¹³C NMR and DSC. The DSC curve of a PB-b-PS with 98.3% cis-1,4 unit and 18.6% polystyrene content shows a T_g of −103.1 °C, which means it has relatively excellent mechanical properties at lower temperature. The results show that these PB/PI-b-PS materials have good application prospects in harsh low temperature environments.

A novel synthesis strategy of butadiene/isoprene–styrene di-block copolymer with high cis-1,4 content was explored based on a neodymium phosphate catalyst, by adjusting the electron cloud density of the catalytic active center via triphenyl phosphine.     

Catalytic pyrolysis of plastic waste for the production of liquid fuels for engines

Catalytic pyrolysis of waste plastics using low cost binder-free pelletized bentonite clay has been investigated to yield pyrolysis oils as drop-in replacements for commercial liquid fuels such as diesel and gasohol 91. Pyrolysis of four waste plastics, polystyrene, polypropylene, low density polyethylene and high density polyethylene, was achieved at a bench scale (1 kg per batch) to produce useful fuel products. Importantly, the addition of binder-free bentonite clay pellets successfully yielded liquid based fuels with increased calorific values and lower viscosity for all plastic wastes. This larger scale pyrolysis study demonstrated that use of a catalyst in powder form can lead to significant pressure drops in the catalyst column, thus slowing the process (more than 1 hour). Importantly, the use of catalyst pellets eliminated the pressure drop and reduced pyrolysis processing time to only 10 minutes for 1 kg of plastic waste. The pyrolysis oil composition from polystyrene consists of 95% aromatic hydrocarbons, while in contrast, those from polypropylene, low density polyethylene and high density polyethylene, were dominated by aliphatic hydrocarbons, as confirmed by GC-MS. FTIR analysis demonstrated that low density polyethylene and high density polyethylene oils had functional groups that were consistent with those of commercial diesel (96% similarity match). In contrast, pyrolysis-oils from polystyrene demonstrated chemical and physical properties similar to those of gasohol 91. In both cases no wax formation was observed when using the bentonite clay pellets as a catalyst in the pyrolysis process, which was attributed to the high acidity of the bentonite catalyst (low SiO₂ : Al₂O₃ ratio), thus making it more active in cracking waxes compared to the less acidic heterogeneous catalysts reported in the literature. Pyrolysis-oil from the catalytic treatment of polystyrene resulted in greater engine power, comparable engine temperature, and lower carbon monoxide (CO) and carbon dioxide (CO₂) emissions, as compared to those of uncatalysed oils and commercial fuel in a gasoline engine. Pyrolysis-oils from all other polymers demonstrated comparable performance to diesel in engine power tests. The application of inexpensive and widely available bentonite clay in pyrolysis could significantly aid in repurposing plastic wastes.

Catalytic pyrolysis of waste plastics using low cost binder-free pelletized bentonite clay has been investigated to yield pyrolysis oils as drop-in replacements for commercial liquid fuels such as diesel and gasohol 91.     

Efficient production of high-molecular-weight hyaluronic acid with a two-stage fermentation

In this paper, the production pattern of hyaluronic acid (HA) was revealed: the chain growth of HA mainly occurred in the first half of fermentation while the product accumulated throughout the fermentation period. Attempts were made to develop a two-stage fermentation process which provided high-level synthesis in both product titer and molecular weight. The pH was kept at 8.0 with a temperature of 31 °C in the first fermentation stage (0–10 h) to promote the growth of weight-average molecular weight (M_w), and the pH and temperature were maintained at 7.0 and 37 °C, respectively, in the following fermentation stage to facilitate HA accumulation. In addition, constant rates of aeration (1 vvm) and agitation (600 rpm) were adopted. The two-stage fermentation provided a balanced result in which a product titer of 4.75 g L⁻¹ and a M_w of 2.36 × 10⁶ Da were achieved under optimized conditions. The process introduces an effective way to produce HA considering the effect of segmented control strategy.

A two-stage fermentation process with a segmented control strategy provides high-level synthesis in both HA titer and molecular weight.     

TiO2 doped polydimethylsiloxane (PDMS) and Luffa cylindrica based photocatalytic nanosponge to absorb and desorb oil in diatom solar panels

Our previous report(s) demonstrated that piezoelectric disc fabricated diatom solar panels worked as micro resonating devices. Such devices have potential to harvest oils from living diatom cultures. However, it is observed that the collection and separation of oil from culture media using these devices are found to be difficult due to the presence of both living and dead diatom cells, which simultaneously get collected during this process. In this study we made a highly biocompatible nanosponge using TiO₂ nanoparticle doped polydimethylsiloxane (PDMS) and Luffa cylindrica. Such hybrid nanosponge selectively absorbs and desorbs oil on exposure to ultraviolet light. The fabricated PDMS-Luffa-TiO₂ nanosponge was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and atomic force microscopy to show the surface characteristics and affinity of nanoparticles to the membranous structure of PDMS-Luffa. A maximum 38% oil absorption was found in PDMS-Luffa-TiO₂ nanosponge which was almost double that of sponges made up of PDMS (19%), PDMS-Luffa (18%) and PDMS-TiO₂ coated (24%). Thus PDMS-Luffa-TiO₂ nanosponge serves as a selective and recyclable oil absorption membranous structure. Furthermore, this hybrid nanosponge exhibited excellent recyclability by repeated absorption–desorption processes on exposure to UV light.

Our previous report(s) demonstrated that piezoelectric disc fabricated diatom solar panels worked as micro resonating devices.     

Electrochemical synthesis of biobased polymers and polymer building blocks from vanillin

Vanillin, one of the few biobased aromatic compounds available on an industrial level, is an attractive candidate for the synthesis of biobased polymers and polymer building blocks. This study presents a detailed investigation of the reductive electrochemical coupling process by pinacolization of vanillin and divanillin in an electrochemical H-type cell setup to the polymer building block hydrovanilloin and to polyvanillin, respectively. Therein, different cathode materials are screened by linear sweep voltammetry for their capability and activity of hydrodimerization of phenolic aromatic aldehydes in alkaline aqueous media. Product distributions and faradaic efficiencies of the electrochemical vanillin reduction are investigated in bulk electrolysis experiments. Dependencies on electrochemical parameters such as current densities, applied charges and cathode materials are studied. Furthermore, the polyvanillin synthesis from divanillin is also investigated by bulk electrolysis experiments. The effects of selected electrochemical parameters (current density, applied charge and electrode material) on yield and structural features (weight-average molecular weight (M_W), number-average molecular weight (M_N), polydispersity (M_W/M_N)) measured by size exclusion chromatography of the obtained polyvanillin were evaluated. Structural features of isolated polyvanillin were determined by 2D-NMR (HSQC, ¹³C/¹H) analyses and by ³¹P-NMR analyses after in situ labeling with Cl-TMDP and possible pathways for their generation are discussed. These two promising electro-synthetic processes studied are free of hazardous materials and reagents and highlight the contributions of preparative electrochemistry to green chemistry and further pave the way toward the application of electrochemistry in the synthesis of biobased building blocks and polymers.

Hydrovanilloin and polyvanillin were synthesized electrochemically investigating the impact of process parameters such as electrode material, charge and current density.     

Vortex fluidic mediated synthesis of polysulfone

Polysulfone (PSF) was prepared under high shear in a vortex fluidic device (VFD) operating in confined mode, and its properties compared with that prepared using batch processing. This involved reacting the pre-prepared disodium salt of bisphenol A (BPA) with a 4,4′-dihalodiphenylsulfone under anhydrous conditions. Scanning electron microscopy (SEM) established that in the thin film microfluidic platform, the PSF particles are sheet-like, for short reaction times, and fibrous for long reaction times, in contrast to spherical like particles for the polymer prepared using the conventional batch synthesis. The operating parameters of the VFD (rotational speed of the glass tube, its tilt angle and temperature) were systematically varied for establishing their effect on the molecular weight (M_w), glass transition temperature (T_g) and decomposition temperature, featuring gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) respectively. The optimal VFD prepared PSF was obtained at 6000 rpm rotational speed, 45° tilt angle and 160 °C, for 1 h of processing with M_w ∼10 000 g mol⁻¹, T_g ∼158 °C and decomposition temperature ∼530 °C, which is comparable to the conventionally prepared PSF.

Polysulfone (PSF) was prepared under high shear in a vortex fluidic device (VFD) operating in confined mode. This involved reacting the pre-prepared disodium salt of bisphenol A (BPA) with a 4,4′-dihalodiphenylsulfone under anhydrous conditions.     

Influence of molecular weight on molecular dynamics and dynamic rheology of polypropylene glycol filled with silica

Molecular weight strongly influences the molecular dynamics and rheological responses of nanocomposites, which is far from being well understood. Herein molecular dynamics and rheological behaviors of hydrophilic fumed silica filled unentangled polypropylene glycol (PPG) were investigated as a function of weight averaged molecular weight (M_w) of PPG and volume fraction (∅) of silica. It is shown that M_w does not affect the glassy layers surrounding the nanoparticles and the segmental dynamics of the mobile PPG phase. On the other hand, the mobile PPG phase in the highly filled nanocomposites exhibits an abnormal “more fragile” to “stronger” transition with increasing M_w. The reinforcement and thinning behaviors are stronger in lower-M_w nanocomposites with the “more fragile” mobile PPG phase. The results suggest that reinforcement of nanocomposites affects the dynamic fragility of the mobile phase of the matrix.

The mobile phase exhibits an abnormal “more fragile” to “stronger” transition with increasing molecular weight of polypropylene glycol in nanocomposites at high silica loadings, which significantly lowers the degrees of reinforcement and thinning.     

Changes of flooding reagents' properties under simulated high temperature/pressure conditions in oil reservoirs and their impact on emulsion stability

It is of great significance to know the fate of the polymers and surfactants used for enhanced oil recovery (EOR) in oil reservoirs at a relatively high temperature/pressure. In this paper, the changes of the properties of a polymer (partially hydrolyzed polyacrylamide, HPAM) and a surfactant (petroleum sulfonate, PS) were investigated under simulated oil reservoir conditions (a temperature of 45, 60 or 75 °C and a pressure of 10, 15 or 20 MPa). The impacts of the property changes to emulsion stability were also highlighted. The results showed that the hydrolysis degree of HPAM increased from 24.3% to 28.9%, 29.7% and 35.4%, whereas the molecular weight (M_w) decreased from 7.60 × 10⁶ g mol⁻¹ to 5.43 × 10⁶ g mol⁻¹, 4.49 × 10⁶ g mol⁻¹ and 2.87 × 10⁶ g mol⁻¹ as a function of raising the temperature to 45, 60 and 75 °C with 20 MPa, respectively, for a duration of one week. However, the increased pressure showed obvious prevention effects on the degradation of HPAM M_w in the investigated pressure range of 10–20 MPa. There were no changes in the oil–water interfacial tension for PS solutions after high temperature/pressure treatment. The stabilization ability of HPAM to the emulsion decreased markedly after treatment because of the decreased viscosity attributed to the reduction of molecular weight, while that of PS did not change. It is reasonable to speculate that the influence of back produced HPAM to the stability of EOR produced water will be quite different in different oil reservoirs because of the differences in reservoir temperature, pressure and retention time, and therefore different strategies should be considered in treating the produced water from EOR.

It is of great significance to know the fate of the polymers and surfactants used for enhanced oil recovery (EOR) in oil reservoirs at a relatively high temperature/pressure.     

Bio-oils from vacuum ablative pyrolysis of torrefied tobacco residues

Fast pyrolysis, in combination with torrefaction pretreatment, was used to convert tobacco residues to value-added bio-fuels and chemicals. Tobacco plant residues were torrefied at 220, 260, and 300 °C, before being pyrolyzed at 450, 500, 550, and 600 °C in a rotating blade ablative reactor under vacuum conditions to test the effects on product yields. With torrefaction, tobacco residues thermally decomposed 20–25% w/w at low temperatures. Torrefaction and pyrolysis temperatures were found to markedly affect pyrolytic product yields of bio-chars and bio-oils, while having no effect on gas-phase products. Bio-oil yields exhibited a direct relation with pyrolysis temperature and an inverse relation with torrefaction temperature. Bio-oils produced were separated into light and heavy oils and analyzed by GC-MS, and ¹H and ¹³C NMR. Nicotine was found to be the main compound in the light and heavy oils along with several phenols and cresols in the heavy oil.

Thermochemical conversion of tobacco residues to value-added bio-fuels and chemicals via fast pyrolysis, in combination with torrefaction pretreatment, in a rotating blade ablative reactor under vacuum conditions.     

A practical adsorption model for the formation of submerged oils under the effect of suspended sediments

Oil sediment interactions play an important role in the formation of submerged oils in coastal marine environments. Thus, the formation processes of submerged oils under the effect of suspended sediments were investigated in this study. Batch experiments were conducted to assess the role of adsorption processes on the suspended sediments in controlling levels of formation of submerged oils using three kind of Bohai crude oils [obtained from the Liaohe oilfield (LX), Bohai south regional oilfield (YYH) and Bohai central regional oilfield (YYS)]. The results showed that the saturated adsorption capacities by sandy sediments were 568, 429 and 352 mg g⁻¹ for LX, YYH and YYS, respectively. Kinetic studies showed that the adsorption rate was about 0.002 mg g⁻¹ min⁻¹ in the first 200 minutes, and the maximum proportion of the submerged oils formed was 43%, 40% and 34% for LX, YYH and YYS, respectively. Partitioning of oils occurs between solid and solution phases during the oil sediment interactions, and always involving a distribution coefficient (K_d). Importantly, an adsorption model was proposed in this study for predicting the formation of submerged oils with most of the experimental data fitting the model defined by a zone with K_d values of 0.5 and 1.5 mL mg⁻¹. Those results can help assess the fate and distribution of oil leakages in marine environments.

An adsorption model was proposed for predicting the formation of submerged oils under the effect of suspended sediments.