Recyclable Liquid Research Articles

Ruthenium-Catalyzed [2 + 2] Cyclization of 1,7-Allenynes in Ionic Liquid and Catalyst Recycling

Ruthenium-Catalyzed [2 + 2] Cyclization of 1,7-Allenynes in Ionic Liquid and Catalyst Recycling

Low energy recycling of ionic liquids via freeze crystallization during cellulose spinning

An energy saving method of freeze crystallization for recycling ionic liquids was investigated in a cellulose spinning process.

Recycled ionic liquid 1-ethyl-3-methylimidazolium acetate pretreatment for enhancing enzymatic saccharification of softwood without cellulose regeneration

In this work, pretreatment of wood meals using a recycled ionic liquid (IL), 1-ethyl-3-methylimidazolium acetate ([Emim]Ac), enhanced glucose liberation by enzymatic saccharification, without dissolution of cellulose and lignin. In contrast, previous studies on IL pretreatment have mostly focused on lignocellulosic dissolution to regenerate cellulose and removing lignin. Softwood (Cryptomeria japonica) was pretreated with [Emim]Ac at 60–100 °C for 2–8 h without collecting regenerated cellulose. The pretreatment did not have a strong effect on wood component dissolution (weight of residues: 91.7–98.8%). The residues contained relatively high amounts of lignin (26.6–32.6%) with low adsorption of [Emim]Ac (0.9–2.7%). Meanwhile, the crystallinity index (C r I) of cellulose in the wood was significantly reduced by pretreatment, from 50.9% to 28.4–37.1%. In spite of the high lignin contents in the residues, their glucose liberation values by enzymatic saccharification using a cellulase mixture were 3–16 times greater than that of untreated wood. A good correlation was found between the saccharification effectiveness of pretreated samples and the C r I. Although lignin dissolved in [Emim]Ac continued to accumulate after repeated use of [Emim]Ac, the pretreatment was found to be effective for three consecutive cycles without the need to remove the dissolved materials.

Effect of Recycled Imidazolium-based Ionic Liquids on Biomass from Rubber Wood

Background: Ionic liquids could be used as a potential solvent to dissolve rubber wood. This is one the most successful methods for the dissolution of rubber wood. Methods: In this study, various imidazolium-based ionic liquids with different anions, e.g acetate, chloride, dycanimide and ethylphosphonate were used to dissolve rubber wood and showed that 1-ethyl-3- methyl imidazolium acetate ([Emim][OAc]) could be recycled four times. There was a small decrease in the cellulose and lignin mass regenerated of the rubber wood using recycled ionic liquids compared to fresh ionic liquids. This method had achieved a recovery ionic liquid efficiency of 90% and the Fourier Transform Infrared (FTIR) and X-Ray Diffraction (XRD) showed that the crystallinity of the cellulose through the recycled ionic liquid has significantly decreased. The yield of the conversion of cellulose to glucose increased as the number of ionic liquid cycles increased, especially at the fourth instance of recycling. On the other hand, Thermogravimetric Analysis (TGA) and 1H NMR (nuclear magnetic resonance) spectroscopy showed no structural changes in the recovered ionic liquids. Conclusion: This work proves that [Emim][OAc] has an excellent reusability. Keywords: Ionic liquids, dissolution, rubber wood, recycle, pre-treatment, anions.

A modeling study of module arrangement and experimental investigation of single stage module for physical absorption of biogas using hollow fiber membrane contactors

In the present work, the effect of module arrangement on the physical absorption of CO2 and H2S in water at high operating pressure using 2 different types of hollow fiber membrane contactor (HFMC) including polyvinylidenefluoride (PVDF) and polytetrafluoroethylene (PTFE) was studied for biogas upgrading application. The simulation was performed at various liquid velocities (0.12–2.0m/s), pressure differences between liquid and gas phases (0.125–1.0bar for PVDF and 1.0–5.0bar for PTFE), operating pressures (1–30bar) under four different module arrangement scenarios, i.e., (i) single stage module, (ii) multistage module, (iii) multistage module with splitting liquid (α = 0.2 and 0.4) and (iv) multistage module with recycle liquid (φ = 0.5 and 1). The modeling results predicted the significant improvement of CO2 and H2S removal performances when the multistage module was applied for both HFMCs. To obtain the highest removal performance, the suitable liquid velocity, pressure difference between liquid and gas phases and the liquid flow pattern of the module arrangement are the key concerns. For PVDF, the multistage module with splitting liquid (α = 0.2) provides the highest performance at the liquid velocity of 0.12m/s, pressure difference of 0.125bar and the operating pressure of 30bar. For PTFE, at the liquid velocity of 2.0m/s and the pressure difference of 1.0bar, the multistage module with recycle liquid (φ = 1) gives the highest performance at the operating pressure of 1–20bar while the multistage module with splitting liquid (α = 0.4) provides the highest performance at the operating pressure of 30bar.

Performance optimization of ultra high-resolution recycling liquid chromatography

The optimization of a twin-column recycling separation process (TCRSP) for maximum resolution or maximum speed-resolution was investigated. The general optimization method was based on the construction of kinetic plots by assuming an ideal TCRSP (no efficiency loss upon recycling). For the optimization, we examined three chromatographic parameters: operation pressure (3000, 6000, 9000, and 12,000psi), column length (10, 15, and 25cm), and column inner diameter (i.d.) (2.1, 3.0, and 4.6mm). Accordingly, the highest TCRSP resolution level is expected for 25cm long columns packed with 2.5, 2.0, 1.7, and 1.6μm particles at pressures of 3000, 6000, 9000, and 12,000psi, respectively. The maximum speed-resolution performance is expected for 10cm columns packed with 3.7, 3.0, 2.6, and 2.4μm particles. 3.0mm i.d. columns are best to minimize the negative impacts of thermal and inter-column dispersion effects on the TCRSP performance. The method was illustrated for the challenging separation (selectivity factor α<1.02) of small molecules in RPLC at a maximum pressure of 6000psi using commercially available columns. Accordingly, 3.0×150mm columns packed with 2.5μm cellulose-1 Trefoil particles (chiral separation, γ-phenylbutyrolactone, α=1.01, efficiency N=4500) and 2.7μm Cortecs-C18 particles (isotope separation, α=1.02, N=14, 500) particles were found to be the most suitable columns to maximize speed-resolution performance. Further optimization of the TCRSP performance was required by reducing the inter-column sample dispersion that could cause undesirable peak tailing. A standard 2.4μL Rheodyne valve and 100μm i.d. tubes were replaced with a home-made 0.5μL low-dispersion prototype valve and 75μm i.d. perfect connection tubes. As a result, the experimental resolution factors were increased by +60% (γ-phenylbutyrolactone, 25 cycles, Rs=0.7→1.1) and +80% (deuterated benzenes, 22 cycles, Rs=1.1→2.0). Direct comparison between the experimental and the predicted TCRSP performance unambiguously demonstrated that the resolution gain was explained by the significant reduction of the peak tailing after a large number of cycles (n>20).

Grinding technique for the tandem synthesis of bis coumarinyl methanes using [BDBDMIm]Br-CAN

3,3-(Butane-1,4-diyl)bis(1,2-dimethyl-1 H -imidazole-3-ium)bromide ([BDBDMIm]Br) is easily used as an efficient and recyclable ionic liquid for the synthesis of bis coumarinyl methanes in the presence of a catalytic amount of ceric ammonium nitrate (CAN) under grinding. All reactions are performed in the absence of solvent in excellent yield during short reaction time. Furthermore, the ionic liquid can be reused and recovered for several times without loss of activity. This method provides several advantages such as simple work-up, environmental friendliness and shorter reaction time along with high yields. All of synthesized compounds were characterized by infrared spectroscopy, 1 H and 13 C nuclear magnetic resonance spectroscopy and elemental analyses. KEY WORDS : Grinding, Ionic liquid, CAN, 4-Hydroxycoumarin, Oxidation, One-pot Bull. Chem. Soc. Ethiop. 2017 , 31(2), 323-329. DOI: http://dx.doi.org/10.4314/bcse.v31i2.13

One‐Pot Synthesis of Hydroxy Pyrazolo[1,2‐a][1,2,4]triazoles and Their Dehydration Using Recyclable Ionic Liquids as Reaction Media

An eco‐friendly, simple, and efficient one‐pot new procedure has been developed for the synthesis of hydroxy phenylhexahydropyrazolo[1,2‐a][1,2,4]triazoles by condensation of 4‐phenylurazole, aldehydes, and ethyl/methyl acetoacetate using ionic liquid [bmim]BF4 in presence of l‐proline at 80°C. The hydroxy pyrazolo[1,2‐a][1,2,4]triazoles could be dehydrated in presence of [bmim]HSO4 to give corresponding phenyltetrahydropyrazolo[1,2‐a][1,2,4]triazoles in high yields. High yields, less reaction time, operational simplicity, and recyclability of reaction media are the advantages of this protocol.

Applications of high-resolution recycling liquid chromatography: From small to large molecules

A twin-column recycling separation process (TCRSP) is assembled and used to generate higher speed and/or higher resolution levels than those of the usual non-recycling process at the same back pressure. It enables the users to solve very challenging separation problems caused by too small selectivity factors and/or too low column efficiencies. The relative gain in speed-resolution performance increases with increasing the number of cycles in the TCRSP, decreasing the maximum allowable pressure imposed by the LC system, decreasing the column permeability, and with reducing the separation speed. TCRSP is then particularly attractive for conventional LC systems (5000psi maximum) and columns packed with sub-2μm to 3.5μm particles. The performance of the real TCRSP was compared to that of the ideal TCRSP for which the retention factor is strictly pressure-independent. A broad range of separation problems encountered in conventional non-recycling chromatography can be easily solved by using a TCRSP assembly based on two 15cm long columns. Under adsorption conditions, the TCRSP enables the full baseline separation of polycyclic aromatic hydrocarbon (PAH) isomers (benzo[a]anthracene and chrysene) on a 3.5μm XSelect-HSS T3 phase, the complete or improved resolution of racemic mixtures (4-phenylbutanol and bromacil) using the same 2.5μm cellulose-1 chiral stationary phase, and the full resolution of isotopic compounds (benzene/1,3,5-benzene-d3/benzene-d6) on a 2.7μm Cortecs-C18 phase. Under non-adsorption conditions or in size-exclusion chromatography (SEC), the fractionation of a polystyrene standard mixture (molecular weights of 35, 66, 130, 277, 552, 1210, and 2500kDa) was completed after only 8 cycles on a 1.7μm BEH 200Åphase. Similarly, a mixture of intact proteins with molecular weights of 16.7, 66.4, 150, 660, and 1320kDa was fully resolved on a 2.5μm BEH 450Åphase after only 6 cycles. Finally, TCRSP enables the complete separation of a few high-molecular-weight species (monoclonal antibody aggregates, small relative abundance of 1 for 250) from the intact monomeric monoclonal antibody (Vectibix).

Green and efficient preparation of hollow titanium silicalite-1 by using recycled mother liquid

A green and efficient preparation of hollow titanium silicalite-1 (TS-1) has been developed by using recycled mother liquid in the post-synthesis treatment. The parent TS-1 was hydrothermally treated with different bases, and hollows appeared in the crystals, due to the controlled desilication from framework. In the presence of tetrapropylammonium cation (TPA+) during post-synthesis treatment, more hollows were generated, and higher concentration of Ti inside crystals was obtained. The reaction substrates could get sufficient contact with the active centers, and this hollow TS-1 exhibited superior catalytic activity in the propylene epoxidation compared to that of parent sample. When the sample was prepared by using ethanolamine and TPABr as desilication medium, the obtained mother liquid can be reused in the next post-synthesis treatment. In the recycling process, the added amount of ethanolamine and TPABr was only 50% and 25% of the amount for the first post-synthesis treatment, respectively. Even the mother liquid was recycled eight times, all obtained hollow TS-1 showed similar catalytic activity in the propylene epoxidation to that of the sample prepared by using TPAOH as desilication medium. This process can almost eliminate the discharge of waste liquid to achieve a sustainable development, and save the cost of hollow TS-1 production.

Oxidized Lignin Depolymerization using Formate Ionic Liquid as Catalyst and Solvent

AbstractLignin has been widely studied as a sustainable source of renewable materials, particularly aromatic feedstock chemicals, which are in great and increasing need in the world. Lignin oxidation and depolymerization presents a promising approach to functionalized phenolic products. In this work, a novel oxidative degradation of lignin using a formate ionic liquid was investigated resulting in ethyl acetate soluble and also water‐soluble depolymerized lignin products. The β‐O‐4 bonds in lignin were oxidized and then depolymerized by a recyclable ionic liquid, 2‐hydroxy ethylammonium formate. 2‐Hydroxy ethylammonium formate, which could dissolve lignin acting as a solvent, was found to also catalyze the depolymerization of the oxidized lignin. The lignin depolymerization products were characterized.

Study on the absorbability, regeneration characteristics and thermal stability of ionic liquids for VOCs removal

A novel method of removal of volatile organic compounds (VOCs) using the ionic liquid [Bmim][NTf2] as an absorbent is developed as a contribution to dealing with recent severe smog incidents in China. The effects of concentration, temperature and flow rates on the ability of [Bmim][NTf2] to absorb VOCs were studied using toluene as a model volatile organic pollutant. The potential of the use of [Bmim][NTf2] as an absorbent for VOCs is shown by the solubility of toluene in the ionic liquid; the absorptivity of the ionic liquid for toluene; and the fact that absorbed toluene can be removed easily from [Bmim][NTf2], permitting recycle of the ionic liquid in multiple reuse phases. The solubility of toluene in [Bmim][NTf2] is 61.5% at 20°C and atmospheric pressure; the highest absorptivity of [Bmim][NTf2] for toluene is 98.3%, achieved at a toluene concentration of 300ppm and a flow rate of 50mLmin−1 at 20°C; and the absorptivity of the ionic liquid is>94% over a wide range of conditions. The ionic liquid can be recovered and recycled in the absorption process at least five times, reducing the reagent cost in the VOC removal process.

Exploration of the Strengthening Effect by Byproduct-Organic Acids on Subcritical Liquid Hot Water Pretreatment

To improve the utilization of phragmites in biorefineries, the strengthening effect of byproduct-organic acids on the subcritical liquid hot water (SLHW) pretreatment was explored. The byproduct-organic acids were accumulated during the direct recycling of pretreated liquid, which could reduce water consumption. The byproduct-organic acids, including acetic acid and lactic acid, were used to strengthen the SLHW pretreatment of raw phragmites at different temperatures (160–200 °C) and times (20–90 min) in the strengthening process. During the SLHW pretreatment, the high yield of C-5 sugars was 60.66% at the severity of 4.85 (200 °C, 75 min). However, the maximum C-5 sugars yield in the strengthening process was 85.01% at 180 °C, for 50 min, and with 2.106 wt % byproduct-organic acids, which were obtained by the direct recycling of pretreated liquid for 3 times at 160 °C and for 30 min. Therefore, the full utilization of byproduct-organic acids could provide another economically feasible way to strengthen t...

Sequential extraction and separation using ionic liquids for stilbene glycoside and anthraquinones in Polygonum multiflorum

In recent years, ionic liquids (ILs) have received more attentions in green extraction and separation process as a kind of novel environment-friendly solvent, and their application in the field of natural products needs to be extended. In this paper, a new method of the sequential extraction for stilbene glycoside and anthraquinones from Polygonum multiflorum was developed for the first time and different ionic liquids was used and compared. It was found two benzothiazolium ILs including [BBth][Br] and [HBth][p-TSA] had good selectivity and high efficiency. In addition, the important extraction conditions were also investigated and optimized. Compared with the traditional acid/alcohol-water extraction process, the extraction assisted by ionic liquid not only can obtain higher yield in shorter time, but also can realize the selective extraction for two different kinds of constituents with less consumption. Furthermore, the recovery of target compounds and recycling of ionic liquid were also studied and it was found that solvent extraction combined with cation-exchange resin had the ideal recovery performance.

A greener approach for the one-pot synthesis of substituted thiazolidinones by using an efficient and recyclable ionic liquid

A greener approach for the one-pot synthesis of substituted thiazolidinones by using an efficient and recyclable ionic liquid

An enhanced counter-current approach towards activated carbon from waste tissue with zero liquid discharge

We studied the applicability of advanced counter-current procedure to convert waste tissue to a highly porous activated carbon (AC) in a zero liquid discharge (ZLD) process with a minimum consumption of the KOH activating agent. AC with a maximum surface area of 1820m2/g was synthesized by a two-step process, including carbonization at 500°C for 1h and KOH activation (ratio: 1–3w/w) at 750°C for 1h. The water in the washing step containing residual KOH was recycled to the carbonization step for successive cycles. The recycling process continued to reach a steady-state condition. Various techniques including XRD, FTIR, TGA, BET and SEM were utilized to compare the characteristics of the AC synthesized during 10 consecutive liquid recycling steps. The results showed that KOH usage was decreased by 99% and the water requisition per cycle was limited to the make-up water to compensate for the water loss due to evaporation. The product characteristics were found entirely similar to the product obtained with fresh water and KOH. The results of this research can be considered as a promising approach for the synthesis of high product quality sorbent for the eco-environmental applications.

Recyclable zinc (II) ionic liquid catalyzed synthesis of azides by direct azidation of alcohols using trimethylsilylazide at room temperature

A new efficient method has been reported for the synthesis of azides by direct azidation of alcohols with TMSN3 in presence of recyclable task specific ionic liquid (TSIL) [bmim]ZnCl3 as a catalyst in DCM at room temperature. Ionic liquid [bmim]ZnCl3 was synthesized under solvent free conditions and characterized by IR, 1H NMR, 13C NMR and HRMS. The Lewis acidity of catalyst was also examined using IR spectroscopy. The main features of this new methodology are high yields of products, recyclability of catalyst, scalability of reaction to gram scale and short reaction time.

Catalytic alcoholysis of bagasse cellulose for the total reducing sugars with temperature-sensitive phase-variable ionic liquid

ABSTRACTThe separation of cellulose hydrolyzate and ionic liquids (ILs) as well as the recycling of ILs is very plagued and needs to be resolved urgently in cellulose hydrolysis. In this study, a temperature-sensitive phase-variable IL was employed to develop a new conversion method for cellulose. It was found that the IL exhibited favorable catalytic activity over six repeated runs, which only decreased by 9.10%. Additionally, a mechanism for this alcoholysis system was proposed. The study is aimed to provide a new scientific way for the cellulose conversion and extend the application of temperature-sensitive ILs in biomass field.

Perfect recycle and mechanistic role of hydrogen sulfate ionic liquids as additive in ethanol for efficient conversion of carbohydrates into 5-ethoxymethylfurfural

Hydrogen sulfate ionic liquid as co-solvent and homogeneous catalyst can promote efficient conversion of carbohydrates into 5-ethoxymethylfurfural (5-EMF). Yields of 5-EMF were as high as 77% and 43% from inulin and sucrose, respectively, in the mixed solvent system of ethanol-[BMIM][HSO4] for 30min reaction time at 130°C. The ionic liquid could be perfectly recycled with a single pretreatment of activated carbon for 24h. Based on the characterization with 1H NMR and ATR-FTIR, the mechanism for the hydrogen sulfate ionic liquid promoted conversion of inulin into 5-EMF through stabilization of 5-hydroxymethylfurfural (5-HMF) with the C-2 hydrogen of the ionic liquid. Hydrogen sulfate ionic liquid as additive allows efficient conversion of carbohydrates into biofuels and as homogeneous catalysts, they can be easily reactivated and recycled with activated carbon treatment.

Recycle and Extraction: Cornerstones for an Efficient Conversion of Cellulose into 5-Hydroxymethylfurfural in Ionic Liquids

Hydrolysis and subsequent degradation of microcrystalline cellulose in five ionic liquids (ILs) using metal salts and/or Bronsted acids as catalysts allowed for the direct access to 5-hydroxymethylfurfural (HMF), an important renewable biofuel precursor and a useful building block. For each catalytic system, several reaction parameters (temperature, reaction time, catalyst, and cellulose loading) have been selectively changed. Four systems ([BMIM]Cl-CrCl3, [BMIM]Cl-FeCl3, [BMIM]Cl-[MIMC4SO3H][HSO4] and the not yet investigated [BMIM]Cl-TiOSO4) were found to be effective for cellulose degradation into HMF. The extraction of HMF from the reaction media represents however the weak point of all these processes being able to affect negatively both HMF recovery and IL recyclability. The critical step which causes the drastic decrease in HMF yield starting from the first recycle has been clearly identified. Furthermore, the possibility to use TiOSO4 as a sustainable and robust catalyst for the conversion of sacc...