Ternary Deep Eutectic Solvents Research Articles

Cresyl violet electropolymerization on functionalized multiwalled carbon nanotubes in carboxylic acid based ternary deep eutectic solvents for hydroquinone sensing

The phenazine dye cresyl violet (CVio) has been evaluated as precursor for the preparation of a new electrochemical sensor based on poly(cresyl violet) deposited on multiwalled carbon nanotube (CNT) modified glassy carbon electrodes (GCE) in neutralized acid-doped ternary deep eutectic solvents (DES). DES with choline chloride as hydrogen bond acceptor and with different hydrogen bond donors (HBD), namely acetic acid, ethylene glycol and oxalic acid were evaluated for CVio electropolymerization by potential cycling. The best polymer films were obtained in ternary DES with the two HBD acetic acid plus ethylene glycol doped with H2SO4 and followed by NaOH neutralization. Electrochemical characterization (voltammetric and electrochemical impedance) showed the formation of anthraquinone groups during electropolymerization, which is initiated on the CNT by the formation of a cation radical. Anthraquinones in the polymer film led to an increased response at the modified electrode for the determination of hydroquinone (H2Q) with low LOD (0.25 µmol L−1) in a broad linear range (1–80 µmol L−1), with good reproducibility, repeatability, and stability. The sensor was successfully applied to the quantification of H2Q in dermatological creams with no matrix effect towards hydroquinone response.

Investigation of effective CO2 capture by ternary deep eutectic solvents based on superbase

The absorption and separation of CO2 is one of the main strategies to reduce carbon emissions and mitigate global climate change. In this context, a series of ternary superbase/betaine-based deep eutectic solvents (DESs) were synthesized to capture CO2, and their density, viscosity and thermal stability were investigated. The effects of temperature, pressure, different hydrogen bond donors (HBDs) and alkalinity of the superbase on their CO2 affinity were evaluated by the isovolumetric saturation method. The uptake of CO2 by the DES synthesized from betaine, 1,2-propanediol and 1,8-diazabicyclo(5.4.0)undec-7-ene reached a maximum of 1.5071 mol·kg−1 at 303.15 K and a pressure of 0.187 MPa. The simultaneous chemical and physical adsorption of CO2 by the ternary DESs was verified by FTIR spectroscopy, and the absorption mechanism was also proposed. The reaction equilibrium thermodynamic model (RETM) was improved to obtain the “Active DES” model, which was correlated with the experimentally determined CO2 solubility. The reaction equilibrium constants and Henry's law constants were obtained for each ternary system. The ternary superbase/betaine DESs proposed in this paper are green, economical and high-performance absorbers for capturing CO2.

Silver Recovery from E-Waste Printed Circuit Board Using Binary and Ternary Deep Eutectic Solvents

Printed Circuit Boards (PCBs) are essential components of electronic devices containing valuable silver metal. Using sustainable methods, silver recovery from electronic trash, like PCBs, demonstrates excellent promise. This research’s objective is to determine the optimum leaching time and solid-to-liquid (S/L) ratio for extracting silver from PCB using deep eutectic solvent (DES) composed of choline chloride and glycerol (glyceline DES). The binary DES’s leaching performance was then compared to choline chloride, glycerol, and citric acid ternary systems. Fourier Transform Infrared Spectroscopy (FTIR) was carried out to analyze the bond interactions. X-ray fluorescence spectrometry (XRF) was employed to determine the PCB’s metal concentration prior to and after the leaching process. Ternary DES was viscous, colorless, stable for 60 days, and less acidic than binary DES, with a 1.21 g/mL density. FTIR peak broadening and shifting indicated the formation of a new hydrogen bond and proved a successful synthesis of ternary DES. XRF result showed that PCB’s initial silver metal content was 2.32%. The optimal silver leaching from PCB using glyceline DES was achieved after 16 hours, with a 1/20 solid-to-liquid ratio. Ternary DES demonstrated a silver leaching efficiency of 93.65%, surpassing 86.77% of glyceline. Ternary DES synthesized in this study has the potential to serve as an efficient and environmentally friendly solvent for extracting silver from PCB, providing a sustainable approach to managing electronic waste.

Efficient and selective absorption of NH3 by supramolecular OHP[5]-based ternary deep eutectic solvents

Developing an efficient absorbent for selective ammonia capture is of significant importance in the recovery and utilization of ammonia resources. Herein, a series of supramolecular-based ternary deep eutectic solvents (DESs) was designed and prepared using per-hydroxy pillar[5]arene (OHP[5]) and ethylamine hydrochloride as the key components. It is found that the supramolecular-based ternary DES EaCl-Gly (1:2)-6% OHP[5] could be employed as an efficient absorbent for reversible absorption of NH3. The NH3 uptake capacity reached 2.39 mmol/g and 10.84 mmol/g at 298.2 K under the pressure of 10 kPa and 100 kPa, respectively. Meanwhile, a higher NH3/CO2 selectivity (84) was obtained at 298.2 K and 100 kPa owing to the low solubility of CO2 in EaCl-Gly (1:2)-6% OHP[5]. The results of 1H NMR and FTIR spectra further clarified the absorption mechanism of NH3 by EaCl-Gly (1:2)-6% OHP[5]. Accordingly, the chemical absorption and physical dissolution capacity of NH3 in EaCl-Gly (1:2)-6% OHP[5] were calculated on the basis of isotherm data and thermodynamic equations. This study offers a promising application of pillar[5]arene to form supramolecular-based DESs for efficient NH3 absorption.

Physicochemical and thermodynamic properties of binary amine-based deep eutectic solvents for carbon capture

Deep eutectic solvents (DESs) have attracted great interest as a new green alternative to ionic liquids. In order to investigate the potential of using DESs to replace traditional organic solvents in carbon capture processes, it is necessary to understand in detail the physicochemical and thermodynamic properties of DESs before and after CO2 absorption. In this paper, choline chloride was used as the hydrogen bond acceptor and ethanolamine as the hydrogen bond donor to prepare the original DES. Afterward, 5 % mass fraction of morpholine/sarcosine is then added to make two kinds of ternary secondary amine functionalized DESs. Six quaternary DESs were finally prepared by mixing 20 % solvent (water/glycerol/ethylene glycol) with the ternary DESs. Subsequently, the physicochemical properties of DESs, such as melting point, density, viscosity and surface tension, were experimentally determined over the temperature range of 303.15–353.15 K. The properties of ternary and quaternary DESs before and after CO2 absorption were especially predicted and analyzed using different models. It was found that the Vogel-Fulcher-Tamman model was more suitable for forecasting viscosity, and the Pelofsky equation was better for prediction of the relationship between surface tension and viscosity. Based on the experimental data and the solvent critical values predicted by the state equation, the thermodynamic properties of ternary and quaternary DESs before and after CO2 absorption, such as molar volume, isobaric expansion coefficient, lattice energy, activation energy, viscous flow entropy and enthalpy, were derived and analyzed.

Polysaccharides extraction from Ganoderma lucidum using a ternary deep eutectic solvents of choline chloride/guaiacol/lactic acid

In this study, a purposefully formulated ternary deep eutectic solvents (DESs), consisting of choline chloride, guaiacol, and lactic acid in a molar ratio of 1:1:1, was synthesized for the extraction of polysaccharides from Ganoderma lucidum. The physicochemical properties of the synthesized DESs, including viscosity, density, pH, and hydrogen bonds, were comprehensively examined. Verification of the formation of the ternary DESs was accomplished through Fourier transform infrared and Nuclear magnetic resonance spectroscopies. Subsequently, response surface methodology was applied to optimize crucial parameters for polysaccharide extraction using DESs, resulting in a maximal extraction yield of 94.72 mg/g under the optimized conditions. Cyclic experiments demonstrated the commendable cyclic stability of the DESs, with a recovery rate exceeding 88 %. Furthermore, experiments on monosaccharide composition, molecular weight, and antioxidant activity of the isolated polysaccharides were conducted. Density functional theory was employed to gain insights into the molecular mechanism of polysaccharide extraction by DESs. The findings revealed a triple hydrogen bond interaction and a high binding energy (65.29 kcal/mol) between the DESs and glucose, highlighting their significant contribution to the high extraction effectiveness. This molecular-level understanding underscores the inherent superiority of DESs in the polysaccharide extraction processes, providing valuable insights for future applications in this field.

Ternary deep eutectic solvents for efficient denitrogenation of a model oil: thermodynamics, extraction efficiency, and recycling performance

Ternary deep eutectic solvents for efficient denitrogenation of a model oil: thermodynamics, extraction efficiency, and recycling performance

Recyclable water-modified deep eutectic solvents for removal of multiple heavy metals from soil

Removing heavy metals from soil has always been a challenge in terms of safety and effectiveness. Deep eutectic solvents (DESs) are recognized as environmentally friendly reagents with great potential in the removal of heavy metals from soil. In this study, water was introduced as a third component to form new ternary deep eutectic water solvents (DEWSs) to improve their performance. The removal capacity, applicable conditions and mechanisms of sixteen DEWSs for heavy metals were systematically investigated. Experimental results showed that the presence of water significantly enhanced the removal efficiency of three DESs (Choline chloride plus Urea, DEU; Choline chloride plus l-lactic acid, DELA; and Choline chloride plus Ethylene glycol, DEEG) for heavy metals. However, as the molar ratio of water increased, the eutectic systems in the DEWSs weakened and eventually disappeared. Under optimum conditions, DEWLA7 (DELA : H2O = 2 : 8) showed the highest removal rate for cadmium, lead, copper and zinc, which were 43.42%, 94.73%, 90.72% and 96.44%, respectively. Hydrogen bonding, adsorption of oxygen functional groups, exchangeable hydrogen substitution, changes in viscosity properties and co-precipitation all contributed to the removal of heavy metals by DEWLA7. Notably, DEWLA7 had no significant effect on the content of major minerals and nutrients in the soil. Furthermore, DEWLA7 proved to be reusable for soil washing, and still retains a high removal rate of 37.32%–83.66% after multi-stage filtration treatment. Therefore, DEWLA7 was an unexplored and excellent soil washing agent with great potential in economic and social benefits.

Study of ternary deep eutectic solvents to enhance the bending properties of ash wood.

Deep eutectic solvents (DESs) are considered one of the most promising biomass pretreatment reagents, and their research applications in woody fibrous biomass are increasing yearly. Inspired by the research related to wood bending, we explored the effects of different DES systems on the bending development of wood, and the results showed that the addition of anhydrous ferric trichloride to the DES system of lactic acid/choline chloride could enhance the treatment effect that increased the bendability and torsion resistance of ash wood. The anhydrous FeCl3 could act as an active site and provide acidic protons to improve the treatment efficiency of DES. In addition, the addition of an appropriate amount of water can reduce the viscosity of the DES system, and the highest lignin removal rate was obtained at 10 wt% of water in the DES, which resulted in the best mechanical properties and tensile resilience of ash wood, with the tensile strength and stability of 97 MPa and 13.6%, respectively, as determined by experiments with different water contents in different mass fractions. Therefore, using a DES can effectively improve the bending properties of wood.

Preparation of PEG/P(U-AM-ChCl) composite hydrogels using ternary DES light polymerization and their properties.

Deep eutectic solvents (DES) were prepared using urea (U) and acrylamide (AM) as hydrogen bond donors (HBD) and choline chloride (ChCl) as hydrogen bond acceptor (HBA), and polyethylene glycol (PEG) was selected as a filler and uniformly dispersed in DES to prepare PEG/P(U-AM-ChCl) composite hydrogels by light polymerization. The composite hydrogels were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The effects of the content of PEG on the swelling properties, mechanical properties and fatigue resistance of the composite hydrogels were investigated. The results showed that the compressive strength and fatigue strength of the composite hydrogels were gradually enhanced with the increase of the PEG content in the composite hydrogels, in which the maximum compressive strength of the hydrogels with 1 wt% PEG added was increased by 1.86 times. The composite hydrogel had excellent swelling properties, and the equilibrium swelling degree of the hydrogel with 1 wt% PEG added reached 10.15. Meanwhile, the PEG/P(U-AM-ChCl) composite hydrogel had excellent self-healing properties, and the self-healing rate of the composite hydrogel with a PFG content of 1 wt% could reach 91.93% after 48 hours of healing. This study provides a convenient and efficient method to prepare composite hydrogels with superior swelling properties and self-healing properties.

Upgrading lignin macromolecular by green and recyclable ternary deep eutectic solvents

Lignin is the most abundant natural aromatic macromolecule in the nature, but its high value-added utilization has been seriously hindered by the highly random and branched structures and the high difficulty in separation and purification. A microwave-assisted ternary deep eutectic solvent (DES) composed by formic acid, lactic acid and choline chloride was developed for lignin pretreatment. The effects of three types of DES on main characteristics of lignin were investigated, and the corresponding dissolution mechanism was proposed. The results showed that, the microwave-assisted ternary DES pretreatment showed an obvious improvement on main characteristics of regenerated lignin, e.g., a higher purity, lower molecular weight with reduced dispersity, improved thermal stability, higher phenolic hydroxyl content, and increased antioxidative activity in comparison with control. It is expected that the lignin macromolecular can be facile regulated and upgraded by the proposed ternary DES.

Glycerol/organic acid-based ternary deep eutectic solvents as a green approach to recover chitin with different molecular weight from seafood waste

In this study, we designed a green and efficient approach for the fractionation of high-purity chitin with tunable molecular weights from seafood waste. This was achieved by using ternary deep eutectic solvents (TDESs) composed of choline chloride as a hydrogen bond acceptor, glycerol as the polyol-based hydrogen bond donor, together with lactic acid or malic acid. Two binary DESs and four TDESs were evaluated for their ability to recover chitin. The extracted chitin exhibited not only high yield with excellent protein and mineral removal, but also high purity with similar crystallinity patterns as standard chitin. However, the average molecular weights, viscosity behavior and morphology of chitin extracted by DESs were varied and influenced by organic acid to glycerol molar ratios. The molecular weights of chitin extracted by lactic acid-based TDES ranged from 264 kDa to 541 kDa, but malic acid-based TEDS displayed a stronger depolymerization effect, resulting in chitin with a smaller molecular weight of less than 300 kDa. Lactic acid-based TDES revealed that the purity of chitin remained higher than 92 % after three cycles. This sustainable and environmentally friendly extraction system holds great potential to recover chitin from seafood waste, opening a new era for chitin extraction and applications.

Aerobic Oxidation of 5-Hydroxymethylfurfural via Hydrogen Bonds Reconstruction with Ternary Deep Eutectic Solvents.

Hydrogen bonding effect exists widely in various chemical and biochemical systems, primarily stabilizing the molecular structure as a positive factor. However, the presence of intermolecular hydrogen bonds among biomass molecules results in a formidable challenge for the efficient utilization of biomass resources. Here in, a novel strategy of "hydrogen bonds reconstruction" was developed by a series of ternary deep eutectic solvent (DESs) as molecular scissors, which disrupting the initial intermolecular hydrogen bonds and reconstructing the new ones to increase the reactivity of the biomass-based compound. The DESs played a crucial role in enhancing the reactivity of 5-hydroxymethylfurfural (HMF) and promoting its oxidation through reconstructing the hydrogen bonds interactions. Furthermore, DESs was also found to activate the Anderson-type catalyst Na5IMo6O24 (IMo6) through an electron-transfer mechanism, which facilitated the generation of oxygen vacancies and significantly enhances its ability to activate molecular oxygen. With this novel catalytic system, oxidation of HMF exhibited remarkable efficiency as HMF was almost entirely converted into FFCA with an impressive yield of 98 % under the optimized conditions. This finding offers novel insights into the utilization of biomass resources and endows the solvent with new functions in the chemical reaction.

Effect of ternary deep eutectic solvents on delignification of stone pine cone

Due to their cost-effectiveness and environmentally friendly nature, deep eutectic solvents (DESs) hold great potential for applications in biomass conversion and the production of green chemicals. In this study, the delignification of the stone pine (Pinus pinea L.) cone was performed using seven different ternary deep eutectic solvents (TDESs). TDES treatments of stone pine cone samples were carried out in a microwave for 30 min. at 150 °C. The two-based components of TDESs were choline chloride (ChCl - 1 mol) and lactic acid (LA - 9 mol). The formic acid (FA – 2 mol), boric acid (BA – 1 mol), acetic acid (AA – 2 mol), sorbitol (S – 1 mol), triethylene glycol (TEG – 2 mol), ethylene glycol (EG – 2 mol), and glycerol (G – 2 mol) were used as third component of TDES. ChCl:LA:BA gave the lowest solid residue yield (57.90%) and highest lignin purity (86.89%). Klason lignin content of control was 35.08%. The lowest lignin content (19.42%) and highest delignification (68.89%) were obtained with ChCl:LA:FA treatment. The lowest and the highest L* values were obtained from ChCl:LA:BA and ChCl:LA:EG treatments with 21.76 and 37.36, respectively. This results showed that the third component of TDES affects the delignification efficiency of stone pine cone.

Ternary Deep Eutectic Solvents System of Colchicine, 4-Hydroxyacetophenone, and Protocatechuic Acid and Characterization of Transdermal Enhancement Mechanism.

This study aimed to prepare colchicine (CO), 4-hydroxyacetophenone (HA), and protocatechuic acid (CA) contained in transdermal rubber plasters into a more releasable and acrylate pressure-sensitive adhesive (PSA) to optimize traditional Touguling rubber plasters (TOU) with enhanced transdermal permeability by using deep eutectic solvents (DES) technology. We compared the difference in the release behavior of CO between rubber plaster and PSA, determined the composition of the patch through pharmacodynamic experiments, explored the transdermal behavior of the three components, optimized the patch formula factors, and improved the penetration of CO through the skin. We also focused on elucidating the interactions among the three components of DES and the intricate relationship between DES and the skin. The melting point of DES was determined using DSC, while FTIR, 13C NMR, and ATR-FTIR were used to explore the intricate molecular mechanisms underlying the formation of DES, as well as its enhancement of skin permeability. The results of this investigation confirmed the successful formation of DES, marked by a discernible melting point at 27.33°C. The optimized patch, formulated with a molar ratio of 1:1:1 for CO, HA, and CA, significantly enhanced skin permeability, with the measured skin permeation quantities being 32.26 ± 2.98 µg/cm2, 117.67 ± 7.73 µg/cm2, and 56.79 ± 1.30 µg/cm2 respectively. Remarkably, the optimized patch also demonstrated similar analgesic and anti-inflammatory effects compared to commercial diclofenac diethylamide patches in different pharmacodynamics studies. The formation of DES altered drug compatibility with skin lipids and increased retention, driven by the interaction among the three component molecules through hydrogen bonding, effectively shielding the skin-binding sites and enhancing component permeation. In summary, the study demonstrated that optimized DES patches can concurrently enhance the penetration of CO, HA, and CA, thereby providing a promising approach for the development of DES in transdermal drug delivery systems. The findings also shed light on the molecular mechanisms underlying the transdermal behavior of DES and offer insights for developing more effective traditional Chinese medicine transdermal drug delivery systems.

P/N/S synergistic flame retardant holocellulose nanofibrils efficiently pretreated from ternary deep eutectic solvents

Cellulose nanofibrils (CNFs) have widely attracted significant attention due to the excellent mechanical performance, biodegradability, and high surface functionality. However, the high flammability of CNFs commonly restricts their wider application. In this study, the intrinsically flame-resistant holocellulose nanofibrils (HCNFs, which is rich in both cellulose and hemicellulose) were obtained from bamboo under pretreatment using a highly efficient ternary deep eutectic solvent (TDES) and subsequential mechanical homogenization. The phytates and sulfate-containing HCNFs (PHCNFs) displayed nanofibril diameter of 3–5 nm and high aspect ratio of (∼500), and the aqueous suspension exhibited colloidal stability and high transmittance. The PHCNF films exhibited excellent fire resistance, mechanical and optical properties. Compared with raw HCNF, the limiting oxygen index (LOI) of PHCNF-120 film was up to 52.5 %, and the total heat release (THR) and peak heat release rate (PHRR) of PHCNF-120 films were significantly reduced by 92.2 % and 82.4 %, respectively. The flame retardant mechanism was attributed to the synergistic effect of P/N/S in both condensed phase and gaseous phases during the burning process. This work provides a novel, efficient strategy for developing eco-friendly flame-resistant and fireproof holocellulose-based nanomaterials.

One-pot strategy to enhance nanofibrillation and esterification of cellulose using ternary deep eutectic solvent

Establishing green and efficient method for the nanofibrillation and modification of cellulose is the foundation to prepare the cellulose functional material. Herein, we provided a "one-pot " strategy to achieve the high-efficiency nanofibrillation and esterification of nanocellulose using the ternary deep eutectic solvents (DESs). The widths of cellulose nanofiber (CNF) with 18.9 ± 2 nm were successfully prepared by swelling with maleic acid/choline chloride (MA/ChCl) DES at 100 °C for 3 h, followed by mechanical colloid milling. The corresponding acid anhydrides maleic anhydrides (MAH) was added to form MAH/MA/ChCl DES for enhanced esterification of nanocellulose. As a result, the nanocellulose achieved a high degree of substitution (DS) of up to 0.84. The feasibility of "one-pot " strategy based on other ternary DESs (acetic anhydride/acetic acid/choline chloride (AAH/AA/ChCl), succinic anhydride/succinic acid/choline chloride (SAH/SA/ChCl) as representative) was further studied to fibrillate and esterify nanofibers, demonstrating it is an efficient method for the nanofibrillation and modification of cellulose.

Pretreatment of corncob powder by choline chloride-urea-ethanolamine to co-produce glucose, xylose and lignin nanospheres

A ternary deep-eutectic solvents (DESs) which consisted of choline chloride-urea-ethanolamine (ChCl-U-EOA) was used for the pretreatment of corncob powder (CCP), and the effect of various pretreatment conditions on the pretreated substrates components and subsequent enzymatic digestion was investigated. The results indicated that under the optimum pretreatment conditions (110 ℃, 60 min, 10% solid concentration), the ChCl-U-EOA pretreatment could selectively remove ∼71.8% of lignin while retaining ∼87.7% of cellulose and ∼74.6% of hemicellulose, and the yields of glucose and xylose after enzymatic digestion reached ∼86.4% and ∼70.5%, respectively. The characterization of various pretreated substrates showed that the removal of lignin, and the fragmentation of pretreated substrates was the key factors to improve glucose/xylose yields. In addition, the lignin in the pretreated hydrolysate was collected by acid precipitation and fractionated by ethanol, and then lignin nanospheres (LNPs) with a particle size under 200 nm were fabricated via a solvent-antisolvent method.

Enhanced biomass processing towards acetone-butanol-ethanol fermentation using a ternary deep eutectic solvent

This work evaluated the effectiveness of ternary deep eutectic solvents (DES) composed of cholinium chloride (ChCl), lactic acid (LA) and a diol (ethylene glycol – EG, or 1,6-hexanediol – HEX) in the pretreatment of rice straw (RS) towards the production of biobutanol. The most promising results were obtained with ChCl:LA:EG 1:5:5 at 120 °C for 4 h, which enabled the highest conversion of biomass polysaccharides into glucose and xylose up to 89.3 % and 53.6 % yields, respectively. Subsequently, the produced sugars were efficiently converted into biobutanol through the acetone-butanol-ethanol (ABE) fermentation process, resulting in the production of 95.7 g butanol/kg RS as one of the highest values reported in literature. Thus, the application of the ternary DES ChCl:LA:EG 1:5:5 represents a competitive and environmentally friendly pathway for RS valorization in comparison to conventional processes.

Comparison of kraft and ternary deep eutectic solvent pulping of scots pine

Kraft method, the most widely used method in pulp production, causes to various environmental problems. Therefore, environmentally friendly pulp production methods have been investigated. In recent years, environmentally friendly deep eutectic solvents (DESs) as cooking liquor have been investigated. In this study, the possibilities of using a ternary DES (TDES) in pulp production from Scots pine (Pinus sylvestris L.) chips were investigated. TDES constituents were choline chloride (ChCl), lactic acid (LA), and glycerol (G). The effects of cooking temperature (145 °C and 155 °C) and cooking time (3 h, 3.5 h, and 4 h) on pulp and paper properties in TDES pulping were investigated. For comparison, kraft pulp from Scots pine was produced with conditions of 18% active alkali, 25% sulfidity, 155 °C cooking temperature, and 3.5 h cooking time. The highest lignin removal was obtained from TDES3 pulping conditions (155 °C and 4 h) with 76.0%. Lignin removal in the kraft pulp was 67.8%. TDES pulps were more quickly beaten to the target freeness level of 25°SR (the times for TDES3 and kraft pulps were 90 sec and 1350 sec, respectively.). Crystallinity index (CrI) values of kraft pulp and TDES3 pulp were 70.7% and 68.0%, respectively. TDES6 pulp had the highest pulp strength. But, the strength properties of all TDES pulps had lower than kraft pulp. TDES pulping can be a greener alternative to kraft pulping.