Degradative Solvent Extraction Research Articles

Degradative solvent-catalyzed extraction of sewage sludge

It is necessary for the further development of sludge degradative solvent extraction (DSE) to significantly increase the bio-oil yield and adjust its composition. In this study, the effects of MCM-41, HZSM-5, and SSZ-13 on the physical properties, yield, and composition of bio-oil were compared. Results show that all three catalysts effectively promote the conversion of volatiles in the residue to the heavy component (heavy-s). The addition of MCM-41 improved the yieldof both the light component (light-s) and heavy-s. Their yields increased from 8.11% and 20.47% to 14.39% and 29.18%, respectively. Its all-silicon structure and weak acidity have no significant effect on the composition of the bio-oil. HZSM-5 addition increases the light-s yield to 25.58%. Its MFI structure and proper acidity are beneficial to the formation of aromatic hydrocarbons and olefins, while effectively reducing oxygenates. SSZ-13 increases the heavy-s yield to 27.89%, and promoted the formation of nitrogen-containing compounds significantly.

Degradative solvent extraction of low rank coal: Structural evolution of extraction products

The degradative solvent extraction method was proposed to convert low rank coals into carbon-enriched products under mild condition. However, limitations in the understanding of the structure evolution of products and reaction mechanism of the extraction process hinder the targeted regulation of the products. Therefore, in this work the structural evolution of products during the extraction for different types of coals and by different types of solvents were investigated. Synthesized molecular structural models of the products were constructed and the reaction mechanism was then discussed. Results show that the industrial compounding solvent (ICS) is capable of extracting more single-ring aromatic organics from coals and increasing the yields of the main products by approximately 10% compared to 1-methylnaphthalene. During the extraction process, the main reaction of the sub-bituminous coal is the breakage of unstable chemical bonds and functional groups, while the reaction of lignite is the thermal decomposition and deoxygenation of massive small molecules in the coal. Moreover, the ICS promotes aromatization reactions during the extraction, which indicates that the ICS is the appropriate industrial solvent for the degradative solvent extraction. This research proved a theoretical guidance for the industrialization of DSE technology and the targeted regulation of the products.

Degradative solvent extraction of cyanobacteria: From reaction kinetics to potential organic matter evolution mechanism

This study proposed a new continuous lumped reaction kinetics model to accurately reveal the control mechanism of cyanobacteria at each stage of degradative solvent extraction and discussed the potential evolution mechanism of organic matter. Results showed that degradation solvent extraction successfully separated nitrogen and phosphorus from cyanobacteria. The solute has high carbon and volatile contents, is almost ash-free, and forms a phosphorus-rich residue. The lowest fitting degree of the continuous lumped reaction model kinetics was 94.5%, suggesting that this model worked well. The depolymerization of the residue dominated between 200 and 350 °C, whereas solute decomposition dominated at 400 °C. Nitrogen-containing compounds, which originate from protein decarboxylation or deamination to generate amides, are the main components of the solute, and amino acids react with reducing sugars to generate nitrogen heterocyclic compounds, which are useful for preparing nitrogen-containing chemicals.

Degradative solvent extraction of subbituminous coal with deep eutectic solvent and effect of reaction conditions on products

A degradative solvent extraction method for upgrading low-rank coal was performed at 200–350 °C for 90 min to obtain a substance dissolved in the solvent at room temperature (Soluble). Because the resulting mixture exhibited a high carbon content without ash, it could be readily used as a fuel. Furthermore, deep eutectic solvents (DESs) have attracted attention for improving the Soluble yield and decreasing the oxygen content in Soluble. DES is known to cleave oxygen-containing functional groups in biomass and is considered effective for deoxidizing low-rank coal. Herein, DES was prepared by mixing choline chloride, FeCl3·6H2O, and Adaro subbituminous coal (AD) and then added to 1-methylnaphthalene (1-MN) in a non-polar solvent, followed by degradative solvent extraction in the range of 200–350 °C. The effects of reaction temperature and added DES amount on the product yield and the composition were evaluated. As the reaction temperature and amount of DES added increased, the Soluble yield and carbon content increased. It was also found that the thermal decomposition temperature and oxygen content decreased with the increasing DES amounts. This decrease indicates that DES promotes the deoxygenation and decomposition of AD and increases the soluble yield of the fuel source.

Elucidation of the interaction effects of cellulose, hemicellulose and lignin during degradative solvent extraction of lignocellulosic biomass

The degradative solvent extraction (DSE) method has been recently developed to deoxygenate and upgrade lignocellulosic biomass wastes into high-quality extracts with a variety of value-added applications. Lignocellulosic biomass is mainly composed of cellulose, hemicellulose and lignin, and the interaction of the three components during the DSE process still remains unclear and needs to be elucidated. Therefore, in this study, the synthetic component mixtures (cellulose/hemicellulose (CH), cellulose/lignin (CL) and hemicellulose/lignin (HL)) were firstly prepared with the model compounds (cellulose, hemicellulose and lignin), and the conversion characteristics of the component mixtures and the superposition of individual component during the DSE process under the same operating conditions were compared to reveal the interaction effect between the three components. The extract yields of cellulose, hemicellulose and lignin were 44.16%, 27.4% and 18.25% respectively, indicating that cellulose contributed mostly to the formation of the extract (the target product) compared with hemicellulose and lignin. Significant interactions were observed for cellulose/lignin and hemicellulose/lignin mixtures, while the interaction effect between cellulose and hemicellulose was relatively small. The interaction intensity between cellulose, hemicellulose and lignin was in the order of HL > CL > CH. The interaction between cellulose/lignin and hemicellulose/lignin promoted the thermal degradation of lignin. Specifically, the interaction between the hemicellulose and lignin mixture reduced the yield of residue by 9.26%. The interaction mechanism between the three components was discussed and revealed based on the detailed characterization of the DSE products. The interaction between the three components could facilitate the production of gaseous products (mainly CO2), indicating that the interaction between the three components significantly promoted the decarboxylation reaction. The interaction between two of the three components all inhibited the aromatization reaction and reduced the aromaticity of the extracts. During the DSE process of cellulose/lignin or hemicellulose/lignin mixtures, the small-molecular free radicals generated by the decomposition of cellulose or hemicellulose could occupy the active sites on lignin fragments, leading to the significant inhibition of the condensation reactions between different lignin fragments. These interactions leaded to the decrease of the extract yields and residue yields during the DSE process of cellulose/lignin or hemicellulose/lignin mixtures.

Calcium oxide-enhanced phosphorus recycling using sewage sludge degradative solvent extraction technology

This study proposes a novel calcium oxide-enhanced phosphorus recycling technique using sewage sludge degradative solvent extraction. We investigated the effects of extraction parameters such as the temperature, holding time, and sludge/extractant ratio on the soluble yield and phosphorus distribution in the residue. The enhancement mechanisms of the apatite phosphorus (AP) content after adding CaO for degradative solvent extraction were also studied. The results showed that the effective separation of organic matter and phosphorus enrichment were simultaneously achieved. An increase in the extraction factors promoted the extraction of organic matter. The peak soluble yield is 13.30 g/100 gSSwhich was obtained at extraction temperature of 300 °C, holding time of 60 min and sludge/extractant ratio of 100/300 g/mL. The soluble matter with high amounts of volatile matter and near-zero ash content has high-value utilization potential. After the degradative solvent extraction, almost all P in the sewage sludge was enriched in the residue. The organic phosphorus (OP) in the residue almost disappeared, and the proportion of non-apatite inorganic phosphorus (NAIP) increased. As the amount of added CaO increased from 0 to 10 g, the proportions of AP in TP increased from 36.55 to 80.15%, while that of NAIP decreased from 61.93 to 14.77%. The transformation of P from OP to the inorganic species during extraction was promoted by the addition of CaO, particularly for the formation of hydroxylapatite.

Degradative solvent extraction of low-rank coal: Role of water on pyrolysis mechanism of low-rank coal in a highly-dispersed medium

A degradative solvent extraction (DSE) method was proposed to upgrade low-rank coals (LRC) for their cascaded utilizations in a highly-dispersed medium. The derived products exhibited well improved properties in comparison to the raw LRCs. Previously, the LRCs were pre-dried to eliminate the potential impact of the varied water content of raw LRCs, but in light of the abundant water in fresh coals, the hydrolyzing effect of water on coals under heating, and the energy cost to pre-dry the LRCs, it is consequently essential to clarify the effect of water so as to verify the necessity of pre-drying process. In this study, the roles of inherent water and extra-added water were respectively investigated, using dried, raw and wet coals from two typical LRCs. The results show that increasing the moisture content of raw LRCs contributed to the extraction ability of DSE method without noticeably changing the elemental composition, chemical structure and thermal decomposition behavior of extractable products, thus pre-drying of LRCs before DSE treatment was proven unnecessary. Additionally, the roles of the inherent water were concluded as: 1) leading to the formation of stable covalent bond during drying process; and 2) acting as H donor to promote extraction ability, while the added water can only function as H donor. Since excessive water will increase the pressure during DSE treatment and lead to the waste water treatment, the LRCs with a water content between 10% and 30% were consequently recommended for the practical application of DSE treatment.

Elucidation of the Interaction Effects of Cellulose, Hemicellulose and Lignin During Degradative Solvent Extraction of Biomass

Elucidation of the Interaction Effects of Cellulose, Hemicellulose and Lignin During Degradative Solvent Extraction of Biomass

1-11 Solid fuel production with high calorific value from low-rank coal by degradative solvent extraction using deep eutectic solvent

1-11 Solid fuel production with high calorific value from low-rank coal by degradative solvent extraction using deep eutectic solvent

Influence of torrefaction, hydrothermal carbonization and degradative solvent extraction pretreatments on moisture absorption and self-ignition characteristics of biomass

Three main pretreatment methods (torrefaction, hydrothermal carbonization and degradative solvent extraction) have been developed to deoxygenate and upgrade biomass into biochar, hydrochar and extract, respectively, which have a variety of high-value applications. However, the influence of the three pretreatment methods on the moisture absorption and self-ignition characteristics of biomass still remains unclear, which greatly affects the subsequent storage, transportation and utilization process of the biochar, hydrochar and extract. Therefore, the effects of torrefaction, hydrothermal carbonization and degradative solvent extraction on the moisture absorption and self-ignition characteristics of biomass were investigated and compared in this study. The resultsshowedthat the moisture absorption ratios of the pretreated products (biochar, hydrochar and extract) were as low as 3.8%, 1% and 0.8%, respectively, which was obviously lower than that of RS (8%), indicating that the moisture absorption propensities of biochar, hydrochar and extract were all obviously inhibited compared to RS. These results were caused by the dramatic removal of oxygen functional groups during the three pretreatment processes. The heat release of biochar (6950 kJ/kg) and hydrochar (7134 kJ/kg) below 300 °C were obviously higher than that of RS (5950 kJ/kg), while the heat release of extract (5063 kJ/kg) below 300 °C was much lower than that of RS. Compared with RS, biochar and hydrochar had higher specific surface areas and higher contents of inorganic metallic elements, which contributed to their higher self-ignition susceptibilities than those of RS. In contrast, the extract had a dense structure and extremely low oxygen functional groups contents as well as low inorganic metallic elements contents, which jointly led to its lower self-ignition susceptibility than that of RS. This research is expected to provide a comprehensive understanding of the influence mechanism of pretreatment on the moisture absorption and self-ignition characteristics of biomass.

Moisture adsorption and spontaneous combustion characteristics of biomass wastes after degradative solvent extraction

The inherent disadvantages such as high oxygen content, low energy density, high moisture adsorption propensity and high spontaneous combustion tendency, have limited the widespread utilization of lignocellulosic biomass. A novel degradative solvent extraction (DSE) method has been recently developed to deoxygenate and upgrade biomass into two high-quality extracts (Soluble and Deposit) with various high-value applications. However, the moisture adsorption and spontaneous combustion characteristics of Soluble and Deposit still remain unclear, which are important for the safe storage, transportation and subsequent application of Soluble and Deposit. Therefore, in this study, the moisture adsorption and spontaneous combustion characteristics of Soluble, Deposit as well as raw biomass were investigated and compared. The moisture adsorption ratios of Soluble and Deposit were lower than 1.5% and 2.5% respectively, which were significantly lower than that of raw biomass, indicating that degradative solvent extraction greatly inhibited the moisture adsorption propensity of biomass. The ignition temperatures of Soluble and Deposit were at least 110 °C higher than that of raw biomass, and the activation energy of low temperature oxidation of Soluble and Deposit were 1.2–2.0 times higher than that of raw biomass. Soluble and Deposit had much higher weight loss temperature, heat release temperature, ignition temperature and higher activation energy of low temperature oxidation, revealing that the spontaneous combustion tendency of Soluble or Deposit was also significantly suppressed in comparison with raw biomass. The physicochemical properties of raw biomass, Soluble and Deposit were detailedly characterized, and it can be concluded that the low content of oxygen-containing functional groups, poor pore structure and dense surface structure jointly suppressed the moisture adsorption propensity and spontaneous combustion tendency of biomass after degradative solvent extraction. This research proves that degradative solvent extraction could not only achieve the upgrading of biomass but also inhibit the moisture adsorption propensity and spontaneous combustion tendency of biomass.

Preparation of activated carbon nanofibers using degradative solvent extraction products obtained from low-rank coal and their utilization in supercapacitors.

In this study, low-rank coal was separated into three solid fractions by a degradative solvent extraction method. The high-molecular-weight extract (termed Deposit) had some outstanding properties such as high carbon content, almost no ash, high aromaticity, good thermoplasticity and high solubility in DMF. Therefore, Deposit with some proportion of polyacrylonitrile (PAN) was used to prepare activated carbon nanofibers by electrospinning and CO2 activation. Moreover, the utilization of these carbon nanofibers as a supercapacitor electrode was preliminarily investigated. The results showed that the specific surface area of the Deposit-based carbon nanofibers (1005 m2 g−1) was significantly higher than that of the nanofibers obtained from pure PAN (688 m2 g−1). TGA simulations showed that this was caused by the different thermal decomposition behaviors of Deposit and PAN during the stabilization and activation processes. In addition, the Deposit-based carbon nanofibers showed a better specific capacitance (192.6 F g−1 at 1 A g−1) and cycling performance (retention rate of 89.8% after 1000 cycles at 5 A g−1) in a 6 M KOH electrolyte. The factors, such as the enhanced surface area and pore volume and decreased average fiber diameter, affected the electrochemical properties of the carbon nanofibers. Thus, it has been proven that the high-molecular-weight extract obtained from low-rank coal by degradative solvent extraction is a promising precursor for the preparation of carbon nanofibers with unique electrochemical properties.

Preparation of carbon nanofiber with specific features by degradative solvent extraction product from biomass wastes

One of the most essential topics in carbon fiber research is seeking a suitable precursor for the carbon fiber preparation. In this work, an extract was obtained from biomass wastes by a degradative solvent extraction method under moderate conditions. This extract had the properties required for carbon fiber preparation, such as high carbon content, low ash content, thermoplastic property etc. The carbon fiber, prepared using the extract by electro-spinning, had a coarser surface with the specific surface area and specific volume respectively reaching to 714.24 m2/g and 164.10 cm3/g, higher than those of PAN-based carbon fiber. The diameter of the extract-based carbon fiber was about 169 nm ~ 200 nm. The R (ID/IG) value was as low as 1.46. The stabilization and carbonization of extract-based and PAN-based fibers were also conducted via a TGA-DSC for a detailed investigation and comparison. It showed that the thermochemical behaviors of both carbon fibers were different. Thus, it proved that the degradative solvent extraction of biomass waste is a promising method for precursor production to prepare nano-scale carbon fiber with specific properties.

Investigation on Conversion Pathways in Degradative Solvent Extraction of Rice Straw by Using Liquid Membrane-FTIR Spectroscopy

Degradative solvent extraction (DSE) is effective in both dewatering and upgrading biomass wastes through the selective removal of oxygen functional groups. However, this conversion mechanism has yet to be elucidated. Here, liquid membrane-FTIR spectroscopy was utilized to examine the main liquid product (Solvent-soluble) without sample modification. Rice straw (RS) and 1-methylnaphthalene (as a non-hydrogen donor solvent) were used as materials, and measurements were performed at treatment temperatures of 200, 250, 300, and 350 °C for 0 min, and at 350 °C for 60 min. The Solvent-soluble spectra were quantitatively analyzed, and changes in the oxygen-containing functional groups and hydrogen bonds at each temperature were used to characterize the DSE mechanism. It was determined that the DSE reaction process can be divided into three stages. During the first stage, 200–300 °C (0 min), oxygen was removed via dehydration, and aromaticity was observed. In the second stage, 300–350 °C (0 min), deoxygenation reactions involving dehydration and decarboxylation were followed by reactions for aromatization. For the third stage, 350 °C (0–60 min), further aromatization and dehydration reactions were observed. Intramolecular reactions are indicated as the predominant mechanism for dehydration in RS DSE, and the final product is composed of smaller molecular compounds.

Interaction between low-rank coal and biomass during degradative solvent extraction

A degradative solvent extraction at around 350°C for low-rank coal or biomass wastes upgrading and fractionation was proposed in our previous work. The extraction yield of low-rank coal is relatively lower than that of biomass. In this work the blends of low-rank coal and biomass were treated by this method at 350°C to investigate the interaction between them. The results showed that the yields and elemental compositions of the extracts obtained from the blends were slight different to the calculated results, which were calculated by assuming that there was no interaction between the coal and biomass. The slight promotion of yield was judged to be caused by the catalytic action of the minerals in the coal for thermal decomposition of biomass. It was worth to note that the elemental composition, molecular weight distribution, chemical structure, thermal decomposition behavior and thermoplastic behavior of the extracts obtained from low-rank coal, biomass and their blend, were rather similar to each other, independent of the properties of the raw feedstocks. Overall, the interaction between low-rank coal and biomass during the extraction was not significant. On the other hand, the proposed degradative solvent extraction method was fit not only by single low-rank coal and biomass but also by their blends to produce the product having similar physicochemical properties. This implied that an industrial system of degradative solvent extraction can use coal, biomass or their blends as feedstock at the same time without modification or adjustment.

Solvent Recycling Operation of the Degradative Solvent Extraction of Biomass to Minimize the Amount of Solvent Required

The authors have recently presented a degradative solvent extraction method to dewater, upgrade, and convert biomass wastes into three solid fractions which we call Soluble, Deposit, and Residue. The carbon based yield of Soluble, which is the smallest molecular weight fraction, reached as high as 70% for some biomass wastes. Solubles were free from water and mineral matters, and their physical and chemical properties were almost independent of raw materials. Soluble is expected to be utilized for preparing functional carbon materials such as carbon fiber, and hence, it is requested to maximize the Soluble yield with minimum energy requirement from a practical viewpoint. Since the largest energy consumption of this extraction method comes from the separation of Soluble from solvent, it is essential to minimize the solvent to Soluble ratio before separating Soluble from the solvent. On the other hand, a large solvent to biomass ratio is required to disperse the biomass in the solvent during the solvent treatment at around 350 °C. To compromise the conflicting demands and to minimize the solvent to Soluble ratio, a new operating scheme, which uses the Soluble–solvent mixture repeatedly before separating Soluble from the solvent by replacing around 10% of the mixture by fresh solvent on every solvent treatment, was proposed. The validity of this operating scheme was examined by treating Thai rice straw (RS) with a general-purpose petroleum based solvent called A150 through 10 repeated uses of the Soluble–A150 mixture. It was found that the new operation scheme was effective from the viewpoints of quality and the yield of the Soluble produced.

Degradative solvent extraction of biomass using petroleum based solvents

The aim of this study was to examine the possibility to use two petroleum based solvents, kerosene and a distillate rich in benzene (A150), as practical solvents for the degradative solvent extraction at 350 °C in reference to 1-MN. It was found that the thermal degradation behavior of two biomass samples, a rice straw and Leucaena, in the three solvents was rather similar and that only the distribution of Soluble, Deposit, and Residue was affected by the difference of solubility of the solvents. Preparation of solvent treated biomass (STB) using the three solvents gave the yields close to the sum of the yields of Soluble, Deposit, and Residue. It was judged that A150 may be used to preparing Soluble and that Kerosene can well be used to prepare STB.

Degradative solvent extraction of low-rank coals by the mixture of low molecular weight extract and solvent as recycled solvent

The authors have proposed a degradative solvent extraction method to dewater, upgrade and separate low-rank coals to upgraded coal, high molecular weight extract (Deposit), low molecular weight extract (Soluble), and a little amount of liquid and gas products. For the practical application of this extraction method, the solvent must be recycled. Furthermore, the separation of the Soluble and solvent, which was implemented by distillation, consumed much energy and added the cost of the whole system significantly. In order to solve these issues, the utilization of the Soluble and solvent as the recycled mixture solvent was proposed and investigated in this work. The results showed that the yields of the Deposit increased by more than two times with the mixture solvent recycle, and got almost stable after 5–7 extraction cycles. This made up for the loss of the part of the extraction product (Soluble) to a large extent. Furthermore, the ratios of O/C, N/C, and S/C of the Deposit decreased with the mixture solvent recycle, indicating that the Deposit was further upgraded. The aromaticity and reactivity of the Deposit decreased and increased with the mixture solvent recycle, respectively. The Cal/Car of the Deposits ranged from 0.35 to 0.84. The ash content of the Deposit increased slightly from 0.25% to 0.29%, and then got almost constant after 4 times of the mixture solvent recycle. Only 0.2–0.4% of the main inorganic elements were transformed from raw coal to the Deposit. The main inorganic elements in the Deposit were Si, Al and Fe. The relatively high contents of some inorganic elements in the Deposit were caused by their high contents and existing form in the raw coal. Thus, it was showed that using the Soluble and solvent as recycled mixture solvent is a feasible way for the practical application of the degradative solvent extraction of low-rank coals.

Torrefaction and Degradative Solvent Extraction As Means of Processing Rice Husk Waste

The high moisture level and ash content of biomass often hinder its further processing. In this study, torrefaction and degradative solvent extraction were employed to upgrade rice husk waste. Biomass torrefied at five different temperatures, in addition to dry raw biomass for comparison, was extracted in 1-methylnaphthalene at 300 °C for 1 h. Two solid fractions were obtained: extracted biomass (EB) and residue biomass (RB). The extraction yields of the EB and RB were 12–19.3% and 31.7–52% (db), respectively. The torrefaction temperature affected the extraction yields and slightly influenced product characteristics. The EB had almost no ash content as it was concentrated in the RB. However, both the EB and RB had higher heat values and carbon content as well as lower oxygen content than the raw biomass. Therefore, our findings suggest that EB could be utilized not only as fuel but also as functional materials.

Effect of Solvent on the Degradative Solvent Extraction of Low Rank Coal

We have proposed a degradative solvent extraction method which upgrades as well as dewaters low rank coals and biomass wastes at 350 °C using 1-methlynaphthalene as a model solvent. The proposed solvent treatment is an effective method to produce high quality extracts having similar physical and chemical properties from several kinds of low rank coals and biomasses. Three solid fractions (Residue, Deposit, and Soluble) were fractionated and recovered after the solvent extraction. Soluble and Deposit are expected to be precursors for producing value added products. In this work the effects of solvent on the degradative solvent extraction of two low-rank coals, Loy Yang (LY) and Pendopo (PD), were examined by using four solvents: 1-methylnaphthalene (1-MN), kerosene, a 1 to 1 mixture of 1-MN and kerosene, and a solvent rich in alkyl benzenes, A150. It was judged that the solvent does not affect the degradation reaction at 350 °C, and hence the performance of this degradative solvent extraction method such as selective deoxygenation and effective dewatering is realized by all of the solvents used. The yield distributions of extracted products were dominated by the solubility of solvent used as expected. The Hildebrand regular solution theory seems to represent the differences in the yields and elemental compositions of Soluble fractions. 1-MN, having 21.3 (J/cm3)1/2 of solubility parameter δ, gave the largest yield of Soluble followed by A150 (δ ≅ 18.8 (J/cm3)1/2), the mixed solvent (δ ≅ 19.1 (J/cm3)1/2), and kerosene (δ ≅ 16.7 (J/cm3)1/2). Preparation of solvent treated coals (STCs) from different solvents gave the yields close to the sum of the yields of Soluble, Deposit, and Residue for all solvents used. Most of the heating values of solid products were over 29 MJ/kg and rather close to subbituminous coal. All Solubles were found to melt completely at rather low temperature. The properties of Solubles can be changed by solvents used. It was found that A150 may be utilized as a practical solvent when Soluble is the target product and that kerosene is expected to be a practical solvent for preparing STC from low-rank coal.