Residue Research Articles

Influence of residue management and simulated rainfall timings on pyroxasulfone efficacy and productivity of wheat in North West India

The adoption of new advanced technology for finest one pass sowing solution in residue in North West India has resulted in increased interest among weed scientists to improve weed management strategies due to herbicide resistant Phalaris minor and herbicide efficacy. A study was conducted over two consecutive crop seasons at Punjab Agricultural University, Ludhiana and Krishi Vigyan Kendra, Muktsar, Punjab, India. The objectives of the study were to find out pyroxasulfone rate required as pre emergence (PRE) in residue removal and incorporation scenarios for weed control and to compare efficacy of PRE application under simulating rainfall at 2, 5 and 10 days after sowing (DAS) and its effect on wheat grain yield. Incorporation of paddy residue (RI) gave 3.8 & 3.7% and 1.8 & 5.1% higher grain yield than residue removal (RR) at Ludhiana and Muktsar during 2020–21 and 2021–22, respectively. At Ludhiana, pyroxasulfone 191.25 g ha−1 recorded significantly less Phalaris minor than pyroxasulfone 127.5 ha-1 but provided similar control of broad leaved weeds (Rumex dentatus and Medicago denticulata). However, both doses of pyroxasulfone recorded similar control of grass and broad-leaved weeds at Muktsar. Simulated rainfall increased the efficacy of pyroxasulfone and recorded less P. minor when given at 2 DAS than 10 DAS at Ludhiana but at Muktsar all simulated rainfall events did not affect weed density and biomass. Phyto-toxicity of pyroxasulfone was not observed on wheat crop when simulated rainfall was applied 2, 5 and 10 DAS in wheat sown under different residue scenarios at both the locations.

Effects of 18 years repeated N fertilizer applications on gross N transformation rates in a subtropical rain-fed purple soil

In this study, a 15N tracing experiment was conducted to determine gross N transformation rates in soils with 18 years of repeated N fertilizer applications and to quantify the underlying mechanisms to explain the variability of crop yield in a subtropical rain-fed purple soil. Six N fertilizer treatments were evaluated: unfertilized control (CK), mineral N fertilizer (NPK), pig manure (OM), mineral N fertilizer plus pig manure (OM-NPK), crop residue (RSD) and mineral N fertilizer plus crop residue (RSD-NPK). The results showed that the soil organic carbon (SOC) concentration in OM (average 13.79 g kg−1) and RSD-NPK (average 13.15 g kg−1) were significantly higher than the other treatments (varied from 5.91 to 11.23 g kg−1) after 18 years. Higher maize yields were observed in NPK, OM, OM-NPK, and RSD-NPK, and especially in RSD-NPK and OM-NPK after 18 years, compared with the data measured in the 11th years. Soil gross N mineralization rates (M) were significantly higher in all N fertilizer treatments (varied from 13.00 to 31.17 mg N kg−1 soil d−1) compared to CK (average 5.53 mg N kg−1 soil d−1). After 18 years of repeated N fertilizer applications, M were significantly higher than those in the 11th years for the same N fertilizer treatment, indicating that long-term repeated N fertilizer application, whether mineral N or organic fertilizer, continuously enhances M. M was positively correlated with SOC (p < 0.05) and total N (TN) (p < 0.05), suggesting that soil organic substrates are key factors regulating M. Maize yield was positively correlated with M (p < 0.05), suggesting that available N produced through soil N mineralization played the important role in yield formation. All N fertilizer treatments continuously stimulated gross autotrophic nitrification rates (ONH4). ONH4 increased with increasing M (p < 0.01) and ammonia-oxidizing bacteria (AOB) abundance (p < 0.05). However, compared to the 11th year, rates of dissimilatory nitrate reduction to ammonium (DNRA) and immobilization of NH4+ (except RSD) and NO3− (except OM-NPK) decreased significantly in the N fertilizer treatments in the 18th year, indicating that N retention capacity is reduced over time and the risk of N losses increased. Considering the best balance among food security, soil C sequestration, and reduction of N leaching, mineral N in combination with straw return (RSD-NPK) can be recommended for regions with similar soils and climates.

Trace metal speciation within sediment from the Arabian Gulf

Geochemical fraction of the trace metal species arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn), collected from varying water depths sediments of Qatar Marine Zone from different locations (N= north, C= central, and S=south) of the Arabian sea were determined using five-stages sequential extraction technique. The total concentration of trace elements trend was as following: Fe (35034.55μg/g) > Mn (757.47μg/g) > Ni (111.65μg/g) > Cr (109.35μg/g) > Zn (81.84μg/g) > As (64.28μg/g) > Cu (61.30μg/g) > Co (18.52μg/g) > Pb (13.82μg/g) > Cd (0.38μg/g). The trace elements were extracted in the following order: exchangeable (EXC), bound to carbonate (CA), Fe-Mn oxide bound (FMO), organic matter bound (OM), and residue (RES), to study the mobility and bioavailability of each metal, as these indicate the potential for metal release to the surrounding environment. Data indicate that 23.40% of Pb concentration was extracted in EXC phase, 58% of Cd concentration was concentrated in the CA phase, an elevated amount of Cr was scavenged by Fe-Mn oxide in the FMO phase, OM phase held a wide variety of non-lithogenic source elements following FMO, and about 84% of the Fe was found in the RES fraction. This phase dominated the fractionation profile of the trace elements except for Cd and Mn.

Chromium adsorption using Sargassum filipendula algae waste from alginate extraction: Batch and fixed-bed column studies

Chromium is a toxic metal widely used in several industrial activities, being frequently found in industrial effluents. The presence of chromium in its soluble ionic form Cr(III) is related to health risks, damage to living beings and to the environment. In this work, the capture of Cr(III) using alginate extraction residue (RES) from the Sargassum filipendula algae was evaluated to investigate the adsorption properties of this waste material. The study steps included batch and continuous adsorption assays, characterizations, and desorption evaluation. The adsorbent residue was not submitted to pre-treatment steps. The investigation of chromium adsorption and the fluid dynamic study are presented in this work. The equilibrium and thermodynamic studies indicated that the uptake of Cr(III) by the RES occurred spontaneously, endothermic, and energetically favorable on a heterogeneous surface with energetically distinct sites, mainly by chemisorption. The Freundlich and Dubinin-Radushkevich, and pseudo-second order models showed better fit to the equilibrium and kinetic experimental data, respectively. In the continuous fixed-bed system, the breakthrough curves showed a smaller mass transfer zone under flow rate and Cr(III) inlet concentration conditions of 0.5 mL/min and 1.0 mmol/L, respectively. The low desorption percentages corroborate the chemical nature of the bonds involved in adsorption. The best result of 67.5% was obtained with the combined eluent of HCl and CaCl2, both at 1 mol/L. SEM and EDX analyzes showed that ion exchange is involved in the adsorptive process with a reduction in the amount of light ions (Na, Ca, Mg, and K) on the RES surface. The characterization analyzes indicated that hydroxyls are the main group involved in the adsorption of metal that occurred on the surface of the RES.

Application of alginate extraction residue for Al(III) ions biosorption: a complete batch system evaluation.

The residue derived from the alginate extraction from S. filipendula was applied for the biosorption of aluminum from aqueous medium. The adsorptive capacity of the residue (RES) was completely evaluated in batch mode. The effect of pH, contact time, initial concentration, and temperature was assessed through kinetic, equilibrium, and thermodynamic studies. The biosorbent was characterized prior and post-Al biosorption by N2 physisorption, Hg porosimetry, He pycnometry, and thermogravimetry analyses. Equilibrium was achieved in 60 min. Kinetics obeys pseudo-second-order model at aluminum higher concentrations. Isotherms followed Freundlich model at low temperature (293.15 K) and D-R or Langmuir model at higher temperatures (303 and 313 K). Data modeling indicated the occurrence of both chemical and physical interactions in the aluminum adsorption mechanism using RES. The maximum adsorption capacity obtained was 1.431 mmol/g at 293 K. The biosorption showed a spontaneous, favorable, and exotherm character. A simplified batch design was performed, indicating that the residue is a viable biosorbent, achieving high percentages of removal using low biomass dosage.

Effect of isopropanolysis on the structure variation and pyrolysis behaviors of Wucaiwan lignite

Alkanolysis has become an effective approach for lignite extraction due to high organic oxygen content in lignite. To better understand the effect of isopropanolysis on the chemical structure and thermal degradation process of lignite, Wucaiwan lignite (WL) and isopropanolyed residue (RI) were systematically analyzed using four multiple direct tools, including Fourier transform infrared spectrometer (FTIRS), X-ray photoelectron spectrometer (XRPES), Thermogravimetric analysis (TGA), and Pyrolysis-gas chromatography/mass spectrometry (PGC/MS). Combining with the analysis of FTIRS and XRPES, much oxygen-containing species were extracted from WL during isopropanolysis process (IP), and RI has higher carbon content than WL. Kinetic parameters such as activation energy (Ea) and pre-exponential factor (A) were determined by using two model-free methods of Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). Average Ea for WL pyrolysis was 235.4 and 235.7 kJ mol−1, respectively, obtained by KAS and FWO methods, were lower than that of RI (354.4 and 351.3 kJ mol−1). Besides, based on the obtained kinetics data, thermodynamic analysis was established to evaluate the pyrolysis complexity of WL and RI. PGC/MS results showed that the main volatile products (VPs) of RI fast pyrolysis (FP) were arenes and alkanes while formation of oxygenated compounds reduced, further confirming the extraction of oxygen-containing species from IP of WL. It is noteworthy that isopropanolysis pretreatment of WL can influence its chemical structure and thermal degradation process.

Investigation on the Structural Features of Hanglaiwan Subbituminous Coal and Its Residues from Solvent Extraction and Thermal Dissolution

Hanglaiwan subbituminous coal (HSBC) was subjected to solvent extraction (SE) with an isometric carbon disulfide/acetone mixed solvent (IMCDSAMS) to obtain a residue (RSE). Thermal dissolution (TD)...

Application of a dealginated seaweed derivative for the simultaneous metal ions removal from real and synthetic effluents

In this study, the alginate extraction residue (RES) from Sargassum filipendula was employed as biosorbent for the simultaneous removal of Cr3+, Ni2+ and Zn2+ from ternary synthetic solutions and for the decontamination of industrial (leather industry) and urban real effluents that were collected from different areas of Strasbourg (France). For this purpose, biosorption experiments in batch mode, multimetals equilibrium isotherms fitting and biosorbent characterization were carried out. In synthetic effluents, RES exhibited a greater affinity for Cr3+ ions, while a still unknown affinity for Al3+ and Pb2+ was verified for real conditions, reaching up to 80 % removal in some cases. At equilibrium, the higher sorption capacities were found at 50 °C as 0.864, 0.302 and 0.347 mmol/g for Cr3+, Zn2+ and Ni2+, respectively. Regarding the equilibrium models fitting, just the Extended Langmuir equation was able to describe the experimental data, showing an increase in qmax as the temperature rose, besides a decay in KL,1, KL,2 and KL,3 at the higher temperatures that indicates a weakening of adsorbent-adsorbate interactions. The characterization analyzes revealed a complex biosorption with a depth participation of carboxylic and hydroxyl groups was revealed by the characterization analyses, whereas the ion exchange mechanism played a really important role. The cation exchange capacity of RES was quantified as 34.12 mg/gRES with main exchangeable position of Ca2+ and Na+ ions. Based on these results, RES could be used as a novel and efficient biosorbent for toxic metals removal even from quite diluted real effluents, contributing to its valorization.

African Walnuts (Tetracarpidium conophorum) Modulate Hepatic Lipid Accumulation in Obesity via Reciprocal Actions on HMG-CoA Reductase and Paraoxonase.

Obesity is characterized by increased body fat and involves an imbalance between the synthesis and degradation of lipids. The study aimed to investigate the effect of African walnuts (Tetracarpidium conophorum) on lipids storage and the regulatory enzymes of hepatic lipid metabolism in obese rats. Nuts were extracted in ethanol (WE) and further separated to obtain the ethyl-acetate fraction (ET) and the residue (RES). These were administered orally to 3 groups of monosodium glutamate- obese rats (n = 6), respectively, for 6 weeks. Other groups in the study were: normal (NC), obese control (OC) and standard control (SC) which received orlistat. Hepatic total lipids, total phospholipids, triacylglycerol (TG), total cholesterol (TCHOL), 3-hydroxyl-3-methylglutaryl-CoA (HMG-CoA) reductase and paraoxonase were studied. Total lipids, TG and TCHOL which increased in OC compared to NC group, decreased. HMG-CoA reductase activity decreased in the 3 study groups relative to OC. Paraoxonase activity which decreased in OC was up-regulated, while the magnitude of hepatic cholesterol decreased from 94.32 % in OC to 52.19, 65.43 and 47.04 % with WE, ET and RES, respectively. Flavonoids, alkaloids, glycosides, tannins and saponins were detected in the nut. GC-MS analysis revealed 16, 18 and 10 volatile components in WE, ET and RES, respectively. Unsaturated fatty acids (linolenic acids: 33.33, 47.95 and 50.93 %, and α-linolenic acids: 25, 19.66 and 26.63 %) in WE, ET and RES, respectively, are the most abundant, and likely to be responsible for the observed activity. African walnuts can prevent hepatic lipid accumulation through reciprocal actions on HMG-CoA reductase and paraoxonase in obesity.

Depositional environment and maturity of Devonian Pimenteira Formation in the São Luís Basin, Brazil

We carried out a detailed organic facies study on shale cutting samples from the Devonian Pimenteira Formation in the São Luís Basin, northwest Brazil, to reconstruct the depositional paleoenvironment and origin of the organic matter. Samples were collected from the stratigraphic well 2-ANP-5-MA and were analyzed for total organic carbon (TOC), total sulfur (%S), insoluble residue (RI), spore coloration index (SCI), vitrinite reflectance (%Ro), palynofacies, and biomarkers. The TOC values of the analyzed sediments range from 0.19 to 0.51%, %S from 0.17 to 0.85%, and the total carbonate (CaCo3) is low (<15%); SCI ranges from 4.0 to 5.0, %Ro from 0.45 to 0.47%, and chitinozoan reflectance from 0.42 to 0.51%. The prasinophyte algae content exhibits a strong correlation (r2 = 0.73) with the TOC content; this suggests that this organic component is the main factor controlling TOC and that variations in prasinophyte content could reflect changes in the sea level associated with marine transgressions and regressions. Two types of palynofacies (PI—phytoclasts, amorphous organic matter [AOM], and spongiophyton-dominated—and PII—palynomorphs and zoomorphs-dominated) were identified. PI is characterized by a palynomorph association dominantly composed of marine palynomorphs like acritarchs and prasinophytes, whereas PII is characterized by phytoclasts and an association with AOM. Chitinozoan, conodonts and spongiophyton are common throughout this sedimentary sequence. The TOC (wt%) vs %S relationship indicates that the organic matter is dominantly marine but has some freshwater influence. The ternary graph including AOM, phytoclasts, and palynomorphs+zoomorphs suggests a depositional environment ranging from oxic proximal shelf to dysoxic proximal-distal shelf with deltaic influence. The presence of marine microplankton and land plants was corroborated by the distribution of the steranes components (C27, C28, and C29). The thermal maturity indicators, including %Ro, chitinozoan reflectance, SCI, Ts/(Ts + Tm) ratios, and C29 20S/(20S + 20R) and C29 ββ/(αα + ββ), indicate that the organic matter is immature.

African walnuts attenuate ectopic fat accumulation and associated peroxidation and oxidative stress in monosodium glutamate-obese Wistar rats

AimsAfrican walnuts were previously shown to modulate hepatic lipid bio-accumulation in obesity. Herein, we investigated the impact of the nuts on fat accumulation in adipose and ectopic regions, and associated oxidatiive stress status in obese rats. Materials and methodsWhole ethanol extract (WE) of the nuts, and its liquid-liquid fractions-ethyl acetate (ET) and residue (RES) were separately administered to obese rats for 6 weeks. The normal (NC) and obese (OC) controls received normal saline and the standard control (SC), orlistat (5.14 mg/kg b.w.), during the same period. Thereafter, the animals were euthanized and the adipose, brain, kidneys and heart tissues were studied. ResultsThe change in body weight to naso-anal length which increased by 63.52 % in OC compared to NC (p < 0.05), decreased by 57.88, 85.80 and 70.20 % in WE, ET and RES-treated groups, respectively, relative to the OC (p < 0.05). Also, adipose tissue weights were lowered upon treatment with the extracts and fractions versus OC (p < 0.05). Total lipids, phospholipids, triacylglycerol and cholesterol concentrations in the studied tissues which were higher in OC (p < 0.05) were lowered (p < 0.05) and compared favorably with SC. Further, malondialdehyde levels in the tissues were lowered upon treatment, compared to the OC (p < 0.05). Glutathione level and activities of glutathione peroxidase, superoxide dismutase and glutathione-S-transferase which were decreased (p < 0.05) in OC, were restored upon treatment with the extracts, relative to the obese control (p < 0.05). SignificanceAfrican walnuts assuaged lipogenesis, oxidative stress and peroxidation in extra-hepatic tissues of obese rats, hence, may attenuate ectopic fat accumulation and its associated pathogenesis.

Exploratory of immobilization remediation of hydroxyapatite (HAP) on lead-contaminated soils.

This study was aimed to investigate the adsorption and fixation effects of hydroxyapatite (HAP) on lead-contaminated soil. According to the experimental results, the microstructure of hydroxyapatite was observed by a scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) showed that OH- and PO43- were the main functional groups in HAP. Optimum adsorption conditions of Pb2+ were obtained: 0.2 g/L, adsorbent; initial solution pH of 5.5; and contact time of 120 min. The kinetic adsorption experiments were carried out with the initial lead solution concentrations of 50 mg/L, 150 mg/L, and 250 mg/L. The kinetics fitting was consistent with the pseudo-second-kinetic model, which indicated that the main process of HAP adsorption of Pb2+ was mainly controlled by surface reactions and chemical reactions. The adsorption isotherms had a satisfactory fit with the Langmuir model, which indicated that the adsorption of Pb2+ by HAP was a monolayer adsorption. According to the experimental results, ion exchange, phosphorus supply, precipitate, and complexation are the main immobilization mechanisms for soil remediation with HAP. In remediation of Pb2+-contaminated soil experiments, the adsorption rate of Pb2+ by HAP was significantly higher than that of non-HAP soil with increasing immobilization days. With the increasing addition of HAP, the weak acid soluble (WA), reducible (RED), oxidizable (OX), and water soluble (WS) are transformed into residue (RES). The application of HAP in contaminated soil effectively reduced the leachable and exchangeable Pb2+, indicating that HAP is a potential material for remediating environmental pollution with Pb2+.

Evaluation of the Kappaphycus alvarezii growth under different environmental conditions and efficiency of the enzymatic hydrolysis of the residue generated in the carrageenan processing

Kappaphycus alvarezii is a red macroalgae generally used for industrial production of hydrocolloids. An alternative is to use the K. alvarezii for carrageenan production and its residue for the manufacture of bioproducts of commercial interest (biofuels, food, cosmetics, nutraceuticals, pharmaceuticals, and biofertilizers). This study reported the cultivation of K. alvarezii strains in different environmental conditions over a period of one year. The productivity, growth rate, and yield of refined carrageenan (RC) and residue (RE) of the studied crops were evaluated. Moreover, the efficiency of the enzymatic hydrolysis of the RE obtained in the carrageenan processing was evaluated. Considering the variations of productivity during different climatic seasons, three differentiated groups (A, B and C) were defined for each studied strain. The productivity and growth rates were more pronounced in the seasons of summer-autumn (group B). The average productivity of untreated biomass of different strains of K. alvarezii was 31.6 kg.m−2year−1. The average yield of the RC and RE of different strains of K. alvarezii were 14.4 and 7.4 kg.m−2year−1, respectively. RCs showed a galactan enrichment, same as commercial-grade carrageenan. REs showed a glucan enrichment, with average content (A, B and C) of 31.5%, 34.3% and 32.6%, respectively. Enzymatic hydrolysis of the glucan fraction of the RE, resulted in a 100% conversion and indicated that the rate of glucose formation from glucan does not depend on the studied cultures or strains. Therefore, these results show that glucose from RE can be obtained throughout the year, reaching an average productivity of 2.7 kg.m−2year−1.

Heating rate effects on pyrolysis, gasification and combustion of olive waste

Pyrolysis, combustion and gasification of solid residues from olive oil processing were investigated. The raw solid residue (RS) contains moisture (21.5%) and residual oil (6.4%). Therefore, from RS, raw samples without water (RSWW) and without oil (RSWO) were produced. Thermal analyses of samples were performed at different heating rates over a temperature range of 150–1050 °C. Pyrolysis behavior of the sample was studied in an argon atmosphere, whereas the combustion and gasification studies were conducted in oxygen and steam atmospheres, respectively. The effects of heating rate on the reaction rate and gas evolution were analyzed. Thermal degradation of RS showed that nearly 90% of the conversion occurred at below 700 °C. Gases produced in the three processes mainly consisted of hydrogen, hydrocarbons and carbon oxides. Alcohols and sulfur compounds were also detected in the temperature range of 300 to 500 °C for pyrolysis. Activation energies were determined from non-isothermal multi-heating rate thermogravimetric measurements. The variation in gas evolution was observed between the samples during gasification.

Reuse of the alginate extraction waste from Sargassum filipendula for Ni(II) biosorption

This study was developed based on the possibility of reusing and valuing the alginate extraction residue (RES) from the algae Sargassum filipendula. The adsorptive properties of RES were explored through kinetic and equilibrium assays in batch mode, in which the kinetic equilibrium time (200 min) was not influenced by the increase of the initial concentration of Ni solutions and the sorption process was favored by the temperature increase. The modeling revealed the simultaneous occurrence of physical and chemical interactions with the external diffusion as the predominant step. The Langmuir model was more representative for the equilibrium results, with an uptake capacity comparable to that of other biomaterials. The thermodynamic study indicated a spontaneous, favorable, and endothermic process, besides the presence of the ion exchange. The isoelectric point was found at pH 5.3, and the pore size distribution allowed the classification of RES as macroporous. The simplified bath sorption design revealed that the required mass of RES become greater for higher quality degrees. However, it is tenable to consider this process viable due to the easy access to the algae biomass and the large amount of the solid waste generated from the alginate extraction (∼50%), termed as residue (RES).

Equilibrium study of binary mixture biosorption of Cr(III) and Zn(II) by dealginated seaweed waste: investigation of adsorption mechanisms using X-ray photoelectron spectroscopy analysis.

The alginate extraction residue (RES) from the Brazilian Sargassum filipendula was successfully employed as biosorbent in this binary equilibrium study, revealing a greater affinity and selectivity for Cr(III) than for Zn(II). Experimental results also revealed that the process is of endothermic nature and well adjusted by Langmuir-Freundlich binary model. The X-ray photoelectron spectroscopy (XPS) analysis revealed that coordination with hydroxyl groups of RES prevailed in Cr removal, followed by carboxyl-metal complexation. As far as Zn(II) is concerned, ion exchange with carboxylate groups of RES was the largest contributor. Nevertheless, scanning electron microscopy coupled with Fourier transform infrared spectroscopy indicated the participation of sulfate functions in a minor degree.

Investigation of the simultaneous biosorption of toxic metals through a mixture design application

This study evaluated the use of the alginate extraction residue (RES) from Sargassum filipendula as biosorbent for the simultaneous biosorption of Cr(III), Ni(II) and Zn(II) applying a mixture design (MD) to evaluate the effects on the total biosorption capacity (qt). Inhibitory effects of Cr(III) on the biosorption of the divalent ions were observed, while Zn(II) exhibited contrary effects on the other ions, inhibiting and inducting Cr(III) and Ni(II), respectively. On the other hand, Ni(II) had the lowest interaction effect, inhibiting Zn(II) only. Ion exchange mechanism was verified by characterization analyses, which also revealed a homogenous distribution of metals over the surface of biosorbent. Major involvement of hydroxyl, carboxylic and sulfonic groups was also revealed, but the participation of other acid functions may occur. Cr(III) was favorably adsorbed by RES in all systems, exerting a significant synergic effect on qt.

Sequential extraction of oak wood sawdust and oxidative degradation of the extraction residue

Oak wood sawdust (OWSD) was extracted under supercritical CO2 sequentially with petroleum, carbon disulfide (CDS), methanol, acetone, and isometric CDS/acetone mixture to afford extracts 1–5 (E1–E5), respectively. Then the extraction residue (RE) was subjected to sequential oxidation with aqueous hydrogen peroxide (AHPO)/acetic anhydride (AAH) at 65 °C to afford soluble portions 1–4 (SP1–SP4). In total, ca. 95.8% of organic matter in OWSD became soluble by the sequential extraction and oxidation. No significant difference in the distribution of functional groups was observed in Fourier transform infrared spectra of OWSD and RE, while the distribution of functional groups in the oxidation residue is significantly different from that in either OWSD or RE. In total, 117 and 168 compounds were detected in E1–E5 and SP1–SP4, respectively, with a gas chromatograph/mass spectrometer. E1–E5 are rich in esters, while carboxylic acids are abundant in SP1–SP4 in addition to esters. HO· released from AHPO/AAH played a crucial role in oxidatively degrading RE.

Chemical structure and molecular weight influence the in vitro fermentability of polysaccharide extracts from the edible seaweeds Himathalia elongata and Gigartina pistillata

Polysaccharides from the brown seaweed Himanthalia elongata and the red one Gigartina pistillata have been extracted by sequential fractionation based on the solubility in water (F-H2O), hydrochloride acid (F-HCl) and potassium hydroxide (F-KOH), remaining a residue (RES). Their structures have been studied through Fourier-transform infrared spectroscopy (FTIR) and molecular weight by molecular exclusion (HPSEC). Sugar composition and sulphate content were also determined. F-H2O and F-HCl from Himanthalia elongata were rich in fucoidans with an estimated Mw of 926 and 430 × 103 g/mol. Laminarans appeared in the mentioned fractions and possibly xylofucoglycuronans and xylomannans are in F-H2O. F-HCl was poorly fermented with low production of total short chain fatty acids (SCFA) and two poor or non-fermentable low-molecular weight polyuronans (68 and 4 × 103 g/mol) appeared in F-KOH. Carrageenans extracted from Gigartina pistillata presented low or non-fermentability. Xylofucoglycuronans and xylomannans, possibly presented in RES and F-H2O from Himathalia, and laminarans in the last mentioned fraction, seem to be more fermentable. Carragenophytes red seaweeds do not seem to be fermentable whereas brown algae could have major potential fermentability, probably due to the presence of laminarans, xylofucoglycuronans and/or xylomannans.

Extraction and thermal dissolution of Piliqing subbituminous coal

Piliqing subbituminous coal (PSBC) was exhaustively extracted with isometric acetone/carbon disulfide mixed solvent under ultrasonic irradiation to afford extractable portion (EP) and extraction residue (RE). Then RE was subjected to sequential thermal dissolution (TD) in ethanol at 200, 240, 280, and 320°C and TD at each temperature was conducted for 2h. The sequential TD provided soluble portions (SPs) 1–4 (SP1–SP4) and residue 4 (R4). EP and the SPs were analyzed with a gas chromatograph/mass spectrometer and Fourier transform infrared (FTIR) spectrometer, while PSBC, RE, and R4 were characterized with a solid-state 13C nuclear magnetic resonance (SS 13C NMR), FTIR, and X-ray photoelectron spectrometer (XPS). In total, ca. 36wt% of organic matter was released from PSBC by the ultrasonic extraction and sequential TD. EP is rich in normal alkanes and arenes, while dialkoxyalkanes are predominant in SP1 and esters are the main compounds in SP2–SP4. No significant difference in the distribution of functional groups was observed in FTIR spectra of PSBC and RE, while the distribution of functional groups in R4 is significantly different from that in either PSBC or RE. According to analysis with XPS, the content of oxygen-containing species in R4 is relatively low. PSBC consists of 32.6% aliphatic carbon atoms, 63.0% aromatic carbon atoms, and 4.4% carbonyl carbon atoms, while the content (2.0%) of carbonyl carbon atoms in R4 is significantly lower than that (4.4%) in PSBC based on analysis with SS 13C NMR.