Insights into Preparation Methods and Functions of Carbon-Based Solid Acids.

With the growing emphasis on green chemistry and the ecological environment, researchers are increasingly paying attention to greening materials through the use of carbon-based solid acids. The diverse characteristics of carbon-based solid acids can be produced through different preparation conditions and modification methods. This paper presents a comprehensive summary of the current research progress on carbon-based solid acids, encompassing common carbonization methods, such as one-step, two-step, hydrothermal, and template methods. The composition of carbon source material may be the main factor affecting its carbonization method and carbonization temperature. Additionally, acidification types including sulfonating agent, phosphoric acid, heteropoly acid, and nitric acid are explored. Furthermore, the functions of carbon-based solid acids in esterification, hydrolysis, condensation, and alkylation are thoroughly analyzed. This study concludes by addressing the existing drawbacks and outlining potential future development prospects for carbon-based solid acids in the context of their important role in sustainable chemistry and environmental preservation.

Microbiological mechanism for "production while remediating" in Cd-contaminated paddy fields: A field experiment.

Security utilization measures (SUMs) for "production while remediating" in moderate and mild Cd-polluted paddy fields had been widely used. To investigate how SUMs drove rhizosphere soil microbial communities and reduced soil Cd bioavailability, a field experiment was conducted using soil biochemical analysis and 16S rRNA high-throughput sequencing. Results showed that SUMs improved rice yield by increasing the number of effective panicles and filled grains, while also inhibiting soil acidification and enhancing disease resistance by improving soil enzyme activities. SUMs also reduced the accumulation of harmful Cd in rice grains and transformed it into FeMn oxidized Cd, organic-bound Cd, and residual Cd in rhizosphere soil. This was partly due to the higher degree of soil DOM aromatization, which helped complex the Cd with DOM. Additionally, the study also found that microbial activity was the primary source of soil DOM, and that SUMs increased the diversity of soil microbes and recruited many beneficial microbes (Arthrobacter, Candidatus_Solibacter, Bryobacter, Bradyrhizobium, and Flavisolibacter) associated with organic matter decomposition, plant growth promotion, and pathogen inhibition. Besides, special taxa (Bradyyrhizobium and Thermodesulfovibrio) involved in sulfate/sulfur ion generation and nitrate/nitrite reduction pathway were observably enriched, which effectively reduced the soil Cd bioavailability through adsorption and co-precipitation. Therefore, SUMs not only changed the soil physicochemical properties (e.g., pH), but also drove rhizosphere microbes to participate in the chemical species transformation of soil Cd, thus reducing Cd accumulation in rice grains.

Phosphorylation of ovalbumin after pulsed electric fields pretreatment: Effects on conformation and immunoglobulin G/immunoglobulin E-binding ability.

Ovalbumin (OVA) is one of major allergens of hen egg white with excellent nutritional and processing properties. Previous research exhibits that pulsed electric field (PEF) treatment could partially unfold OVA. This may contribute to the improvement of OVA phosphorylation. In this study, the effect of PEF pretreatment combined with phosphorylation on the structure and immunoglobulin (Ig) G/IgE-binding ability of OVA was investigated. The structural changes were measured by circular dichroism (CD), ultraviolet absorption, and fluorescence spectroscopy. The IgG- and IgE-binding abilities were determined by inhibition enzyme-linked immunosorbent assay (ELISA) using rabbit polyclonal antibodies and egg-allergy patients' sera, respectively. The results showed that PEF pretreatment combined with phosphorylation markedly reduced the IgG- and IgE-binding abilities. It was attributed to the changes in secondary and tertiary structure, which was reflected in the increase of ultraviolet (UV) absorbance, α-helix content, and the increase the molecular weight. Moreover, it suggested PEF pretreatment improved the phosphorylation of OVA and enhanced the reduction of IgG/IgE-binding capacity of phosphorylated OVA. Therefore, PEF pretreatment combined with phosphorylation has the potential for developing a method for OVA desensitization.

Thermo-catalytic conversion of waste plastics into surrogate fuels over spherical activated carbon of long-life durability.

Recovery of value-added fuels or chemicals from waste plastics by pyrolysis is a promising way to eliminate the waste plastics accumulation and alleviate the energy crisis, while developing efficient catalysts of high durability remains a challenge. Herein, activated carbon spheres of various surface chemistry were fabricated and subsequently used in ex-situ catalytic pyrolysis of low-density polyethylene to produce jet fuel and gasoline-ranged hydrocarbons. Experiment results indicate that with the increase of activation time and temperature, the acidity of activated carbon increased slightly owning to the oxygen-containing functional groups increased, and the specific surface area reached the maximum value (707 m2/g) at the activation condition of 800℃ for 60 min. The enlarged specific surface area promotes the C-C bond cleavage that releases more small gases at the expense of liquid yield, and the increase in density of oxygen-containing functional groups and acidity boosts the formation of aromatic hydrocarbons in liquid. When the activated carbon spheres were activated at 800℃ for 80 min, 100% of the hydrocarbons in the liquid belonged to jet fuel and gasoline, and their selectivity was 81.70 area.% and 96.25 area.%, respectively. More importantly, the catalyst exhibits excellent catalytic activity after four reactivation cycles, where the quality of the liquid product is similar to or even better than that achieved by the fresh catalyst. Furthermore, the catalyst still showed excellent performance in the catalytic pyrolysis of waste plastic mixture.

Corncob pyrolysis: Improvement in hydrocarbon group types distribution of bio oil from co-catalysis over HZSM-5 and activated carbon.

Zeolite and activated carbon (AC) have been demonstrated as promising and facile catalysts in degrading biomass into high-value added chemicals and bio-fuels, while the effects of combining zeolite and AC on the catalytic degradation of biomass have not been well understood. Here, co-catalytic pyrolysis of corncob over HZSM-5 and AC to produce aromatic-rich bio-oils was investigated for the first time. The effects of HZSM-5/AC ratio, pyrolysis temperature and catalyst/corncob ratio on products yields and components were explored. The optimal conversion condition was HZSM-5/AC ratio of 2:1, pyrolysis temperature of 500 ℃ and catalyst/corncob ratio of 1:1. Up to 97.47% of the obtained bio-oil chemicals were jet-fuel ranged hydrocarbons, in which the selectivity of aromatics was 96.56%. The results revealed the existence of synergistic effect between HZSM-5 and AC. The present work suggested an economical and novel pathway to produce transportation jet fuel to ultimately expand the biomass application.

Renewable jet-fuel range hydrocarbons production from co-pyrolysis of lignin and soapstock with the activated carbon catalyst.

The current study aims to investigate the effects of agricultural waste-derived activated carbon catalyst on the jet-fuel range hydrocarbons distribution from raw biomass pyrolysis under the hydrogen donor condition provided by a solid waste. Ex-situ catalytic fast co-pyrolysis of lignin with and without soapstock was carried out using the corn stover-derived activated carbon catalyst in a facile fixed bed reactor. Results showed that the soapstock, as the hydrogen donor, exhibited a positive synergistic effect with lignin on enhancing the production of valuable aromatics in the obtained bio-oil. Additionally, biomass-derived activated carbon catalyst has the robust catalytic ability to convert pyrolysis vapors into high-density jet fuel-ranged aromatic hydrocarbons rather than phenols with the assistance of soapstock solid waste. Results indicated that the proportions of jet-fuel range aromatics increased monotonically with elevating pyrolytic temperatures from 400 to 550 °C, and the optimal lignin/soapstock ratio was 1:2 with regarding the yield of attained bio-oils. The maximum proportion of jet-fuel ranged aromatics (87.8%) and H2 concentration (76.4 vol%) could be achieved with the pyrolytic temperature, lignin/soapstock ratio, and catalyst/feedstock ratio of 550 °C, 2:1, and 1:1, respectively. The current study may provide a novel route of converting solid wastes into value-added jet fuels and hydrogen-enriched fuel gases, which will advance the utilization of renewable biomass.

Conversion of woody oil into bio-oil in a downdraft reactor using a novel silicon carbide foam supported MCM41 composite catalyst.

This study reports the synthesis of a SiC-MCM41 composite catalyst by a microwave-assisted hydrothermal process and the composite catalyst had the characteristics of MCM41 and SiC, and the surface of SiC grew evenly with a layer of MCM41 after characterization of the catalysts by various means (X-ray diffraction, Brunauer-Emmett-Teller, scanning electron microscopy). The catalyst was applied in the pyrolysis of waste oil to investigate how it influences the bio-oil component proportion compared with no catalyst, only SiC, only MCM41 catalysis and the catalytic effect was also investigated at different temperatures and different catalyst to feed ratios. In a downdraft system with a pyrolysis temperature of 550 °C, a catalyst to feed ratio of 1 : 2, and a catalytic temperature of 400 °C, 32.43% C5-C12 hydrocarbons and 41.10% mono-aromatics were obtained. The composite catalyst combined the catalytic effect of SiC and MCM41 because it increased the amount of C5-C12 hydrocarbons and decreased the amount of oxygen-containing compounds in bio-oil. After repeated uses, the composite catalyst still retained the catalytic properties.

Catalytic fast pyrolysis of torrefied corn cob to aromatic hydrocarbons over Ni-modified hierarchical ZSM-5 catalyst.

Catalytic fast pyrolysis (CFP) of torrefied corn cob using Ni-modified hierarchical ZSM-5 catalyst was conducted in this study. The prepared catalysts were characterized by N2 adsorption and desorption (N2-BET), X-ray diffraction (XRD), and temperature-programmed desorption of NH3 (NH3-TPD). NaOH solution treatment resulted in the lower peak intensities of hierarchical ZSM-5 catalyst in the XRD patterns while Ni modification improved the catalyst framework. In addition, NaOH solution treatment created some mesopores or macropores, but the incorporation of Ni reduced BET surface area and volume of micropores. Though the addition of Ni lowered the acidity of catalyst, Ni-modified hierarchical ZSM-5 catalyst led to higher yields and of aromatic hydrocarbons. What is more, hierarchical ZSM-5 catalysts significantly improved the selectivities of mono-aromatics. Kinetic analysis shows that CFP of torrefied corn cob was second-order reaction and the addition of Ni can obtain a lower activation energy compared with hierarchical ZSM-5 catalyst.

New Insight into the Mechanism of the Hydrogen Evolution Reaction on MoP(001) from First Principles.

Molybdenum phosphide-based catalysts have recently exhibited excellent catalytic activities for the hydrogen evolution reaction (HER) in wide pH range conditions; the intrinsic reaction mechanism, on the other hand, has not been well established. Herein, by employing the MoP as the prototypical molybdenum phosphide-based catalyst, HER activities in both acid and neutral conditions were studied by conducting periodic density functional theory calculations. Thermodynamic analysis of hydrogen atoms absorbed on both P- and Mo-terminated surfaces were compared, as well as all the reaction energy and activation energy barriers for reactions involved in the HER process. Calculation results revealed that, in an acid condition, the Volmer-Heyrovsky and Volmer-Tafel reaction mechanisms were dominated on the P-terminated and Mo-terminated catalyst surfaces, where Heyrovsky and Volmer reactions were the rate-determining step, respectively. Additionally, water splitting was introduced to the current reaction mechanism and a small reaction activation energy barrier was revealed on the P-terminated surface. Besides, a relevant small activation energy was obtained in the Tafel reaction on the defect of the P-terminated surface in a neutral solution. Theoretical results proved that HER could take place readily on both P- and Mo-terminated catalyst surfaces via different reaction mechanisms in the acid condition from the view of atom scale. More important, computational results uncovered that HER could also occur on the P-terminated surface with the assistance of surface defect in the neutral condition, which sheds new light on the HER mechanism on transition metal phosphite-based catalysts. The doping effect on HER activity was further investigated in theory and calculation results, indicating that catalytic performance could be improved by substitutional doping of the Mo atom with metals such as Mn and W.

Co-pyrolysis of microwave-assisted acid pretreated bamboo sawdust and soapstock.

Fast microwave-assisted co-pyrolysis of pretreated bamboo sawdust and soapstock was conducted. The pretreatment process was carried out under microwave irradiation. The effects of microwave irradiation temperature, irradiation time, and concentration of hydrochloric acid on product distribution from co-pyrolysis and the relative contents of the major components in bio-oil were investigated. A maximum bio-oil yield of 40.00 wt.% was obtained at 200 °C for 60 min with 0.5 M hydrochloric acid. As pretreatment temperature, reaction time and acid concentration increased, respectively, the relative contents of phenols, diesel fraction (C12 + aliphatics), and other oxygenates decreased. The gasoline fraction (including C5-C12 aliphatics and aromatics) ranged from 55.77% to 73.30% under various pretreatment conditions. Therefore, excessive reaction time and concentration of acid are not beneficial to upgrading bio-oil.

Ex-situ catalytic upgrading of vapors from fast microwave-assisted co-pyrolysis of Chromolaena odorata and soybean soapstock.

Fast microwave-assisted catalytic co-pyrolysis of Chromolaena odorata (C. odorata) and soybean soapstock with HZSM-5 as an ex-situ catalyst was investigated. Effects of catalytic temperature, feedstock: catalyst ratio and C. odorata: soybean soapstock ratio on the yield and composition of the bio-oil were discussed. Results showed that catalytic temperature greatly influenced the bio-oil yield. Co-pyrolysis of C. odorata and soybean soapstock improved the bio-oil yield, and the maximum bio-oil yield of 55.14% was obtained at 250 °C. However, the addition of HZSM-5 decreased bio-oil yield but improved the quality of bio-oil. Moreover, the proportion of oxygen-containing compounds decreased dramatically with the addition of soybean soapstock. The C. odorata: soybean soapstock ratio of 1:2 and feedstock: catalyst ratio of 2:1 were the optimal condition to upgrade the bio-oil. In addition, the resulted biochar contained various essential elements and could be used as soil repair agent.

Microwave-assisted co-pyrolysis of pretreated lignin and soapstock for upgrading liquid oil: Effect of pretreatment parameters on pyrolysis behavior.

The co-pyrolysis of pretreated lignin and soapstock was carried out to upgrade vapors under microwave irradiation. Results showed that the yield of 29.92-42.21 wt% of upgraded liquid oil was achieved under varied pretreatment conditions. Char yield decreased from 32.44 wt% for untreated control to 24.35 wt% for the 150 °C pretreated samples. The increased temperature, irradiation time and acid concentration were conducive to decrease the relative contents of phenols and oxygenates in liquid oils. The main components of the liquid oil were gasoline fraction (mono-aromatics and C5-C12 aliphatics), which ranged from 57.38 to 71.98% under various pretreatment conditions. Meanwhile, the diesel fraction (C12+ aliphatics) ranged from 13.16 to 22.62% from co-pyrolysis of pretreated lignin and soapstock, comparing with 10.18% of C12+ aliphatics from co-pyrolysis of non-pretreated lignin and soapstock. A possible mechanism was proposed for co-pyrolysis of pretreated lignin and soapstock for upgraded liquid oils.

Microwave-assisted acid pretreatment of alkali lignin: Effect on characteristics and pyrolysis behavior.

This study performed microwave-assisted acid pretreatment on pure lignin. The effects of microwave temperature, microwave time, and hydrochloric acid concentration on characteristics and pyrolysis behavior of lignin were examined. Results of ultimate analysis revealed better properties of all pretreated samples than those of raw lignin. Fourier transform infrared spectroscopy analysis showed breakage of ßO4 bond and aliphatic side chain, decrease in OH groups, and formation of CO groups in pretreatment. Microwave temperature exerted more significant influence on lignin structure. Thermal stability of treated lignin was improved and insensitive to short microwave time and acid concentration under mild conditions. Resulting from improved alkyl-phenols and decreased alkoxy-phenols, microwave-assisted acid pretreatment of lignin yielded bio-oil with excellent quality. Total yield of phenols in pyrolysis vapors (200 °C) improved to 14.15%, whereas that of guaiacols decreased to 22.36%. This study shows that microwave-assisted acid pretreatment is a promising technology for lignin conversion.

Hydrothermal pretreatment of bamboo sawdust using microwave irradiation.

In the present study, the effect of temperature and residence time during microwave hydrothermal pretreatment (MHT) on hydrochar properties and pyrolysis behaviors was investigated. Experimental results indicated that higher heating value (HHV) and fixed carbon content gradually increased with increased pretreatment severity. Obvious reduction of oxygen content was found under MHT at 230°C-15min and 210°C-35min. Although lower mass yield was observed under severe conditions, corresponding energy yield was relatively higher. Crystallinity indexes of hydrochar demonstrated an upward trend with increased residence time. Unlike hydroxyl group, dissociation of acetyls was more favorable under prolonged residence time rather than increased temperature. Peaks in thermogravimetric and derivative thermogravimetric curves shifted to higher temperature region under severe conditions, indicating better thermal stability. Py-GC/MS analysis suggested that acids content was decreased but sugars increased with increased MHT severity. Moreover, compared to temperature, residence time was mainly responsible for acetic acid formation.

Fast microwave-assisted ex-catalytic co-pyrolysis of bamboo and polypropylene for bio-oil production.

The ex-catalytic co-pyrolysis of bamboo and polypropylene (PP) with HZSM-5 was investigated with microwave assistance. The influences of catalytic temperature, feedstock/catalyst ratio, and bamboo/PP ratio on the product yields and chemical components of bio-oil from the co-pyrolysis were studied. When the catalytic temperature, feedstock/catalyst ratio, and bamboo/PP ratio were 250 °C, 1:2, and 2:1, respectively, the bio-oil yield reached its maximum value at 61.62 wt%. The oxygenate proportion compounds decreased with increasing catalyst content. The PP addition improved the proportions of aromatics and naphthenic hydrocarbons. The bio-oil was upgraded significantly from the jet fuel perspective. A synergistic effect also existed between bamboo and PP.

Ex-situ catalytic co-pyrolysis of lignin and polypropylene to upgrade bio-oil quality by microwave heating.

Microwave-assisted fast co-pyrolysis of lignin and polypropylene for bio-oil production was conducted using the ex-situ catalysis technology. Effects of catalytic temperature, feedstock/catalyst ratio, and lignin/polypropylene ratio on product distribution and chemical components of bio-oil were investigated. The catalytic temperature of 250°C was the most conducive to bio-oil production in terms of the yield. The bio-oil yield decreased with the addition of catalyst during ex-situ catalytic co-pyrolysis. When the feedstock/catalyst ratio was 2:1, the minimum char and coke values were 21.22% and 1.54%, respectively. The proportion of cycloalkanes decreased and the aromatics increased with the increasing catalyst loading. A positive synergistic effect was observed between lignin and polypropylene. The char yield dramatically deceased and the bio-oil yield improved during co-pyrolysis compared with those during lignin pyrolysis alone. The proportion of oxygenates dramatically and the minimum value of 6.74% was obtained when the lignin/polypropylene ratio was 1:1.

Gelatin quantification by oxygen-18 labeling and liquid chromatography-high-resolution mass spectrometry.

Combined with high-performance liquid chromatography (HPLC) and linear-ion trap/Orbitrap high-resolution mass spectrometry, trypsin-catalyzed (16)O-to-(18)O exchange was used to establish an accurate quantitative method for bovine or porcine gelatin. The sophisticated modifications for these two mammalian gelatins were unambiguously identified by accurate mass and tandem mass spectrometry. Eighteen marker peptides were successfully identified for the bovine and porcine gelatin, respectively. The gelatins were subjected to (18)O or (16)O labeling in the presence of trypsin and mixed together in various ratios for quantification. All of the (18)O-labeled peptides were also confirmed by accurate mass and tandem mass spectrometry. The 10 marker peptides with the strongest signals were chosen to calculate the average ratios of (18)O-labeled and (16)O-labeled gelatin. The measured ratios of (18)O-labeled and (16)O-labeled peptides were very close to the mixing ratios of 20:1, 5:1, 1:1, and 1:5 with low standard deviation values. The samples with a mixing ratio of 1:1 (18)O-labeled and (16)O-labeled peptides were determined to 1.00 and 0.99 with standard deviations of 0.02 and 0.04 for bovine and porcine gelatins, respectively, indicating the high accuracy of this method. Trypsin-catalyzed (18)O labeling was proved to be an excellent internal calibrant for gelatins. When combined with HPLC and high-resolution mass spectrometry, it is an accurate and sensitive quantitative method for gelatin in the food industry.