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The enzymatic depolymerization is a promising route to valorize the lignin polymers by turning the cross-linked polymers into monomers or oligomers. However, the lignin polymers cannot be effectively converted into small chemicals, as the oligomers are prone to polymerization, which is particularly challenging to monitor and thus regulate. Here, we develop a microstructured fiber Bragg grating (mFBG) sensor to probe the dynamic polymerization process of typical lignin oligomer surrogates─guaiacol (monomer) and guaiacylglycerol-β-guaiacyl ether (GBG, dimer)─catalyzed by laccase in an operandoway. The mFBG sensor was developed with its reliability well validated by control experiments at first. Further, operandomonitoring of the polymerization reaction process of the typical lignin monomer (i.e., guaiacol) and dimer (guaiacylglycerol-β-guaiacyl ether, GBG) was demonstrated under various conditions with the mFBG sensor. The GC-MS and UV–vis absorption measurements were carried out as a further check. Finally, the specific polymerization characteristics and reaction mechanism were studied. The mFBG sensor enables operandomonitoring of the heterogeneous polymerization process of lignin monomers and oligomers and can potentially be tailored to probe more complex lignin depolymerization processes and unveil enzymatic synergistic mechanisms for the biological transition of biomass.

Microalgal biofilm, a stable community of many algal cells attached to a solid substrate, plays a significant role in the efficient accumulation of renewable energy feedstocks, wastewater treatment, and carbon reduction. The adhesion tendency of microalgal cells on solid substrates is the basis for controlling the formation and development of microalgal biofilm. To promote the adhesion of microalgal cells on solid substrates, it is necessary to clarify which surface properties have to be changed in the most critical factors affecting the adhesion. However, there have been few systematic discussions on what surface properties influence the adhesion tendency of algal cells on solid substrates. In this study, the essential principle of microalgal cell adhesion onto solid substrates was explored from the perspective of the interaction energy between microalgal cells and solid substrates. The influence of surface properties between microalgal cells and solid substrates on interaction energies was discussed via extended Derjaguin–Landau–Verwey–Overbeek (eDLVO) theory and a sensitivity analysis. The results showed that surface properties, including surface potential (ξ) and surface free energy components, significantly affect the adhesion tendency of microalgal cells on different solid substrates. When the solid surface possesses positive charges (ξ > 0), reducing ξ or the electron donor components of the solid substrate (γs–) is an effective measure to promote microalgal cell adhesion onto the solid substrate. When the solid surface possesses negative charges (ξ < 0), an increase in either γs–or the absolute value of ξ should be avoided in the process of microalgae adhesion. Overall, this research provides a direction for the selection of solid substrates and a direction for surface modification to facilitate the adhesion tendency of microalgal cells on solid substrates under different scenarios.

Microalgae is a promising candidate for reducing greenhouse gas and producing renewable biofuels. For microalgae biofilm cultivation, a strong adhesion ability of microalgae cells onto the surface is a prerequisite to resist the fluid shear stress, while strong adhesion is not of benefit to the biofilm harvesting process. To solve this dilemma, a thermoresponsive surface (TMRS) with lower critical solution temperature of 33 °C was made by grafting N-isopropylacrylamide onto a silicate glass slide. The wettability of the TMRS changed from hydrophilic (contact angle of 59.4°) to hydrophobic (contact angle of 91.6°) when the temperature rose from 15 to 35 °C, resulting in the increase of adhesion energy of the TMRS to Chlorella vulgariscells by 135.6%. The experiments showed that the cells were more likely to attach onto the TMRS at the higher temperature of 35 °C owing to the surface microstructures generated by the hydrogel layer shrinkage, which is similar in size to the microalgae cells. And the cell coverage rate on TMRS increased by 32% compared to the original glass surface. Conversely, the cells separate easily from the TMRS at a lower temperature of 15 °C, and the cell adhesion density was reduced by 19% due to hydrogel layer swelling to a relatively flat surface.

Although resection is the primary treatment strategy for pheochromocytoma, surgery is associated with a high risk of morbidity. At present, there is no nomogram for prediction of severe morbidity after pheochromocytoma surgery, thus the aim of the present study was to develop and validate a nomogram for prediction of severe morbidity after pheochromocytoma surgery.The development cohort consisted of 262 patients who underwent unilateral laparoscopic or open pheochromocytoma surgery at our center between 1 January 2007 and 31 December 2016. The patients’ clinicopathological characters were recorded. The least absolute shrinkage and selection operator (LASSO) binary logistic regression model was used for data dimension reduction and feature selection, then multivariable logistic regression analysis was used to develop the predictive model. An independent validation cohort consisted of 128 consecutive patients from 1 January 2017 and 31 December 2018. The performance of the predictive model was assessed in regards to discrimination, calibration, and clinical usefulness.Predictors of this model included sex, BMI, coronary heart disease, arrhythmia, tumor size, intraoperative hemodynamic instability, and surgical duration. For the validation cohort, the model showed good discrimination with an AUROC of 0.818 (95% CI, 0.745, 0.891) and good calibration (Unreliability test, P= 0.440). Decision curve analysis demonstrated that the model was also clinically useful.A nomogram was developed to facilitate the individualized prediction of severe morbidity after pheochromocytoma surgery and may help to improve the perioperative strategy and treatment outcome.

Fatty acid photodecarboxylase, recently found in Chlorella variabilisNC64A (CvFAP), could efficiently catalyze C16-C18 fatty acids into C1-shortened hydrocarbons under visible light. This provides an alternative approach for hydrocarbon fuels production in mild conditions compared with hydrotreating of oils. In this study, a cascade system integrating lipase hydrolysis and CvFAP decarboxylation was demonstrated for the efficient production of hydrocarbon fuels from waste oils. The continuous CvFAP-catalyzed decarboxylation characteristics and performance of free fatty acids derived from waste oil were investigated for the first time. A hydrocarbon fuel production rate of 18.4 mM/h was obtained at a residence time of 50 min. The regulation of pH value from 6.8 to 8.5 significantly improved the activity of CvFAP, thereby obtaining an optimal conversion of 61.2%. The precipitation of palmitic acid caused a low conversion (37.9%) compared with the other fatty acids, further inhibiting hydrocarbon production. In such a cascade system, various oils can be converted to hydrocarbon fuels with a concentration of 8.97–15.3 mM. A high energy production rate of 204.3 kJ/L/h was achieved, which exhibited the advancement in high-quality biofuel production.

The recycling of spent lithium-ion batteries has gained increasing attention due to its economic and environmental benefits. The oxidizing roasting has been preliminarily proven to be a feasible method to pre-treat and recycle spent LiFePO4battery. However, the kinetics and thermal conversion mechanism of spent LiFePO4battery during oxidizing roasting process remains indefinable and needs to be elucidated. Therefore, the kinetic analysis and thermal conversion mechanism of the spent LiFePO4battery during the oxidizing roasting process were investigated in this study. The results indicated that the oxidizing roasting process of the electrode materials (LiFePO4and C) could be divided into four weight loss stages, and the maximum weight loss took place in the third weight loss stage (500–800 °C). The model-free methods (Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose models) could well describe the oxidizing roasting process, and the corresponding Eαobtained were 257.38 and 255.35 kJ/mol respectively. The model-fitting methods showed that the three-dimension diffusion model was the most suitable kinetic reaction model for the electrode materials oxidizing roasting process. The graphite in the electrode materials could be easily oxidized to CO2(the major gaseous product). Besides, the LiFePO4was firstly oxidized and converted into Li3Fe2(PO4)3and Fe2O3. Then the Li3Fe2(PO4)3was decomposed into Li3PO4and P2O5. Finally, P2O5could react with Fe2O3to form FePO4. The physical state of oxidizing roasting products changed from powder to molten state from 600 to 800 °C because of the lower melting point temperature of Li3Fe2(PO4)3, and the oxidizing roasting temperature was suggested to be controlled below 800 °C. The final products obtained from the oxidizing roasting process of the spent LiFePO4battery electrode materials were Li3Fe2(PO4)3, FePO4and Li3PO4. This study provides a comprehensive understanding of the kinetics and thermal conversion mechanism during spent LiFePO4battery oxidizing roasting recovery process.

The effect of coal ash on the electrochemical performance of solid oxide electrolyte-based carbon fuel cells (SO-CFCs) is investigated in this study. The polarization and durability performance of SO-CFCs fueled by lignite char, ash-free char, and ash-added char were measured and compared from 1023 to 1123 K. The influence of five different coal ashes and six typical inorganic species was evaluated in SO-CFCs during short-term operation. The anode morphologies were analyzed to clarify the cell degradation. The results indicate that lignite char shows a higher initial cell performance but a lower stability than ash-free char in SO-CFC. The higher initial cell performance is attributed to the superior CO2gasification reactivity, while the lower stability is more likely caused by carbon and ash deposits. The effect of coal ash on the cell performance is strongly dependent upon the ash composition. Inorganic Ca, K, and Fe species in coal ash improve the initial cell performance by catalyzing char–CO2gasification reactivity. Inorganic S and Fe species in coal ash tend to react with anode Ni particles and form large aggregations on the anode surface, leading to anode deactivation. In combination with inorganic Ca, Fe, and K, Si and Al compounds in ash could form irregular-shape deposits on the anode surface and clog up the anode pores. The ash with a high content of SiO2and Al2O3(93.39 wt % in total) shows no adverse effect on the cell performance. This study suggests that proper coal ash pretreatment should be conducted to improve the cell stability of coal-fueled SO-CFCs.

The degradative solvent extraction (DSE) has been found to be an effective method to convert and upgrade biomass wastes into high-quality extracts with various applications. However, the reaction pathways and kinetics of this DSE process are still not clear and need to be clarified. Hence, in this study, the biomass was treated in 1-methylnaphthalene at various conditions (300–350 °C and 0–90 min) by the DSE method and separated into five products: residue (unreacted biomass), two extracts (deposit and soluble), liquid, and gas. A lumped reaction model was proposed to simulate this biomass DSE process. The kinetic parameters were estimated by the least squares fit based on the experimental data and the model, which was optimized by the MATLAB optimization program. The results showed that the proposed model was valid and well-capable of describing the biomass DSE process. It can be concluded that different conversion pathways existed at 300 and 350 °C. At 300 °C, the dominant reactions were the conversion of residue (unreacted biomass) to the extraction products [deposit (k= 0.0104 min–1), soluble (k= 0.0042 min–1), and liquid (k= 0.0044 min–1)]. The deoxygenation reactions mainly occurred at relatively mild conditions. While at 350 °C, the rate-controlled process was the conversion of high-molecular-weight extract (deposit) to low-molecular-weight extract (soluble) (k= 0.0155 min–1). A comprehensive understanding of the reaction pathways of the biomass DSE conversion process was provided.

The rapid depletion of fossil fuels has attracted more attention being geared toward the fast pyrolysis of biomass to produce bio-oils. However, the produced bio-oils usually contain high water, oxygen, and acid contents and low calorific values, which have limited their wide application. Therefore, in this study, a novel two-stage method combining degradative solvent extraction with subsequent pyrolysis was proposed to improve the quality of derived bio-oils. The raw biomass was initially dewatered and deoxygenated using a degradative solvent extraction method to obtain a low-molecular-weight extract (named “Soluble”). The Solubles were then pyrolyzed at 500 °C to prepare bio-oils. The carbon contents and calorific values of bio-oils produced from the Solubles were as high as 90.09% and 44.63 MJ/kg, respectively, which were 1.5–2.0 times higher than those from the raw biomasses. In addition, the water and oxygen contents of bio-oils from the Solubles were significantly lower than the bio-oils from the raw biomasses. Furthermore, the bio-oils from the Solubles contained much fewer corrosive and reactive acids and more value-added aromatic hydrocarbons compared to those from raw biomasses. In summary, the quality of the bio-oils produced from the Solubles was obviously superior to the bio-oils from the direct pyrolysis of the raw biomasses. It was shown that degradative solvent extraction combined with subsequent pyrolysis is an effective method to convert raw biomasses into high-quality bio-oils.

The intrinsic kinetics of char combustion were commonly investigated using thermogravimetric analysis (TGA) in previous works at low temperatures to prevent oxygen limitations and temperature deviation. However, the low temperatures caused excess test time because the reaction rate was too slow. In this study, the microfluidized bed (MFB), which has effective heat and mass transfer, was used to investigate the intrinsic kinetics of char combustion at a higher temperature within less time. TGA was used to check the reliability of the MFB. The results suggested that, for fine particles (74–100 μm), the particle temperature deviation and gas distortion could be disregarded in the MFB. For four coal samples, the activation energy measured by the MFB was similar to the result measured by TGA, but the test time using the MFB was greatly shortened as a result of the higher temperatures. The kinetic parameters measured by the MFB were used to predict the char oxidation rate. The predicted rate fit the TGA experiment well at lower temperatures. These results demonstrated the reliability of the MFB and TGA measurements. However, at higher temperatures, the combustion rate in TGA was limited by oxygen diffusion, suggesting that the TGA measurement should be carried out at relatively low temperatures to prevent oxygen diffusion limitation. Instead, the MFB measurement was still valid at higher temperatures as a result of the effective mass and heat transfer.

Fatty acid photodecarboxylase of Chlorella variabilisNC64A (CvFAP) is a novel photoenzyme with great potential in the treatment of waste lipids and production of sustainable aviation fuel. However, the fragile nature of CvFAP to blue light is an urgent challenge. Herein, we demonstrated anaerobic environment could significantly improve the photostability of CvFAP for the first time. The decarboxylation of palmitic acid by CvFAP for 3 h under anaerobic environment increased pentadecane yield by 44.7% as compared to that under aerobic environment. The residual activity of CvFAP after blue-light preillumination in the absence of palmitic acid for 0.5 h under anaerobic environment was 80.4%, which was 258.7 times higher than that under aerobic environment. Remarkable accumulation of superoxide radical and singlet oxygen in CvFAP under aerobic environment led to the poor photostability of CvFAP. Anaerobic environment helped to mitigate the production of superoxide radical and singlet oxygen in CvFAP, improving the photostability of CvFAP.

This paper describes the synthesis of a novel chlorinated sorbent through one-step pyrolysis of waste polyvinyl chloride (PVC)/coal blends and its application for elemental mercury removal. The effects of pyrolysis temperature (600, 700, 800 °C) and mixing ratio (9:1, 3:1) on Hg0adsorption efficiency was tested in a laboratory-scale fixed bed reactor. For sorbents T8C9P1 and T83P1, a complete removal of mercury was maintained for 30 min at 140 °C. Ion chromatography (IC) analysis, Brunauer–Emmett–Teller (BET) surface area, and X-ray photoelectron spectroscopy (XPS) analysis were used to characterize the sorbents. The results suggested that co-pyrolysis of PVC and coal could fix the pernicious element to a certain extent, leading to a few percent reduction of Cl emission (2.6–13.3%). The XPS and temperature-programmed-desorption (TPD) data showed that parts of the C–Cl functional group were converted into ionic Cl during the Hg0adsorption process, which indicated that the C–Cl bond is the major active component for mercury removal via chemisorption. The adsorption kinetics analysis demonstrated that the elemental mercury adsorption on chlorine-modified sorbent was mainly controlled by chemisorption, and the effect of intraparticle diffusion became apparent after an elapsed time of 25 min. Most C–Cl bonds were assumed to be formed when high molecular weight carbon free radicals and HCl (or Cl free radical) appeared synchronously during co-pyrolysis. Based on the results, the co-pyrolysis of PVC and coal is a multifunctional process for Cl fixation and satisfies the requirements for the synthesis of candidate mercury sorbent.

Approaches to the accurate measurement of combustion kinetics are essential for the numerical simulation, reactor design and process optimization of MSW-fired systems. The micro-fluidized bed reaction analyzer (MFBRA), which consisted of a micro-fluidized bed reactor and electrical control devices, was applied in the investigation of the combustion behaviors and kinetic modelling of noodles char (NC) and bamboo chopsticks char (BC). And the kinetics obtained from the thermogravimetric analyzer (TGA) were compared. The results indicated that the TGA might not fully meet the requirement for kinetic study of MSW char combustion due to the temperature deviation and prolonged testing time. Besides, the lower activation energy suggested insufficient heat and mass transfer in TGA. The combustion rate was strongly temperature dependent in MFBRA and BC exhibited around two times higher reactivity than NC. The combustion behavior would transfer from chemically controlled regime into pore diffusion controlled regime at 973 K for NC, and 923 K for BC. Volumetric reaction model (VRM) would overestimate the combustion rate due to the active surface variation during combustion. In contrast, random pore model (RPM) could well predict the conversion process for both samples at high temperatures, which might correspond to the pore enlargement and coalescence. The obtained activation energies of NC and BC combustion in the chemically controlled regime were 56.12 and 48.73 kJ/mol, respectively. Therefore, elevating the oxygen partial pressure and increasing the feeding rate were feasible ways for acquiring fast combustion rate of MSW char as a result of good reactivity in industrial applications.