Transformation, Morphology, and Dissolution of Silicon and Carbon in Rice Straw-Derived Biochars under Different Pyrolytic Temperatures

Biochars are increasingly recognized as environmentally friendly and cheap remediation agents for soil pollution. The roles of silicon in biochars and interactions between silicon and carbon have been neglected in the literature to date, while the transformation, morphology, and dissolution of silicon in Si-rich biochars remain largely unaddressed. In this study, Si-rich biochars derived from rice straw were prepared under 150–700 °C (named RS150-RS700). The transformation and morphology of carbon and silicon in biochar particles were monitored by FTIR, XRD, and SEM-EDX. With increasing pyrolytic temperature, silicon accumulated, and its speciation changed from amorphous to crystalline matter, while the organic matter evolved from aliphatic to aromatic. For rice straw biomass containing amorphous carbon and amorphous silicon, dehydration (<250 °C) made silicic acid polymerize, resulting in a closer integration of carbon and silicon. At medium pyrolysis temperatures (250–350 °C), an intense cracking of carbon components occurred, and, thus, the silicon located in the inside tissue was exposed. At high pyrolysis temperatures (500–700 °C), the biochar became condensed due to the aromatization of carbon and crystallization of silicon. Correspondingly, the carbon release in water significantly decreased, while the silicon release somewhat decreased and then sharply increased with pyrolytic temperature. Along with SEM-EDX images of biochars before and after water washing, we proposed a structural relationship between carbon and silicon in biochars to explain the mutual protection between carbon and silicon under different pyrolysis temperatures, which contribute to the broader understanding of biochar chemistry and structure. The silicon dissolution kinetics suggests that high Si biochars could serve as a novel slow release source of biologically available Si in low Si agricultural soils

Purification effect and microorganisms diversity in an <i>Acorus calamus</i> constructed wetland on petroleum-containing wastewater

A constructed wetland system with Acorus calamus (A. calamus) was developed to investigate the purification efficiency of petroleum-containing wastewater. High-throughput sequencing was employed to investigate bacterial richness and diversity, bacterial community structure variation between spring and summer, and the effect of bacteria on petroleum-containing wastewater purification in the system. The results showed that the constructed wetland systems with A. calamus purified the petroleum-containing wastewater well. The average removal rates of petroleum pollutants, chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were 97%, 80%, 67%, and 54%, respectively. A total of 22 strains were identified by 16SrDNA clone library gene sequencing. The bacteria mainly contained Acinetobacter, Rhizobium, and Rhodobacter. These bacteria had significant effects on organic matter decomposition and nitrogen removal, and played a major role in the removal of petroleum pollutants, COD, and TN in the constructed wetland. The bacterial richness and community diversity were higher in the summer sample than that in the spring sample. The treatment effect on petroleum pollutants was better in summer. Petroleum pollutant removal rate by the A. calamus system has a significant positive correlation with the Chao1 and Ace diversity indices (p < 0.05).</p

Hydrophobic Solid Photothermal Slippery Surfaces with Rapid Self-repairing, Dual Anti-icing/Deicing, and Excellent Stability Based on Paraffin and Etching

Ice and snow disasters have greatly affected both the global economy and human life, and the search for efficient and stable anti-icing/deicing coatings has become the main goal of much research. Currently, the development and application of anti-icing/deicing coatings are severely limited due to their complex preparation, structural fragility, and low stability. This work presents a method for preparing hydrophobic solid photothermal slippery surfaces (SPSS) that exhibit rapid self-repairing, dual anti-icing/deicing properties, and remarkable stability. A photothermal layer of copper oxide (CuO) was prepared by using chemical deposition and etching techniques. The layer was then impregnated with stearic acid and solid paraffin wax to create a hydrophobic solid photothermal slippery surface. This solves the issue of low stability on superhydrophobic surfaces caused by fragile and irretrievable micro/nanostructures. In addition, the underlying photothermal superhydrophobic surface provides good anti-icing/deicing properties even if the paraffin on the surface evaporates or is lost during operation. The findings indicate that when subjected to simulated light irradiation, the coating’s surface temperature increases to 80 °C within 12 min. The self-repair process is completed rapidly in 170 s, and at −15 °C, it takes only 201 s for the ice on the surface to melt completely. The surface underneath the paraffin exhibited good superhydrophobic properties, with a contact angle (CA) of 154.1° and a sliding angle (SA) of 6.8° after the loss of paraffin. Simultaneously, the surface’s mechanical stability and durability, along with its self-cleaning and antifouling properties, enhance its service life. These characteristics provide promising opportunities for practical applications that require long-term anti-icing/deicing surfaces

A Hybrid Large Neighborhood Search Method for Minimizing Makespan on Unrelated Parallel Batch Processing Machines with Incompatible Job Families

This paper studies a scheduling problem with non-identical job sizes, arbitrary job ready times, and incompatible family constraints for unrelated parallel batch processing machines, where the batches are limited to the jobs from the same family. The scheduling objective is to minimize the maximum completion time (makespan). The problem is important and has wide applications in the semiconductor manufacturing industries. This study proposes a mixed integer programming (MIP) model, which can be efficiently and optimally solved by commercial solvers for small-scale instances. Since the problem is known to be NP-hard, a hybrid large neighborhood search (HLNS) combined with tabu strategy and local search is proposed to solve large-scale problems, and a lower bound is proposed to evaluate the effectiveness of the proposed algorithm. The proposed algorithm is evaluated on numerous compatible benchmark instances and newly generated incompatible instances. The results of computational experiments indicate that the HLNS outperforms the commercial solver and the lower bound for incompatible problems, while for compatible problems, the HLNS outperforms the existing algorithm. Meanwhile, the comparison results indicate the effectiveness of the tabu and local search strategies

Quantification of Chemical States, Dissociation Constants and Contents of Oxygen-containing Groups on the Surface of Biochars Produced at Different Temperatures

Surface functional groups such as carboxyl play a vital role in the environmental applications of biochar as a soil amendment. However, the quantification of oxygen-containing groups on a biochar surface still lacks systematical investigation. In this paper, we report an integrated method combining chemical and spectroscopic techniques that were established to quantitatively identify the chemical states, dissociation constants (p<i>K</i>_a), and contents of oxygen-containing groups on dairy manure-derived biochars prepared at 100–700 °C. Unexpectedly, the dissociation pH of carboxyl groups on the biochar surface covered a wide range of pH values (pH 2–11), due to the varied structural microenvironments and chemical states. For low temperature biochars (≤350 °C), carboxyl existed not only as hydrogen-bonded carboxyl and unbonded carboxyl groups but also formed esters at the surface of biochars. The esters consumed OH^– via saponification in the alkaline pH region and enhanced the dissolution of organic matter from biochars. For high temperature biochars (≥500 °C), esters came from carboxyl were almost eliminated via carbonization (ester pyrolysis), while lactones were developed. The surface density of carboxyl groups on biochars decreased sharply with the increase of the biochar-producing temperature, but the total contents of the surface carboxyls for different biochars were comparable (with a difference <3-fold) as a result of the expanded surface area at high pyrolytic temperatures. Understanding the wide p<i>K</i>_a ranges and the abundant contents of carboxyl groups on biochars is a prerequisite to recognition of the multifunctional applications and biogeochemical cycling of biochars

Chitosan-Derived Porous N‑Doped Carbon as a Promising Support for Ru Catalysts in One-Pot Conversion of Cellobiose to Hexitol

Tailoring the metal properties over N-doped carbon materials is essential to lignocellulose/cellobiose hydrogenation reactions. In this contribution, using a facile Na2CO3-assisted mechanochemical synthesis approach and tuning the weight ratio of Na2CO3/CTS (chitosan), the surface properties of Ru, including metal particle size, dispersion, and surface Ru0/RuO2 species, were tailored by adjusting the metal–support interaction between Ru and the CTS-derived carbons for cellobiose hydrogenation. The total content of N was tunable with the weight ratio of Na2CO3/CTS, further moderating the metal–support interactions. Excellent catalytic performance at 95% of hexitol yield was achieved over the 0.75 wt %Ru/CTS-0.5 catalyst at 185 °C with a moderate N content. The results indicated that the dominated nitrogen species (pyridinic and oxidized N species) in CTS-x carbon worked as the anchor sites for Ru loading. The structure–performance analysis demonstrated that the metal dispersion of Ru and the relative content of surface-exposed Ru0 were sensitive to the total content of N and determined the catalytic performance in cellobiose hydrogenation. The insightful understanding may extend the CTS-derived N-doped carbon materials as ideal supports for a wide range of biomass hydrogenation

IrMo Nanocluster-Doped Porous Carbon Electrocatalysts Derived from Cucurbit[6]uril Boost Efficient Alkaline Hydrogen Evolution

Electrocatalysts based on noble metals have been proven efficient for high-purity hydrogen production. However, the sluggish kinetics of the hydrogen evolution reaction (HER) in alkaline media caused by high water dissociation energy largely hampers this electrochemical process. To improve the electrocatalytic activity, we fabricate an effective porous carbon matrix derived from cucurbit[6]uril using a template-free method to support iridium–molybdenum (IrMo) nanoclusters. As proof of concept, the resulting IrMo-doped carbon electrocatalyst (IrMo-CBC) was found to boost the alkaline HER significantly. Owing to the unique in-plane hole structure and the nitrogen-rich backbone of cucurbit[6]uril as well as the ultrafine IrMo nanoclusters, IrMo-CBC exhibits pronounced alkaline HER activity with an extremely low overpotential of 12 mV at 10 mA cm–2, an ultrasmall Tafel slope (28.06 mV dec–1), a superior faradic efficiency (98%), and a TOF of 11.6 H2 s–1 at an overpotential of 50 mV, outperforming most iridium-based electrocatalysts and commercial Pt/C

Down-Cycling Sustainability of Flexible Polyurethane Foam in Improving Asphalt Performance through a Proper Pyrolysis Approach

The down-cycling process of waste polymers in asphalt binder achieves a win–win situation in terms of economic modification and efficient disposal of valuable waste. By combining the “controllable pyrolysis” and “down-cycling” concepts, this study specified the application potential of sustainable recycling flexible polyurethane foam (FPUF) in improving asphalt performance. A proper pyrolysis method was proposed to selectively decompose waste FPUF into fibers. Subsequently, eco-friendly and cost-effective properly pyrolyzed FPUF fiber-modified asphalt (PyFMA) was developed. The microscopic, chemical, and mechanical investigations were carried out to clarify modification mechanisms and application feasibility. The results showed that the proper pyrolysis method efficiently produced flexible reticulated PFUF fibers of different sizes grafted with polar groups. The PFUF fibers interlocked spatially and well-coordinated with the asphalt matrix, contributed an elastic component in the mixed hybrid, and positively influenced the asphalt performance. The performance enhancement was the result of a combination of chemical interaction, physical reinforcement, and the volumetric filling effect. In addition, the PyFMA had adequate workability at a high fiber dosage of 24% to achieve a massive recycling goal. It is promising and feasible to use waste FPUF as a sustainable and high-performance asphalt modifier, which countermeasures the rapidly increasing abandonment and meets economical asphalt modification requirements

Photoelectrochemical Water Splitting SystemA Study of Interfacial Charge Transfer with Scanning Electrochemical Microscopy

Fast charge transfer kinetics at the photoelectrode/electrolyte interface is critical for efficient photoelectrochemical (PEC) water splitting system. Thus, far, a measurement of kinetics constants for such processes is limited. In this study, scanning electrochemical microscopy (SECM) is employed to investigate the charge transfer kinetics at the photoelectrode/electrolyte interface in the feedback mode in order to simulate the oxygen evolution process in PEC system. The popular photocatalysts BiVO₄ and Mo doped BiVO₄ (labeled as Mo:BiVO₄) are selected as photoanodes and the common redox couple [Fe­(CN)₆]^3–/[Fe­(CN)₆]^4– as molecular probe. SECM characterization can directly reveal the surface catalytic reaction kinetics constant of 9.30 × 10⁷ mol^–1 cm³ s^–1 for the BiVO₄. Furthermore, we find that after excitation, the ratio of rate constant for photogenerated hole to electron via Mo:BiVO₄ reacting with mediator at the electrode/electrolyte interface is about 30 times larger than that of BiVO₄. This suggests that introduction of Mo⁶⁺ ion into BiVO₄ can possibly facilitate solar to oxygen evolution (hole involved process) and suppress the interfacial back reaction (electron involved process) at photoanode/electrolyte interface. Therefore, the SECM measurement allows us to make a comprehensive analysis of interfacial charge transfer kinetics in PEC system