Substrate Pretreatment Research Articles

Robust, Fluorine-Free Superhydrophobic Films on Glass via Epoxysilane Pretreatment.

Durable and fluorine-free superhydrophobic films were fabricated by a simple two-step process involving the pretreatment of glass substrates with an epoxysilane, which acted as an adhesive. The next step involved the aerosol-assisted chemical vapor deposition of a simple mixture of polydimethylsiloxane (PDMS) and SiO2 nanoparticles (NPs). Various parameters were studied, such as deposition time as well as PDMS and SiO2 loadings. The optimum film generated was with a 1:1 loading of PDMS and SiO2, deposited at 360 °C for 40 min. The resultant film demonstrated excellent water repellency with a water contact angle of 165 ± 3° and a sliding angle of 2°. The epoxysilane underlayer provided the adhesion between the film and substrate. The films maintained superhydrophobicity and durability after being exposed to solvents such as diethyl ether, toluene, and ethanol for up to 5 h, 400 tape peel cycles, UV exposure, and heat exposure at 400 °C. The robustness results indicated enhanced durability relative to the superhydrophobic film without the epoxysilane underlayer.

Cold-spray repair of CuCrZr crystallizers: Effect of substrate pretreatment

Cold spraying is a promising technique for repairing damaged CuCrZr crystallizers, and the interface between the repair coating and the substrate plays a critical role in determining the heat transfer efficiency of the repaired crystallizers. In this study, two coating/substrate interfaces were prepared through polishing and grit-blasting the CuCrZr substrate surface. Effect of substrate pretreatment on microstructure and performance of the CuCrZr coating was studied using electron backscatter diffraction, adhesive shear strength and thermal conduction tests. Results show that the surface preparation method does not affect the microstructure and hardness of the CuCrZr coating, but the coating sprayed on the grit-blasted substrate has a lower shear adhesive strength and heat conductivity than the coating sprayed on the polished substrate. This difference is attributed to the formation of a work hardening zone during the grit-blasting process. After releasing this work hardening by annealing at 500°C, the difference in heat conductivity then disappears, but the average shear adhesive strength of the annealed coating on the polished substrate is still higher than that on the grit-blasted substrate. Therefore, polishing the substrate could serve as a more viable option for the cold spray repair of CuCrZr crystallizers.

Saccharification and co-fermentation of lignocellulosic biomass by a cockroach-gut bacterial symbiont and yeast cocktail for bioethanol production

BackgroundThe eco-friendly transformation of agro-industrial wastes through microbial bioconversion could address sustainability challenges in line with the United Nations’ Sustainable Development Goals. The bulk of agro-industrial waste consists of lignocellulosic materials with fermentable sugars, predominantly cellulose and hemicellulose. A number of pretreatment options have been employed for material saccharification toward successful fermentation into second-generation bioethanol. Biological and/or enzymatic pretreatment of lignocellulosic waste substrates offers eco-friendly and sustainable second-generation bioethanol production opportunities that may also contribute to waste management without affecting food security. In this study, we isolated a promising filamentous bacterium from the guts of cockroaches with commendable cellulolytic activity. The matrices of sequential statistics, from one-factor-at-a-time (OFAT) through significant variable screening by Placket-Burman design (PBD) to Box‒Behnken design of a surface methodology (BBD-RSM), were employed for major medium variable modeling and optimization by solid-state fermentation. The optimized solutions were used to saccharify lignocellulose in real time, and the kinetics of reducing sugar accumulation were subsequently evaluated to determine the maximum concentration of sugars extracted from the lignocellulose. The hydrolysate with the highest reducing sugar concentration was subjected to fermentation by Saccharomyces cerevisiae, Klyuveromyces marxianus and a mixture of both, after which the ethanol yield, concentration and fermentation efficiency were determined.ResultsSequential statistics revealed that rice husk powder, corn cob powder, peptone and inoculum volume were significant variables for the bioprocess at 59.8% (w/w) rice husk powder, 17.8% (w/w) corn cob powder, 38.8% (v/w; 109 cfu/mL) inoculum volume, and 5.3% (w/w) peptone. These conditions mediated maximum cellulolytic and xylanolytic activities of 219.93 ± 18.64 FPU/mL and 333.44 ± 22.74 U/mL, respectively. The kinetics of saccharification of the lignocellulosic waste under optimized conditions revealed two peaks of reducing sugar accumulation between 16 and 32 h and another between 56 and 64 h.ConclusionsAlthough K. marxianus had a significantly greater fermentation efficiency than S. cerevisiae, fermentation with a 50:50 (% v/v) mixture of both yeasts led to 88.32% fermentation efficiency with 55.56 ± 0.19 g/L crude bioethanol, suggesting that inexpensive, eco-friendly and sustainable bioethanol production could be obtained from renewable energy sources.

Insights into Biohydrogen Production Through Dark Fermentation of Food Waste: Substrate Properties, Inocula, and Pretreatment Strategies

The growing population and economic expansion have led to increased energy demand while presenting complex waste generation and management challenges, particularly in light of climate change. Green hydrogen, which is considered a major clean energy carrier, can also be generated from food waste through a process known as dark fermentation. The production of dark fermentative hydrogen from food waste and biomass residues, in general, is influenced by the type of feedstock, source of inoculum, and their pretreatment and handling strategies. Food waste is a suitable substrate for dark fermentation and has a variable and complex composition, which is a major factor limiting the hydrogen yield. This review critically assesses food waste sources, focusing on their physical and chemical composition, pretreatment methods, and strategies for optimizing dark fermentative hydrogen production. This paper also highlights and critically discusses various inoculum sources and innovations regarding the pretreatment and enrichment applications of inocula for dark fermentative hydrogen production. Based on the literature analysis, advanced research is required to develop more sustainable and specific pretreatment strategies that consider the properties of food waste and the source of the inoculum. This approach will aid in preventing inhibition and inefficiency during the dark fermentation process.

General Corrosion and Electrode Potential in Metal-Nanoparticle-Assisted Etching of p-Type and n-Type Silicon Using Gold and Silver

IntroductionWhen silicon (Si) modified with noble metal catalysts is immersed in a hydrofluoric acid (HF) aqueous solution containing an oxidizing agent, such as hydrogen peroxide (H2O2), a porous layer is formed on the Si surface [1]. This phenomenon is called metal-assisted etching, and it has attracted attention as a new method for producing porous Si. The etching reaction is explained by a local cell mechanism consisting of a cathodic reaction in which the oxidizing agent is reduced on the metal catalysts and an anodic reaction in which Si is oxidized. It is known that etching behavior varies greatly depending on the type of metal catalysts and other treatment conditions, but the mechanism is not clear. We have previously reported that the entire Si surface is dissolved during metal-assisted etching, resulting in general corrosion [2]. In this study, metal-assisted etching of p-type and n-type Si was performed using gold (Au) and silver (Ag) nanoparticles, and the general corrosion depth and the potential of Si during etching were investigated.ExperimentalSingle crystal p-type and n-type Si wafers (CZ, (100), 0.5~10 Ωcm) were used as the Si substrates. The pretreated Si substrate was immersed in a tetrachloroauric(III) acid aqueous solution or a silver(I) nitrate aqueous solution containing 0.15 M HF, and Au or Ag nanoparticles were deposited on Si with the metal coverage of approximately 40%. The metal-deposited Si was immersed in a 6.6 M HF aqueous solution containing 0.1 M H2O2 for 120 s in the dark. The general corrosion depth was estimated from the mass loss of the Si substrate and the depth of pores observed with scanning electron microscope (SEM) [2]. The potential of Si during etching was measured using an electrochemical cell with a platinum ring as the counter electrode and a silver/silver chloride (Ag/AgCl) electrode as the reference electrode.Results and discussionFigure 1 shows a schematic illustration of cross sections of Si after etching. Under all conditions, the Si surface beneath the metal particles was dissolved and vertical pores were formed. The pore depth formed by the Ag-assisted-etching was larger than that formed by the Au-assisted etching. On the other hand, the general corrosion depth in the Ag-assisted etching was smaller than that in the Au-assisted etching. In the case of Ag-assisted etching of n-Si, the general corrosion did not occur. As for the potential during etching, the potential was shifted to positive direction by the deposition of metal particles, except for the Ag-deposited n-Si. The positive shift of potential indicates that the Si substrate is anodically polarized during etching and the Si surface away from the metal catalysts can be dissolved. This corresponds to the results that the general corrosion occurred in the Au-assisted etching of p/n-Si and Ag-assisted etching of p-Si. On the other hand, the potential of n-Si was not shifted by the deposition of Ag nanoparticles, and the general corrosion did not occur in the Ag-assisted etching of n-Si. These results suggest that the potential during etching contributes to general corrosion.[1] Z. Huang, N. Geyer, P. Werner, U. Gösele ; Adv. Mater., 23, 285 (2011).[2] A. Matsumoto, H. Son, M. Eguchi, K. Iwamoto, Y. Shimada, K. Furukawa, S. Yae ; RSC Adv., 10, 289 (2020). Figure 1

Modeling of the biomethane production from ultrasonic pretreated fruit and vegetable waste via anaerobic digestion

The global dependency on the depleted fossil fuels has led to the quest for acquiring alternative energy sources. Different types of waste material are generated at a high rate and tapping into their use for greener, alternative energy production is an option. The mesophilic anaerobic co-digestion of fruit and vegetable waste and wastewater treatment plant sewage sludge experiments were conducted using ultrasonic pretreated substrates. Sonication exposure times from 0 to 45 min were selected for the experiments. An automatic methane potential test system (BMP) was used to determine the production rate of biomethane of the fruit and vegetables waste containing 60% fruit and 40% vegetables. The highest cumulative methane production of 238 mL g−1 VS was achieved at sonication time exposure of 45 min. It was observed that an increase in ultrasonic sonication exposure time, improved methane yield. The resulting experimental data was fitted with the modified Gompertz, co-digestion modified Gompertz, original Richards, modified Richards and co-digestion modified Richards models. IBM SPSS Statistics software was used for curve fitting and the estimation of the models’ kinetic parameters. The modified Gompertz and Richards models showed higher goodness fit, both with R 2 of 0.93 and modified Richards models did not produce a good fit for the data, with R 2 of 0.7. The developed co-digestion models considered a combination of substrates that were easily digested as well as complex substrates that required multiple steps of digestion. The results show that the co-digestion modified Gompertz model had a goodness of fit of 0.98. Co-digestion modified Richard’s model perfectly fit the experimental data, with R 2 of 1. Both the co-digestion modified models are recommended due to their fitting performance. Fruit and vegetable waste comprise multiple substrates including simple sugars that digest readily and much more complex cellulose substrates that require more steps to digest and requiring the second step of digestion after undergoing hydrolysis. Both models took that into account. The aim of this study was to evaluate the suitability of the Gompertz and Richards model in the co-digestion of fruit and vegetables waste with sludge, as well as to develop co-digestion models for the substrates at hand.

Innovative Zinc Anodes: Advancing Metallurgy Methods to Battery Applications.

Aqueous zinc metal batteries (AZMBs) are emerging as a powerful contender in the realm of large-scale intermittent energy storage systems, presenting a compelling alternative to existing ion battery technologies. They harness the benefits of metal zinc's high safety, natural abundance, and favorable electrochemical potential (-0.762V vs Standard hydrogen electrode, SHE), alongside an impressive theoretical capacity (820mAhg-1 and 5655mAhcm-3). However, the electrochemical performance of ZMBs is impeded by several challenges, including poor compatibility with high-loading cathodes and persistent side reactions. These issues are intricately linked to the inherent physicochemical properties of the zinc metal anodes (ZMAs). Here, this review delves into the traditional methods of ZMAs production, encompassing extraction, electrodeposition, and rolling processes. The discussion then progresses to an exploration of cutting-edge methodologies designed to enhance the electrochemical performance of ZMAs. These methods are categorized into alloying, pre-treatment of substrate, advanced electrodeposition techniques, and the development of composite anodes utilizing zinc powder. The review offers a comparative analysis of the merits and drawbacks of various optimization strategies, highlighting the beneficial outcomes achieved. It aspires to inspire novel concepts for the advancement and innovation of next-generation zinc-based energy storage solutions.

Synergising hydrothermal pre-treatment and biological processes for enhancing biohydrogen production from palm oil mill effluent

The high quantity of nutrient-rich palm oil mill effluent (POME) waste in the industry will have a severe negative environmental impact and a high cost of treatment. However, POME waste could be converted into bioenergy via environmentally sustainable processes. Several studies have explored using hydrothermal carbonisation for solid biomass products in biofuel production, but the potential of the liquid phase produced during these processes has received less attention. Therefore, this study aims to assess the potential of biohydrogen production from treated POME as a substrate by hydrothermal process. This study is presented in two phases: the first phase involves substrate pre-treatment using a hydrothermal process to improve biomass properties at different temperatures, and the second phase explores the potential for biohydrogen production from treated POME through dark fermentation. Substrate pre-treatment was conducted at 180, 210, and 240 °C using 100 % raw POME. Next, the treated POME was incubated for biohydrogen production at 50 °C for 24 h. A microbial analysis was conducted to determine the most dominant species present in the sample. Our findings show that at 180 °C, the total chemical oxygen demand (COD) removal efficiency was 80 %, and acetic acid concentration was 28 %. Compared to raw POME, treated POME generated a maximum hydrogen yield and rate (HPR) of 52.19 mL H2 g−1 CODrem and 0.59 mL H2 mL POME−1 day−1 with a 2.32-fold and 1.59-fold increase, respectively. Meanwhile, Clostridium was a dominant bacterial species identified in the treated POME. These findings demonstrated the feasibility of implementing a hydrothermal process to treat POME and improve its biohydrogen production efficiency. The treated POME from the hydrothermal process is more homogenous and readily consumable by microorganisms used in dark fermentation. Hydrothermal pre-treatment could potentially increase the rate and efficiency of microbial digestion, leading to enhanced hydrogen production. The high COD removal efficiency during the process significantly reduces the environmental impact of POME discharge, and converting POME into a valuable resource through the hydrothermal and dark fermentation process aligns with sustainable waste management practices.

A deep eutectic solvent with a lignin stabilization and functionalization for lignocellulosic biomass pretreatment

This study synthesized a functional deep eutectic solvent (DES) using betaine and glyoxylic acid (GA) for lignocellulosic biomass pretreatment. The Betaine/GA DES pretreatment resulted a high delignification efficiency of 81.89% and xylan removal of 83.25% while preserving most of cellulose. During pretreatment, lignin was stabilized by GA, preventing its condensation and introducing carboxyl groups onto its molecular backbone. The GA stabilized lignin (GASL), with a high β-O-4 linkage content of 62.92%, was depolymerized for phenolic monomer production with a bio-oil yield of 55.40%. Additionally, the functional lignin was used as a surfactant for GASL-based O/W emulsion (GA-O/W emulsion) preparation. With 0.5% of lignin addition and an optimal O/W ratio of 6:4, the resulting GA-O/W emulsion exhibited a high cream index value of 100% and excellent storage stability without any phase transition or emulsion aggregation. When using the lignin to prepare curcumin-encapsulated microcapsules, a cumulative curcumin remaining of 74.19% under UV radiation and an extraordinary encapsulation efficiency of 62.86% were achieved. Furthermore, this DES pretreatment promoted enzymatic saccharification of the pretreated cellulose substrate, resulting in a glucose yield of 91.49%. After adding 15 wt% of the fibers in soft wood pulp for papermaking, the tear index, ring crush strength index, and tensile index of the produced paper-sheets reached 112.04%, 98.58%, and 83.55% of those of the pure softwood pulp papers, respectively.

Influence of surface pretreatment of steel substrate on the interfacial microstructure and tensile properties of laser Al/steel joints

The influence of surface-pretreatments, viz., subtractive manufactured (SMed), additively manufactured (AMed), and untreated (UTed) steel substrates on dissimilar laser aluminum (Al)/steel joints were comparatively investigated, for the first time, in terms of the interfacial microstructure and mechanical properties. Compared to the UTed joints, the interfacial microstructure of SMed joints remained unchanged with both composing of Fe-Al-Si and Fe-Al IMCs, but the joint fracture energy increased from 1.89 kJ to 2.39 kJ. Differently, the interfacial microstructure changed to a composite structure consisting of a high entropy alloys (HEAs) skeleton and reaction regions, and the joint fracture energy further increased to 4.38 kJ in the case of AMed joints. The mechanisms of the altered interfacial microstructure and tensile properties were also investigated.

Novel self-pretreatment of biomass by in-situ preparation of acid-assisted carbohydrate-derived DES

Deep eutectic solvents (DES) can greenly and efficiently fractionate biomass, but their utilization efficiency is severely limited by the high ratio of DES required and the wasted hemicelluloses released during the pretreatment. Herein, this work first developed a novel self-pretreatment of biomass by in-situ preparation of acid-assisted carbohydrate-derived DES with the aid of ball milling to facilitate enzymatic hydrolysis. The effect of hydrogen bond acceptor types, water content, acid content, and ball-milling time on enzymatic hydrolysis was studied systematically. Under the optimal condition (tetrabutylammonium chloride (TBAC), 1000 wt% H2O, 100 wt% acids, ball milling for 2 h), the yields of glucose and xylose produced from the pretreated substrates after enzymatic hydrolysis were >99.9 % and 88 %, respectively. Furthermore, the structural integrity of the residual lignin was well-preserved, making it suitable for positional structural characterization and ideal substrates for lignin degradation. Characterization suggested that the hemicelluloses fragments via in-situ acid hydrolysis acted as hydrogen bond donors and combined in situ with TBAC to form DES. This strategy avoided the use of high dosages of DES and the wastage of hemicelluloses, and promoted the sustainability of the entire biorefinery process.

Friction and wear characteristics of DLC-terminated coatings deposited on AlSi10Mg alloy produced by Additive Manufacturing

Al–Si alloys are attractive materials for the fabrication of mechanical components, mainly because of their high strength-to-density ratio. Though the advent of Selective Laser Melting (SLM) has potentially expanded the range of their applicability, their poor tribological performances limit their effective use. Identifying post-processing protocols and coating strategies enhancing these properties and compatible with large-scale production is fundamental to the industrial uptake of SLM-fabricated Al–Si parts. This work tests the possibility of depositing self-lubricating Diamond-Like Carbon (DLC)-terminated films on AlSi10Mg built by SLM and subjected to different surface finishing processes. The applied coating architectures consist of an electroless nickel‐phosphorus buffer layer deposited on the AlSi10Mg surface, plus a series of interlayers and a DLC top film grown by Plasma Assisted – Chemical Vapor Deposition. The wear resistance and frictional behavior of the samples are evaluated for different substrate pre-treatments and coating assemblies under two applied loads. Cast substrates, processed and coated in a similar way, are also studied for comparison. The DLC film lends good tribological performances to all the coating-substrate combinations explored, being mechanically assisted by the underlying Ni–P layer. The friction coefficients stabilize around 0.20 at the lowest load, independently of the sample surface roughness (Sq), which spans the range 0.47–4.6 μm. Conversely, the counterpart wear rates increase with roughness up to 10−5 mm3/(N⋅m). Both tribological parameters decrease by nearly 20 % and 70 %, respectively, after a tenfold increase in load. These results indicate that DLC-terminated multilayers are extremely efficient on AlSi10Mg even in the presence of significant roughness. Their application requires a limited number of well-established processing steps also in the case of SLM grown parts.

Engineering Triphasic Nanocomposite Coatings on Pretreated Mg Substrates for Biomedical Applications.

Biodegradable polymer-based nanocomposite coatings provide multiple advantages to modulate the corrosion resistance and cytocompatibility of magnesium (Mg) alloys for biomedical applications. Biodegradable poly(glycerol sebacate) (PGS) is a promising candidate used for medical implant applications. In this study, we synthesized a new PGS nanocomposite system consisting of hydroxyapatite (HA) and magnesium oxide (MgO) nanoparticles and developed a spray coating process to produce the PGS nanocomposite layer on pretreated Mg substrates, which improved the coating adhesion at the interface and their cytocompatibility with bone marrow derived mesenchymal stem cells (BMSCs). Prior to the spray coating process of polymer-based nanocomposites, the Mg substrates were pretreated in alkaline solutions to enhance the interfacial adhesion strength of the polymer-based nanocomposite coatings. The addition of HA and MgO nanoparticles (nHA and nMgO) to the PGS matrix, as well as the alkaline pretreatment of the Mg substrates, significantly enhanced the interfacial adhesion strength when compared with the PGS coating on the nontreated Mg control. The average BMSC adhesion densities were higher on the PGS/nHA/nMgO coated Mg than the noncoated Mg controls under direct contact conditions. Moreover, the addition of nHA and nMgO to the PGS matrix and coating the nanocomposite onto Mg substrates increased the average BMSC adhesion density when compared with the PGS/nHA/nMgO coated titanium (Ti) and PGS coated Mg controls under direct contact. Therefore, the spray coating process of PGS/nHA/nMgO nanocomposites on Mg substrates or other biodegradable metal substrates could provide a promising surface treatment strategy for biodegradable implant applications.

Enzymatic hydrolysis of highly concentrated substrates obtained from Miscanthus giganteus

This work is the first to study the enzymatic hydrolysis of four types of substrates obtained from Miscanthus giganteus of the KAMIS variety of Russian breeding. The study was conducting using the authors’ methodology based on a chemical pretreatment of substrates at atmospheric pressure with HNO3 and NaOH dilute solutions. A one-stage pretreatment of Miscanthus giganteus allows the polysaccharide content to be increased up to 90.4–90.8%, compared to 98.3–99.4% following a two-stage treatment. The experimental results of enzymatic hydrolysis of the four obtained substrates in the range of initial concentrations from 30 to 120 g/l are approximated using fractal kinetics approaches. An increase in the initial substrate concentrations in the specified range leads to an increase in the initial hydrolysis rate by 2.8–3.3 times and a decrease in the yield of reducing sugars by 12.4–13.1%. All four pretreatment types turned out to be extremely effective for Miscanthus giganteus, ensuring an increase in the reactivity to enzymatic hydrolysis by 34–36 times compared to the starting raw material. Lowered yields of reducing sugars are observed during enzymatic hydrolysis of the alkaline delignification product of Miscanthus giganteus, which is associated with the resistance of Miscanthus giganteus to treatment with sodium hydroxide. An increase in the initial concentration of substrates from 60 to 90 g/l does not lead to a significant decrease in the yield of reducing sugars. Therefore, enzymatic hydrolysis of highly concentrated substrates can be successfully used to produce biofuels and biochemicals.

A Comprehensive Review of Group-III Nitride Light-Emitting Diodes: From Millimeter to Micro-Nanometer Scales.

This review describes the development history of group-III nitride light-emitting diodes (LEDs) for over 30 years, which has achieved brilliant achievements and changed people's lifestyles. The development process of group-III nitride LEDs is the sum of challenges and solutions constantly encountered with shrinking size. Therefore, this paper uses these challenges and solutions as clues for review. It begins with reviewing the development of group-III nitride materials and substrates. On this basis, some key technological breakthroughs in the development of group-III nitride LEDs are reviewed, mainly including substrate pretreatment and p-type doping in material growth, the proposal of new device structures such as nano-LED and quantum dot (QD) LED, and the improvement in luminous efficiency, from the initial challenge of high-efficiency blue luminescence to current challenge of high-efficiency ultraviolet (UV) and red luminescence. Then, the development of micro-LEDs based on group-III nitride LEDs is reviewed in detail. As a new type of display device, micro-LED has drawn a great deal of attention and has become a research hotspot in the current international display area. Finally, based on micro-LEDs, the development trend of nano-LEDs is proposed, which is greener and energy-saving and is expected to become a new star in the future display field.

Enhancement of biogas production by means of ultrasonic pre-treatment: state of art and review

Currently, fossil fuels are being used in an aberrant manner and greenhouse gases are negatively impacting the environment, causing research into renewable energy sources to be pioneered. As highlighted during the COP conferences, the international community is striving to expedite worldwide climate action by reducing emissions, intensifying adaptation initiatives, and increasing the availability of suitable financial resources. Production of biogas is a way to help overcome these challenges by reducing wastage and preventing environmental damage. The anaerobic digestion technique faces some barriers like elongated reaction times, cost of heating or low biogas yields. Several techniques have been used to enhance the biogas yield. Among these techniques the use of ultrasound technology as a pretreatment in biogas production revolutionized the process with its widespread application, providing an environmentally friendly and low-cost alternative. This paper reviews several research studies on ultrasonic pretreatment of several substrates categorized according to different sources, for biogas production and puts an effort to compare and advise various operation parameters.

Assessment of the Impact of Pretreatment of Spent Coffee Grounds with Diluted Sulfuric Acid on the Efficiency of Methane and Lactic Acid Fermentation

Lignocellulosic materials are composed of three major biocomponents such as cellulose, hemicellulose and lignin, which form a compact lignocellulosic complex. Characterized by high caloric content, lignocellulosic biomass, including coffee grounds, is a valuable energy source that can be efficiently used in various bioconversion and biotransformation processes. Due to the high consumption of coffee in the world, there is an increasing amount of coffee grounds, which is a rich waste and at the same time a valuable secondary raw material, and its use fits perfectly into a closed-loop economy. Coffee grounds biomass contains polysaccharides, mainly mannans, proteins, lipids, polyphenols, which will allow the development of different biorefinery strategies, the creation of new value-added products with reduced waste generation. The research describes the pre-treatment of coffee grounds with dilute sulfuric acid to evaluate the effect of acid concentration, hydrolysis time on biogas yield, including methane and lactic acid biosynthesis during anaerobic fermentations. A yield of 381.12 mL of CH4/g-VS methane was obtained, accounting for 72.48% of the total biogas composition. It was found that the most efficient sample in terms of substrate pre-treatment for lactic acid biosynthesis was coffee grounds after 90 min hydrolysis with 1.5% H2SO4 at 121 °C.

A durable superhydrophobic surface with bud-particle structure prepared by one-step spray method

Superhydrophobic surfaces play an essential role in numerous applications such as anti-fouling, waterproofing, and drag reduction due to their water-repellent. However, for most fabrication methods, there are high requirements for the preparation process and conditions. Meanwhile, the superhydrophobic surfaces generally have the problem of insufficient durability. In this study, a one-step method to fabricate a stable superhydrophobic surface by spraying is proposed. A new bud-particle structure is obtained by modifying micron and nano Aluminium hydroxide(Al(OH)3) particles, which helps the coated surface to demonstrate excellent superhydrophobicity with the water contact angle ∼157.0° and rolling angle ∼2.0°, and it shows great repellency to water droplet impact. Due to the compatibility of Al(OH)3with the pretreatment substrate and the reinforcing effect of nanoparticles, the coating maintained the superhydrophobicity well in the sandpaper wear and the ultrasonic damage test, which reflects the outstanding robustness of the coating.Moreover,benefiting from the control of the wetting state by micronand nanoparticles doping,the coating showed an excellent underwater drag reduction effect in the rheometer experiment, with a drag reduction rate of ∼67.7 %. The one-step spraying method proposed is a simple and convenient way to create the surface with excellent superhydrophobicity and durability, which has great potential applications in improving metal surface oxidation resistance and underwater reducing drag.

Energy efficiency of hydrogen production during dark fermentation

It is widely known that most of the world's energy is produced from non-renewable energy sources such as crude oil and coal. Hydrogen is an ideal fuel candidate with a high energy content and clean combustion product. Biohydrogen is an environmentally friendly, renewable biofuel with high energy density, making it a viable alternative to fossil fuels in the future. At the same time, despite the large number of articles on the intensification of both dark fermentation and anaerobic bioconversion in general, the operating costs of the proposed intensification methods are not well covered in the literature. The goal of the work was to estimate the conversion coefficient of thermal and electrical energy spent on the functioning of the process of dark fermentation of various organic wastes into the energy of produced hydrogen. A block diagram of the energy flows of the dark fermentation system and the structure of the energy consumption of the system were developed. The obtained literature and experimental data suggest that the conversion coefficient of energy into biohydrogen in the process of dark fermentation is less than 1, so to obtain 1 kWh of hydrogen it is necessary to expend more than 1 kWh of energy. At the same time, the use of a vortex layer apparatus for dark fermentation of the food waste model made it possible to increase the energy output of the process by more than 7 times, thereby bringing the values of the conversion coefficients of thermal and electrical energy closer to 1. Despite the fact that the energy efficiency of most known methods for producing hydrogen is higher than the energy efficiency of dark fermentation, it is worth noting that the raw material for producing hydrogen in the dark fermentation process is organic waste, and not high-energy fuel (natural gas, methane, coal) or water in the case of electrolysis. In addition, the use of a vortex layer apparatus for pre-treatment of the dark fermentation substrate made it possible to achieve electricity conversion coefficient values 40% higher than with water electrolysis.

Saccharification of Different Delignified Sawdust Masses from Various Trees Along the Lagos Lagoon in Nigeria

Sawdust, a major waste product of the forestry industry, is accumulating along the Lagos Lagoon in Lagos, Nigeria, without it being effectively managed. Besides its use in The saccharification of sawdust could contribute to the development of renewable energy sources and feedstock for bioproduct development. The process is, however, not that straightforward as variables such as the type of cellulase enzyme, pretreatment of the cellulose substrate, and optimizing of cellulase to cellulose ratio are a few that need to be optimized for the process to be effective in terms of glucose production.manufacturing sound-absorbing boards to reinforce concrete beams and for energy purposes, its potential as a renewable energy source and feedstock for bio-product development has not yet been realized. Cellulose, a glucose biopolymer and structural component of cellulose can be hydrolyzed by a hydrolytic enzyme known as cellulase. During the process, the enzyme breaks the B-1,4-glucosidic bond, which keeps the glucose units together, and by acting on this bond, numerous glucose units are released. As part of sawdust, the cellulose molecule is not freely available for the degradation action of the cellulase enzyme as it is strongly associated with lignin, which acts as bio-glue, keeping cellulose and hemicellulose together. Delignification is an effective technique that was used to make the sawdust from ten different trees along the Lagos Lagoon in Nigeria more susceptible to saccharification by cellulase isolated from the fungus Aspergillus niger. Delignified and non-delignified sawdust masses between 2 mg and 10 mg were incubated with the A. niger cellulase solution (2 mg.mL-1), whereafter, the amount of sugar produced by the cellulase action was determined. The percentage saccharification of each sawdust material was also linked with the amount of sugar produced during cellulase action. From these investigations was concluded that delignification increased sugar production when almost all the masses of different sawdust materials were degraded. It was also observed that the ratio of sawdust mass to enzyme concentration is an important variable that influences the effectiveness of the saccharification process. The percentage saccharification of the various sawdust materials was also determined, and it indicated that the highest percentage of saccharification was not obtained when the highest amount of sawdust was degraded, producing the highest amount of sugar.