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Integrating Fenton Process with Plasma Technology for Enhanced Biogas Production from High-Lignocellulosic Biomass
No full textThe rising energy demands, and depleting reserve of fossil fuels have resulted in the need to explore sustainable and renewable energy alternatives (Ashokkumar et al. 2022). Lignocellulosic biomass, which is primarily composed of cellulose, hemicellulose, and lignin, is a promising renewable energy source that has the potential to meet global energy demands while mitigating climate change (Zeng et al. 2017). However, the complex and recalcitrant structure of lignocellulosic biomass, particularly its high lignin content, presents a major barrier to its efficient use for direct bioenergy production (Carrere et al. 2016). Anaerobic digestion (AD) is a well-established biological process that converts organic matter into biogas, a valuable renewable energy source in the absence of oxygen (Jwan J Abdullah and Chenyu Du 2020). However, the often high lignin content biomass hinders the utilization of biomethane in AD processes, necessitating pretreatment strategies to improve biodegradability and biomethane yield (Mohammad Rahmani et al. 2022). The pretreatment methods can be broadly classified into mechanical, chemical, thermal, biological, and combined approaches (Karthikeyan et al. 2024). The Fenton process, which is known for its strong oxidising properties, disrupts lignin's complex polymeric structure, increasing the accessibility of cellulose and hemicellulose to microbial digestion (Grbić et al. 2023). Concurrently, microbubble plasma technology, known for its high mass transfer efficiency and reactive species generation, can improve biomass degradation (Wright et al. 2020). This research integrates the Fenton process with plasma technology using a microbubble plasma reactor (Fig. 1) to address and the issue of low biodegradability and increase biomethane production. We applied the proposed pretreatment to maize and rice husks, as representatives of the most commonly grown crops with abundant post-harvest residues.
Combining the two pretreatment approaches results in a highly oxidised pretreatment environment setting, which aims to increase lignin breakdown, improve substrate biodegradability, increase substrate surface area, and maximise biomethane yield.
Plasma pretreatment with Fenton reagents was performed under various operating conditions, including different H2O2:Fe ratios (based on their mass) and pretreatment durations. The untreated and treated biomass was characterised using Attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) to monitor functional group changes, scanning electron microscopy (SEM) to examine surface morphology, and X-ray diffraction (XRD) to evaluate the crystalline structure, while biomethane production was assessed using the biomethane potential test (AMPTS II). Biogas production tests were carried out in a batch anaerobic digestion system to determine the biogas yield. The National Renewable Energy Laboratory protocol (Sluiter et al. 2008) was used to quantify Klason lignin content for pretreated and untreated biomass samples. Gas chromatography was used to determine the biogas composition. Simultaneously, lignin and hemicellulose fractions were recovered from the liquid phase after pretreatment, presenting opportunities for obtaining value-added products through biorefinery approaches. Preliminary FTIR characterization results for whole maize plants and rice husks indicate that stand-alone microbubble plasma pretreatment for 1h and 3h pretreatment duration reduces the intensity of the peak associated with lignin and carbohydrate linkage, as shown in Fig. 2.
This study demonstrates the potential of integrating the Fenton process with microbubble plasma technology to improve biomethane production. It addresses the ongoing challenges of lignocellulosic biomass degradation, thereby facilitating the development of sustainable bioenergy solutions and waste management processes. Ultimately, this approach facilitates a critical shift towards a circular bioeconomy, thereby establishing a pathway to achieve the net zero target
Aktivirani ugljenični cvetovi dopirani azotom u vodenim superkondenzatorima
No full textU ovom radu su ispitana kapacitivna svojstva hijerarhijskih poroznih ugljeničnih materijala u obliku
cvetova, koji su nastali optimizivanom termičkom obradom sintetisanih čestica poliakrilonitril (PAN)
polimera. Rezultati pokazuju da materijali zadržavaju svoj originalni morfološki oblik nakon
karbonizacije i aktivacije, uz visoku specifičnu površinu i sadržaj azotnih funkcionalnih grupa.
Zahvaljujući ovim svojstvima, materijali poseduju visoku specifičnu kapacitivnost do 100 F g–1 u 6 M
vodenom rastvoju kalijum hidroksida, kao i sposobnost brzog prenosa jona kroz poroznu strukturu.
Interakcije azotnih grupa sa jonima vodenih elektrolita dodatno doprinose Faradejskim redoks
procesima, čime se poboljšava kapacitivno ponašanje, odnosno povećava se gustina energije. Ovi
materijali koriste ekološki prihvatljive i bezbedne vodene elektrolite, čime se unapređuje njihova
održivost i praktičnost za primenu u savremenim superkondenzatorima. Dobijeni rezultati ukazuju na
potencijal ovih materijala za primenu u uređajima za skladištenje energije sa visokim performansama
Contribution to the study of toughness in creep resistant steel welded joint
No full textSteel P91 is widely used in power stations due to its good creep resistance and predictable performance. The aim of this work was to compare the toughness values of different zones in the weld joint with a sample subjected to a simulated thermal cycle. The workpieces were welded using Gas Tungsten Arc Welding (GTAW) for the root pass and Manual Metal Arc (MMA) for the filler deposition. Post Welding Heat Treatment (PWHT) was carried out at 740 °C for 2 hours. The welded joint was tested for microstructure, macrostructure, hardness, strength and toughness. The macrostructure showed all typical zones with a tempered martensite microstructure. The difference in the carbide distribution, which were confirmed by the hardness measurements, are the result of variations in the chemical composition. The tensile strength and the fracture which occurred in the base metal, indicate good properties of the welded joint. The crack initiation energies determined were similar in the Base Metal (BM), Heat-Affected Zone (HAZ), and Weld Metal (WM), while the crack propagation energy was lowest in the WM. This indicates that carbides control the crack initiation energy, while their distribution influences the crack propagation. The simulated HAZ samples showed lower toughness compared to the welded specimens, which can be attributed to the differences in the performed thermal cycles. During welding, the HAZ undergoes several thermal cycles in each pass, resulting in smaller austenitic grains compared to the simulated HAZ. Lower values of toughness indicate that the simulation provides a conservative approach, i.e. the measured toughness is lower than the toughness in a real welded butt
Antimicrobial peptides (AMP)-producing Bacillus spp. for the management of Fusarium infection and alfalfa growth promotion
No full textAlfalfa is the most extensively cultivated forage legume worldwide. Its yield and quality may be affected by various pests and pathogens. Among them, fungal pathogen Fusarium oxysporum, the causal agent of Fusarium wilt, is considered as the main threat. The aim of the present study was to investigate the potential of the Bacillus spp. isolated from alfalfa rhizosphere to be used as biocontrol agents against F. oxysporum, as well as plant-growth promoting agents. RESULTS: A total of six isolates were identified as B. halotolerans LA1K3 and LA1NK3, B. toyonensis LA1K2, B. thuringiensis LA1K4, B. megaterium LA2K1, and B. safensis LA1NK1. Suppression of F. oxysporum was recorded in a range from 2.86% (LA2K1) to 31.43% (LA1NK3), except for LA1K2. The presence of antimicrobial peptide biosynthetic genes was detected: bacyllomicin and fengycin (LA1NK1); subtilin and fengycin (LA1K2); subtilin (LA1K4 and LA2K1), and bacyllomicin (LA1NK3 and LA1K3) by PCR method. Bacillus halotolerans LA1NK3 showed six PGP traits (production of indole-3-acetic acid, siderophores, HCN, protease, cellulase and amylase). Bacterial inoculation increased the germination percentage of infected seeds from 42.85% (LA2K1) to 85.71% (LA1NK1, LA1NK3), as well as the yield of infected alfalfa plants of 186.07% (LANK1), compared to the infected control. CONCLUSION: The results of this study highlight the potential of rhizosphere soil to harbor beneficial bacterial strains that could be exploited for disease control and plant growth promoting. Bacillus safensis LANK1 stood out as the most effective strain in promoting the growth of alfalfa infected by F. oxysporum under controlled conditions
Comparative Study of Natamycin Encapsulation in Liposomes: Thin-Film vs. Proliposome Methods for Enhanced Stability, Controlled Release, and Efficacy Against Milk Spoilage and Pathogenic Microorganisms
No full textThe aim of this study was to evaluate liposomal particles as a potential delivery system for natamycin, a widely known antimicrobial agent used in the food industry. The goal was to prolong its diffusion into the surrounding medium. Natamycin-loaded liposomes were prepared using two methods (proliposome and thin-film) and two different phospholipid mixtures. The characterization of natamycin-loaded liposomes was performed in terms of their chemical composition (FT-IR analysis), encapsulation efficiency (EE), and antimicrobial potential against spoilage and pathogenic microorganisms that can be found in milk and milk products. During the 60-day storage period, their size, polydispersity index (PDI), and zeta potential were measured. The in vitro release kinetics of natamycin from liposomes were also assessed, and the results showed a significantly lower release rate of the drug when it was encapsulated. EE showed a high level of natamycin encapsulation (>80%), which was confirmed with FT-IR analysis. The stability study indicated that these systems were stable over a 60-day storage period, as the zeta potential of all formulations was ~−25 mV. Satisfactory antimicrobial performance of the developed liposomes against Listeria monocytogenes, Yersinia enterocolitica, Candida tropicalis, Candida parapsilosis, and Aspergillus flavus (MIC values from 0.00625 to 4 mg/mL) indicates that loading of natamycin into liposomal carriers was an adequate method for their encapsulation and delivery in the milk industry
Fly Ash-Based Geopolymers Modified with Chitosan and Polyvinyl Alcohol for Dye Adsorption from Water
No full textObjective: In this work, fly ash was utilized as a precursor for the production of geopolymeric adsorbents for the removal of organic dyes from water. To achieve efficient removal of organic dyes from contaminated water, fly ash is subjected to alkaline activation, resulting in the formation of a geopolymer matrix. Subsequently, the geopolymer surface is functionalized via coating with chitosan and polyvinyl alcohol (PVA), thereby enhancing the surface functionality and adsorption affinity of the material towards organic dye molecules. This functionalization strategy enables improved interaction between the geopolymer adsorbent and target contaminants, optimizing its application in wastewater treatment processes. Moreover, this approach synergistically integrates industrial waste management with environmental remediation by exploiting the intrinsic physicochemical and structural properties of geopolymers derived from fly ash
Supercritical CO2-assisted infiltration of MAPbBr3 into TiO2 nanotubes for enhanced optoelectronic performance of perovskite photodiodes
No full textOrgano-inorganic perovskites have significantly advanced photovoltaic research due to their high absorption coefficients, tunable band gaps, and low-cost solution-based fabrication methods [1]. Among them, methylammonium lead bromide (MAPbBr3) has shown considerable potential in optoelectronic applications. However, achieving uniform and well-infiltrated films in nanostructured architectures remains challenging with conventional deposition techniques [2]. This study aims to enhance the interfacial area between perovskite and TiO2 by infiltrating MAPbBr3 into TiO2 nanotubes, thereby improving electron transport. Supercritical carbon dioxide (sCO2) has emerged as a promising co-solvent for low-temperature perovskite deposition due to its liquid-like density, gas-like viscosity, zero surface tension, and excellent mass transport properties [3]. In this work, MAPbBr3 was deposited from a dimethylformamide (DMF) solution onto TiO2 nanotube arrays obtained by Ti foil anodization, using sCO2-assisted infiltration at pressures of 100 and 200 bar, temperatures of 35 °C and 50 °C, and an exposure time of 1 hour. The TiO2 nanotubes, with diameters of approximately 103 ± 17 nm and lengths of ~350 nm, function as efficient one-dimensional electron transport layer, facilitating charge separation and reducing recombination [4]. Field emission scanning electron microscopy (FESEM) revealed significantly improved perovskite infiltration when deposition was assisted by sCO2. X-ray diffraction (XRD) analysis confirmed the crystalline structure of MAPbBr3, consistent with literature reports [5]. Diffuse reflectance spectroscopy of prepared TiO2 nanotubes/MAPbBr3 photodiodes showed a red shift in the absorption edge, indicating enhanced visible light absorption. Under visible light, current–voltage (I–V) measurements revealed hysteretic photodiode characteristics, with the sample prepared at 200 bar and 50 °C exhibiting the highest photocurrent, reaching up to 600 μA. These results highlight the potential of sCO2-assisted deposition as an effective strategy for improving interfacial contact and charge transport in perovskite-based photodiodes
Validation of a multi-residue GC-MS/MS method for the determination of 120 pesticide residues in herbal tea
No full textObjective
Herbal teas are popular for their perceived health benefits. However, due to intensive agricultural
practices, they may contain harmful substances such as pesticide residues. Their complex
composition and strong pigmentation pose analytical challenges [1]. This study aimed to validate
a multi-residue GC-MS/MS method for the determination of 120 pesticides in dried herbal tea
samples and to apply it to commercial samples
BioMEMS-based biosensors
No full textMany modern problems in different areas can be solved by using microelectromechanical systems (MEMS) technology, which enables different devices to be miniaturized and integrated into electrical circuits. Benefits from miniaturization include, but are not limited to, lower cost of production, portable applications, lower power and sample consumption, increased sensitivity, etc. Nowadays, the interest in bio-microelectromechanical systems (BioMEMS) has drastically increased in many areas especially for biological and medical applications. BioMEMS may be applied as biosensors, drug delivery systems, diagnostic tools, therapeutics and tissue engineering devices, lab-on-a-chip systems, and many more. However, contrary to their wide and impressive investigations and applications lies the lack of their concise and systematic classification and summarization. This is not surprising having in mind the rapid development and multidisciplinary nature of this field. Therefore, the key goal of this review is to help researchers and scientists from different fields by introducing and instructing them on the main principles and problems related to this topic. With that aim, this chapter first gives a brief introduction to the BioMEMS topic along with a comprehensive overview of their classification according to different parameters. It is followed by a thorough description of technologies and materials for BioMEMS production. Finally, the main areas of biomedical applications are systematically presented along with appropriate examples. Although a full review of all BioMEMS applications is far beyond the scope of this chapter, as it is too extensive area to be accomplished even in a whole book, the main references for further reading are presented