Characterization of paper mill sludge as a renewable feedstock for sustainable hydrogen and biofuels production

Paper and pulp mills generate substantial quantities of cellulose-rich sludge materials that are disposed in landfills at a large scale. For sustainability purposes, sludge materials can be bioprocessed to produce renewable fuels and useful chemicals. The enzymatic hydrolysis of cellulose is the process bottleneck that affects the conversion economics directly by using zero-cost raw materials. In order to study and optimize the process, the characteristics of the sludge raw materials should be first evaluated. In this work, sludge samples were obtained from paper mills located at different locations in Wisconsin and Minnesota. Part of the sludge samples was washed (de-ashed) with hydrochloric acid while the other part remained unwashed. The samples were subjected to multiple spectroscopic analyses techniques to evaluate the morphological properties of cellulose fibers and to estimate the total structural carbohydrate content. The results showed that the de-ashing process changed some fiber characteristics and cellulose crystallinity structure in all sludge samples. Sludge sample A (obtained from Kraft pulp and recycled paper mill region) showed a high percentage of fiber, with crystalline cellulose, compared to the other two sludge samples suggesting that sludge A is a valuable source to make value-added products. Aspen Plus mass and energy calculations performed in view of the ‘zero’ cost and the reliable supply of sludge raw materials producing 2 mol H₂/mol glucose. Moreover, the results showed that extracting crystalline cellulose from these sludge samples is more profitable than crystalline cellulose made from the other lignocellulosic feedstocks. The results reported here showed that the utilization of these sludge materials would be an economically attractive and promising alternative for the production of hydrogen.     

Techno-economic analysis and a novel assessment technique of paper mill sludge conversion to bioethanol toward sustainable energy production

A novel bioprocess design to convert paper mill sludge (PMS) to biofuels is proposed in this work. The design utilizes cellulosic fiber recovered from the PMS via optimized de-ashing (HCl washing) step. This work specifically provided a technical and economic analysis of paper mill sludge conversion into biofuel production using a novel protocol. The protocol is based on scanning electron microscopy (SEM) analysis to assess the quality of the contained cellulose prior to further processing. The results are crucially important to determine the suitability of the PMS feedstock to produce biofuels. SEM analysis was employed as a preliminary screening tool to evaluate sludge digestibility and conversion. The SEM characterization technique established a direct relationship between the fiber morphology, presence of crystals salts and sugar yield after enzymatic hydrolysis. Substantial structural changes were observed before and after de-ashing the sludge samples, leading to a correlation between the surface morphology and the washing step. The results suggested that de-ashing changes the surface morphology and upon analysis, increased the sugar yield up to about 86% as opposed to 2.2% in sludge sample A as an example. The PMS conversion into biofuel was simulated using Aspen PLUS and compared to a similar process using corn stover as feedstock. The simulation results showed it is 20% cheaper to produce bioethanol from PMS compared to corn stover. The simulation revealed less energy demand by around 13 320 MJ/h compared to that when corn stover was used.     

Discrete and Polymeric Lead(II) Complexes Containing 4-Methyl-1,2,4-triazole-3-thiol Ligand: X-ray Studies,Spectroscopic Characterization,and Thermal Analyses

[Pb(Hmptrz)₄(NO₃)₂] complex (1) and [Pb(μ-mptrz)₂(H₂O)]_n complex (2) (Hmptrz is 4-methyl-1,2,4-triazole-3-thiol) were prepared from the reaction of 4-methyl-1,2,4-triazole-3-thiol with Pb(NO₃)₂ and Pb(OAc)₂·3H₂O in CH₃OH/H₂O, respectively. Both complexes were characterized by elemental analysis, IR, UV–Vis, ¹H NMR, ¹³C{¹H}NMR, and luminescence spectroscopy and their structures were studied by single-crystal X-ray crystallography. The thermal stabilities of the title complexes were studied by thermogravimetric and differential thermal analyses. Complex 1 is a discrete and complex 2 is a polymer; both structures are without precedent in the literature.     

Sailfish Optimizer with EfficientNet Model for Apple Leaf Disease Detection

Recent developments in digital cameras and electronic gadgets coupled with Machine Learning (ML) and Deep Learning (DL)-based automated apple leaf disease detection models are commonly employed as reasonable alternatives to traditional visual inspection models. In this background, the current paper devises an Effective Sailfish Optimizer with EfficientNet-based Apple Leaf disease detection (ESFO-EALD) model. The goal of the proposed ESFO-EALD technique is to identify the occurrence of plant leaf diseases automatically. In this scenario, Median Filtering (MF) approach is utilized to boost the quality of apple plant leaf images. Moreover, SFO with Kapur's entropy-based segmentation technique is also utilized for the identification of the affected plant region from test image. Furthermore, Adam optimizer with EfficientNet-based feature extraction and Spiking Neural Network (SNN)-based classification are employed to detect and classify the apple plant leaf images. A wide range of simulations was conducted to ensure the effective outcomes of ESFO-EALD technique on benchmark dataset. The results reported the supremacy of the proposed ESFO-EALD approach than the existing approaches.     

Engineering Aptamer Switches for Multifunctional Stimulus-Responsive Nanosystems

Although RNA and DNA are best known for their capacity to encode biological information, it has become increasingly clear over the past few decades that these biomolecules are also capable of performing other complex functions, such as molecular recognition (e.g., aptamers) and catalysis (e.g., ribozymes). Building on these foundations, researchers have begun to exploit the predictable base-pairing properties of RNA and DNA in order to utilize nucleic acids as functional materials that can undergo a molecular “switching” process, performing complex functions such as signaling or controlled payload release in response to external stimuli including light, pH, ligand-binding and other microenvironmental cues. Although this field is still in its infancy, these efforts offer exciting potential for the development of biologically based “smart materials”. Herein, ongoing progress in the use of nucleic acids as an externally controllable switching material is reviewed. The diverse range of mechanisms that can trigger a stimulus response, and strategies for engineering those functionalities into nucleic acid materials are explored. Finally, recent progress is discussed in incorporating aptamer switches into more complex synthetic nucleic acid-based nanostructures and functionalized smart materials.     

Synthesis and Characterization of Water-Based Epoxy-Acrylate/Graphene Oxide Decorated with Fe3O4 Nanoparticles Coatings and Its Enhanced Anticorrosion Properties

ABSTRACT

In this article, water-based epoxy–acrylate (EP/AC) emulsion coatings and its nanocomposites with Fe₃O₄ nanoparticles, graphene oxide nanosheets and graphene oxide which was decorated with Fe₃O₄ nanoparticles were synthesized. This was executed by means of a pre-emulsion seeded semi-batch emulsion polymerization handle with a blend of conventional anionic surfactant (Polyalkylene glycol ether sulfate, ammonium salt-EXOSEL 20 S) and typical nonionic type emulsifier (Octylphenol polyoxyethylene ether OP-10) for emulsion polymerization (schematic 1). Prepared nanoparticles were investigated with different analyzing methods like FT-IR, XRD, SEM-EDAX and TGA. The impact of the distinctive nanostructures in an (EP/AC) resin, on coated steel panels with the features of corrosion conservation, was investigated by the test of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Morphology of surface and thermal behavior of nanocomposite tests were executed using surface filtering electron microscopy (FE-SEM) and thermal gravimetric analysis (TGA). Different analyses resulted from nanostructures and nanocomposites approved very good dispersion of fillers in nanocomposite beads. Besides, they indicate the effective role of nanoparticles especially graphene oxide which was decorated with Fe₃O₄ nanoparticles in corrosion resistance of water-based EP/AC coatings and other properties of coated instances.     

Multivariate Optimization and Adsorption Characterization of As(III) by Using Fraxinus Tree Leaves

This study introduces Fraxinus tree leaves as a new, efficient biosorbent of As(III). A suitable response surface was achieved by running a central composite design. Simultaneous optimization of both responses (R% and q) was carried out and 67% of the goal of desirability function was attained. The results obtained for simultaneous optimization are R = 70% and q = 80.6 mg g^?1 with 67% desirability in m = 600 mg L^?1 where s = 0.10 g and pH = 3.9. Langmuir and Freundlich isotherms model were applied in explaining the sorbent–sorbate equilibrium study, and maximum capacity uptake equals 99.97 mg g^?1 and K_L = 0.05 L mg^?1 has been obtained. Fourier Transfer Infra-Red (FT-IR) and kinetic results were considered to examine the functional groups involved and the adsorption mechanism.     

Effect of location on virgin olive oils of the two main Tunisian olive cultivars

The olive oil content in phenolic compounds depends on the variety of the fruit used for its extraction as well as on the predominant climate conditions in the tree cultivation area. Here, we report on the characterization of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivars Chemlali and Chétoui, grown in three different Tunisian locations, Zaghouan (North), Sousse (Center) and Sfax (South). Chétoui olive oil samples obtained from fruits of olive trees cultivated in Zaghouan and Chemlali olive oil samples obtained from fruits of olive trees cultivated in Sousse were found to have a higher mean total phenol content (1004 and 330 mg/kg, respectively). Olive oil samples obtained from fruits of both cultivars had different phenolic profiles and a higher content in 3,4‐DHPEA‐EDA when the olive trees were cultivated in Zaghouan. Both olive cultivars were found to have different responses to environmental conditions. Chétoui olive oil showed decreased oxidative stability when the fruits were obtained from olive trees cultivated in the center of Tunisia (34.8 h) and in Sfax (16.17 h). Furthermore, statistical data showed that the phenolic composition and oxidative stability of Chétoui olive oil varied more by location than those of Chemlali olive oils.