Boosting Portland cement-free composite performance via alkali-activation and reinforcement with pre-treated functionalised wheat straw

Utilising wheat straw reinforced OPC-free composites in the construction industry requires efficient, eco-friendly pre-treatment coupled with surface functionalisation methods to turn it into a high-performance material. Herein, alkali-activated material (AAM) was used as an OPC-free matrix, while eco-friendly hybrid pre-treatment and surface functionalisations were applied to mitigate the surface quality deficiencies of wheat straw and improve its compatibility with low-carbon binders. Wheat straw particles were subjected to a mild physical pre-treatment (hot-water followed by steam) and surface functionalisation using attapulgite nanoclay and graphene nanoplatelets to improve their capacity as an effective reinforcing material in AAM. Comprehensive characterisation verified successful pre-treatment and surface functionalisation, which led to the improved interfacial bond between wheat straw and AAM. The best results were obtained for the AAM samples reinforced with pre-treated straw that was functionalised with attapulgite nanoclay (i.e., H+S-AT), in which the volume of permeable voids decreased by 18%, while compressive and flexural strength at 90 d increased by 41% and 27%, respectively, compared to the control sample. However, the effect on the thermal properties of the resulted composites was not significant.This work was funded as part of the HP-CSB project, which has received funding from the Engineering and Physical Sciences Research Council with the following reference: EP/S026487/1. The authors acknowledge Nanesa S.r.l for graphene material supply and Dr. C. Lehmann from TU Berlin for SEM assessments

Enhancing the Fresh and Early Age Performances of Portland Cement Pastes via Sol-Gel Silica Coating of Metal Oxides (Bi2O3 and Gd2O3)

Data Availability Statement: The datasets generated and/or analyzed during this study are available from the corresponding author upon reasonable request.Copyright © 2023 by the authors. Incorporating metal oxide nanoparticles into cement-based composites delays the hydration process and strength gain of cementitious composites. This study presents an approach toward improving the performance of bismuth oxide (Bi2O3) and gadolinium oxide (Gd2O3) particles in cementitious systems by synthesizing core–shell structures via a sol-gel process. Two types of silica coatings on cementitious pastes with 5% and 10% substitution levels were proposed. The rheology, hydration, and mechanical properties of the pastes were analyzed to determine the relationship between the coating type and nanoparticle concentration. The results indicate that despite the significant disparities in the performance of the resulting material, both methods are appropriate for cement technology applications. Bi2O3’s silica coatings accelerate the hydration process, leading to early strength development in the cement paste. However, due to the coarse particle size of Gd2O3, silica coatings exhibited negligible effects on the early age characteristics of cement pastes.National Science Centre, Poland (project no. 2020/39/D/ST8/00975 (SONATA-16))

Filled carbon nanotubes as anode materials for lithium-ion batteries

Downsizing well-established materials to the nanoscale is a key route to novel functionalities, in particular if different functionalities are merged in hybrid nanomaterials. Hybrid carbon-based hierarchical nanostructures are particularly promising for electrochemical energy storage since they combine benefits of nanosize effects, enhanced electrical conductivity and integrity of bulk materials. We show that endohedral multiwalled carbon nanotubes (CNT) encapsulating high-capacity (here: conversion and alloying) electrode materials have a high potential for use in anode materials for lithium-ion batteries (LIB). There are two essential characteristics of filled CNT relevant for application in electrochemical energy storage: (1) rigid hollow cavities of the CNT provide upper limits for nanoparticles in their inner cavities which are both separated from the fillings of other CNT and protected against degradation. In particular, the CNT shells resist strong volume changes of encapsulates in response to electrochemical cycling, which in conventional conversion and alloying materials hinders application in energy storage devices. (2) Carbon mantles ensure electrical contact to the active material as they are unaffected by potential cracks of the encapsulate and form a stable conductive network in the electrode compound. Our studies confirm that encapsulates are electrochemically active and can achieve full theoretical reversible capacity. The results imply that encapsulating nanostructures inside CNT can provide a route to new high-performance nanocomposite anode materials for LIB

Functional Bi2O3/Gd2O3 Silica-Coated Structures for Improvement of Early Age and Radiation Shielding Performance of Cement Pastes

Data Availability Statement: The datasets generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.Copyright © 2024 by the authors. This study presents a new approach towards the production of sol-gel silica-coated Bi2O3/Gd2O3 cement additives towards the improvement of early mechanical performance and radiation attenuation. Two types of silica coatings, which varied in synthesis method and morphology, were used to coat Bi2O3/Gd2O3 structures and evaluated as a cement filler in Portland cement pastes. Isothermal calorimetry studies and early strength evaluations confirmed that both proposed coating types can overcome retarded cement hydration process, attributed to Bi2O3 presence, resulting in improved one day compressive strength by 300% and 251% (depending on coating method) when compared to paste containing pristine Bi2O3 and Gd2O3 particles. Moreover, depending on the type of chosen coating type, various rheological performances of cement pastes can be achieved. Thanks to the proposed combination of materials, both gamma-rays and slow neutron attenuation in cement pastes can be simultaneously improved. The introduction of silica coating resulted in an increment of the gamma-ray and neutron shielding thanks to the increased probability of radiation interaction. Along with the positive early age effects of the synthesized structures, the 28 day mechanical performance of cement pastes was not suppressed, and was found to be comparable to that of the control specimen. As an outcome, silica-coated structures can be successfully used in radiation-shielding cement-based composites, e.g. with demanding early age performances.National Science Centre of Poland within Project no. 2020/39/D/ST8/00975 (SONATA-16)

Removal of Ni²⁺ from Aqueous Solutions by Adsorption Onto Magnetic Multiwalled Carbon Nanotube Nanocomposite

The removal of Ni2+ from aqueous solution by magnetic multiwalled carbon nanotube nanocomposite (MMWCNTs-C) was investigated. MMWCNTs-C was characterized by X-ray Diffraction method (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), surface area (BET), and Fourier Transform-Infrared Spectroscopy (FTIR). The effects of initial concentration, contact time, solution pH, and temperature on the Ni2+ adsorption onto MMWCNTs-C were studied. The Langmuir and Freundlich isotherm models were applied to fit the adsorption data. The results showed that the adsorption isotherm data were fitted well to the Langmuir isotherm model with the maximum monolayer adsorption capacity of 2.11 mg g–1. The adsorption kinetics was best described by the pseudo-second-order model. The thermodynamic parameters, such as ΔHo, ΔGo and ΔSo, were also determined and evaluated. The adsorption of Ni2+ is generally spontaneous and thermodynamically favorable. The values of ΔHo and ΔGo indicate that the adsorption of Ni2+ onto MMWCNTs-C was a physisorption process

Equilibrium and kinetics studies for the adsorption of Ni2+ and Fe3+ ions from aqueous solution by graphene oxide

In this study, the adsorption of Ni2+  and Fe3+  metal ions from aqueous solutions onto graphene oxide (GO) have been explored. The effects of various experimental factors such as pH of the solution, initial metal ion concentration and temperature were evaluated. The kinetic, equilibrium and thermodynamic studies were also investigated. The adsorption rate data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model. Kinetic studies indicate that the adsorption of both ions follows the pseudo-second-order kinetics. The isotherms of adsorption data were analyzed by adsorption isotherm models such as Langmuir and Freundlich. Equilibrium data fitted well with the Langmuir model. The maximum adsorption capacities of Ni2+  and Fe3+  onto GO were 35.6 and 27.3 mg g-1 , respectively. In addition, various thermodynamic parameters, such as enthalpy (ΔHO), entropy (ΔSO) and Gibbs free energy (ΔGO), were calculated

Reduced graphene oxide and inorganic nanoparticles composites – synthesis and characterization

Graphene – novel 2D material, which possesses variety of fascinating properties, can be considered as a convenient support material for the nanoparticles. In this work various methods of synthesis of reduced graphene oxide with metal or metal oxide nanoparticles will be presented. The hydrothermal approach for deposition of platinum, palladium and zirconium dioxide nanoparticles in ethylene glycol/water solution was applied. Here, platinum/reduced graphene oxide (Pt/RGO), palladium/reduced graphene oxide (Pd/RGO) and zirconium dioxide/reduced graphene oxide (ZrO2/RGO) nanocomposites were prepared. Additionally, manganese dioxide/reduced graphene oxide nanocomposite (MnO2/RGO) was synthesized in an oleic-water interface. The obtained nanocomposites were investigated by transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), Raman spectroscopy and thermogravimetric analysis (TGA). The results shows that GO can be successfully used as a template for direct synthesis of metal or metal oxide nanoparticles on its surface with a homogenous distribution

PANI/NaTaO3 composite photocatalyst for enhanced hydrogen generation under UV light irradiation

A PANI/NaTaO3  composite was successfully synthesized by an oxidative polymerization of aniline monomer in hydrochloric acid solution containing sodium tantalate. NaTaO3  at a monoclinic structure was produced via hydrothermal method. The photocatalytic activities of the unmodified NaTaO3  and PANI/NaTaO3  were evaluated for hydrogen generation from an aqueous HCOOH solution and under UV light irradiation. The results showed that the evolution rate of H2  increased significantly when NaTaO3  was modified with PANI. The enhancement of the photocatalytic activity of PANI/NaTaO3  composite was ascribed to the effective charge transfer and separation between NaTaO3  and PANI, which reduced their recombination. This indicates that PANI modification of tantalate photocatalysts may open up a new way to prepare highly efficient catalytic materials for H2  generation

Development of graphene-based biosensor for medical diagnostics

The explosion of information provided by the “-omics,” (genomics, proteomics, etc.) has resulted in a pressing need to develop matching diagnostic technologies, so-called biosensors. Rapid, sensitive, selective, and cost-effective analysis of different biomolecules and microorganisms is crucial in clinical diagnosis and efficient treatment of patients. Further, there is a growing demand for decentralized laboratory methodologies that can be implemented in doctor’s office, emergency room or in the field for the analysis of such analytes as DNA, RNA, proteins, antibodies, bacteria, viruses, small compounds etc. Lab-on-a-chip platforms and miniaturized point-of-care devices based on biosensors fulfill these demands and are foreseen to revolutionize the future of medical diagnostics. Because of excellent electric and optical properties, graphene has recently found to be highly attractive in biosensing applications and may thrust new possibilities into the field of miniaturized medical diagnostic devices. The main objective of this project is to develop a multifunctional grapheme biosensor for effective electrochemical detection of specific DNA microbial targets in biological samples. Novel nanocomposites consisting of chitosan and nanoparticle-modified graphene will be combined with locked nucleic acid molecular beacons with the goal of producing “ink” for ultrasonic non-contact printing of electrical circuits. The developed technology will allow fabrication of low cost, highly sensitive biosensors for point-of-care diagnosis

High-performance polylactic acid compressed strawboard using pre-treated and functionalised wheat straw

The authors acknowledge Nanesa S.r.l for graphene material supply.Copyright © 2022 The Authors. An eco-friendly pre-treatment coupled with surface functionalisation were developed to enhance the quality of wheat straw particles to be used for development of high-performance polylactic acid (PLA) compressed strawboard. Eco-friendly hybrid pre-treatment (i.e., hot water followed by steam, H+S) and surface functionalisation processes employing attapulgite nanoclay (AT) and graphene nanoplatelets (G) were used to obtain an appropriate wheat straw surface quality while increasing its compatibility with the PLA matrix. The successful pre-treatment and surface functionalisation of wheat straw particles was verified through characterisation techniques, including SEM, FTIR, XRD, Raman spectroscopy, and TGA. Tensile strength and water absorption properties of compressed strawboards were examined to investigate the influence of pre-treatment and surface functionalisation of wheat straws. The maximum tensile strengths of 28 MPa and 27 MPa were recorded for 10 H+S-AT and 10 H+S-G samples, respectively, which are considerably higher than the value (i.e., 9.7 MPa) registered for the sample without pre-treatment and surface functionalisation (i.e., 10UN). The lowest water absorption after 24 h of immersion was registered for 10UN-G (i.e., 1.6%), which is 11% and 31% lower than the 10UN and 10 H+S samples, respectively. The effect is attributed to an improved interfacial bond between wheat straw and PLA matrix due to the graphene surface functionalisation, as evidenced by the SEM.Engineering and Physical Sciences Research Council with the following reference: EP/S026487/1