Enthalpy Research Articles

Thermodynamics property and structure evolution of the TiO2-containing molten slag with different CaO/SiO2 ratio and TiO2 content

The influences of temperature and compositions (TiO2 and CaO/SiO2) on thermodynamics properties and structural evolutions of TiO2-CaO-Al2O3-MgO-SiO2 slags were investigated in this work. The slag viscosities increased with decreasing the temperature and declined with adding TiO2. With the raising of CaO/SiO2 ratio, the viscosity decreased under high temperatures, while it increased with the temperature further decreased lower than 1420 °C. The enthalpy change of the slag increased with raising the temperature as well as the TiO2 content and reduced with the CaO/SiO2 ratio increasing. Both the liquidus temperature and break point temperature of the slags decreased with adding TiO2 and increased with raising the CaO/SiO2 ratio. Temperature had a significant effect on slag structure evolutions, which decreased the slag polymerization degree. With adding TiO2 and CaO/SiO2 ratio in slags, the slag structure stability was weakened by increasing the amount of simpler silicate and TiO6 units and reducing the proportion of complex Ti-O units. Both the temperature and compositions (TiO2 and CaO/SiO2) depolymerized the slag structure to decline the viscosity.

Hexavalent chromium scavenging performances of one-pot synthesized hydrous cerium-copper-mixed oxide from contaminated water with plausible mechanism

ABSTRACT Prolonged use of the chromate [Cr(VI)]-contaminated water originates severe health problems for the public. Thus, the societal urgency is a reusable and cost-effective material for efficient scavenging of Cr(VI) from contaminated industrial wastewater. Aiming this, we had targeted to prepare some cheap and effective materials for scavenging Cr(VI) from the contaminated water. Herein, we report the preparation of hydrous cerium-copper oxide (HCCO) with some tailored compositions and employed toward the abstraction of chromate from water solution. The HCCO (Ce: Cu = 1:4, mole/mole) has shown the highest Cr(VI) scavenging capacity. Experimentally, highest Cr(VI) abstraction efficiency is recorded at pH ~ 3.0 (508.853 mg. g−1 at 303 K). Kinetically, the Cr(VI) scavenging reaction with HCCO surfaces agrees better with the pseudo second-order model (R2 = 0.987) equation and the equilibrium Cr(VI) distribution data explain the Freundlich isotherm model (R2 = 0.998) equation, which anticipates the multi-layered adsorption on heterogeneous sites of the adsorbent. A negative value of the Gibbs free energy change indicates that the Cr(VI) adsorption over HCCO surfaces is spontaneous. The positive enthalpy change indicates the endothermic nature of the said reaction.

A separation column for liquid mixture based on phase transform: Experiment and simulation

The concentric internally heat-integrated distillation column (HIDiC) has advantages of low energy consumption and high thermodynamic efficiency. However, its drawbacks of limited heat transfer area, complex internal structure, and large number of control parameters hinder its widespread industrial applications. To solve these challenges, in this work a novel sleeve-like concentric heat integrated separation column, namely temperature-controlled phase change column (TCPC), was developed to separate liquid mixtures in a more effective and energy-saving way with reflux section being moved and trays being replaced with spiral corrugation blades. The comprehensive performances of TCPC in ethanol–water system was firstly evaluated by experiments. The results showed that TCPC performs well in ethanol/water separation due to the internal spiral corrugation significantly reducing the vapor–liquid contact in separation section. Meanwhile, compared to the concentric HIDiC, TCPC has a higher total heat transfer coefficient due to the larger heat transfer area. Computational fluid dynamics simulation reveals the internal design of TCPC inducing secondary vortices of the vapor, enhancing condensation heat transfer and separation efficiency. Further, increasing mass flow rate within a certain range would enhance the comprehensive performance factor and lead to more effective separation.

Thermal analysis of cooling plate motor jacket and radiator for managing an electric bike energy storage system

The performance of electric bikes has increased with their increased use commercially and it has led to a corresponding increase in the charge and discharge rates for the batteries, and associated battery temperatures. Unfortunately, the cooling mechanisms for these electric bikes have not been able to keep up, with most organizations not implementing any cooling aside from passive ambient air cooling. This has led to a general decrease in battery life and charge capacity for these electric bikes. The proposed research has focused on the development of a novel electric bike cooling system under the practical industrial and environmental framework. It is cheap, effective, and simple to manufacture. Contemporary papers related to the topic have been studied, and the most feasible have been shortlisted to 4 distinct cooling plate designs, 3 Radiator Designs and 5 motor cooling jacket designs, which have been modeled in CAD software and then analyzed through use of CFD software. For the cooling plate design 1 had the lowest cooling capability, design 2 showed a 53.3% increase in total heat transfer from plate to coolant, design 3 showed a 107.52% increase, and design 4 showed a 183.03% increase relative to design 1. For the radiator, design number 2 has been recommended due to optimal cooling and temperature drop of coolant, within the dimensional and space constraints on the electric bike. For the motor cooling jacket, design number 5 was deemed to be the most feasible due to the high heat extraction from motor and good temperature uniformity of contact surface. Their respective advantages and disadvantages are discussed, and the most effective one of them all has been proposed for use. Further potential improvements to its design have also been recommended along with Thermoelectric Generator (TEG) integration for harvesting waste heat to produce energy.

Optimization design analysis on sodium chloride solution evaporative crystallization system driven by high-temperature heat pump

Industrial crystallization is an essential procedure for food, chemistry, and seawater desalination, whereas it accompanies with considerable energy consumption. Although the mechanical vapor recompression serves as an effective tool for heat recovery, it cannot adapt to the lower evaporation temperatures of crystallization process (45–90 °C). To address the above issues, this paper proposed a composited system consisting of high-temperature heat pump and draft tube baffle evaporative crystallizer, which can achieve higher energy efficiency. The coupling mathematical model is solved through the Newton iterative method. The optimized input parameter is determined based on thermal analysis, and the coefficient of performance can reach 5.85. Moreover, the system employs R1234ze as the working medium, achieving the minimum total heat exchange area of 19.27 m2. Simultaneously, this system with different evaporation capacities exhibit similar cycle rates, approximately 58.3. After the system is constructed, the energy-saving and economic evaluation is performed. The result indicates that the system demonstrates an annual carbon dioxide emission reduction about 550 tons, an annual cost reduction of 221,718 CNY, and a dynamic payback period of only 0.89 years, presenting significant economic advantages. By this study, it provides some theoretical guidance for practical engineering applications.

An Evaluation of the Fire Safety of Waste Paper-Based Internal Finishing Materials Combined with Expandable Graphite According to Changes in Magnesium Hydroxide Content

Inflammable building finishing materials act as a major cause of fire propagation, and they, therefore, pose significant risks to life and can lead to property damage. To replace such flammable building finishing materials, many countries have established regulations limiting their use, which has led to extensive research on the development of flame-retardant building finishing materials. Such methods have included adding flame retardants to construction materials to reduce the heat release rate and total heat release. The present study aimed to enhance the fire performance of cellulose-based architectural finishing materials by creating a dual flame-retardant mixture using expandable graphite and magnesium hydroxide added to recycled paper waste. Specimen fabrication involves using a pressing method to apply uniform pressure to compress the mixture in a mold. The total heat release (THR), CO, and CO2 production of the produced specimens were measured using a cone calorimeter while varying the magnesium hydroxide additive ratio. The combustion gases were measured through NES 713 experiments to determine any changes in the Toxic Index corresponding to variations in the magnesium hydroxide content. The experiment results established a correlation between the magnesium hydroxide additive ratio and the total heat release, as well as the existence of variations in CO and CO2 production for the dual flame-retardant recycled paper material. A database for combustion gases was also obtained. It was confirmed that the fire performance was improved by confirming that the total heat release decreased by 52% from the previous one in the magnesium hydroxide content of 30 g, and it was confirmed that the inflection points of the Toxic Index value due to the change in CO and CO2 gas production occurred in the magnesium hydroxide content of 20 g due to the improvement of the fire performance. Through the ISO 5660-1 experiment data, we have secured data that can be used as foundational information for performance-oriented fire risk assessments, thereby ensuring the fire safety of cellulose materials that are vulnerable to fire.

Improvement of Air Compressor Cooling with Intercooler Fine Pruning

An intercooler serves as a heat exchanger between the several stages of the working compressor, assisting in the transmission of thermal energy between fluids of varying temperatures. This article is about the experimental analysis of the effectiveness of an intercooler. Multiple variables oversee the performance evaluation under different circumstances. Standard operational values are used to calculate performance evaluation metrics such as total heat transfer coefficient and others. Heat rejection of intercoolers has been enhanced from 61% to 65% by the variation of different fin lengths. Furthermore, the recently added intercooler's isothermal efficiency, which reached an astounding 56.5% significantly, outperformed the earlier unit. This serves to highlight how well the intercooler design was modified. Furthermore, the effectiveness of the Intercooler was assessed considering the circumstances during operation. The intercooler fin is primarily concerned with the performance of the air compressor. This work analyses the many characteristics of fin length, fin number, and fin diameter. When compared to the existing intercooler, this modified intercooler has a high performance

Improve the thermal performance of precooler by enhancing the utilization of chemical heat sink: Refined design method and characteristic analysis

The chemical heat sink of the coolant plays a crucial role in enhancing the performance of the precooler, which affects the overall performance of the air-breathing precooled engines. The conventional thermal design method for precoolers cannot accurately evaluate the chemical heat sink of coolants. To address this crucial issue, this paper proposes a refined model that considers the chemical reaction processes of n-Decane, based on a two-dimensional discretization unit model and the plug flow reactor model incorporating molecular-level chemical reaction mechanisms. The validation of this model is conducted by comparing it with publicly accessible data and computational fluid dynamics simulations, thereby demonstrating its excellent accuracy. Subsequently, an analysis is conducted on the factors influencing the chemical heat sink release of the coolant within the precooler, and enhanced design criteria for optimizing chemical heat sink utilization are proposed. Building upon these considerations, the performance of a precooler with a design point of Mach number 5 under off-design conditions was analyzed. The findings indicate that employing rational design methods can enhance the chemical heat sink efficiency of endothermic fuels by 8.0%, along with a concurrent 10.3% increase in the total heat sink. This underscores the significance of considering the impact of the chemical heat sink of endothermic fuels in the design of precoolers. In the case presented in this paper, the contribution of the chemical heat sink to the total heat sink within the n-Decane precooler could reach 35.3%.

Thermal runaway and combustion of lithium-ion batteries in engine room fires on oil/electric-powered ships

The thermal characteristics of traditional fuel fires can be altered by the thermal instability of lithium-ion batteries (LIBs) in–oil-electric hybrid ships. The thermal runaway (TR) and combustion of 18,650 LiFePO4 LIBs with 0 %, 50 %, and 100 % states of charge (SOC) in pool fires were studied with different annular n-heptane pools. The goal is to simulate the thermal safety of LIBs in hybrid ships within the thermal environment of pool fires. The flame morphologies resulting from the combustion of the battery and pool fires, temperatures of the battery surface and flame, exhaust characteristics of the battery, heat radiated from the pool fire to the battery, and mass losses were analyzed. The results showed that the risks of thermal runaway and combustion with LIBs were significantly higher in a thermal fire environment. Lithium batteries produce jet fires that increase the width and height of the flame during pool fires. Moreover, the battery with a 0 % SOC doesn’t experience thermal runaway during the fire, but thermal runaway of the battery with a 100 % SOC is more severe than that of the battery with a 50 % SOC, and the maximum rates for their temperature increases are 12.98 °C/s and 7.12 °C/s, respectively. In addition, the energy balance method showed that the pressure relief by the battery safety valve during a fire was not dependent on the SOC. An equivalent network diagram was constructed for the radiative heat transfer between the lithium battery and the pool fire. It is proposed that the total heats required to induce thermal runaway of batteries with the same SOCs are almost the same in different thermal environments, but the energy required for the 50 % SOC battery is greater than that required for the 100 % SOC battery, 10,161 ± 59 J and 9724 ± 43 J, respectively. Moreover, the combustion rates were proportional to the height of the flame during the mixed combustion of a lithium battery jet fire and pool fire. A dimensionless model was developed for the relationship between flame height and mixed combustion rate.

Porous liquids assisted in-situ generated Co-LDH@MOF heterostructure with abundant defects for flame retardant and mechanical enhancement in polyurea composites

Preventing aggregation and inducing homogeneous dispersion of flame retardant nanofillers is critical to enhance the fire safety and mechanical properties of nanocomposites. Although chemical modifications are commonly used to improve the filler’s compatibility with the polymer chain, such methods are often cumbersome and limited. Herein, porous liquids (PLs) with flame retardant function were constructed in which porous defect-Co-LDH@ZIF-67 (d-LDH@ZIF) heterostructure particles were converted into liquid materials by electrostatic interaction with a large-volume solvent. This is also the first report of PLs in the field of flame retardant. Specifically, the d-LDH@ZIF heterostructure was designed by defect engineering and in situ growth strategy to compensate for the low catalytic activity and specific surface area of Co-LDH, and to serve as a rigid porous framework for PLs. Numerous cobalt/oxygen vacancies and lattice defects in the d-LDH@ZIF heterostructure have also been proven to confer higher flame retardancy relative to Co-LDH. d-LDH@ZIF porous liquids (PLs-d-L@Z) presents favorable liquid characteristics and achieves a monodisperse state in the polyurea matrix. The limiting oxygen index of polyurea composites blended with 20 wt% PLs-d-L@Z (3 wt% d-LDH@ZIF content) can be increased to 24.2 % and pass the V-0 rating in the UL-94 test. Moreover, the peak of heat release rate, total heat release, and total smoke production are reduced by around 40.4, 27.0, and 39.9 %, respectively, compared to neat polyurea. Emphatically, the PLs-modified polyurea composites exhibit significantly improved mechanical and impact resistance properties, as well as favorable chemical resistance. This strategy of liquefying solid flame retardant fillers will open an avenue to the design of functional nanomaterials for fire safety and other potential applications.

Copper oxide decorated one-dimensional mineral nanorods: Construction of strengthened gas-phase and condensed-phase coupled intumescent flame retardant

Polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) features superior mechanical properties but suffers from high flammability, presenting a grand challenge in enhancing its flame retardancy with halogen-free additives. Herein, we developed an efficient flame-retardant system (BH/CuATP) by incorporating phosphazene additive (HP), copper oxide modified attapulgite (CuATP) and bisphenol A bis (diphenyl phosphate) (BDP). This system achieves a UL-94V-0 rating without melt-dripping and leads to reductions in the peak heat release rate (43.1 %), total heat release (29.8 %) and total smoke production (5.7 %). The strength effect of CuATP in both gas-phase and condensed-phase significantly contributes to its enhanced fire safety. Additionally, the mechanical properties of PC/ABS/B1H1/CuATP1 are improved due to the rod-like CuATP, showing enhanced comprehensive properties superior to other reported systems. This work presents valuable insights into the effectiveness of mineral-strength intumescent flame retardancy for PC/ABS, offering practical guidance for the development of high-performance PC/ABS composites.

Characterization of oxygen initiation process in the autothermic pyrolysis in-situ conversion of Huadian oil shale

The oxygen initiation process, one of the key processes in the early stage of the autothermic pyrolysis in-situ conversion technology, has not been deeply investigated, which seriously limits its development. In this study, the reaction behaviors, kinetic parameters, heat and product release characteristics during the isothermal oxygen initiation process of Huadian oil shale in O2/N2 mixtures with different oxygen concentrations and initiation temperatures were investigated via TG/DSC-FTIR. The results show that the samples exhibit three different reaction behaviors during the initiation stage, consisting of two main parts, i.e., the oxidative weight-gain and the oxidative reaction phases. The former phase is mainly characterized by the oxygen addition reaction that produces oxidizing groups which increase the sample mass. And the latter stage consists of two main subreactions. The first subreaction involves the oxidative cracking and pyrolysis of oxidizing groups and kerogen to produce fuel deposits such as residual carbon, while the second subreaction focuses on the oxidation of the resulting fuels. Furthermore, increasing the oxygen concentration significantly promotes the above reactions, leading to an increase in the reaction intensity and reaction rate. Owing to the combined effect of oxygen concentration and residual organic matter content, the total heat release increases with the increasing initiation temperature and reaches its maximum at 330–370 °C. In addition, the preheating stage primarily produces hydrocarbon gases, while the initiation stage predominantly generates CO2. As the preheating temperature increases, the CO2 output intensifies, the required reaction time shortens, and the release becomes more concentrated. Based on these findings, a reaction mechanism for the oxygen initiation process of Huadian oil shale was proposed, and recommendations were provided for optimizing the construction process.

DETERMINATION OF THE FEATURES OF THERMAL DECOMPOSITION OF SUNFLOWER HUSK IN A FLUIDIZED BED

Sunflower husk (SH) is a plant waste fuel. The carbon content in different samples of SH ranges from 40.5% to 54.5% in an operating state, with ash content ranging from 1.5% to 8.5%, moisture content ranging from 6.9% to 9.5%, chlorine content ranging from 0.05% to 0.3%, and lower heating value ranging from 14.5 MJ/kg to 20.5 MJ/kg. These characteristics make it a suitable substitute for fossil fuels in power boilers. Waste-to-energy (WTE) technologies are rapidly developing worldwide, offering the potential for generating renewable energy from waste, including agricultural and food industry waste such as SH. According to our estimates, Ukraine has an annual energy potential of approximately 3.4 million tons of SH or about two million tons of fuel equivalent. Approximately half of this volume is currently being burned in oil extraction plants' boilers; however, up to one million tons of SH end up in landfills annually, resulting in significant energy losses. To develop new and improve existing WTE technologies that utilize SH as a fuel source, it's essential to understand the thermal processing characteristics of SH under conditions similar to those found in different zones within real power boilers - specifically the heating of fuel particles at rates up to 500 °C/s over a temperature range of 500–1000 °C. In this study, we aimed to investigate the thermal processing characteristics by subjecting SH particles within a laboratory fluidized bed reactor to high-speed heating within the aforementioned temperature range. During rapid heating between 500–1000 °C temperatures range, SH particles undergo conversion into volatile compounds and solid carbon residue. Two distinct stages can be observed on the dynamic yield curves for volatiles. The release and burnout of volatiles occurs during the first stage while the second stage involves coke ash residue burnout. We obtained empirical temperature-dependents for total heat treatment time and carbon residue burnout time under fast heating conditions in the investigated temperature range. The stage of carbon residue combustion is the most enduring and determines the overall duration of thermal treatment. This stage determines the degree of fuel transformation, especially in cases where low-reactivity carbon residue enters the low-temperature combustion chamber area of the boiler. The obtained regularities have practical significance in designing combustion chambers for thermal processing of sunflower husk.

Fabrication of superior flame-retardant phosphorylated chitosan biobased porous composites reinforced by superhydrophobic silicone interpenetrating crosslinking networks

Chitosan-based porous materials have potential to develop into a new generation of high performance sustainable thermal insulation materials. In this study, hydrophobic and enhanced phosphorylated porous materials (PCSM) were constructed by the in-situ crosslinking of methytrimethoxylsilane (MTMS), and modified SiO2 nanoparticles (H-SiO2) were further incorporated into the crosslinking networks to fabricate superhydrophobic and reinforced PCSM-H-SiO2 porous composites. The morphology of PCSM-H-SiO2 porous materials exhibited special micro-nanoscale “pearl string-like” rough and interpenetrating pore wall structure, which endowed them superhydrophobicity and self-cleaning ability. The water contact angles (WCAs) of PCSM-H-SiO2 porous composites achieved up to 150o, and the compressive and specific moduli of PCSM2-H-SiO2–2 porous composite significantly increased to 11.0 MPa and 89.6 m2·s−2, 5.39 and 1.74 times higher than those of PCS porous material, respectively. The limited oxygen index (LOI) values of PCSM2-H-SiO2–2 porous composite were above 80 %. The cone calorimeter test result demonstrated the peak heat release rate and total heat release rate values of PCSM-H-SiO2–2 porous composite were lower than those of PCS porous material. The ultra-high flame-retardant PCSM-H-SiO2–2 porous composite with superhydrophobicity and excellent compressive property is a promising biodegradable thermal-insulation material as replacement of petroleum-based material.

Temperature distribution in the PGAA system: Collimator, shutter, and filter in TRIGA Mark II reactor

This article examines the impact of temperature on the steel collimator cap and the primary beam shutter. These components will be used to implement the Prompt Gamma Activation Analysis (PGAA) technique in the Moroccan TRIGA Mark-II research reactor. The steel collimator plug is essential for forming the neutron beam, while the main role of the shutter is to stop the beam when the channel is inactive. This study analyzes the effect of temperature on the collimator and shutter system, particularly focusing on the variation in maximum temperature over a month of operation with 8-h cycles per day, the behavior of temperature over 24 h, the total heat flux as a function of the length of the experimental device, the temperature distribution in mild steel (E235) and 304L stainless steel materials, and the total displacement and strain gradient as a function of temperature. All calculations were performed using COMSOL Multiphysics simulation software, based on the finite element method.

Influence of additional intermediate thick Al layers on the reaction propagation and heat flow of Al/Ni reactive multilayers

This study investigates the effects of sputtering and electron beam evaporation (e‐beam) on the microstructure and reactive properties of Al/Ni reactive multilayers (RML). The intermixing zone, a critical factor influencing reaction kinetics, was characterized using high‐resolution transmission electron microscopy and found to be consistently 3 nm for both fabrication methods. Differential scanning calorimetry revealed that e‐beam samples, with thicker Al layers, exhibited slightly higher total molar enthalpy and maintained high reaction temperatures despite reduced reaction velocities in comparison to sputtered samples. X‐ray diffraction confirmed the formation of both Al3Ni2 and AlNi phases in the e‐beam samples. These findings indicate that while thicker bilayer structures reduce reaction velocity, they keep thermal output and mitigate the impact of intermixing zones, leading to similar total molar enthalpy. This analysis underscores the significance of deposition technique and bilayer thickness in optimizing the performance of Al/Ni RML, offering the possibility to establish different phase formations in thicker RML. It advances the control over the reactive properties of reactive multilayers in their applications, for example reactive bonding.This article is protected by copyright. All rights reserved.

Simulation of the work of glass furnaces with the purpose of searching for reserves and increase their efficiency

The object of research is the operation of a glass furnace. The work involved modeling the operation of a glass furnace by changing the technical and economic indicators of its operation in order to optimize the technological processes of manufacturing glass products, increase the energy efficiency of the process, and reduce the ecological burden on the environment. Glass furnaces are complex heat engineering units that require a large amount of energy to operate. Therefore, increasing their effectiveness is the main task of our research. In the work, computer modeling of thermal processes in the furnace was carried out, heat balances were calculated and analyzed, and the performance of the furnace was analyzed after changing and improving the technological regimes of combustion processes, glass boiling and furnace construction. Studies have shown that in order to increase the technical and economic performance of glass furnaces, it is advisable to conduct additional thermal insulation of the furnace enclosures. The thermal insulation of the vault increases the efficiency of the furnace by 2–3 %, and the thermal insulation of the remaining areas of the furnace in total allows to increase the efficiency of the heating unit up to 3 %. Such measures improve the sanitary and technical working conditions of the staff in the machine-bath shop. Studies have shown that additional heating of the air used for burning fuel significantly increases the efficiency of the furnace. Thus, an increase in air temperature by 100 °C increases the efficiency of the furnace by approximately 2.5 %. However, such a measure is possible with a corresponding increase in the volume of regenerator nozzles. A significant increase in the efficiency of the furnace was achieved when additional electric heating was installed. This allows to reduce the total energy costs, and at the same time, the introduction of every 10 % of additional electric heating increases the efficiency of the furnace by up to 3 % and improves the quality of the glass mass. Such additional heating can be recommended in the amount of 20–30 % of the total heat consumption for the operation of the furnace. The analysis of the obtained results showed a fairly good convergence of the results, which indicates the acceptable adequacy of the models. The obtained process simulation results allow choosing the optimal design and operation parameters of the glass furnace. The results of the work can be used in practice for the design of efficient glass furnaces of various purposes and performance.

Construction of composite self-assembly coating based on chitosan for enhancing the flame-retardant and antibacterial performances of cotton fabric

In this work, the step-by-step dip-coating (SBS) method was used to effectively improve the drawback of LBL by reducing the construction of a multilayer polyelectrolyte. Bio-based flame retardants, phytic acid (PA), and chitosan (CS) were further self-assembly on the surface of cotton fabric treated by epichlorohydrin-modified aramid nanofibers (AEP), ionic liquid (IL), and Cu ion. The pure cotton fabric was immersed in each dipping liquid only once, improving fire safety and antibacterial performance. The treated cotton self-extinguished with a 59 mm char length in the vertical flammability test, and the limiting oxygen index (LOI) value increased from 18.5 % to 38.5 %. The result of the cone calorimeter test (CCT) revealed that the fire hazard of flame-retardant cotton noteworthy declined (e.g., ~44.1 % and 55.4 % decline in peak heat release rate (pHRR) and total heat release rate (THR)). Conspicuously, the treated cotton exhibited a remarkably inhibiting effect on E. coli and S. aureus activity. The cotton fabric after flame-retardant finishing exhibited excellent fire safety and antibacterial performance.

Adsorption−desorption of Zn2+ ions using hydroxyapatite and recovery of zinc by electrochemical precipitation method into deep eutectic solvent

Hydroxyapatite has a nanostructure, the chemical formula of Ca10(PO4)6(OH)2 and a specific surface area of 91.42 m2/g. In this paper, hydroxyapatite is used to adsorb Zn2+ ions as effective adsorbent. The influence of some factors on Zn2+ adsorption capacity and efficiency has been studied. Under the suitable adsorption conditions were hydroxyapatite mass of 0.15 g in 50 mL solution, 50 mg L−1 initial Zn2+ concentration, pH 5.0, exposure time of 60 min at room temperature (25 °C), Zn2+ adsorption efficiency and capacity reached 94.79 % and 15.80 mg g−1, respectively. The process of desorption of Zn2+ from the loaded adsorbent and recovery of metallic Zn was also investigated. Zinc recovery efficiency reached 93.26 % under appropriate conditions such as applied current intensity of 7.5 mA, electrolysis time of 10 h, loaded hydroxyapatite mass of 0.1 g, temperature 60 °C. After desorption process, the adsorbent was regenerated for further studies. The adsorption isotherm was studied based on three Langmuir, Freundlich and Redlich-Peterson models. The adsorption thermodynamics were investigated and calculating the parameters. The adsorption kinetics were examined using two pseudo-first-order and pseudo-second-order kinetic models. The negative value of Gibb’s free energy change showed that the adsorption process was feasible and spontaneous in nature. The positive value of enthalpy change indicated that the process was endothermic. The positive value of entropy change showed increased randomness at the solid and solution interface.

Fully biobased thermal insulating aerogels with superior fire-retardant and mechanical properties

Biomass-based aerogels offer a promising potential as alternatives to plastic-based foams for thermal insulation applications. However, their inherent flammability has hindered their practical usage. In this work, we addressed this issue by employing a layer-by-layer assembly technique to deposit two oppositely charged biobased materials, namely phytic acid and chitosan, onto a fully biobased aerogel system. These aerogels were fabricated using cellulose filaments and chitosan and cross-linked with citric acid, resulting in a mechanically robust 3D structure. The synergistic effects of phytic acid and chitosan in the layer-by-layer deposited aerogels significantly enhanced their fire resistance and mechanical strength. The developed aerogel with six bilayer depositions (LBL6), showed an outstanding peak heat release rate (pHRR) of 6.0 kW.m−2, and total heat release (THR) of 0.4 MJ.m−2, substantially lower than the previously developed cellulose-based aerogels and foams. LBL6 also demonstrated immediate self-extinguishing behaviour, boasting an impressive limiting oxygen index (LOI) value of 63 %, which is the highest reported for a biobased aerogel. Furthermore, the developed aerogels exhibited a superior Young’s modulus of up to 4.5 MPa, surpassing previously developed flame-retardant aerogels. Additionally, they excelled in thermal insulation properties, with a thermal conductivity of less than 38.2 mW·m−1·K−1, placing them in the same range as, or even lower than, commercially available thermal insulators. Given the simplicity of the aerogel development process and the well-known advantages of a completely biobased system, our developed aerogels present a sustainable and environmentally friendly alternative to current commercial thermal insulators that are derived from petroleum-based materials.