Physical Aging Process Research Articles

Enhancing CO2/CH4 separation performance in PIM-1 based MXene nanosheets mixed matrix membranes

This study presents an approach by integrating MXene nanosheets (Ti2C3Tx) into polymer of intrinsic microporosity (PIM-1) matrix to develop mixed matrix membranes (MMMs) for biogas upgrading. Different concentrations (1–5 wt%) of MXene were incorporated into PIM-1, and the resulting materials were characterized to 1H NMR, FTIR, XRD, TGA, nitrogen adsorption, SEM and EDS to assess their physicochemical properties. The research focused on evaluating the gas separation performance, particularly CO2/CH4 separation, as well as the aging behavior of the MMMs. The incorporating of MXene nanosheets significantly enhanced the CO2 permeability and selectivity of PIM-1 by enhancing gas solubility and diffusivity. The most promising results were observed at 5 wt% filler loading, achieving a 13.5 CO2/CH4 separation selectivity at 7652 Barrer of CO2 permeability. In all membranes with aging time (60 days), there was a decrease in CO2 permeability and a slight increase in CO2/CH4 selectivity, observing that the introduction of MXene slightly mitigates the physical aging process in the PIM-1 polymer. Additionally, the permeability tests revealed higher CO2 permeability and (CO2/CH4) selectivity values for mixed gases compared to single gases. Overall, the study highlights the potential of MXene/PIM-1 MMMs as effective materials for CO2/CH4 separation, outperforming pristine PIM-1.

Correlations between the Aging Behavior and Finite Element Method Simulation of Three Silicone Elastomers.

The material parameters required to describe material behavior can change with the age of the components due to chemical and physical aging processes. The finite element method (FEM) is a tool for designing components for later use. The aim of this study is to correlate the change in the mechanical properties of silicone elastomers from standard tests over a longer period of time with the parameters of the Mooney-Rivlin model. To date, there are no publications on the development of the Mooney-Rivlin parameters of silicone elastomers over a storage period. For this purpose, the Shore A hardness, rebound elasticity, compression set and tensile properties were investigated over an aging period of approx. 200 days on two liquid silicone rubbers (LSRs) and one room-temperature-vulcanizing (RTV) silicone rubber. Depending on the silicone elastomer used, different trends in the characteristic values can be observed over the storage period. In general, increases in the Shore A hardness, rebound resilience and stress at a 100% strain with a decrease in the compression set can be determined. In addition to standard tensile tests, the material's multiaxial behavior under tension was probed, and it was found that the similarly stress at a 100% strain increased. Finite element simulations verified the standard tensile test and corresponding Mooney-Rivlin model parameters. These parameters from the uniaxial tensile were validated in the multiaxial behavior, and the model's accuracy in representing material properties and the influence of aging on the FEM simulation were affirmed.

The Correlation of Plasma Sirt 1 Level and Frailty Degree in The Elderly Outpatients

Background: Frailty is a syndrome related to the physical aging process and is characterized by a vulnerability to health decline. Sirtuin 1 (SIRT1) plays a crucial role in weakness, especially in the elderly, serving as a protective factor against frailty. The aim of the study determine the correlation between plasma SIRT 1 level and frailty degree in the elderly outpatientsMethods: This research employed a cross-sectional methodology, involving the observation or measurement of 118 elderly subjects selected through non-probability sampling, Comprehensive medical records were collected, encompassing demographic data such as age, gender, formal education, ethnicity, caregiver status, and marital status. The frailty scale was employed, where 0= robust, 1-2= pre-frailty, and 3-5= frailty. For genetic analysis, 3 cc of blood was collected using the DNA isolation Kit from Promega. Results: Pearson correlation analysis indicated no significant relationship between plasma SIRT1 levels and the presence of positive fertility (r=0.177). However, the F-test revealed a simultaneous and significant association between plasma SIRT1 levels and frailty with a significance level of 0.036 (p < 0.05). The data from the ANOVA test predominantly showed that the frail group had plasma SIRT1 levels slightly above the pre-frail category (>50 ng/ml). Conclusion: There is no significant relationship between plasma SIRT1 levels and frailty scale, while the F-test suggests a simultaneous significant association between plasma SIRT1 levels and frailty

Influence of volume expansion in NaCl crystallization on the physical properties and molecular structure of asphalt: A MD simulation study

The pavement damage caused by salt-induced volume expansion is becoming increasingly noticeable. Molecular dynamics (MD) method was applied to evaluate the effects of varied volumes of NaCl crystals on physical properties and structure of asphalt. The effects of NaCl crystals on the compatibility between styrene–butadiene–styrene triblock copolymer (SBS) and asphalt, as well as the influence of SBS on the diffusion coefficient of NaCl crystals in the asphalt system, were investigated alongside their effects on the physical modulus and molecular structure of asphalt. The results show that the solubility parameter of the asphalt blends decreases as the volume of NaCl crystals increases. Specifically, the solubility parameter decreases by 52.5 % for the biaxial crystalline growth of NaCl and asphalt blends compared to the matrix asphalt. The analysis of the ion diffusion coefficient reveals that the primary disruption of NaCl crystals in asphalt blends is due to early Cl- and late Na+ diffusion. Furthermore, the rise in shear modulus of the asphalt blends suggests that the salt erosion process of SBS-modified asphalt is advantageous for its high temperature and shear resistance. The changes in peak radial distribution function and radius of gyration indicate that the inclusion of NaCl and SBS into asphalt is a physical aging process. In this case, SBS incorporation acts as a reinforcement to the asphalt to retard the erosion of NaCl.

3D printed denture base material: The effect of incorporating TiO2 nanoparticles and artificial ageing on the physical and mechanical properties

ObjectivesTo evaluate the physical and mechanical properties of three-dimensional (3D) printed denture base resin incorporating TiO2 nanoparticles (NPs), subjected to a physical ageing process. MethodsAcrylic denture base samples were prepared by a Stereolithography (SLA) 3D printing technique reinforced with different concentrations (0.10, 0.25, 0.50, and 0.75) of silanated TiO2 NPs. The resulting nanocomposite materials were characterized in terms of degree of conversion (DC), and sorption/solubility flexural strength, impact strength, Vickers hardness and Martens hardness and compared with unmodified resin and conventional heat-cured (HC) material. The nanocomposites were reassessed after subjecting them to ageing in artificial saliva. A fractured surface was studied under a scanning electron microscope (SEM). ResultsThe addition of TiO2 NPs into 3D-printed resin significantly improved flexural strength/modulus, impact strength, Vickers hardness, and DC, while also slightly enhancing Martens hardness compared to the unmodified resin. Sorption values did not show any improvements, while solubility was reduced significantly. The addition of 0.10 wt% NPs provided the highest performance amongst the other concentrations, and 0.75 wt% NPs showed the lowest. Although ageing degraded the materials’ performance to a certain extent, the trends remained the same. SEM images showed a homogenous distribution of the NPs at lower concentrations (0.10 and 0.25 wt%) but revealed agglomeration of the NPs with the higher concentrations (0.50 and 0.75 wt%). SignificanceThe outcomes of this study suggested that the incorporation of TiO2 NPs (0.10 wt%) into 3D-printed denture base material showed superior performance compared to the unmodified 3D-printed resin even after ageing in artificial saliva. The nanocomposite has the potential to extend service life of denture bases in future clinical use.

On the correlation between hygroscopic properties and chemical composition of cloud condensation nuclei obtained from the chemical aging of soot particles with O3 and SO2

Soot particles released in the atmosphere have long been investigated for their ability to affect the radiative forcing. Although freshly emitted soot particles are generally considered to yield only positive contributions to the radiative forcing, atmospheric aging can activate them into efficient cloud condensation or ice nuclei, which can trigger the formation of persistent clouds and ultimately provide a negative contribution to the radiative forcing. Depending on their residence time in the atmosphere, soot particles can undergo several physical and chemical aging processes that affect their chemical composition, particle size distribution and morphology, and ultimately their optical and hygroscopic properties. The impact of the physical-chemical aging on the properties of soot particles is still difficult to quantify, as well as their effect on the radiative forcing of the atmosphere.This work investigates the hygroscopic properties of chemically aged soot particles obtained from the combustion of aviation fuel, and in particular the interplay between aging mechanisms initiated by two widespread atmospheric oxidizers (O3 and SO2). Activation is measured in water supersaturation conditions using a cloud condensation nuclei counter. Once particle morphology and size distribution are taken into account, the hygroscopicity parameter κ is derived using κ-Köhler theory and correlated to the change of the chemical composition of the particles aged in a simulation chamber. While fresh soot particles are poor cloud condensation nuclei (κ < 10−4) and are not significantly affected by either O3 or SO2 at the timescale of the experiments, rapid activation is observed when they are simultaneously exposed to both oxidizers. Activated particles become efficient cloud condensation nuclei, comparable to the highly hygroscopic particulate matter typically found in the atmosphere (κ = 0.2–0.6 at RH = 20 %). Statistical analysis reveals a correlation between the activation and sulfur-containing ions detected on the chemically aged particles that are absent from the fresh particles.

Physical Ageing of Amorphous Poly(lactic acid)-Indapamide System Studied by Differential Scanning Calorimetry.

The process of isothermal and non-isothermal physical ageing of amorphous polylactide (PLA) with the active pharmaceutical ingredient, indapamide (IND), was investigated. A PLA-IND system with a 50/50 weight ratio was obtained and characterized using differential scanning calorimetry (DSC). In the 50/50 (w/w) mixture, two glass transitions were observed: the first at 64.1 ± 0.3 °C corresponding to the glass transition temperature (Tg) of PLA, and the second at 102.6 ± 1.1 °C corresponding to the Tg of IND, indicating a lack of molecular mixing between the two ingredients. The PLA-IND system was subjected to the isothermal physical ageing process at different ageing temperatures (Ta) for 2 h. It was observed that the highest effect of physical ageing (enthalpy relaxation change) on IND in the PLA-IND system occurred at Ta = 85 °C. Furthermore, the system was annealed for various ageing times at 85 °C. The relaxation enthalpies were estimated for each experiment and fitted to the Kohlrausch-Williams-Watts (KWW) equation. The KWW equation allowed for the estimation of the relaxation time and the parameter describing the distribution of relaxation times of the isothermal physical ageing process of IND in the PLA-IND system. The physical ageing of the PLA-IND mixture (50/50) was also discussed in the context of heat capacity. Moreover, the activation energy and fragility parameters were determined for the PLA-IND (50/50) system.

Fast vs slow physical aging of a glass forming liquid.

Using electric fields to initiate the process of physical aging has facilitated measurements of structural recovery dynamics on the time scale of milliseconds. This, however, complicates the interesting comparison with aging processes due to a temperature jump, as these are significantly slower. This study takes a step toward comparing the results of field and temperature perturbations by providing data on field-induced structural recovery of vinyl ethylene carbonate at two different time scales: 1.0ms at 181K and 33s at 169K, i.e., 4.5 decades apart. It is found that structural recovery is a factor of two slower than structural relaxation in equilibrium, with the latter determined via dielectric relaxation in the limit of linear response. The relation between recovery and relaxation dynamics remains temperature invariant across the present experimental range.

On revealing structural relaxation of ionic liquids by high-field dielectric techniques

Using dielectric relaxation techniques at low and high electric fields, it is demonstrated how the conductivity and structural relaxation times can be obtained under identical sample conditions, e.g., for ionic liquids. This approach is useful for conductive materials for which low field dielectric loss spectra fail to display signatures of structural relaxation. The approach is based on field induced structural recovery in the regime of milliseconds, i.e., the process of fast physical aging in response to a small perturbation. For the case of viscous 1‑butyl‑3-methyl imidazolium tetrafluoroborate, this experiment reveals a decoupling quantified by structural relaxation being about nine times slower than conductivity relaxation.

Mitigation of Physical Aging of Polymeric Membrane Materials for Gas Separation: A Review

The first commercial hollow fiber and flat sheet gas separation membranes were produced in the late 1970s from the glassy polymers polysulfone and poly(vinyltrimethyl silane), respectively, and the first industrial application was hydrogen recovery from ammonia purge gas in the ammonia synthesis loop. Membranes based on glassy polymers (polysulfone, cellulose acetate, polyimides, substituted polycarbonate, and poly(phenylene oxide)) are currently used in various industrial processes, such as hydrogen purification, nitrogen production, and natural gas treatment. However, the glassy polymers are in a non-equilibrium state; therefore, these polymers undergo a process of physical aging, which is accompanied by the spontaneous reduction of free volume and gas permeability over time. The high free volume glassy polymers, such as poly(1-trimethylgermyl-1-propyne), polymers of intrinsic microporosity PIMs, and fluoropolymers Teflon® AF and Hyflon® AD, undergo significant physical aging. Herein, we outline the latest progress in the field of increasing durability and mitigating the physical aging of glassy polymer membrane materials and thin-film composite membranes for gas separation. Special attention is paid to such approaches as the addition of porous nanoparticles (via mixed matrix membranes), polymer crosslinking, and a combination of crosslinking and addition of nanoparticles.

Experimental and Numerical Investigation into the Effect of Water Uptake on the Capacitance of an Organic Coating.

Water uptake by organic coating systems used for corrosion prevention on airframes is one of the principal contributors to the loss of barrier properties of the coating. We used equivalent circuit analyses of electrochemical impedance spectroscopy (EIS) data to track changes in coating layer capacitance for a two-layer coating system consisting of an epoxy primer and polyurethane topcoat immersed in NaCl solutions with different concentrations and temperatures. The capacitance curve exhibited two different response regions, consistent with the "two-stage kinetics" mechanisms for water uptake by the polymers. We tested several numerical diffusion models of water sorption and found the most successful to be one that varied the diffusion coefficient as a function of polymer type and immersion time and accounted for physical aging processes in the polymer. We employed the Brasher mixing law along with the water sorption model to estimate the coating capacitance as a function of water uptake. The predicted capacitance of the coating was found to be consistent with the capacitance obtained from the EIS data, which is consistent with theories that water uptake occurs via initial rapid transport followed by a much slower aging process. Thus, both these water uptake processes need to be considered when making EIS measurements to assess the state of a coating system.

Suppressed physical aging in PMMA‐titanium oxide nanocomposites by controlling alignment of nanoparticles

AbstractThis study investigates the physical aging process of PMMA‐TiO2 nanocomposites with different particle alignments. By using an external electric field to control the alignment of TiO2 particles, a uniform distribution of TiO2 particles in PMMA is transformed into a micrometer‐level pillar structure. The physical aging process is measured using differential scanning calorimetry, and the particle alignment is confirmed by microscopy. Comparison of the aging behavior of different samples shows that the addition of randomly distributed TiO2 nanoparticles accelerates the aging rate of the material. However, when the nanoparticles are realigned into a pillar structure, the aging rate significantly decreases. Moreover, in our experimental time scale, a dual‐relaxation mechanism of aging is observed in the PMMA/TiO2 nanocomposites. This work highlights the importance of particle alignment and structure on the aging behavior of polymer nanocomposites, which could have implications for designing materials with improved stability in applications that require slow aging.

Effects of physical aging processes on the bioavailability of heavy metals in contaminated site soil amended with chicken manure and wheat straw biochars

The physicochemical properties of biochars undergo slow changes in soils due to the natural aging processes, which influences their interaction with heavy metals. The effects of aging on immobilization of co-existing heavy metals in contaminated soils amended with fecal and plant biochars possessing contrasting properties remain unclear. This study investigated the effects of wet–dry and freeze–thaw aging on the bioavailability (extractable by 0.01 M CaCl2) and chemical fractionation of Cd and Pb in a contaminated site soil amended with 2.5% (w/w) chicken manure (CM) biochar and wheat straw (WS) biochar. Compared to that in the unamended soil, the contents of bioavailable Cd and Pb in CM biochar-amended soil decreased by 18.0% and 30.8%, respectively, after 60 wet–dry cycles, and by 16.9% and 52.5%, respectively, after 60 freeze–thaw cycles. CM biochar, which contained significant levels of phosphates and carbonates, effectively reduced the bioavailability of Cd and Pb and transformed them from the labile chemical fractions to the more stable ones in the soil during the accelerated aging processes, mainly through precipitation and complexation. In contrast, WS biochar failed to immobilize Cd in the co-contaminated soil in both aging regimes, and was only effective at immobilizing Pb under freeze–thaw aging. The changes in the immobilization of co-existing Cd and Pb in the contaminated soil resulted from aging-induced increase in oxygenated functional groups on biochar surface, destruction of the biochar's porous structure, and release of dissolved organic carbon from the aged biochar and soil. These findings could help guide the selection of suitable biochars for simultaneous immobilization of multiple heavy metals in co-contaminated soil under changing environmental conditions (e.g., rainfall, and freezing and thawing of soils).

The β relaxation process of La-based amorphous alloy: Effect of annealing and strain amplitude

The dynamic relaxation process of amorphous alloys is an important issue to understand the diffusion behavior, plastic deformation as well as glass transition phenomenon. In the current research, (La&lt;sub&gt;0.6&lt;/sub&gt;Ce&lt;sub&gt;0.4&lt;/sub&gt;)&lt;sub&gt;65&lt;/sub&gt;Al&lt;sub&gt;10&lt;/sub&gt;Co&lt;sub&gt;25&lt;/sub&gt; amorphous alloy with a pronounced β relaxation process was selected as a model system to study the dynamic mechanical relaxation processes. Influence of driving frequency, physical aging and applied strain amplitude on the β relaxation of the La-based metallic glass was probed process using dynamic mechanical analysis. The experimental results demonstrated that the peak of the β relaxation process shifts to high temperature by increasing the driving frequency. Physical aging below the glass transition temperature induces a decrease of the intensity of the β relaxation process. The “defects” of amorphous alloy decreases during the physical aging process, which is ascribed to the glassy system shifts to more stable state induced by physical aging treatment. In parallel, the intensity of the β relaxation process of the amorphous alloy increases by increasing strain amplitude. The research sheds new light on further understanding the physical origin of β relaxation process of the amorphous alloy.

Aging of colloidal contaminants and pathogens in the soil environment: Implications for nanoplastic and COVID-19 risk mitigation.

Colloidal contaminants and pathogens are widely distributed in soil, whose tiny sizes and distinct surface properties render unique environmental behaviours. Because of aging, colloids can undergo dramatic changes in their physicochemical properties once in the soil environment, thus leading to diverse or even unpredictable environmental behaviour and fate. Herein, we provide a state-of-art review of colloid aging mechanisms and characteristics and implications for risk mitigation. First, we review aging-induced formation of colloidal contaminants and aging-associated changes. We place a special focus on emerging nanoplastic (NP) contaminants and associated physical, chemical, and biological aging processes in soil environments. Second, we assess aging and survival features of colloidal pathogens, especially viruses. Viruses in soils may survive from several days to months, or even several years in groundwater, depending on their rates of inactivation and the reversibility of attachment. Furthermore, we identify implications for risk mitigation based on aging mechanisms. Hotspots of (photo)chemical aging of NPs, including plastic gauzes at construction sites and randomly discarded plastic waste in rural areas, are identified as area requiring greater research attention. For COVID-19, we suggest taking greater care in regions where viruses are persist for long periods, such as cold climate regions. Soil amendment with quicklime (CaO) may act as an effective means for pathogen disinfection. Future risk mitigation of colloidal contaminants and pathogens relies on a better understanding of aging mechanisms and more sophisticated models accurately depicting processes in real soil environments.

Successful Aging among Immigrant and Canadian-Born Older Adults: Findings from the Canadian Longitudinal Study on Aging (CLSA).

Background: Few studies in Canada have focused on the relationship between immigrant status and successful aging. The concept of successful aging used in this study includes the ability to accomplish both activities of daily living (ADLs) and instrumental activities of daily living (IADLs), freedom from mental illness, memory problems and disabling chronic pain, adequate social support and older adults’ self-reported happiness and subjective perception of their physical health, mental health and aging process as good. Methods: The present study analyzed the first two waves of data from the comprehensive cohort of the Canadian Longitudinal Study on Aging (CLSA). The sample includes 7651 respondents aged 60+ at time 2, of whom 1446 respondents were immigrants. Bivariate and multivariable binary logistic regression analyses were conducted. Results: Canadian-born older adults had a slightly higher prevalence and age-sex adjusted odds of achieving successful aging than their immigrant counterparts (aOR = 1.18, 95% CI: 1.04, 1.34, p < 0.001). After adjusting for 18 additional factors, immigrant status remained statistically significant (aOR = 1.24, 95% CI: 1.09, 1.41, p < 0.001). Significant baseline factors associated with successful aging among immigrants included being younger, having higher income, being married, not being obese, never smoking, engaging in moderate or strenuous physical activities, not having sleeping problems and being free of heart disease or arthritis. Conclusions: Immigrant older adults had a lower prevalence of successful aging than their Canadian-born peers. Further research could investigate whether policies and interventions supporting older immigrants and promoting a healthy lifestyle enhance older adults achieve successful aging in later life.

Physical aging of the 62.5GeS2-12.5Sb2S3-25CsCl chalcogenide glass: Assessing the mechanisms of equilibration and crystallization

The goal of this work is to provide an answer to the important scientific question: will a glass-forming liquid reach its equilibrium state or not before to crystallize during physical aging process, i.e. when it is maintained below its glass transition temperature? For this goal the physical aging process in a 62.5GeS2-12.5Sb2S3-25CsCl glass has been investigated for a long period (5 months) at 30°C below the glass transition temperature Tg. A crystallization was observed during this process, and was characterized through X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Temperature Modulated Differential Scanning Calorimetry (MT-DSC) analyses. By evaluating the enthalpy loss related to the physical aging and by comparing this experimental quantity to the theoretical one, we have proved that this glass has reached its thermodynamic equilibrium state before crystallizing. Thus, this work evidences experimentally the ability for a glass former to crystallize under Tg after reaching its equilibrium state.

ПРОБЛЕМАТИКА ЕКСПЛУАТАЦІЙНОЇ ДОВГОВІЧНОСТІ ТЕХНІЧНИХ ЗАСОБІВ ОРГАНІЗАЦІЇ ДОРОЖНЬОГО РУХУ

Introduction. The efficiency of road transport functioning greatly depends on the technical level and condition of roads. Modern roads must ensure traffic safety. Also, it has to be considered that the transport and operational level of a modern road is determined not only by the combination of geometric elements of the route, the number of traffic lanes, the condition of the roadway and roadsides, but also the engineering equipment of the road. Mostly, traffic safety requirements are met dut to a wide and skillful use of engineering equipment. Modern standards include, among other things, technical means of traffic control of the roads. Problem statement. The impact of various factors on the durability of polymeric materials Purpose. Solving the issues of operational durability of technical means of traffic control. Materials and methods. Theoretical and empirical methods of scientific researches are used to analyze the impact of various factors on the durability of polymeric materials. Results. The analysis of foreign researches concerning the impact of various factors, and especially ultraviolet radiation on durability of polymeric materials is performed. Conclusions. When conducting tests on artificial aging in order to predict changes in the properties of polymeric materials, it is necessary first of all to select and justify the simulated external factors and their maximum values. When determining the allowable amplification of the selected external factor as compared to its influence under operating conditions, it is necessary to be guided by the following: at the maximum value of the external aging factor in artificial conditions, the physical and chemical aging processes must be identical to those occurring in real operating conditions. Since, taking into account this condition, we will be able to obtain the most qualitative and accurate indicators.

Densification of a polymer glass under high-pressure shear flow

The properties of glasses can change significantly as they evolve toward equilibrium. Mechanical deformation appears to influence this physical aging process in conflicting ways, with experiments and simulations showing both effects associated with rejuvenation away from and overaging toward the equilibrium state. Here we report a significant densification effect in a polymer undergoing shear flow under high pressure. We used the high-aspect ratio geometry of the layer compression test to measure the uniform and homogeneous accumulation of plastic strain during isothermal confined compression of a deeply quenched film of polystyrene glass. Combined scanning transmission x-ray microscopy (STXM) and atomic force microscopy confirmed defect-free deformation leaving up to 1.2% residual densification under conditions of confined uniaxial strain. At higher peak strain, plastic shear flow extruded glass from below the compressing punch under conditions of a high background pressure. A further density increase of 2% was observed by STXM for a highly thinned residual thickness of polymer that nevertheless showed no signs of crystallization or internal strain localization. While the confined uniaxial densification can be accounted for by a simple elastic--plastic constitutive model, the high-pressure extrusion densification cannot.

Effects of physical and chemical aging on polycyclic aromatic hydrocarbon (PAH) content and potential toxicity in rice straw biochars.

Polycyclic aromatic hydrocarbons in biochars threaten their environmental application. The aging process may affect the concentration of PAHs, potential toxicity, and the properties of biochar. In this study, the aged biochars were obtained by simulated physical aging method (freeze-thaw treatment) and chemical aging method (H2O2 chemical oxidation). The PAH contents in biochars were measured, and their potential toxicity was assessed. Meanwhile, the influence of aging process on the physicochemical properties of biochar was also investigated. This study shows that the change of PAH content of aged biochars depended on pyrolysis temperature, ambient temperature, and oxidant concentration. Furthermore, physical and chemical aging process influenced the distribution of different ring PAHs in biochars. High-ring-number PAHs (four, five, six-ring PAHs) appeared in some aged biochar. Aging at ±20 °C and 0.01 M H2O2 increased the toxic equivalent quantity of all biochars which may be attributed to the change of the physicochemical properties influencing the different PAH ring distribution in biochars. The contribution of PAHs with different rings to TEQ varied in pristine and aged biochars. Physical and chemical aging process significantly affected the properties of biochars, such as element content, ash content, surface area, pore volume, pH, functional groups, and surface morphology. Correlation analysis confirmed that surface area and pore volume are dominant factors determining the PAH content in the biochars. Therefore, the aging process indeed affected the PAH concentration and toxicity of PAHs in biochar. Assessing PAH behavior in biochar over long timescales should not be overlooked.