Dynamic Equilibrium Research Articles

Exploring the influencing factors of environmental deterioration: evidence from China employing ARDL–VECM method with structural breaks

PurposeThe environmental deterioration has become one of the most economically consequential and charged topics. Numerous scholars have examined the driving factors failing to consider the structural breaks. This study aims to explore sustainability using the per capita ecological footprints (EF) as an indicator of environmental adversities and controlling the resources rent [(natural resources (NR)], labor capital (LC), urbanization (UR) and per capita economic growth [gross domestic product (GDP)] of China.Design/methodology/approachThrough the analysis of the long- and short-run effects with an autoregressive distributed lag model (ARDL), structural break based on BP test and Granger causality test based on vector error correction model (VECM), empirical evidence is provided for the policies formulation of sustainable development.FindingsThe long-run equilibrium between the EF and GDP, NR, UR and LC is proved. In the long run, an environmental Kuznets curve (EKC) relationship existed, but China is still in the rising stage of the curve; there is a positive relationship between the EF and NR, indicating a resource curse; the UR is also unsustainable. The LC is the most favorable factor for sustainable development. In the short term, only the lagged GDP has an inhibitory effect on the EF. Besides, all explanatory variables are Granger causes of the EF.Originality/valueA novel attempt is made to examine the long-term equilibrium and short-term dynamics under the prerequisites that the structural break points with its time and frequencies were examined by BP test and ARDL and VECM framework and the validity of the EKC hypothesis is tested.

The mechanochemistry of lanthanum dihydride (LaH\(_{2}\)) with hydrogen (H\(_{2}\)) using the ball-mill process and the effect of oxidation on the resulting products

The complex behavior of LaH2 during ball milling was investigated in this study, with its mechanical, chemical, and morphological changes explored. The relationship between milling time and hydrogen pressure reduction was uncovered through detailed experiments, reflecting the dynamic nature of the process. A transient yet significant event was observed upon unsealing the milling jar post-milling: the emergence of a minor fire ember, indicative of the interplay between mechanical forces and chemical reactivity within the LaH2 powder. Profound changes in the structure, composition, and shape were unraveled using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX), and particle size distribution analysis. The resulting powder exhibited a dual-phase composition of lanthanum dihydride (LaH2, 68.1% to 71.5%) and lanthanum oxide (La2O3, 28.5% to 31.9%), reflecting a dynamic chemical equilibrium during milling. Particle size distribution analysis revealed a notable increase in average diameter to 6420 nm, accompanied by a polydispersity index (PDI) of 0.831, signifying a broadening compared to the initial LaH2 powder. The morphological evolution of the powder was elucidated through SEM imaging, showing predominantly spherical and rounded forms, indicating extensive particle agglomeration and plastic deformation during milling. Additionally, the formation of oxide layers on the powder surface, intertwined with pronounced particle agglomeration, was highlighted through EDX mapping, shedding light on the mechanical aspects of morphological evolution during milling. These findings contribute to our understanding of LaH2 behavior under extreme mechanical and chemical conditions and have implications for materials processing, hydrogen storage technologies, and broader applications in materials science and engineering.

Modelling dynamic fracture and fragmentation of rocks under multiaxial coupled static and dynamic loads with a parallelised 3D FDEM

In this study, a three-dimensional (3D) combined finite-discrete element method (FDEM) based simulator, which enables the robust simulation of full-scale triaxial Hopkinson bar (Tri-HB) testing system, including the capture of fracture and fragmentation processes of rock specimens as well as the detection and analysis of generated rock fragments, is developed for investigating the dynamic responses of rocks subjected to multiaxial coupled static and dynamic loads. An innovative two-step approach is proposed to first efficiently achieve the static stress state in the entire Tri-HB system and then apply dynamic loading to the system. The proposed approach with the schemes of mass scaling and local damping can significantly reduce the run time for static computation involving cohesive elements and complex contact mechanics in the framework of explicit time-integration. The developed program is well validated by achieving dynamic stress equilibrium in the Tri-HB system and comparing the simulated stress wave profiles with those from laboratory experiments. Then, the progressive dynamic fracture and fragmentation processes of rocks under different static stress conditions in a full-scale Tri-HB system are investigated, which vividly exhibit the confinement dependence of the dynamic behaviours of rocks in the testing system. It is found that, even with the same loading rate, separate input parameter sets for rock need to be established in FDEM for different confinement conditions to capture the actual rate dependent behaviour of rock. Further studies are also conducted to investigate the effect of interfacial friction on the fracture behaviour, and the results indicate that higher interfacial frictions significantly disturb the dynamic stress variations and the true rock behaviour in the system. Through high performance computing of 3D FDEM, this study is expected to contribute to the understanding of dynamic responses of rocks subjected to multiaxial coupled static and dynamic loads in deep underground engineering.

Mechanism of folding and stability of Met80Gly mutant of cytochrome-c

The present study deals with identifying conformational ensembles underlying the folding pathway of a model protein, the wild type (WT) horse cytochrome-c (cyt-c) and its mutant (M80G) in water and 8 M urea at different temperatures (300–450 K). Outcomes of this study revealed that the structural dynamics of both proteins remain restricted to the marginal changes in water and urea at 300 and 350 K. The dynamic equilibrium shifted towards unfolding at 400 K, and structures of both proteins are lost completely at 450 K, however, it occurred distinctly in water and urea. Free energy landscape analyses suggested that the unfolding of the WT and M80G proteins happens through different conformational states, the native (N), meta-stable intermediate (IN), intermediate (I), partially unfolded (IU) and completely unfolded (U) states. In urea at 400 K, IN state of M80G mutant is relatively long-lived as compared to the WT protein. However, the structure of M80G protein is lost more frequently in urea at 450 K. Our in vitro studies of the urea-induced denaturation of the WT cyt-c and its M80G mutant at pH 6.0 and 25 °C showed that the mutant is more stable than the WT protein. This conclusion is reached from the analysis of the denaturation curve (mean residue ellipticity at 222 nm versus urea concentration plot).

Advanced Thick FGM Plates-Cylindrical Shells in Linear Unsteady Supersonic Flow

Introduction:: Thick functionally graded (FG) plates-cylindrical shells with third-order shear deformation theory (TSDT) of displacement models under thermal vibration in linear unsteady supersonic flow are investigated by using the generalized differential quadrature (GDQ) method. Method:: The nonlinear coefficient term of TSDT models and the advanced nonlinear shear correction coefficient expression are used to study the thermal vibration of thick FG plates and cylindrical shells in linear unsteady supersonic flow. At the intersection of FG plates-cylindrical shells, the displacements, stress resultants, and moment resultants could be reasonably assumed in the continuity condition for the differential volume in linear unsteady supersonic flow, respectively. Result:: The dynamic equilibrium differential equations of thick FG plates and cylindrical shells in linear unsteady supersonic flow, respectively in terms of partial derivatives of displacements and shear rotations subjected to partial derivatives of thermal loads, mechanical loads consist of the linear supersonic aerodynamic pressure and inertia terms can be presented. Two parametric effects including environment temperature and functionally graded material (FGM) power law index on the thermal stress and center displacement of thick FG plates-cylindrical shells in linear unsteady supersonic flow are investigated. Conclusion:: The linear unsteady supersonic flow over the outer surface of thick FG platescylindrical shells provides the additional aerodynamic effect on the values of displacements and stresses.

Erythrocyte aggregability, and fibrinogen during atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Academician N. Kipshidze University Clinic - Republican Hospital; IVANE BERITASHVILI CENTER OF EXPERIMENTAL BIOMEDICINE, Department of rheology and diagnostic analytical services. Introduction Despite all biomedical efforts, the prevalence of atrial fibrillation and its associated morbidity and mortality are increasing globally year after year. The disease's unfavorable epidemiological picture determined the reality of the project. There are many hypotheses to explain the pathogenesis of atrial fibrillation. All the hypotheses are based on mechanisms at local points and microwaves (in whole or in part). None of them consider the role of hemodynamics and hemorheology in the formation and progression of atrial fibrillation. It is also unknown how atrial fibrillation affects intracardiac macro- and microcirculation. Purpose The goals of this project were to determine how hemodynamics and hemorheology change in patients with atrial fibrillation. In order to gain a better understanding of the pathological processes underlying AF, we sought to access the relationships between hemodynamics, rheological properties,and the coagulation system of blood. Methods The Erythrocyte (RBC) Aggregation Index (EAI) was monitored in the development and validation cohorts (90 patients and 20 healthy individuals) using the textural analysis system (Tas-Plus, Leitz, Germany) and an innovative "Georgian technique" with the unique function of a quantitative assessment of the EAI. The method was developed by Georgian scientists and is well-known around the world for being direct, numerical, and precise. In all patients Coagulogram and 12-lead standard ECG were performed. Results According to the data obtained, the patients' rheological and coagulation system conditions are the same, and they are distinct from the control group. During the statistical processing of the total amount of fibrinogen (Fib), the patients were divided into three categories. The average Fib in Category I patients was 336.40 ±27,77 mg/dl, and the average EAI-RBC value was 32.8± 9.4. Category II: FIB: 373.00±22.65mg/dl; EAI-RBC: 39.8±13.8 and Category III: FIB:471.27±21.58 mg/dl; EAI-RBC: 42.6±10.4. The control group: FIB: 301±18,1 mg/dl, EAI-RBC: 25.6±1.29. Fibrinogen and the Index of Erythrocyte Aggregation were found to have a linear relationship. The higher the concentration of fibrinogen, the more severe the hemorheological disorders. It should be noted that the categories were chosen without taking into account the forms of atrial fibrillation. Conclusions The findings clearly show the existence of two parallel mechanisms in the body. These are the coagulation systems, characterized by dynamic equilibrium, and the rheology systems, which lack a physiologically balanced opposing system. Coagulation control does not accurately describe hemorheological parameters, which are one of the most powerful mechanisms for atrial fibrillation formation In order to better understand the diseases' occurrence and progression, the simultaneous studies of fibrinogen concentration and rheological parameters are especially important for both fundamental and practical medicine.

Authigenic quartz reveals the triple oxygen isotope composition and diagenetic temperature of saline brines

Triple oxygen isotope compositions of authigenic minerals are an emerging tool for the reconstruction of fluid temperatures and the fluid isotopic composition. In this study, we analyzed euhedral authigenic quartz crystals from a halite deposit of the Upper Permian Zechstein evaporitic basin for their triple oxygen isotope composition using laser fluorination isotope ratio mass spectrometry. In the triple oxygen isotope space, additional information, such as the triple oxygen isotope composition of the ambient water, provides insights into equilibrium conditions during quartz formation that cannot be identified from δ18O alone. The triple oxygen isotope composition of authigenic quartz shows, that single oxygen isotope (δ18O) thermometry is not applicable for samples from evaporitic environments, where the fluids' δ18O deviates from dynamic oxygen isotope equilibrium. By combining the Craig and Gordon evaporation model with H2O – SiO2 triple oxygen isotope equilibrium fractionation, we reconstruct the formation temperature of authigenic quartz and the triple oxygen isotope composition of the marine-derived saline brine pore fluid in equilibrium with the quartz. We obtain temperatures of 90 to 130 °C that is interpreted as crystallization temperatures of microcrystalline quartz in pore fluid of halite during burial diagenesis. The triple oxygen isotope composition of authigenic quartz from evaporitic environments is suited as a geochemical tracer for fluid oxygen isotope compositions and ancient fluid or diagenetic temperatures.

Heterogeneous Multi-Phase Grains Improving the Strength-Ductility Balance in Warm-Rolled Fe-18Mn-3Ti Steel.

The thermal properties, microstructure, and mechanical properties of Fe-18Mn-3Ti (wt%) were investigated, focusing on the effects of different heat-treatment processes. Results revealed that the 450 °C warm-rolling sample (450 WR) exhibited promising mechanical properties. Specifically, this sample displayed a yield strength of 988 MPa, an ultimate tensile strength of 1052 MPa, and total elongation of 15.49%. Consequently, a favorable strength-ductility balance was achieved. The strain-hardening ability surpassed that of the cold rolling sample (CR). Microstructure analysis indicated the simultaneous occurrence of dynamic equilibrium between grain deformation and re-crystallization because of the co-influence of thermal and strain in the warm rolling process. This desirable mechanical property was attributed to the presence of a multi-phase (α-martensite, austenite, and ε-martensite) and heterogeneous microstructure. The improvement of ultimate tensile strength was based on grain refinement, grain co-deformation, and the transformation-induced plasticity (TRIP) effect in the early stage of plastic deformation (stage Ⅰ). The improvement of ultimate elongation (TEL) was ascribed to the TRIP effect in the middle stage of plastic deformation (stage Ⅱ).

Aerobic exercise improves motor dysfunction in Parkinson's model mice via differential regulation of striatal medium spiny neuron.

The striatum plays a crucial role in providing input to the basal ganglia circuit and is implicated in the pathological process of Parkinson's disease (PD). Disruption of the dynamic equilibrium in the basal ganglia loop can be attributed to the abnormal functioning of the medium spiny neurons (MSNs) within the striatum, potentially acting as a trigger for PD. Exercise has been shown to mitigate striatal neuronal dysfunction through neuroprotective and neurorestorative effects and to improve behavioral deficits in PD model mice. In addition, this effect is offset by the activation of MSNs expressing dopamine D2 receptors (D2-MSNs). In the current study, we investigated the underlying neurobiological mechanisms of this effect. Our findings indicated that exercise reduces the power spectral density of the beta-band in the striatum and decreases the overall firing frequency of MSNs, particularly in the case of striatal D2-MSNs. These observations were consistent with the results of molecular biology experiments, which revealed that aerobic training specifically enhanced the expression of striatal dopamineD2 receptors (D2R). Taken together, our results suggest that aerobic training aimed at upregulating striatal D2R expression to inhibit the functional activity of D2-MSNs represents a potential therapeutic strategy for the amelioration of motor dysfunction in PD.

Mathematical modelling of hanging rope problem subject to rotation

The hanging rope problem is considered. The rope is subject to rotation with the rotation axis being parallel to the rope. Using a continuum model and the basic principles of dynamics, the differential equation governing the motion is derived. The dynamic equilibrium case without vibrational motion is assumed in deriving the equation. The equation is cast into a dimensionless form first. It is shown that there are two dimensionless parameters affecting the motion, the dimensionless angular velocity parameter and the dimensionless radius of rotation. The differential equation is solved exactly as well as approximately and the effects of parameters on the motion are discussed in detail. The problem can be discussed in a mechanics or differential equation course at the undergraduate level within the context of applications of differential equations to real-world problems.

Capital Control Taxes in an Emerging Market Economy

Historically, Emerging Markets (EMs) that own foreign debt and exhibit a high degree of dollarization have demonstrated vulnerability to a range of both real and financial shocks. Governments often use a range of capital control measures, particularly in nations burdened with external debt, with the aim of mitigating sudden swings in both inflows and outflows of capital. These policies are implemented to lessen exchange rate volatility and prevent dollarization. This study employs second moments analysis, impulse response functions and the welfare analysis to investigate the impact of a tax policy that restricts international capital flows on several macroeconomic variables in an emerging economy. A dynamic stochastic general equilibrium (DSGE) model is employed to examine the impact of the tax imposed on foreign borrowing on the economy, including both real shocks such as technology and growth, as well as financial shocks such as country risk premium. The findings of the study indicate that capital control taxes have a diminishing effect on the variability of significant macroeconomic variables, such as investment and consumption, when imposed at lower levels. Conversely, these taxes exhibit a stabilizing impact on the volatility of the trade balance-to-output ratio when implemented at higher levels. Moreover, quantitative evidence reveals that country risk premium shocks exert a substantial influence on variations in both the trade balance-to-output ratio and the level of investment, accounting for around 25% and 50% of the fluctuations, respectively. Finally, the existence of such a taxation enhances the intertemporal utility function at the steady state and reduces its volatility in the case of technology and growth shocks.

Analysis of the transmission of carbon taxes using a multi-sector DSGE

Carbon tax has attracted increasing attention as a means of curbing greenhouse gas (GHG) emissions. While the implementation of carbon taxes necessarily involves consideration of the impact across different sectors and different periods, most existing studies use models which do not provide a detailed account of either sectoral interaction or the dynamic nature of the responses of households and firms. To fill this gap, we construct a New Keynesian multi-sector dynamic stochastic general equilibrium (DSGE) model with an input–output structure of intermediate inputs and an investment network calibrated to Japan’s economy. We study the impact over time of carbon tax on different sectors, on aggregate GDP, and on GHG emissions. We then consider the long-term implications through a steady-state analysis, and the short- to medium-term implications by a simulation from 2020 to 2050, under various scenarios with different tax base compositions and announcement timings. We show that the impact on the trade-off between output and GHG emissions is importantly affected by inter-sectoral interactions among firms, and by the intertemporal decisions of households and firms. For example, an orderly implementation of carbon tax may mitigate a decline in value added of the most affected industry and the aggregate economy in 2050 by about 7% and 2% points, respectively, and contain an increase in the stock of GHG in 2050 by 3% points compared with the case of disorderly implementation. Also, keeping GHG emissions constant, GDP in 2050 can vary by 0.5% points depending on tax sources.

Air–plant interaction and air–soil exchange of polycyclic aromatic hydrocarbons in a large human-influenced reservoir in southwest China

The Three Gorges Reservoir (TGR) is totally manmade, strongly influenced by anthropogenic activity, and lies on the upper reaches of Yangtze River. The periodic storage and discharge of water from the Three Gorges Dam could have altered the original air-plant/soil interactions of contaminants in TGR. Herein, paired atmospheric gas–particle, air–plant, and air–soil samples were collected to investigate the air–plant interaction and air–soil exchange of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs). The air–plant interaction based on McLachlan's framework to our datasets suggests that PAHs were absorbed via gaseous deposition that was restricted by the plant–gas dynamic equilibrium. The equilibrium indicates a dynamic balance between the gaseous phase and plant surface in PAH absorption. The main limiting factor influencing the PAH uptake was the plant species rather than the atmospheric PAH concentration. The air–soil exchange of PAHs exhibited a net volatilization flux of 16.71 ng/m2/d from the soil to the air based on annual average. There was more volatilization and less deposition in summer and more deposition and less volatilization in autumn and winter. The soil serves as a secondary source of atmospheric PAHs. As the first attempt on probing the multi-interface geochemical process of PAHs, this study highlights the influence of manual water level manipulation from the TGD and environmental factors (such as temperature, humidity, and soil properties) on the regional fate of PAHs in the TGR.

Cysteine‐Based Dynamic Self‐Assembly and Their Importance in the Origins of Life

AbstractThe knowledge regarding the origins of life from inanimate materials is still elusive. It was proposed that biological building blocks evolved from the inorganic substances present in the early earth conditions. However, the process by which chemistry can be converted into biology has not yet been achieved in the laboratory. The artificial system in the out‐of‐equilibrium state must maintain a few critical features of life, like compartmentalization, metabolism, and replication, to be considered alive. In this direction, working with cysteine (Cys)‐based molecules is strategic to understand the life evolution process. The presence of the sulphydryl (−SH) group in the Cys‐residue can build a dynamic equilibrium state through disulfide redox chemistry under the proper guidance of oxidizing and reducing agents. In this review article, our primary focus is to discuss the Cys‐containing short‐peptide‐based self‐assembly and disassembly processes. The formation of disulfide bonds sometimes helps in the self‐assembly process and gelation, but the reverse is also true in some cases. In the later part of this article, we cover the fact that these sulphydryl‐based systems have shown their adaptability to mimic different life‐essential criteria to participate in Darwinian evolution.

The monetary policy of the State Bank of Vietnam, households and income distribution: the evidence from DSGE model

PurposeThis paper aims to propose a dynamic stochastic general equilibrium (DSGE) model for the State Bank of Vietnam (SBV) to assess the response from the household sector to monetary policy shocks through the consumption function. Moreover, the transmission from monetary policy to household consumption and income distribution is experimented with through the vector autoregression (VAR) model.Design/methodology/approachIn this study, the authors used the maximum likelihood estimation to estimate the DSGE and VAR models with the sample from 1996Q1 to the end of 2021Q4 (104 observations).FindingsThe DSGE model’s results show that the response of the household sector is as expected in the theory: a monetary policy shock occurs that increases the policy interest rate by 0.29%, leading to a decrease in consumer spending of about 0.041%, the shock fades after one year. Estimates from the VAR model give similar results: a monetary policy shock narrows income inequality after about 2–3 quarters and this process tends to slow down in the long run.Research limitations/implicationsBased on the research results, the authors propose policy implications for the SBV to achieve the goal of price stability, and stabilizing the macro-economic environment in Vietnam.Originality/valueThe findings of the study have theoretical contributions and empirical scientific evidence showing the effectiveness of the implementation of the SBV’s monetary policy in the context of macro-instability, namely: flexibility, caution and coordination of different measures promptly.

Impact of Internet Community, Consumer Creativity, Enterprise Utilization, and Exploratory Dynamic Equilibrium on Product Innovation Performance

Impact of Internet Community, Consumer Creativity, Enterprise Utilization, and Exploratory Dynamic Equilibrium on Product Innovation Performance

Segregation and mixing of binary mixtures of spherical particles in a bubbling fluidized bed

Abstract This work reports a CFD-DEM study on the segregation and mixing of binary mixtures of particles in a bubbling fluidized bed. A simplified mixing index was applied to determine the instantaneous mixing state in the bed, with which the effects of superficial gas velocity and initial packing state on the fluidization behavior were further discussed. For the well-mixed initial conditions, the mixing index decreases with fluidization time until a dynamic equilibrium between segregation and mixing is achieved. In contrast, the mixing index first increases and then decreases with fluidization time for completely-segregated initial conditions. However, the final equilibrium between segregation and mixing will not be affected by initial packing states for a given superficial gas velocity. Moreover, the bubbling behavior shows a marked impact on segregation and mixing, i.e., mixing is enhanced during the formation and grow-up of bubbles, while segregation is strengthened during the eruption of bubbles. This makes it possible to improve the fluidization of binary mixtures of particles based on the bubbling behaviors in the fluidized bed.

Estimation of industry-level basic digital capital services in China: A variable depreciation rate estimation method based on DSGE

Accurately measuring the input of digital capital is of great significance for understanding the development pattern of China's digital economy, nurturing new quality productivity, and achieving high-quality development. However, existing representative studies often assume a constant depreciation rate for capital goods, which does not align with reality. In this paper, we address this limitation by introducing dynamic stochastic general equilibrium (DSGE) model that estimates the variable depreciation rate for each capital good. By setting the depreciation rate as a function of capital maintenance expenditures and utilization rates, we provide a more realistic approach. The empirical results obtained through Monte Carlo simulation demonstrate that the trend of depreciation rates for all types of capital goods aligns with China's economic development. Additionally, we find that investment-specific technology shock plays a significant role in affecting changes in the depreciation rates of capital goods. This shock leads to an increase in capital utilization rates and a decrease in capital maintenance expenditures, resulting in higher depreciation rates. Notably, the depreciation rate of basic digital capital is more sensitive to exogenous shock compared to non-digital capital. Furthermore, the paper estimates the basic digital capital service of 19 industries in China from 1981 to 2020. The results indicate a steady increase in the services provided by basic digital capital, with particularly rapid growth observed in industries such as information transmission, software and information technology services, and the financial sector. When comparing our estimation results with those of representative literature, we find that the national-level productive capital stock and the basic digital capital services estimated using our methodology closely align with existing literature. This validation confirms the effectiveness of our methodology and the reliability of the estimated industry-level basic digital capital services.

Global insights into seed dispersal mutualism with cooperative efforts and environmental variability

Seed dispersal mutualisms assume a crucial role in sustaining overall ecosystem functionality. This study extends the foundational framework of seed dispersal mutualism by incorporating animal cooperation and environmental variability. Through the integration of stability theory and phase analysis, we investigate the global dynamics of seed dispersal mutualism in deterministic environments. Theoretical findings reveal that the deterministic system exclusively exhibits equilibrium dynamics, ruling out periodic solutions and chaotic phenomena. Notably, in cases of multiple coexisting equilibria, adjacent equilibria display distinct stability properties. Furthermore, employing stochastic analysis and Lyapunov exponents, we ascertain the uniqueness of global positive solutions in the stochastic model, along with stochastic ultimate boundedness, and precise thresholds for the stochastic persistence and extinction. These results illuminate the theoretical mechanisms governing transitions in seed dispersal mutualism across various stable population levels and underscore the insights into how essential biological factors, including animal cooperation efforts and environmental variability, impact the long-term dynamics of seed dispersal mutualism.

Self-foaming calcium modified carbon foam derived from a liquefied product resin of tobacco stalks for the removal of Pb2+ in water

This study demonstrated a self-foaming plus in-situ modification strategy that led to an efficient and environmentally friendly carbon foam adsorbent for removal of Pb2+ from aqueous solution. Specifically, the resin derived from liquefied tobacco stalk (TSLPR resin) was used as the precursor of carbon foams. Various characterization techniques were employed to investigate the morphology, structure, surface area, pore size, and adsorption capacity of the materials. Upon carbonization of the resin foam at 800 ℃, considerable CaO and CaCO3 converted from Ca (NO3)2 were distributed on the surface of the cell wall, indicating the success of the in-situ modification. By using a carbon foam loaded with 7% calcium (Ca@CF-7) as an adsorbent for removal of Pb2+ at a pH of 4 and 25 ℃, the dynamic adsorption equilibrium was achieved within 480 minutes. The theoretical maximum adsorption capacity (qm) obtained by Sips model reached 348.8 mg·g−1, which is more than 4.5 times higher than the pristine carbon foam. The findings of this study indicated that the chemical co-precipitation of Pb3(CO3)2(OH)2 played a significant role for removal of Pb2+, which could be attributed to the surface alkaline environment provide by CaO and CaCO3. This study offers a novel approach for in-situ modification of carbon foam and also demonstrated the potential of the straw biomass with low lignin content in production of high-performance carbon adsorbents.