Equilibrium Capacity Research Articles

Comparison of aging behavior and adsorption processes of biodegradable and conventional microplastics

With the increasing severity of the plastic pollution issue, biodegradable plastics are considered a critical approach to addressing plastic pollution. However, the aging process of biodegradable plastics and the resulting microplastics adsorption of pollutants in the environment are not clearly understood. This study investigated the physicochemical property changes of different microplastics (Biodegradable microplastics and non-biodegradable microplastics) during aging, examined the adsorption processes and mechanisms of biodegradable plastics and non-degradable plastics towards typical pollutants in the environment, and elucidated the different aging mechanisms and adsorption mechanisms of biodegradable plastics and non-biodegradable plastics. The experimental results indicated that compared to non-biodegradable microplastics, biodegradable microplastics are more prone to aging in the environment, forming smaller microplastic particles and easier adsorption of environmental pollutants. Biodegradable microplastics have abundant oxygen-containing functional groups on the surface, which enhance age biodegradable microplastics adsorption capacity for pollutants through electrostatic interactions, chelation, and hydrogen bonding. The experimental results show that a strong oxidation system has unique advantages in the aging removal of biodegradable microplastics and can effectively reduce the adsorption equilibrium capacity of biodegradable microplastics. This research contributes to a deeper understanding of biodegradable microplastics’ aging and adsorption behaviors in the environment, highlighting their significant role as carriers of pollutants.

Maximizing methane production in adsorptive nitrogen removal from natural gas: The impact of dehydration temperature on Ba-ETS-4 separation performance

Ba-ETS-4 is a promising adsorbent for nitrogen removal from low-grade natural gas. However, the Ba-ETS-4 adsorption characteristics, i.e., both adsorption kinetics and equilibrium capacity, change by dehydration temperature owing to structural shrinkage and pore contraction which finally impact the separation performance of the adsorption bed. In this paper, experimental breakthrough data are provided for N2/CH4 separation at various Ba-ETS-4 dehydration temperatures (250°C-450 °C) followed by a separation performance analysis in generating methane as the main product. Additionally, isotherm data at different temperatures (20 °C, 40 °C, 60 °C and 80 °C) are presented for selected dehydration temperatures (250 °C, 350 °C, 400 °C and 440 °C). The results revealed that an increase in dehydration temperature leads to a decrease in adsorption capacity but a better separation by providing more hindrance for CH4 diffusion, while not affecting the N2 breakthrough wavefront. At a dehydration temperature of 250 °C, the N2 breakthrough time is the highest, indicating the ability to process a larger feed. However, this also leads to the least CH4 production (0.037 mmol/g), as most of the fed CH4 is adsorbed onto the bed. Interestingly, an increase in dehydration temperature leads to an increase in CH4 production up to 420 °C (0.140 mmol/g), after which the CH4 production decreases sharply.

Uptake of selected heavy metals from contaminated waters utilizing cost-effective and environmentally friendly biosorbents prepared from the residues of a traditionally fermented Ethiopian alcoholic beverage (Tella)

In the current study, the adsorption capacity of Tella residues (residues of fermented alcoholic beverage) for quantitative uptake of Cu(II), Cd(II), Zn(II) and Pb(II) was evaluated. Chemical treatment of the local beer residue (LBR) has improved the removal efficiency of the adsorbent, which was achieved at pH = 5, 1.0 g adsorbent, 50 mg/L initial concentration, 180 min contact time and agitation speed of 100 rpm. The adsorption was found to fit the Langmuir adsorption isotherm model, and the theoretical equilibrium capacities were well fitted with the experimental equilibrium capacities, resulting in chemical adsorption (chemisorptions) on the adsorbent surface while the equilibrium kinetics follows the pseudo-second-order. The adsorption capacity (Qo) of LBR decreases in the following order: Zn(II) > Cu(II) > Pb(II) > Cd(II) as metal concentration ranged from 20-200 mg/L. Thermodynamic parameters, including standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated to predict the nature of adsorption. The negative values of ΔG° and the positive value of ΔH° indicate that the adsorption process was spontaneous and endothermic. Adsorption capacities were found to increase when the temperature ranged from 25-60 °C. Thus, the findings suggest a promising application of LBR as an alternative low-cost novel adsorbent for the removal of toxic heavy metals from wastewater.

Use of molecular simulation to design modification of a chromium‐based MOF for adsorptive removal of inhalation anaesthetic agents

AbstractMIL‐101‐Cr‐X (X = OH−, F−) has been reported to be the most suitable material so far for adsorptive removal of inhalation anaesthetic agents (IAA) sevoflurane and desflurane at the working conditions in hospital operation rooms. To further enhance its affinity and uptake capacity towards IAA, several structural modifications were proposed, and their isotherms were predicted using our molecular simulation approach adopted in our previous publication for the case of the pristine MIL‐101‐Cr (X = F−, OH−) structure. The proposed modifications include (1) grafting the metal‐cluster site with coordinated NH3 ligands to produce MIL‐101‐Cr@NH3 (X = F−, OH−), (2) anion exchange of the fluorine atom bonded to chromium with chlorine to synthesize MIL‐101‐Cr (X = Cl−), and (3) functionalization of the benzene rings of the ligand linkers in the MOFs with amino‐ and nitro‐ groups in order to form NH2‐MIL‐101‐Cr (X = Cl−) and NO2‐MIL‐101‐Cr (X = Cl), respectively. Simulated adsorption isotherms of IAA on these modifications were verified by the experimental results using the standard volumetric technique and they clearly demonstrated that MIL‐101‐Cr@NH3 (X = F−, OH−) possesses the highest equilibrium capacity for IAA. This observation can be attributed to the electron‐transfer contribution of the coordinated ammonium molecules to the unsaturated coordinated sites of the MOF while doing away with steric hindrance inside the pore cages. The new compound can significantly enhance the economy of adsorptive removal of IAA from vented gas mixtures.

Removal of Chromium and Arsenic from Water Using Polyol-Functionalized Porous Aromatic Frameworks.

Chromium and arsenic are two of the most problematic water pollutants due to their high toxicity and prevalence in various water streams. While adsorption and ion-exchange processes have been applied for the efficient removal of numerous toxic contaminants, including heavy metals, from water, these technologies display relatively low overall performances and stabilities for the remediation of chromium and arsenic oxyanions. This work presents the use of polyol-functionalized porous aromatic framework (PAF) adsorbent materials that use chelation, ion-exchange, redox activity, and hydrogen-bonding interactions for the highly selective capture of chromium and arsenic from water. The chromium and arsenic binding mechanisms within these materials are probed using an array of characterization techniques, including X-ray absorption and X-ray photoelectron spectroscopies. Adsorption studies reveal that the functionalized porous aromatic frameworks (PAFs) achieve selective, near-instantaneous (reaching equilibrium capacity within 10 s), and high-capacity (2.5 mmol/g) binding performances owing to their targeted chemistries, high porosities, and high functional group loadings. Cycling tests further demonstrate that the top-performing PAF material can be recycled using mild acid and base washes without any measurable performance loss over at least ten adsorption-desorption cycles. Finally, we establish chemical design principles enabling the selective removal of chromium, arsenic, and boron from water. To achieve this, we show that PAFs appended with analogous binding groups exhibit differences in adsorption behavior, revealing the importance of binding group length and chemical identity.

Improved Cupressus sempervirens L. galls for methylene blue removal: adsorption kinetics optimisation using the DA-LS algorithm, characterisation, and machine learning modeling

ABSTRACT In this study, an investigation was conducted on the effectiveness of three bioadsorbents – galbuli of Cupressus sempervirens L. almond shells, and Luffa – for removing methylene blue (MB) from water. Various activation techniques and operational conditions were employed to enhance the adsorption capacity. The study focused on adsorption kinetics and equilibrium capacity. The results showed that microwave-dried galbuli of Cupressus sempervirens L. exhibited the highest adsorption capacity of 38.05 mg/g with an adsorption efficiency of 17.4%. To improve this capacity, the Dragonfly Algorithm-integrated least squares (DA-LS) was proposed to optimise the fitting of 32 adsorption isotherm models, which included a proposed modified Langmuir model. After optimisation, the sixth chemical treatment of Cupressus sempervirens L. reached a Langmuir isotherm qmax value of 84.44 mg/g, suggesting the high efficiency of the bioadsorbent compared to previous studies. Characterisation using microscopy and ATR-FTIR techniques revealed that chemical modifications led to rougher, microporous cellulose fibres and significant changes in the chemical structure, potentially enhancing the surface area and adsorption efficiency. To predict the adsorption capacity, the Support Vector Machine for Regression with DA (SVMR-DA) was utilised, achieving a root mean square error (RMSE) of 1.357 and an R2 of 0.9913. This high accuracy indicates a reliable model with a robust error distribution. These results suggest that Cupressus sempervirens L. can be an effective bioadsorbent for water treatment, with significant potential for industrial application.

Adsorption mechanism of hexavalent chromium on electron beam-irradiated aged microplastics: Novel aging processes and environmental factors

Microplastics are widely present in the natural environment and exhibit a strong affinity for heavy metals in water, resulting in the formation of microplastics composite heavy metal pollutants. This study investigated the adsorption of heavy metals by electron beam-aged microplastics. For the first time, electron beam irradiation was employed to degrade polypropylene, demonstrating its ability to rapidly age microplastics and generate a substantial number of oxygen-containing functional groups on aged microplastics surface. Adsorption experiments revealed that the maximum adsorption equilibrium capacity of hexavalent chromium by aged microplastics reached 9.3 mg g−1. The adsorption process followed second-order kinetic model and Freundlich model, indicating that the main processes of heavy metal adsorption by aged microplastics are chemical adsorption and multilayer adsorption. The adsorption of heavy metals on aged microplastics primarily relies on the electrostatic and chelation effects of oxygen-containing functional groups. The study results demonstrate that environmental factors, such as pH, salinity, coexisting metal ions, humic acid, and water matrix, exert inhibitory effects on the adsorption of heavy metals by microplastics. Theoretical calculations confirm that the aging process of microplastics primarily relies on hydroxyl radicals breaking carbon chains and forming oxygen-containing functional groups on the surface. The results indicate that electron beam irradiation can simultaneously oxidize and degrade microplastics while reducing hexavalent chromium levels by approximately 90%, proposing a novel method for treating microplastics composite pollutants. Gas chromatography-mass spectrometry analysis reveals that electron beam irradiation can oxidatively degrade microplastics into esters, alcohols, and other small molecules. This study proposes an innovative and efficient approach to treat both microplastics composite heavy metal pollutants while elucidating the impact of environmental factors on the adsorption of heavy metals by electron beam-aged microplastics. The aim is to provide a theoretical basis and guidance for controlling microplastics composite pollution.

МОДЕЛИРОВАНИЕ ПАРАМЕТРОВ ДОРОЖНОГО ДВИЖЕНИЯ С УЧЕТОМ «УЗКИХ МЕСТ» В ТРАНСПОРТНЫХ ПОТОКАХ

The article examines a macromodel of traffic flow considering a static bottleneck in order to study the impact on traffic conditions. Analytical results show that the proposed model can qualitatively de-scribe the equilibrium flow and capacity reduction in the event of traffic congestion

On Comparing Packed Beds and Monoliths for CO2 Capture from Air Through Experiments, Theory, and Modeling.

This study compares the performance of amine-functionalized γ-alumina sorbents in the form of 3 mm γ-alumina pellets and of a γ-alumina wash-coated monolith for CO2 capture for direct air capture (DAC). Breakthrough experiments were conducted on the two contactors to analyze the adsorption kinetics and performance for different gas feeds. A constant pattern analysis revealed dominant mass transfer resistances in the gas film and in the pores, with axial dispersion also observed, particularly at higher concentrations. A 1D, physical model was used to fit the experiments and thus to estimate mass transfer and axial dispersion coefficients, which appear to be consistent with the hypotheses derived from constant pattern analysis. A dual kinetic model to describe mass transfer was found to better describe the tail behavior in the monolith, whereas a pseudo-first-order model was sufficient to describe breakthroughs on packed beds. A substantial two-order magnitude decrease in mass transfer coefficients was noted when reducing the feed concentration from 5.6% to 400 ppm CO2, thus underscoring the significant mass transfer limitations observed in DAC. Comparison between the contactors revealed notably higher mass transfer coefficients in the monolith compared to the packed beds, which are attributed to shorter diffusion lengths and lower equilibrium capacity. While the faster mass transfer coefficients observed in the monolith experiments led to reduced specific energy consumption and increased adsorption productivity compared to the packed bed at 400 ppm, no significant improvement was observed for the same process at the higher concentration of 5.6% CO2 in the feed. This finding highlights the need to tailor the contactor design to the specific gas separation requirements. This research contributes to the understanding and quantification of mass transfer kinetics at DAC concentrations in both packed bed and monolith contactors. It demonstrates the crucial role of the contactor in DAC systems and the importance of optimizing the adsorption step to enhance productivity and DAC performance.

Zeolite-coated 3D-printed gyroid scaffolds for carbon dioxide adsorption

3D-printed adsorbents are gaining increased attention owing to their potential in overcoming operational challenges faced by the conventionally structured counterparts. In this work, cylindrical scaffolds of triply periodic minimal surface (TPMS) configuration were synthesized using 3D-printing by stereolithography. This unique gyroid sheet TPMS network was selected as it offers a high surface-area-to-volume ratio. The surface of the scaffolds was modified by a silanization process followed by coating via grafting with zeolite 13X crystals toward CO2 adsorption application. A secondary zeolite coating step was also employed to enhance the zeolite 13X loading, resulting in zeolite loadings of 16 wt% and 23 wt% after the primary and secondary coatings, respectively. Following morphological and structural characterization, the CO2 adsorption performance of the 3D-printed materials was evaluated with respect to adsorption capacity, kinetics, selectivity, and heat of adsorption. Cyclic stability was also assessed over CO2 adsorption–desorption pressure swing adsorption cycles at 25 °C. Comparative analysis showed that the 3D-printed coated samples exhibited higher CO2/N2 selectivity and improved cyclic stability with a slightly lower CO2 adsorption capacity than the zeolite 13X powder. The heat of adsorption ranged from 18 to 41 kJ mol−1 for both the powder and the coated adsorbents, indicating physisorption. The gyroid lattice of the 3D-printed structures, featuring a densely arranged network of smooth, interconnected flow channels, facilitated molecular transport thus yielding higher CO2 adsorption kinetics than the powder. Indicatively, the primary and secondary coatings attained an equilibrium capacity of 4 mmol g−1 at 25 °C in 62 and 57 min, respectively, while the powder required 110 min at the same conditions. The 3D-printed materials exhibited also significantly higher CO2/N2 selectivity values of 569 and 115 at 50 mbar and 1 bar, respectively, for the primary coating sample, and 536 and 73 at 50 mbar and 1 bar, respectively, for the secondary coating one. The findings highlight the potential of 3D-printing to produce coated structured adsorbents with complex geometries for sustainable CO2 capture and gas adsorption processes.

Efficient removal of tizanidine and tetracycline from water: A single and competitive sorption approach using carboxymethyl cellulose granulated iron-pillared clay

This study deals with the development of a granulated Fe-pillared clay (Fe-PC) using carboxymethylcellulose (CMC) as a binder to present it as an innovative adsorbent for the individual and competitive adsorption of tetracycline (Tc) and tizanidine (Tz) from water. An optimum pH value of 7 was determined for both individual and multi-component adsorption. The optimal dosage of granulated Fe-PC was determined to be 1.5 g/L for Tz and 3 g/L for Tc, resulting in constant removal rates of 80 % for Tc and 90 % for Tz. Tizanidine showed a higher affinity for powdered or granulated Fe-PC compared to tetracycline, due to its smaller molecular size and increased amine functional groups. Consequently, Tz showed improved kinetic rates (initial pseudo-second order sorption rates of 170.79 and 25.62 mg/g.h for Tz and Tc, respectively) and equilibrium capacities (maximum monolayer adsorption capacity of granulated Fe-PC at room temperature over Tc and Tz, 54.89 mg/g and 66.40 mg/g). Granulation affected the kinetic rate for both adsorbates, albeit with a more pronounced effect for Tc. The adsorption of Tz was less sensitive to temperature changes, indicating a lower enthalpy change of adsorption (14.24 and 77.91 kJ/mol for Tz and Tc, respectively). HCl for Tc and NaCl for Tz were identified as optimal desorption eluents, confirming the involvement of cation exchange in Tz adsorption. Surface functional group analysis confirmed the proposed complexation mechanisms. Tz consistently showed a higher affinity for granular Fe-PC than Tc, especially at lower adsorbent dosages. This article provides a comprehensive insight into the characterization of the prepared adsorbents and their cyclic adsorption-desorption performance for Tc and Tz.

Comparative Analysis of Hydrogel Adsorption/Desorption with and without Surfactants.

In this particular study, a hydrogel known as SAP-1 was synthesized through the grafting of acrylic acid-co-acrylamide onto pullulan, resulting in the creation of Pul-g-Poly (acrylic acid-co-acrylamide). Additionally, a sponge hydrogel named SAP-2 was prepared by incorporating the surfactant sodium dodecyl benzene sulfonate (SDBS) into the hydrogel through free radical solution polymerization. To gain further insight into the composition and properties of the hydrogels, various techniques, such as Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance (1H NMR), atomic absorption spectroscopy, and field emission scanning electron microscopy (FE-SEM), were employed. Conversely, the absorption kinetics and the equilibrium capacities of the prepared hydrogels were investigated and analyzed. The outcomes of the investigation indicated that each of the synthesized hydrogels exhibited considerable efficacy as adsorbents for cadmium (II), copper (II), and nickel (II) ions. In particular, SAP-2 gel displayed a remarkable cadmium (II) ion absorption ability, with a rate of 190.72 mg/g. Following closely, SAP-1 gel demonstrated the ability to absorb cadmium (II) ions at a rate of 146.9 mg/g and copper (II) ions at a rate of 154 mg/g. Notably, SAP-2 hydrogel demonstrated the ability to repeat the adsorption-desorption cycles three times for cadmium (II) ions, resulting in absorption capacities of 190.72 mg/g, 100.43 mg/g, and 19.64 mg/g for the first, second, and third cycles, respectively. Thus, based on the abovementioned results, it can be concluded that all the synthesized hydrogels possess promising potential as suitable candidates for the adsorption and desorption of cadmium (II), copper (II), and nickel (II) ions.

Facile Preparation of Magnetic Chitosan Carbon Based on Recycling of Iron Sludge for Sb(III) Removal

In this study, following the concept of “treating waste with waste”, magnetic chitosan carbon (MCC) was developed through the pyrolysis of chitosan/iron sludge (CHS) beads created using an embedding method in a closed environment for antimony removal. The results indicate MCC has a good magnetic recovery rate and that its magnetic saturation strength can reach 33.243 emu/g. The iron proportion and acid resistance of MCC were all better than those of CHS, and at 25 °C, its adsorption saturation capacity improved from 24.956 mg/g to 38.234 mg/g. MCC has a quick adsorption equilibrium time, and in about 20 min, 90% of the final equilibrium capacity can be achieved. The primary mechanism of Sb adsorption by MCC is the formation of an inner sphere complex between Fe-O and Sb, while surface complexation, hydrogen bonding, and interaction also play a function. Thus, MCC, a lower-cost and greener adsorbent for Sb removal, has been made using iron sludge. This enabled it to utilize iron sludge as a resource and served as a reference for the sustainable management of water treatment residuals.

Preparation of PVA/SA-FMB Microspheres and Their Adsorption of Cr(VI) in Aqueous Solution

Biochar, a carbon-dense material known for its substantial specific surface area, remarkable porosity, diversity of functional groups, and cost-effective production, has garnered widespread acclaim as a premier adsorbent for the elimination of heavy metal ions and organic contaminants. Nevertheless, the application of powdered biochar is hindered by the challenges associated with its separation from aqueous solutions, and without appropriate management, it risks becoming hazardous waste. To facilitate its use as an immobilization medium, biochar necessitates modification. In this investigation, sodium alginate, celebrated for its superior gelation capabilities, was amalgamated with polyvinyl alcohol to bolster mechanical robustness, thereby embedding biochar to formulate sodium alginate biochar microspheres (PVA/SA-FMB). A meticulously designed response surface methodology experiment was employed to ascertain the optimal synthesis conditions for PVA/SA-FMB. Characterization outcomes unveiled a highly developed surface abundant in functional groups and confirmed the successful incorporation of iron ions. Adsorption trials revealed that at a temperature of 25 °C and a pH of 2, the adsorption capacity of PVA/SA-FMB for Cr(VI) was 13.7 mg/g within the initial 30 min, reaching an equilibrium capacity of 26.03 mg/g after 1440 min. Notably, the material sustained a Cr(VI) removal efficiency exceeding 90% across five cycles, underscoring its rapid and effective Cr(VI) eradication performance. Kinetic and isothermal adsorption analyses suggested that the adsorption of Cr(VI) adheres to a pseudo-second-order kinetic model and the Freundlich isotherm, indicative of monolayer adsorption dominated by reaction mechanisms. X-ray photoelectron spectroscopy (XPS) analysis inferred that the adsorption mechanism predominantly encompasses electrostatic attraction, redox processes, and complex formation.

An equilibrium capacity expansion model for power systems considering Gencos' coupled decisions between carbon and electricity markets

Equilibrium capacity expansion is an effective tool to help regulators predict the generation evolution of power systems by analyzing the decision-making of generation companies (Gencos). With the development of carbon markets (CMs) and electricity markets (EMs), Gencos' decisions in these two markets (encompassing investment and bidding decisions related to carbon emission allowances and electricity) are deeply intertwined through market clearing results. However, existing studies mainly focus on equilibrium capacity expansion with fixed carbon prices and usually ignore the realistic clearing process of CMs, which cannot simulate Gencos' coupled decision-making and accurately predict generation evolution under the CMs and EMs. This paper proposes a two-level equilibrium capacity expansion model for power systems which considers the coupled decisions of Gencos between CMs and EMs. At the upper level, multiple Gencos' coupled decision models are proposed based on their interaction with market clearing results. At the lower levels, CMs and EMs are respectively cleared to determine the varying carbon and electricity prices. Furthermore, the developed equilibrium capacity expansion model is reformulated as an equilibrium problem with equilibrium constraints (EPEC), which is solved by a diagonalization-based solution procedure. Finally, a provincial power system of southeast China is used to validate the performance of the proposed framework. The results illustrate that under CMs and EMs, non-fossil energy would account for 81.3% of total capacity and 73.88% of total generation in 2050. Compared to the existing model using fixed carbon prices, the consideration of realistic carbon market clearing will promote the installation of renewable energies and improve social welfare. The proposed model can provide beneficial references for regulators to perceive the evolution of power systems in CMs and EMs.

Pecan shells-based activated carbon for the removal of copper metal ions: optimization of the adsorption process using a full factorial design

ABSTRACT This work investigates the removal of copper ions (Cu2+) from an aqueous solution by adsorption onto the surface of activated carbon (AC) produced from pecan shells. The research aims to identify a feasible and effective route for cleaning the wastewater from Cu2+. Chemical activation was carried out using sodium hydroxide. The AC physicochemical properties were characterised by scanning electron microscopy, Fourier-transform infrared, X-ray diffraction, and Brunauer-Emmett-Teller for measuring its specific surface area. To obtain a suitable removal of this metal ion, four physicochemical factors, including the contact time (120–360 min) the adsorbent dose (10–100 mg), initial concentration (10–50 mg/L), and pH (2–6) were optimised using the 24-full factorial design approach. A quadratic regression model representing the capacity of Cu2+ adsorption (Q e) was developed and validated by the analysis of variance. This approach was used to determine independent factors’ main and interaction effects on adsorption equilibrium capacity. The results consolidate similar studies showing that all the factors were significant, and the interactions among the factors were also significant. The optimum conditions for circumscribed fractional factorial design were adsorption time (120 min), adsorbent amount (10 mg), initial metal ions (50 mg/L), and pH 6. The pseudo-first-order model correctly describes the adsorption kinetics with Q e, reached 51.41 mg/g. Modeling adsorption isotherms showed that the Freundlich model adequately describes the adsorption process.

Optimal lane allocation strategy for shared autonomous vehicles mixed with regular vehicles

Autonomous driving technology has the potential to alter the way we travel and is rapidly evolving. Sharing rides in autonomous vehicles may become a popular mode of public transportation in the future. One strategy to enhance operational efficiency is to deploy designated autonomous vehicle (AV) lanes for shared autonomous vehicles (SAVs). This study investigated optimal allocation for dedicated AV lanes considering mixed SAVs and regular vehicles (RVs) flows. First, the standard bottleneck model for morning rush hour was extended to account for both ridesharing and automation, and user equilibrium (UE) solutions were obtained by assuming dedicated AV lanes co-exist with general-purpose (GP) lanes. The equilibrium capacity allocation for dedicated AV lanes was determined for multi-modal traffic scenarios. The study found that commuters may prefer to use SAVs because SAVs were more cost-effective and time-saving. Furthermore, analysis of the fixed payment for ridesharing in SAVs revealed that the system performance could be negatively impacted by high fixed payments. The study proposed an enumeration algorithm for developing lane strategies for discrete lane settings. It was found that the deployment of dedicated AV lanes should be matched to the penetration rate of SAVs and different management objectives, following a gradual rather than a radical process. Finally, a sensitivity analysis was performed considering the value of travel time for SAVs and the bottleneck capacity of a dedicated AV lane. This work provides a new solution to AV lane capacity allocation and offers theoretical support for managers to deploy dedicated AV lane allocation.

An Effective Sol-Gel-Functionalized Polyurethane Foams Solid Platform Packed Minicolumns for Complete Extraction of Chromium (VI) from Water: Kinetic, Sorption Isotherms, Thermodynamic Study, and Analytical Utility.

In the modern era, sol-gel plays a key role in the progress of a new generation of dispersive solid-phase microextractors (d-µ SPMEs) for the removal of organic and inorganic pollutants in complex matrices. Thus, the current study reports the use of sol-gel-functionalized polyurethane foams (PUFs) as a novel solid platform for complete extraction of chromium (VI) species from aqueous media. The planned protocol was based upon the complete extraction of the formed binary complex ion associates between the protonated ether and/or urethane groups of PUFs and chlorochromate anion [CrO3Cl]- aq in aqueous HCl (≥1M) medium in addition to H-bonding and the electrostatic π-π interaction that resulted between the CrO3Cl- and the silanol group (Si/ZrO2, Si-O-Zr) and siloxane (Si-O-Si) groups of the sol-gel. The impact of the analytical parameters (solution pH, natural mineral acids, shaking time, temperature, and chromium (VI) concentrations) was critically studied. At the optimal conditions, the uptake capacity of the established extractor (9.9 mg·g-1) was in agreement with the Langmuir adsorption capacity (12.08 mg·g-1) of the monolayer. The sorption data fitted well with the pseudo first-order kinetic model (R 2 = 0.9961) with an overall rate constant (k 1) of 0.081 min-1 and an equilibrium capacity (q e ) of 8.6 mg·g-1, which is in a good agreement with the experimental value (9.9 mg·g-1). The sorption of the oxyion [CrO3Cl]- aq onto the solid sorbent is an endothermic and spontaneous process as reflected from the values of ΔH (6.99 kJ·mol-1) and ΔG (-8.14 kJ·mol-1 at 293 K), respectively. The ΔS value (15.13 kJ·mol-1·K-1) reflects that the [CrO3Cl]- aq retention onto the sol-gel-treated PUFs sorbent proceeded in a more unplanned fashion. Sol-gel-treated PUFs sorbent-packed minicolumns were successfully used for the complete removal of trace levels of chromium (VI) species from water samples. Sorbed chromium (VI) species were recovered with NaOH (0.5 M) and analysed by spectrophotometry, which supports the utility of the sol-gel-treated PUFs as a low-cost solid extractor for water treatment.

Highly efficient eco-friendly sodium titanate sorbents of Cs(i), Sr(ii), Co(ii) and Eu(iii): synthesis, characterization and detailed adsorption study.

Development of useful all-around materials which can quickly and efficiently adsorb radionuclides in response to environmental radioactive contamination is an urgent research objective. In response to this need, our team developed a simple preparation method for stable sodium titanates which can serve as efficient agents for removal of radionuclides from water. With an emphasis on an environmentally friendly synthesis, the resulting materials were defined by a range of means and methods measuring e.g. pH, ionic strength, contact time or metal ion concentration in order to assess their potential for use and applications as sorbents. The data obtained from measurements revealed rapid removal kinetics (up to 10 minutes), wide range of pH use and high equilibrium capacity. The maximum amount of adsorbed ions as calculated from the Langmuir isotherm was equal to 206.3 mg g-1 for Cs(i), 60.0 mg g-1 for Sr(ii), 50.2 mg g-1 for Co(ii) and 103.4 mg g-1 for Eu(iii), significantly exceeding published data obtained with related materials. The removal mechanism is most likely ion exchange followed by complexation reactions, as indicated by TEM/EDS analyses. Given their extraordinary sorption capacity and facile synthesis under mild conditions, these materials are promising candidates for the efficient removal of radionuclides from aqueous solutions during the clean-up of radioactive pollution in the environment.

Alkali activated winter melon peel as absorbent: Characterization and its adsorption performance for heavy metal ions in aqueous solutions

Agricultural waste winter melon peel was used as raw material as adsorbent material. In order to improve adsorption characteristic, this material modified with NaOH (AWMP). The AWMP was characterized by IR, XRD and XPS. The adsorption performance of AWMP on Cu (II) and Pb (II) in aqueous solution were investigated.The effects of the initial concentration of Cu(II) and Pb(II), contact time, solution pH, and temperature are studied in batch adsorption. The kinetics shows that the equilibrium reached in 60 min and the adsorption is favored above pH 5.0. The highest adsorption capacity for Langmuir isotherm for Cu(II) and Pb(II) onto AWMP was observed to be 197.8 mg/g and 188.8 mg/g respectively. Based on predicted and experimental values of equilibrium capacity, kinetic modeling demonstrated the suitability of the pseudo-second-order kinetic model. Finally, the regeneration of AWMP was also studied up to 10 cycles. Thus, AWMP showed excellent adsorption characteristics during the uptake of Cu(II) and Pb(II) from wastewater effluent and can be used as low-cost agricultural waste biomass as an adsorbent.