Adsorption Characteristics Research Articles

Phosphorus recovery from aqueous solutions by a Mg/Al-modified biochar from date palm wastes in column mode: adsorption characteristics and scale-up design parameters assessment

Phosphorus recovery from aqueous solutions by a Mg/Al-modified biochar from date palm wastes in column mode: adsorption characteristics and scale-up design parameters assessment

Enhanced Lead and Zinc Removal via Prosopis Cineraria Leaves Powder: A Study on Isotherms and RSM Optimization

This study investigates the potential of Prosopis cineraria Leaves Powder (PCLP) as a biosorbent for removing lead (Pb) and zinc (Zn) from aqueous solutions, optimizing the process using Response Surface Methodology (RSM). Prosopis cineraria, commonly known as Khejri, is a drought-resistant tree with significant promise in environmental applications. The research employed a Central Composite Design (CCD) to examine the independent and combined effects of key process variables, including initial metal ion concentration, contact time, pH, and PCLP dosage. RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal, allowing the determination of optimal operating conditions. The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals, suggesting favorable adsorption characteristics. Additionally, the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process. For lead removal, the optimal conditions were found to be 312.23 K temperature, pH 4.72, 58.5 mg L−1 initial concentration, and 0.27 g biosorbent dosage, achieving an 83.77% removal efficiency. For zinc, the optimal conditions were 312.4 K, pH 5.86, 53.07 mg L−1 initial concentration, and the same biosorbent dosage, resulting in a 75.86% removal efficiency. These findings highlight PCLP’s potential as an effective, eco-friendly biosorbent for sustainable heavy metal removal in water treatment.

Size-dependent guest-memory switching of the flexible and robust adsorption characteristics of layered metal-organic frameworks.

Flexible-robust metal-organic frameworks (MOFs), which exhibit unique hybrid nature comprising both flexible and rigid framework characteristics, exhibit high potential for hydrocarbon separations. However, no clear guidelines have been established to regulate their hybrid characteristics owing to limited understanding of their adsorption mechanism. This study investigates the effects of the particle size of a flexible-robust MOF on its adsorption and structural transition behaviors. The robust nature originates from the structural transition of a metastable guest-free structure, while its flexible nature arises from another guest-free structure. The type of guest-free structure is predominantly determined by the particle size; particles below the critical size are trapped in the metastable guest-free structure. Notably, the critical size varies with the type of guest molecule to be removed; consequently, the difference in critical size results in guest-memory characteristics, enabling guest-free structure switching. These results underscore the importance of controlling the particle size to fine-tune hybrid adsorption characteristics of flexible-robust MOFs.

Unveiling heavy metal removal mechanisms in mulberry and rice husk biochars via sacrificial mineral descriptors.

Rice husk biochar (RBC) and mulberry biochar (MBC) have gained significant attention in the removal of heavy metals in aquatic environments. Their easy affordability and eco-friendly nature make these biochar's a powerful adsorbent for sustainable water remediation applications. Although their heavy metal adsorption characteristics of individual biochar's have been widely studied, a clear understanding of how the inherited mineral composition in RBC and MBC influences Pb2+, Cd2+, and Zn2+ removal in both deionized water (DIW) and Organization for Economic Co-operation and Development (OECD) water is currently lacking. In this study, heavy metal removal mechanisms of RBC and MBC in these water systems were investigated using various kinetic models and correlated them with their mineral composition. With the highest correlation coefficient of modified two-compartment first-order kinetic model (MTCFOKM), the measured qe values highlight MBC as a promising candidate for heavy metal removal in both acidic and alkaline conditions. pH edge experiments revealed significant differences in metal removal efficiency between these biochars, despite their similar specific surface areas and surface charges (pHpzc). XRD and FTIR characterization provided a strong support in explaining the high heavy metal removal ability of MBC stem from calcite mineral that inherited from biomass. Furthermore, the pH edge experiment combined with MINEQL+ speciation profiles revealed that heavy metal removal by MBC at low pH is linked to calcite leaching, shift in system pH, and heavy metal precipitation.

Novel gas sensing mechanisms of Pd and Rh-doped h-BN monolayers for detecting dissolved gases (H2、CH4、and C2H4) in transformer oil

Detecting dissolved gases in transformer oil is crucial for assessing the operational status of transformers. The gas composition in transformer oil can reflect the health status of the equipment and help identify potential failure risks in a timely manner. Based on density functional theory (DFT), Pd and Rh atoms were doped into the h-BN monolayer, and the most stable adsorption structures for each were first explored. Then, the sensing performance of the Pd-doped and Rh-doped h-BN monolayers for H2, CH4, and C2H4 gases was analyzed. The results indicate that Pd-BN and Rh-BN exhibit enhanced sensitivity to H2 and C2H4 gases compared to pristine h-BN. However, they show poor adsorption characteristics for CH4. Both Pd-BN and Rh-BN demonstrate strong chemisorption for H2 and C2H4. In contrast, CH4 adsorption is predominantly physisorbed. The desorption time of H2 from Pd-BN at 398 K is 164 s, reflecting its excellent desorption performance. Additionally, Pd-BN and Rh-BN monolayers exhibit exceptional C2H4 capture capabilities, with adsorption energies of −1.697 eV and −2.188 eV, respectively, indicating their potential as C2H4 gas adsorbents. These findings provide theoretical insights for selecting materials for dissolved gas detection in oil and lay the groundwork for the development of Pd-BN and Rh-BN-based gas sensors.

Innovation in radiolabeling methods: iodine adsorption characteristics on porous silica nanoparticles

Innovation in radiolabeling methods: iodine adsorption characteristics on porous silica nanoparticles

Study on adsorption characteristics of biochars and their modified biochars for removal of organic dyes from aqueous solution

Abstract To address organic dye pollution and agricultural waste comprehensive utilization, the biochar (ZB) was prepared using Rosa roxburghii residue as the material for preparation. Three modified biochars (ZBO, ZBS, and ZBH) were created using NaOH, Na2S, and H3PO4 as modifying agents. The morphology, structure, pore size, and elemental composition of biochars were characterized and analyzed by a combination of FTIR, SEM-EDS, and N2 adsorption–desorption techniques. Furthermore, the adsorption performance of the as-prepared biochars was investigated in the adsorption of RhB and MB dye process. The experimental findings showed that adsorption equilibrium for these dyes was achieved in 180 min. Moreover, the dye adsorption on biochars followed a pseudo-second-order kinetic equation. For the biochar (ZB), the Langmuir equation proved to be more appropriate than the Freundlich equation. In contrast, the Freundlich equation was more apt for the modified biochars. More importantly, Pearson's correlation analysis revealed that the adsorption rate and capacity of RhB positively correlated with the specific pore volume, t-plot micropore area, and BET surface area, but a negative one with the pore size. The MB adsorption showed the opposite correlations. This study reveals a novel biochar for adsorbing organic dyes, which provides a strategy for the treatment of Rosa roxburghii residue.

Electric Field-assisted Photocatalytic Reduction of Carbon Dioxide over Titanium Dioxide: Influence of the Type and Strength of Electric Field

This study focuses on investigating the sole impact of an external electric field on the photocatalytic activity of TiO2-based materials. Typically, built-in electric fields are used to efficiently separate free energy carriers and improve the photocatalytic performance of semiconductors. The creation of such field requires modifications to the photocatalyst that alter various properties such as adsorption and optical characteristics. These modifications make it challenging to isolate and interpret the promotion effect associated with the electric field alone. The investigations were carried out in the gas-phase conditions in a specially constructed reactor equipped with two electrodes connected to a high – voltage that provides a field strength of up to 5.7·103 V/cm. The results showed that the effect of electric field promotion varied significantly depending on the properties of titanium dioxide, such as structure, adsorption, and presence of impurities. The strength and the type (direct or alternating current) of the electric field also played a determining role. The greatest promoting effect was observed for rutile, the photocatalytic activity of which under an electric field increased threefold in the process of reduction of CO2 with water vapor.Graphical

Characteristics of fluoride adsorption in different soil types: potential factors and implications for environmental risk assessment.

The adsorption of fluoride by soils influences its mobility and bioavailability. Therefore, the fluoride adsorption process in soils has garnered widespread attention. Yet research on assessing environmental risk based on the characteristics of fluoride adsorption in soil is still limited. Here, a suite of batch experiments were conducted using three soil types with distinct properties. The results demonstrate that soil organic matter (SOM) and pH are critical factors determining fluoride adsorption in soils. Paddy soil (PS) with its higher SOM content has a higher adsorption capacity compared with loessal soil (LS) and brown soil (BS). Under acidic conditions, BS and LS whose Ca2+ content is higher exhibited a higher adsorption capacity. The fluoride adsorption process in soils may involve electrostatic adsorption, complexation, and precipitation. The desorption results showed stronger fluoride binding to PS and LS than BS, while the fluoride adsorbed onto BS was almost completely desorbed. This research demonstrates that a deeper understanding of regional differences in soil properties is crucial for better studying the migration and accumulation characteristics of fluoride and its bioavailability in various soils. This study provides a theoretical basis for evaluating the bioavailability, exposure risk, and groundwater pollution risk of fluoride in different soils.

Adsorption equilibria and kinetics of CO2 and N2 on silica-alumina gels for reducing gas production by CO2 removal from iron flue gases

In industrial fields, hydrogen-containing flue gases generally contain a certain amount of CO2 and N2. After removing CO2, the raffinate gases can be used in various applications to mitigate carbon emissions. Furthermore, the concentrated CO2-rich extract contributes to efficient CO2 capture. Silica-alumina gel can be a high potential adsorbent because of its high CO2 adsorption capacity and energy-saving desorption. Three different silica-alumina gels with different amounts of alumina (FJ, KD, and WS) were compared to study the impact of the alumina content on the adsorption characteristics. The adsorption behaviors of CO2 and N2 were measured at 293K, 308K, and 323K at pressures up to 1000 kPa. The isotherms correlated with the dual-site Langmuir model, showing that the adsorption capacity for CO2 was much higher than that for N2 across all the adsorbents. The surface areas and adsorption capacities followed the opposite order of alumina content: FJ > KD > WS. However, the difference intervals in the isotherms did not align consistently with the alumina content, but the micropore volume changed by alumina contributed highly to the adsorption capacity. In the adsorption kinetic analysis, the diffusional time constants and kinetic parameters in a non-isothermal adsorption kinetic model showed minor dependence on pressure and temperature. The adsorption rate was higher for N2 than for CO2. It increased with alumina content, following the order WS > KD >> FJ. The results contribute to the establishment of guidelines for the selection of silica-alumina gel and the design of the adsorption process.

Adsorption and removal of Pb (II) via layer double hydroxide encapsulated with chitosan; synthesis, characterization adsorption isotherms, kinetics, thermodynamics, & optimization via Box-Behnken design

The study aimed to enhance the stability and efficiency of removing bivalent Pb(II) by encapsulating AlNi-layered double hydroxide (LDH) in chitosan and itaconic acid to create an adsorbent with chemically active sites. The resulting material, AlNi-LDH/CS, underwent thorough property analysis using XRD, FT-IR, XPS, EDX, N2 adsorption/desorption isotherm, and FESEM to find out what textural characteristics it has. Specifically, nitrogen adsorption/desorption isotherms were utilized to assess the textural properties of AlNi-LDH/CS. The Al/Ni-LDH/CS surface displayed a specific surface area of 71.95 m2/g and an average pore size of 2.537 nm, consistent with the platelets' external surface. The effects of dose, pH, temperature, and starting concentration on the adsorption process were also investigated in this study. The adsorption characteristics have been examined by means of equilibrium and adsorption kinetics. The adsorption process adhered to the pseudo-second-order and Langmuir isotherm models. The predominant adsorption process was found to be chemisorption, which had an adsorption energy of 28.42 kJ·mol−1. An endothermic and spontaneous adsorption process is suggested by the increase in metal absorption at increasing temperatures. The Box-Behnken design software was utilized to establish the optimal adsorption parameters as pH 5, a dosage of 0.2 g of AlNi-LDH/CS per 25 mL, and an adsorption capacity of 453.05 mg/g for the Pb(II) arsenate solution. For the composite sponge to be most effective in adsorbing arsenate and be used in water purification procedures, these factors are essential. The adsorption process was successfully improved with few planned tests by applying the Box-Behnken design and response surface technique aspects of the Design-Expert software. An evaluation of the adsorbent's reusability using six successive cycles of adsorption and desorption confirmed its stability and showed no discernible decrease in removal efficiency. Additionally, it retained its original chemical composition before and after reuse, showcased consistent efficiency, and maintained uniform XRD data.

The preparation path, adsorption characteristics and manganese dissolution loss mechanism of manganese-based ion-sieve MnO2·0.5H2O for liquid phase lithium resource recovery

The preparation path, adsorption characteristics and manganese dissolution loss mechanism of manganese-based ion-sieve MnO2·0.5H2O for liquid phase lithium resource recovery

Adsorption characteristics and mechanism of novel ink melanin composite modified chitosan for Cd(II) in water

In this study, chitosan (CS), carboxymethyl chitosan (CMCS), and chitosan quaternary ammonium salt (HACC) were successfully loaded with ink melanin (ME) as efficient adsorbents for Cd(II) removal. The results of batch adsorption experiments and structural characterization showed that the modified CS loaded with ME improved the adsorption capacity of the composites for Cd(II). The pseudo-second-order kinetic and Langmuir equations were better suited to describe the batch adsorption experiments. The adsorption of Cd(II) was chemisorption with desirable adsorption effect when the concentration of the three composites was 0.5 mg/mL and the pH value was neutral. Among them, HACC-ME demonstrated remarkable Cd(II) adsorption performance (107.18 mg/g) and sustained an 85 % efficiency in Cd(II) removal over five adsorption-desorption cycles. Ion exchange, complexation, electrostatic attraction, and hydrophobic interaction were the primary mechanisms for Cd(II) removal. Overall, HACC-ME could be employed as a low-cost and highly efficient new natural adsorbent material for the removal of Cd(II) ions from wastewater. These findings illuminate pathways for the development of efficient and novel natural adsorbent materials for environmental cleanup purposes.

Impact of high-intensity ultrasound on interfacial protein adsorption of non-dairy whipping cream: Whipping properties and foam stabilization model

In this paper, the competitive adsorption and practical application characteristics of ultrasound treatment on the oil-water interface in non-dairy whipping cream were explored. The results showed that ultrasound treatment promoted the competitive adsorption of casein, resulting in an increase of interfacial protein loading in the system by 4.82 mg/m2 and a decrease in oil droplet size by 0.20 μm. In addition, due to the increase of interfacial protein in the system, the partial coalescence of the fat globule of systems decreased, which led to a rapid collapse of the foam after 2 days of storage. Ultrasound weakened the strength of the gel network inside emulsions, which weakened the anti-deformation ability of emulsions. Although the LVR of the ultrasonically treated samples narrowed after churning, the G′ value increased. In addition, the stress yield point of the foams shifted to higher strains as the ultrasonic power increased, implying better resistance to deformation.

Dynamic response characteristics of coal/rock during water injection and freezing process under gas atmosphere and its control effect on gas outburst

The freezing method compensates for the defect of sacrificing coal integrity to reduce gas content, which is the case with traditional methods, achieving the improvement of coal body strength while reducing coal seam gas energy storage, improving the safety of coal and gas outburst accidents in deep coal seams during the process of rock cross-cut coal uncovering. This study conducted water injection and low-temperature freezing experiments on coal/rock samples under the gas atmosphere, analyzing the effects of water and temperature on sample temperature, deformation, and gas adsorption and desorption characteristics. The results indicate that water can displace adsorbed gas in coal/rock samples, and the relationship between the gas displacement and the water content of the sample satisfies an improved exponential function. The center temperature Tm of low water content coal/rock samples decreases with time and gradually tends to stabilize, while the Tm of high water content samples experiences a short-term deceleration or stagnation due to the phase transition heat release of water when it drops to around 0 °C. The cooling rate of samples with low water content and no gas is higher and that of rocks is higher than that of coal samples. Coal/rock samples with high water content experience frost heave during the freezing process, but the overall deformation is still dominated by cold shrinkage, and the amount of deformation is negatively correlated with temperature and water. The gas adsorption capacity of coal decreases linearly with the temperature. At the same time, an increase in water content and a decrease in freezing temperature will significantly reduce the gas desorption capacity of coal samples, effectively reducing the gas expansion energy of coal samples, especially the desorption gas expansion energy. In engineering implementation of this method, the ice phase network can fill the coal pores and cracks and improve the mechanical properties of the coal/rock mass, and the gas pressure in the coal seam and stress concentration near the coal rock interface can be reduced by low temperature and cold shrinkage, thereby achieving safe exposure of the coal seam and preventing accidents from occurring.

Optimal Design of the Hole Shape of the Air Suction Porous Turntable and Analysis of Adsorption Characteristics of Flexible Blades

ABSTRACTTo improve the adsorption effect of air suction sorting equipment, in this study, flexible blades were used as test materials, and porous turntables with circular holes (A), rectangular holes (B), and rectangular‐circular holes (C) were designed. Fluent software was used to simulate and analyze the aerodynamic characteristics of the flow field at the porous turntable, and the blade falling adsorption bench test was built. Under the same test conditions, the adsorption blades of the porous turntable were photographed by a high‐speed camera. Based on the C‐hole turntable and the tuyere air pressure of 380 Pa, it is verified by a single‐factor test that the blade falling in the distance of the porous turntable, the rotating speed of the turntable, and the number of blades extending perpendicular to the direction of movement have a direct effect on the blade adsorption of the porous turntable. To obtain the optimum adsorption conditions for the bench test, an orthogonal test was used, and a certain number of leaves were used for the test while the adsorption efficiency was considered; it is found that when the distance from the porous turntable is 40 mm, the rotation speed of the turntable is 60 r/min and the number of transverse blades of the conveyor belt is 4, and 100% adsorption can be achieved. In summary, the research results and methods of this experiment can provide reference and guidance for the research group to carry out the follow‐up research and development of multi‐stage air suction sorting equipment.

Adsorption‐Based Electrochemical Sensor Design for the Aqueous Detection of Paracetamol

This study investigates the critical role of adsorption in the development of electrochemical sensors, focusing on carbon (Vulcan XC72R, acetylene black, and graphite) and zeolite (high‐silica ZSM‐5 and all‐silica zeolite β) materials. Based on the paracetamol adsorption characteristics of these materials, an optimized disposable electrochemical sensor is created. This sensor exhibits a linear range of up to 5 μM and a remarkable detection limit of 150 nM (S/N = 3), ≈1000‐time improvement over the blank sensor. Moreover, paracetamol can be measured selectively because glucose has no adsorption affinity for the selected sensor materials. These findings underscore the significance of adsorption properties in sensor material selection in enhancing sensitivity and robustness against interfering species.

Experimental and theoretical investigation of Ce/Ti-doped LaMnO3 catalysts effect on catalytic oxidation rarefied CH4 for natural gas engine

To mitigate the high greenhouse effect caused by methane emissions of natural gas engines, this study employed the citric acid complexation method to synthesize Ce/Ti-doped LaMnO3 perovskite catalysts. Firstly, the properties of perovskite catalysts were investigated through several characterization techniques and activity evaluations. Secondly, density functional theory (DFT) calculations were performed to study the effects of Ce/Ti doping on perovskite unit cell properties and methane adsorption characteristics. Results indicate that Ce/Ti doping is conducive to enhancing the magnetic properties and attractive forces between particles, thereby improving the crystallinity and specific surface area of catalyst. Additionally, it enhances the oxygen migration rate, promotes the formation of low-temperature reduction active components and reduces the reduction temperature for the catalysts. When Ce/Ti are co-doped, the ratios of the surface-active elements Mn4+/Mn3+ and O−/O2− on the catalyst reach their maximum values of 1.56 and 1.53, respectively. The co-doping also leads to the formation of alkaline sites such as Mn-O and Ti-O metal pairs, which facilitate the dehydrogenation oxidation of methane. Ce/Ti-co-doped LaMnO3 perovskite exhibits the optimal low-temperature oxidation activity towards methane, with an ignition temperature reduced to 269 °C and complete methane conversion at 479 °C. Ce/Ti doping enhances the adsorption behavior of methane on catalyst surface, with the adsorption energy of −5.4361eV. Meanwhile, Ce/Ti doping results in a significant transfer of electrons from H1 atoms of methane to Mn atoms and increases the charge directivity of the surface-active atoms of catalysts, and in turn, it leads to higher catalytic performance and structural stability.

Adsorption Characteristics of Congo Red Dye onto Calcinated Mytilus edulis Shell Powders

Adsorption Characteristics of Congo Red Dye onto Calcinated Mytilus edulis Shell Powders

Plasma-engineered sugarcane bagasse: a novel strategy for efficient mercury removal from aqueous solutions.

Metal ion adsorption using agro-industrial residues has shown promising results in remediating contaminated waters. However, adsorbent effectiveness relies on their properties, often necessitating processing for modification. Considering this, plasma treatment is effective in modifying material surfaces physically and chemically. This study investigated the modification of sugarcane bagasse (SB) using plasma treatment and evaluated its efficacy as a novel adsorbent for mercury removal from aqueous solutions. SB underwent low-temperature plasma treatment with sulfur hexafluoride (SF6) as the working gas, varying treatment times (2, 30, and 60min), and fixed powers (80, 190, and 300 W) at 16Pa pressure. Characterization via SEM/EDS, FTIR, XPS, and pHpzc revealed significant structural changes like increased in porosity and alteration in proportion atomic. Additionally, the successful incorporation of fluorine was confirmed in all treatment conditions, while sulfur was detected in only some samples. Amongst the tested conditions, the SB treated with 300 W for 60min demonstrated the highest mercury removal efficiency, achieving an impressive 83.67% removal rate compared to untreated SB, which yielded only 57.95%. The adsorption mechanism exhibited both physical and chemical behavior, with chemisorption being the dominant process. The Freundlich model provided the best fit to the experimental data, with an R2 value of 0.97. In conclusion, plasma treatment can be a promising alternative for improving the physical and chemical characteristics of SB adsorbents, thereby improving their efficiency in removing mercury from aqueous solutions.