Adsorption Isotherm Characteristics Research Articles

Bactericide adsorption by purple soil modified by decomposed liquid and humic substance from Bischofia javanica

To investigate the effect of plant decomposition products on bactericide adsorption, purple soil (P) was modified using different ratios of decomposed liquid (Dl) and humic substance (Hs) from Bischofia javanica. Isothermal adsorption characteristics of fenaminosulf and hymexazol by different Dl- and Hs-modified Ps (Dl-P and Hs–P) were studied using the batch method. The effects of pH, ionic strength, and temperature on bactericides adsorption were analyzed. The adsorption process of fenaminosulf and hymexazol on modified Ps was suitable to be described by the Freundlich model. Meanwhile, the adsorption capacity of two bactericides on Hs-Ps was higher than that on Dl-Ps. Acidic conditions and low temperatures were more favorable for the adsorption of fenaminosulf and hymexazol on modified Ps. The adsorption amount of fenaminosulf increased first and then decreased, but that of hymexazol decreased with the increase in ionic strength. The adsorption process of two bactericides was a spontaneous, exothermic entropy-increasing reaction, and the physical adsorption mechanism mainly controlled the adsorption rate. In conclusion, Dl-Ps and Hs-Ps showed potential environmental remediation applications.

Study on supercritical water regeneration of bio-based activated carbon saturated with acid red G

The dye and textile industry commonly employs activated carbon adsorption technology due to its cost-effectiveness and high efficiency. However, disposing of waste-activated carbon has a significant environmental and human health impact, and it’s a huge economic waste. This study investigates the kinetic and isothermal adsorption characteristics of Acid Red G dye adsorption by Powdered Activated Carbon derived from coconut shells. To effectively reuse activated carbon and maximise resource conservation, regeneration experiments were carried out using Supercritical Water at 24 MPa and 400 ℃ for 30 min. The experimental results demonstrated that, in comparison with thermal regeneration, supercritical water possesses the benefits of environmental protection, economic efficiency and extensive applicability. This is of considerable importance to the field of research concerning the regeneration of activated carbon.

The Characteristics of Adsorption of Di-n-Butyl Phthalate by Surface Sediment from the Three Gorges Reservoir.

Phthalic acid esters (PAEs), recognized as endocrine disruptors, are identified as predominant organic pollutants in the Three Gorges Reservoir (TGR). Di-n-butyl phthalate (DBP), a representative PAE, has been extensively studied for its sources, distribution and ecological risks. However, there are few studies on the adsorption of DBP by sediment from the TGR, and the adsorption characteristics of surface sediment on DBP are not clear. Therefore, based on the actual sediment contents and particle sizes in the TGR, the kinetics and isothermal adsorption characteristics of surface sediment on DBP were investigated in this study. The results showed that the equilibrium time was 120 min, the adsorption kinetics were more in line with the pseudo-second-order kinetic model, and the sediment in water from the Yangtze River exhibited a higher adsorption rate and maximum adsorption amount on DBP than that observed in deionized water. Additionally, a decrease in DBP adsorption was observed with increasing sediment content, while sediment particle size and specific surface area had a slight influence. Analysis using SEM, TGA and FTIR revealed that organic matter on the sediment surface significantly contributed to DBP adsorption. This study contributes valuable insights into the adsorption characteristics of DBP by the surface sediment from the TGR, providing a scientific foundation for understanding the migration and transformation of DBP in this critical reservoir in China.

Cd(II) and Pb(II) adsorption in karst soils amended with litter extract from Ficus virens

In this study, different proportions of Le were used to amend purple, yellow, and yellow–brown soils of karst areas to investigate the effect of litter extract (Le) from Ficus virens on Cd(II) and Pb(II) adsorption in karst soils. The basic physicochemical properties of Le-amended karst soils were determined, and the microscopic morphology of Le-amended karst soils was detected. The batch method was used to study the isothermal adsorption characteristics of Cd(II) and Pb(II) adsorption on different Le-amended karst soils. Physicochemical properties and microscopic morphology results showed that Le was amended on the karst soil surface and changed the surface properties of the karst soil. The maximum adsorption capacity range of Cd(II) and Pb(II) by Le-amended karst soils was 92.10–241.61 and 108.91–262.12 mmol/kg, respectively, and the peak value was reached when the karst soils were amended with 20 % of Le. Increasing the pH and temperature were beneficial to Cd(II) and Pb(II) adsorption in each Le-amended karst soil. The adsorption amount of Cd(II) and Pb(II) initially increased and thendecreased with the increase in ionic strength. Cd(II) and Pb(II) adsorption was a spontaneous, endothermic, and entropy-increasing process, and electrostatic attraction, precipitation, complexation, and ion exchange were the main adsorption mechanisms. The adsorption amount of Cd(II) and Pb(II) by Le-amended yellow–brown soil maintained approximately 85 % of original sample after three rounds of regeneration.

Novel modified semi-carbonized fiber prepared using discarded clothes for derisking Cu(II) and Pb(II) contaminated water

We report a novel modified semi-carbonized fiber (CF) prepared using cotton and acrylic clothes for derisking contaminated water to realize the resource utilization of discarded clothes in wastewater treatment. In this study, amphoteric and auxiliary modifiers were used to modify CFs for preparing amphoteric and amphoteric-auxiliary CFs. The basic physicochemical properties of different modified CFs were determined, and the microscopic morphology of modified CFs was detected. The isothermal adsorption characteristics of Cu(II) and Pb(II) on different modified CFs were investigated by the batch method, and the effect mechanisms of temperature, pH, ionic strength, and material dose were compared. Physicochemical properties and microscopic morphology results proved that amphoteric and auxiliary modifiers were modified on the CF surface and changed the surface properties of CF. The adsorption capacities of Cu(II) and Pb(II) on modified CFs increased with the increase in equilibrium concentration of Cu(II) and Pb(II), and the isotherm was more suitable for Freundlich model fitting than that of the Langmuir model. The maximum adsorption capacities (qm) of Cu(II) and Pb(II) on different modified CFs were 60.72–81.26 mg/g and 102.58–161.72 mg/g, respectively, and presented the trend of amphoteric-auxiliary CFs > amphoteric CFs > CFs. Increasing pH and temperature and decreasing ionic strength and material dose were beneficial to Cu(II) and Pb(II) adsorption. The Cu(II) and Pb(II) adsorption process was a spontaneous, endothermic, and entropy-increasing reaction, and the adsorption rate was controlled by chemisorption. The adsorption amount of amphoteric-auxiliary CFs maintained about 65% of original materials after 3 times of regeneration. Electrostatic attraction, precipitation, complexation, and ion exchange were the main adsorption mechanisms. The cation exchange capacity and total pore volume of modified CFs were key to determining qm of Cu(II) and Pb(II).

Solid-phase extraction with the functionalization of calcium-sensing receptors onto magnetic microspheres as an affinity probe can capture ligands selectively from herbal extract.

Magnetic solid phase extraction with the functionalization of protein onto micro- or nano-particles as a probe is favorable for the discovery of new drugs from complicated natural products. Herein, we aimed to develop a rapid method by immobilizing halogenated alkane dehalogenase (Halo)-tagged calcium-sensing receptor (CaSR) directly out of crude cell lysates onto the surface of magnetic microspheres (MM) with no need to purify protein. Thereby we achieved CaSR-functionalized MM for revealing adsorption characteristics of agonist neomycin and screening ligands from herbal medicine Radix Astragali (RA). About 43.87mg CaSR could be immobilized per 1g MM within 30min, and the acquired CaSR-functionalized MM showed good stability and activity for 4weeks. The maximum adsorption capacity of neomycin on CaSR-functionalized MM was determined as 4.70 × 10-4 ~ 3.96 × 10-4mol/g within 277 ~ 310K, and its adsorption isotherm characteristics described best by the Temkin model were further validated using isothermal titration calorimetry. It was inferred that CaSR's affinity for neomycin was driven by electrostatic forces in a spontaneous process when the system reached an equilibrium state. Moreover, the ligands from the RA extract were screened, three of which were assigned as astragaloside IV, ononin, and calycosin based on HPLC-MS. Our findings demonstrated that the functionalization of a receptor onto magnetic materials designed as an affinity probe has the capability to recognize its agonist and capture the ligands selectively from complex matrices like herbs.

Adsorption isotherm and kinetic characteristics of sawdust, shrimp shell, and wild sugarcane-based activated carbon for CO2 capture

Adsorption isotherm and kinetic characteristics of sawdust, shrimp shell, and wild sugarcane-based activated carbon for CO2 capture

Exploring the inhibitory effect of H2O on CO2/CH4 adsorption in coal: Insights from experimental and simulation approaches

To investigate the inhibitory effect of H2O on the adsorption of CH4/CO2 in coal, the anthracite was selected for physical adsorption experiments on CH4/CO2 gases in this study. Combined with Materials Studio software, the effect of moisture on the isothermal adsorption characteristics of CH4/CO2 in coal was investigated by using density functional theory and giant canonical Monte Carlo simulation. The intermolecular interaction energies were obtained, as well as the effects of electrostatic potentials, adsorption sites, and hydrogen bonding of oxygen-containing functional groups. The results show that: ①According to the CH4/CO2 isothermal adsorption experiments, it was found that moisture significantly inhibited the adsorption of CH4/CO2 by coal. For CH4, the relationship between adsorption constants a/b and moisture content can be expressed by the equations y = 43.447-3.348x and y = 3.225-0.751x. For CO2, adsorption constant a follows a power function relationship with moisture content, expressed as y = 29.114x-0.063, while adsorption constant b is represented by the polynomial fitting equation y = 1.672+0.508x+0.083x2. ② The findings have revealed correlations between the moisture influence coefficient and moisture content. The exponential functional equation η = exp(-0.188ω) was found to be more accurate for coal adsorbing CH4, whereas the linear functional equation η = 1/(1 + 0.243ω) was considered more appropriate for CO2. ③ The van der Waals and electrostatic energies between coal and CH4/CO2 decreased with an increase in moisture content, whereas the van der Waals and electrostatic energies between coal and H2O increased. ④ The orders of hydrogen bond formation ability between CH4/CO2 and functional groups were as follows: –CHO > –COOH > –OH > –CH3 and –OH > –COOH > –CHO > –CH3. The ability of H2O to form hydrogen bonds with –COOH, –OH, –CHO, and –CH3 is as follows: –COOH > –OH > –CHO> –CH3. This study provides a theoretical basis for the integrated use of hydraulic fracturing techniques and coalbed gas injection and replacement.

Adsorption Properties of Fe (II) from Activated Carbon Composite of Empty Palm Oil Bunches with Metal Organic Frameworks Cu-TAC

This study aims to determine the adsorption capacity, study the kinetics and adsorption equilibrium of activated carbon/AC and composite carbon/AC-Cu(TAC) in the adsorption process of Fe metal. Oil palm empty fruit bunches (EFB) were used as activated carbon and modified with MOFs Cu(TAC) composite. The concentration of Fe(II) ions adsorbed during the adsorption process was analyzed using AAS. The variations used to determine the optimum conditions for absorption of Fe(II) ions are the mass variation of the adsorbent, the variation of the adsorbate concentration and the contact time between the adsorbent and the adsorbate. Through variations in concentration, the adsorption isotherm characteristics were determined and through variations in contact time, the adsorption kinetics model was determined. The results of AC characterization showed a sharp absorption in the presence of OH, CH and CO groups which indicated the presence of cellulose. AC is amorphous and AC-Cu(TAC) is crystalline and the pore size is mesoporous. The optimum condition for AC is the mass variation of 1 g with an absorption capacity of 0.1816 mg/g, a variation of the concentration of 60 ppm with an absorption capacity of 3.49 mg/g and a contact time of 75 minutes with an absorption capacity of 3.82 mg/g. The optimum condition for ACCu(TAC) was the mass variation of 1 g with an absorption capacity of 0.7275 mg/g, a variation of the concentration of 180 ppm with an absorption capacity of 10.52 mg/g and a contact time of 15 minutes with an absorption capacity of 10.85 mg/g. AC-Cu(TAC) has a better adsorption ability in adsorbing Fe(II) ions. For AC and AC-Cu(TAC) the suitable adsorption isotherm is Freundlich isotherm and the suitable adsorption kinetics model is pseudo second order

Filling–adsorption mechanism and diffusive transport characteristics of N2/CO2 in coal: Experiment and molecular simulation

Enhanced coalbed methane (ECBM) is an effective development technology to improve energy utilisation and reduce greenhouse gas emissions by injecting N2/CO2 into coal seams. The process involves the adsorption, desorption, and diffusion of N2/CO2 in multi-scale coal pores. This results in gas storage and transport characteristics limited by the coal's structural distribution of nanoscale pores (≤100 nm). Thus, studying N2/CO2 storage and diffusive transport characteristics in pores at different scales is vital for efficiently implementing N2/CO2-ECBM. This paper performed low-pressure adsorption with N2/CO2 (LPA-N2/CO2) to evaluate coal samples' isothermal adsorption characteristics and pore structure, revealing the dual filling-adsorption mechanism of N2/CO2 in coal. A new coal pore classification method was proposed. Pores (≤50 nm) in coal-N2 or coal-CO2 adsorption systems were classified as inaccessible pores (<0.364 nm or < 0.33 nm), filling pores (0.364–1.65 nm or 0.33–1.36 nm), transition pores (1.65–2 nm or 1.36–1.60 nm), and adsorption pores (>2 nm or > 1.60 nm). Combining the experimental results to construct micropore and mesopore models, molecular dynamics were applied to simulate the loading and migration processes of N2/CO2 in the pore models. Filling, transition, and adsorption pores completed loading gas within 0.1–1 MPa, 1–5 MPa and 5–10 MPa in that order, visualising the gas filling-adsorption process in coal. Then, the adsorption capacity of N2 was controlled by the pore size and adsorption pressure, while CO2 was mainly influenced by adsorption pressure.

Comparison of adsorption performance for Cd(II) removal from aqueous solution using biochar derived from different types of carbon sources: aquatic plants, pine branches and peat

AbstractBACKGROUNDGuizhou Province, China is rich in forest, peat and aquatic plants. The effect of biochar prepared by pyrolysis carbonization on the Cd(II) adsorption has not been effectively studied. In this work, the physicochemical structural characteristics of different biochars were investigated. On this basis, the influence of pH value, acid washing, adsorption time on Cd(II) removal efficiency and the characteristics of adsorption isotherms of four biochars were studied. The adsorption mechanism was discussed by adopting the Langmuir and Freundlich kinetic model.RESULTSThe findings exhibited that PT contained a great amount of free humic acid, fulvic acid and montan wax, which had a considerable impact on the Cd(II) adsorption. The surface of biochar AP300 has a fine crack structure, and the specific surface area (SSA) is the largest, reaching 2.9006 m2/g. When the solution range in pH value above 6, the removal efficiency of PT and biochar AP300 for Cd(II) exceeds 80%. The acid‐washed biochar with increased SSA did not exhibit an increase in Cd(II) removal efficiency, or even decreased significantly. Under the same adsorption time, the Cd(II) removal efficiency was in the following order: PT&gt;AP300&gt;PT300&gt;PB300. The fitting effect of the Freundlich model for the four biochars was more than a match for Langmuir model, and the former is more appropriate to expression of the adsorption mechanism of Cd(II). Among the four biochars, AP300 had the smallest ΔG°, and the Cd(II) adsorption was the most easily performed.CONCLUSIONBoth PT and AP carbon material adsorbents can both meet the removal of Cd (II) in water, and can be promoted to treat heavy metals in soil later. © 2023 Society of Chemical Industry (SCI).

Sustainable Biochar Carbon Microparticles Based on Mangosteen Peel as Biosorbent for Dye Removal: Theoretical Review, Modelling, and Adsorption Isotherm Characteristics

Environmental problems and global energy demand increase every day. The quality of water and sanitation is a very hot topic of discussion. The principles of sustainable development (SDGs) by utilizing renewable materials need to be applied to overcome this problem. One way is through the use of agricultural waste as a renewable carbon material. The study aims to analyze the adsorption characteristics of sustainable carbon microparticles based on mangosteen peel for dye removal. This study also evaluates adsorption isotherms based on its microparticle size effects. In short, carbon preparation was started by mangosteen peel carbonization at 250˚C for 5 hours and tested using sieves (i.e., 125, 250, 500, 1000, and 2000 μm) to obtain a certain size of carbon. Adsorption was evaluated based on a specific particle size using a batch adsorption reactor. Curcumin was used as a model organic dye. The findings showed that particle sizes influence physical adsorption with repulsive interactions between adsorbates. Adsorption in the large particles (i.e. 2000 and 1000 μm) occurs in the multilayer adsorption process with pore filling, while that in the small particles (i.e., 500 μm) occurs in the monolayer adsorption process with pore filling. Small-sized carbon does not provide enough active sites (such as the absence of a pore structure on the surface) for the adsorbate, leading to the creation of a monolayer during adsorption. Meanwhile, in large-sized carbon, the pore-filling mechanism in the adsorbent surface cause the formation of multilayer adsorption. This research is important to understand the application of adsorption using agricultural waste-based adsorbents by observing the phenomena occurring during the adsorption process.

Application of Synthesized Biomass Bamboo Charcoal–Iron Oxide “BC/Fe” Nanocomposite Adsorbents in the Removal of Cationic Methylene Blue Dye Contaminants from Wastewater by Adsorption

In this work, synthesized, raw-bamboo-biomass-based magnetic “BC/Fe” bamboo charcoal–iron oxide nanocomposite adsorbents were characterized and tested for their effects on the removal of aqueous-phase cationic methylene blue (MB) dye pollutants from synthetic wastewater through a laboratory batch adsorption study. This batch adsorption study aimed to identify various physico-chemical process parameters such as initial dye concentration, solution pH, adsorbent dose, temperature, and their effects on the adsorption kinetics and adsorption isotherm characteristics. From the kinetic studies, it was found that the amount of MB dye adsorption by synthesized adsorbents qe (mg/g) increased from 9.50 mg/g to 15.30 mg/g with the increase in the initial dye concentration range of 10 to 30 ppm, as per contact time, but decreased with the increase in the temperature range from 30 to 60 °C and the adsorbent doses from 20 to 40 mg, respectively, under specified experimental process conditions. From the kinetic study, it was also found that equilibrium was reached within 120 min, the adsorption kinetics followed three mechanistic steps, and the pseudo-second-order (PSO) kinetic model was applicable to explain the data of the batch adsorption kinetics. The various kinetic model parameters were determined from a fitted model equation. Furthermore, there was an increase in the amount of the MB dye adsorption qe (mg/g) from 9.87 mg/g to 17.62 mg/g with the increase in the solution pH from 3 to 7, and a reduction in the amount of dye adsorption qe (mg/g) was found at the solution pH of 10 for a 20 ppm MB dye solution at 30 °C. Both the Freundlich and Langmuir isotherm models were applicable to the equilibrium data, and the maximum adsorption capacity from the Langmuir isotherm fitting was 111.11 mg/g, which was comparative to or even better than many other magnetic adsorbents for methylene blue dye adsorption. Finally, the regeneration and reusability of the magnetic “BC/Fe” bamboo charcoal–iron oxide nanocomposite materials as well as the limitations of these batch adsorption studies are also discussed here.

Isothermal adsorption characteristics of various phases of CO2 and CH4 in different rank coals

ABSTRACT Using the remaining coal seams of closed coal mines for CO2 geological storage can effectively slow down the greenhouse effect and realize the redevelopment and utilization of closed coal mines. The burial depth of coal seams in closed coal mines in China covers an extensive range, and CO2 and CH4 could exist in various phases in the coal. The existing experimental objects for CO2 adsorption in coal are mainly associated with the supercritical and gaseous phases, and a research gap comparison between the CO2 adsorption characteristics in the liquid phase and those of other phases is very obvious. Herein, the isotherm adsorption experiments of CO2 and CH4 in different phases on different rank coal samples are methodically conducted in the pressure range of 0-12MPa. The experimental results indicate that the excess adsorption capacity of gaseous CO2 and CH4 (gas pressure <4MPa) rapidly raises with the growth of the adsorption pressure; however, a significant difference for the case of the medium- and high-pressure stage (>4MPa) is detectable. With the growth of the adsorption pressure, the excess adsorption capacity of the supercritical CH4 gradually reaches the maximum value and then remains stable, where the maximum experimental value is 1.009 mmol/g. While the excess adsorption capacity of CO2 near the critical pressure of liquid and supercritical state rapidly reduces and then tends to be stable. The maximum adsorption capacity is capable of touching 2.096 mmol/g, which is stable around 0.5 mmol/g. The analysis indicates that the change in the excess adsorption amount of CO2 near the critical pressure corresponds to the change in its density. The absolute adsorption capacity of CO2 and CH4 monotonically grows in the pressure range of 0-12MPa, and the absolute adsorption capacity of the same coal sample follows the following order: liquid CO2 > supercritical CO2 > CH4. The maximum adsorption capacity values for these substances in order are 2.493, 2.345, and 1.296 mmol/g. With the growth of the coal rank, the Gibbs free energy, specific surface area, and adsorption capacity of the understudied coal samples exhibit a U-shape relationship as a function of their coal ranks.

Fate and Transport of Lead and Copper in Calcareous Soil

Heavy metals transport to groundwater relies on the characteristics of soil, such as carbonate and clay minerals, organic matter content, soil pH, and some other factors. Most of the heavy metals in calcareous soils are precipitated as metal carbonate minerals; consequently, their transport to the groundwater is not anticipated. Therefore, the current study focused on the impacts of calcium carbonate presence on the adsorption and transport of lead (Pb) and copper (Cu) in calcareous soil using batch and column experiments. To elucidate the contaminants removal mechanisms in calcareous soils, extensive laboratory batch investigations were conducted to study the equilibrium kinetic and adsorption isotherm characteristics of the two studied heavy metals. The quick adsorption of Pb2+ and Cu2+ by soil was seen in kinetics trials. In addition, Pb2+ and Cu2+ sorption onto the soil was best described by the pseudo-second order kinetic model (R2 = 0.9979 and 0.9995 for Cu2+ and Pb2+, respectively). To explain the equilibrium sorption data, the Freundlich isotherm showed the best fitness to Pb2+ (R2 = 0.96) and Cu2+ (R2 = 0.98), collectively. The Freundlich parameters revealed that the Pb2+ has favorable adsorption; however, Cu2+ has unfavorable adsorption onto the soil. The results of column experiments showed the higher binding of Pb2+ than Cu2+ to the top surface of the soil column, making the movement of these two metals very slow. In columns, most of the Pb2+ and Cu2+ ions were sorbed at an initial 5 and 10 cm, respectively. The findings of this study will help in understanding the fate of heavy metals in calcareous soils.

Effect mechanism of litter extract from Alternanthera philoxeroides on the selective absorption of heavy metal ions by amphoteric purple soil

Plant litter causes a serious waste of resources. Thus, plant litter extract (LE) should be used in the soil remediation of heavy metals. In this study, different proportions of LE from the Alternanthera philoxeroides were used to modify dodecyl dimethyl betaine (BS)-modified purple soil (P). The basic physicochemical properties of LE + BS-modified Ps (LE + BS-Ps) were determined, and the microscopic morphology of LE + BS-Ps was studied by using scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, and specific surface area detection. The isothermal adsorption characteristics of heavy metal ions (Pb2+, Cu2+, and Cr6+) on different LE + BS-Ps were investigated by the batch method, and the effect mechanisms of temperature, pH, ionic strength, and LE + BS-P's property were compared. Results showed that the cation exchange capacity and specific surface area of LE + BS-Ps increased, pH of LE + BS-Ps decreased, and TOC of LE + BS-Ps increased first and then decreased with increasing proportion of LE. FTIR, SEM, and EDS results proved that LE was modified on the surface of BS-P. Langmuir and Freundlich models could be used to describe the adsorption isotherms of heavy metal ions on different LE + BS-Ps, and the fitting correlation of the Langmuir model was higher than that of the Freundlich model. The maximum adsorption capacity (qm) of Pb2+, Cu2+, and Cr6+ were 107.60–295.66, 133.00–342.11, and 33.59–75.41 mmol/kg, respectively. The qm of Pb2+, Cu2+, and Cr6+ on LE + BS-Ps all increased first and then decreased with increasing proportion of LE, and the peak value was observed in 20%LE + BS-Ps. High pH improved Pb2+ and Cu2+ adsorption but inhibited Cr6+ adsorption. The adsorption amounts of Pb2+, Cu2+, and Cr6+ all increased first and then decreased with incresing ionic strength and were maintained at the maximum value of 0.1–0.2 mol/L. The Pb2+, Cu2+, and Cr6+ adsorption mechanisms on different LE + BS-Ps showed a positive temperature effect and presented spontaneous, exothermic and entropy-adding processes.

Temperature based Enhanced Desorption of Adsorbed Biomethane Stored on Sustainable Nanoporous Materials

In recent years, adsorbed natural gas storage has been seen as a better alternative to storing methane-rich gas on porous materials. Especially when these porous materials can be derived from a source like biomass whole process becomes valuable development. However, the problem of lower delivery capacity and the amount of gas released upon releasing the pressure remains unsolved. The micropores developed on the activated carbons retain the gas as they cannot get the activation energy to detach from the surface. The thermodynamics of the desorption process discourages the overall technological development of the system. We have carried out studies under particular temperatures by placing material and gas-filled cylinder in a water bath to overcome this challenge. Coconut based activated carbons were used in the study, which were procured from the market. Adsorption isotherm and other characteristics were performed for activated carbons. The desorption amount of the gas was recorded for different temperatures of 40, 45, 50 and 55 °C. At room temperature, nearly 54% of adsorbed gas is being released. Whereas, at 55 °C, approximately 80% of the gas is being recovered. This work will be useful for the externally cylinder fitted vehicles where the exhaust stream can be channelised to warm the surrounding of the cylinder to facilitate the higher discharge of the adsorbed gas.

Characteristics of adsorption kinetics and isotherms of Cu(II) by sediment under different hydrodynamic of the Ganjiang river, China

Abstract Discharges from industrial and agricultural processes into water bodies can result in the accumulation of heavy metals such as Cu(II) in the sediment via various physical and chemical interactions. While there are many studies of the adsorption of heavy metals by sediment, few have considered the effects of hydrodynamic conditions. Here, the adsorption of Cu(II) by sediments under different hydrodynamic conditions was studied using a particle entrainment simulator. The sediment samples were obtained from the Poyang Lake basin in China. Models describing pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion kinetics and the Langmuir, Freundlich, Temkin and Dubin Radushkevich adsorption isotherms were used to evaluate the adsorption of Cu(II) by the sediments under different hydrodynamic conditions. The results showed that adsorption equilibrium for Cu(II) by the sediment was attained within 4 hours and increased with increasing shear stress; the kinetics were consistent with pseudo-second-order and Elovich models, indicating that chemical processes were involved in adsorption; the adsorption isotherms could be described by the Langmuir and Freundlich models. Changes in the sediment shear stress had little effect on the maximum adsorption capacity and values ranged from 0.9425 to 1.0634 mg/g. The results indicated that the adsorption sites for Cu(II) in soil were heterogeneous.

Energy efficient green synthesized MOF-801 for adsorption cooling applications

Utilization of water as a refrigerant in adsorption cooling systems is a challenging task due to the unavailability of suitable adsorbents. Recently, a new class of porous material, metal–organic frameworks (MOFs), is heightening interest as the potential adsorbent for water adsorption due to its crucial S-shaped adsorption isotherm characteristics. Additionally, the high surface area, large pore volume, and higher affinity towards water vapor outshined MOFs over other porous materials to be used as adsorbent in water-based adsorption cooling system (ACS). However, their industrial production could be obstructed due to economic and ecological limitations. Therefore, in this study, an energy-efficient, environment friendly, rapid and ultrasonication assisted room temperature green synthesis procedure for MOF-801 is reported with additional finding of optimum synthesis condition. Several characterization techniques are employed to ensure the structural stability of the synthesized MOFs and their applicability in ACS. The reaction time of the green synthesized MOF-801 was reduced by eight times than the conventional one while ensuring excellent system performance, which makes this process promising for industrial production.

Study on heat adsorption based on the experiment of coal adsorption of methane by using the weight method

The study of heat adsorption plays an important role in understanding the mechanism of methane adsorption from coal. The gravimetric method was used to conduct 303 K, 308 K, and 313 K isotherm adsorption experiments on two sets of coal samples; the equivalent heat adsorption of methane adsorption by coal was calculated, and the thermodynamic properties of coal adsorption of methane were analyzed. The research results showed that the calculated isometric heat of adsorption is 30.51 kJ/mol and 23.14 kJ/mol in the experimental temperature, pressure, and corresponding adsorption capacity, respectively, indicating that the adsorption of methane by coal belongs to physical adsorption. The increase in adsorption capacity increases monotonously and slowly, which is the result of the dominant interaction force between the adsorbed methane molecules. The 318 K isotherm adsorption characteristics are predicted using the 303 K and 313 K isothermic adsorption heat data, which are compared with the laboratory measured isotherm adsorption data. The two groups have the same trend. The relative errors of the two groups of coal samples are between 2.26%-5.72% and 0.29%-2.19%, respectively. A new method is proposed for using isosteric heat adsorption to predict isothermal adsorption characteristics under different temperature and pressure conditions.