Adsorption最新文献

A novel strategy was used to successfully remove rhodamine B dye from contaminated water by combining magnetized multi-walled carbon nanotubes (MWCNTs) with myrrh gum as an adsorbent. The shape and structure of the prepared adsorbent were charecterized using X-ray powder diffraction analysis, FTIR, SEM, and TEM. A batch approach was used to study the effect of the adsorbent on rhodamine B removal, and several variables were considered, including pH, agitation time, and adsorbent dosage. The findings revealed that rhodamine B dye removal was best at a basic pH of 8, with a 0.05 g adsorbent dosage, within 30 min. Different models were utilized to analyze the isotherm data obtained during the investigations. The adsorbent exhibited the highest adsorption capacity for rhodamine B removal, reaching 332.22 mg/g. The regression analysis indicated appropriate adsorption kinetics with a pseudo-second order kinetics and an R² value of 0.999. The thermodynamic analysis specified that the removal process exhibits endothermic characteristics, spontaneous behavior, and involves chemisorption. The obtained results demonstrate the efficacy of the adsorbent in the context of water treatment.

In this work, using first-principles calculations, we explored the sensing properties of formaldehyde (CH₂O) on pristine antimonene (p-Sb), single vacancy modified antimonene (SV-Sb), and triple X-doped (X = B, N) SV-Sb (SV-3X-Sb). It is found that CH₂O is physically adsorbed on p-Sb with adsorption energy E_a of -0.11 eV. The E_a slightly increased in SV-Sb (-0.17 eV). The maximum E_a was observed for SV-3B-Sb and SV-3N-Sb with E_a of -0.81 (-0.86) eV, respectively. Because of moderate adsorption strength, the electronic and magnetic properties of SV-Sb and SV-3X-Sb are slightly altered in the presence of CH₂O. The SV-Sb with CH₂O exhibits half-metallic character. The direct band gap (E_g) of SV-3B-Sb is slightly increased after adsorption, and in the presence of CH₂O the semiconducting SV-3N-Sb showed a metallic character. These changes in electronic properties are attributed to charge transfer from absorbent to CH₂O. These findings suggest that the sensitivity of antimonene for CH₂O detection can be tuned with defects.

A new set of Lennard–Jones parameters to account the short interactions between atoms of MOFs and of guest molecules is proposed. The Slater‒Kirkwood relationship was used to obtain the LJ parameters for the framework atoms, so the proposed force set of parameters was named the Slater–Kirkwood force field (SKFF). GCMC simulations using SKFF were performed to predict the adsorption of CO₂, CH₄ and linear alkanes on several IRMOFs. The results predicted by SKFF were compared to those obtained by the traditional general force fields used in screening MOFs (UFF and Dreiding). The performance of the proposed SKFF was superior to those of the UFF and Dreiding force fields, without accounting electrostatic contributions. Additionally, the proposed set of parameters was able to accurately predict the adsorption behavior of binary (CO₂–CH₄, CO₂–N₂, CH₄–N₂) and ternary (N₂–CO₂–CH₄) mixtures on IRMOF-1 at 297 K. To evaluate the transferability of SKFF to other MOFs, the adsorption isotherms of CO₂, CH₄ and N₂ on UiO-66, UiO-67, DUT-52, CuBTC, MIL-100(Cr), MIL-47(V), ZIF-8 and ZIF-97 were also predicted. The results presented good agreement with the experimental data.

(upgamma)-alumina is highly employed as support for hydrotreatment catalysts prepared by impregnation and as adsorbent in water treatment. These applications consist of contacting (upgamma)-alumina with aqueous solutions, leading to the transport of ions inside the alumina pores and their adsorption on the pore surface. These physicochemical phenomena are governed by the (upgamma)-alumina pore surface and the solution characteristics. Predicting the physicochemical phenomena at the liquid/solid interface is crucial to optimize the design of catalysts and of water treatment adsorption processes. However, this is very challenging using conventional analytical techniques. In this work, the diffusion of protons and their counter-ions inside (upgamma)-alumina pores and the adsorption of protons on the pore surface are modeled at unsteady state during contact with acid solutions at different initial pH levels. Diffusion inside pores is represented using a combination of the zero current method and the Poisson-Boltzmann equation, while the proton adsorption is described by the Langmuir adsorption isotherm. Simulations agree well with the results of proton adsorption experiments in a batch system. The model accurately predicts the distribution of species inside the electrostatic double layer at the liquid/solid interface. It also computes the surface charge and the maximal adsorption capacities of different types of hydroxyl sites present on the alumina pore surface; both are very difficult to determine experimentally. This model can serve as a guide for the comprehension of the liquid/solid interface inside (upgamma)-alumina structures and their interaction with aqueous solutions during the initial stages of impregnation.

In this work, three solid adsorbents were synthesized, namely, nanozeolite-Y prepared from rice husks ash by a sol-gel method as a green biosource (ZN), chitosan as a cationic biopolymer (CS), and nanozeolite-Y/chitosan composite (CSZ). An eco-friendly composite that consists of chitosan and nanozeolite-Y was used to combine the advantages of nanoparticles with biopolymers two materials to increase the removal % of methylene blue dye. All the synthetized solid adsorbents were investigated using TGA, nitrogen adsorption, SEM, TEM, FTIR, XRD, and zeta potential. The results showed that CSZ particles had a high specific surface area (432.3 m²/g), mesoporosity (with an average pore diameter of 2.59 nm), a smaller TEM particle size (between 28.6 and 60.7 nm), a lot of chemical functional groups, and high thermal stability. CSZ exhibited the maximum adsorption capacity (141.04 mg/g) towards methylene blue. The adsorption nature of methylene blue onto CS and CSZ is endothermic, spontaneous, and a physical adsorption process, while it is exothermic, nonspontaneous, physical adsorption process in the case of ZN, as confirmed by thermodynamic results. Pseudo-second order, Elovich, Dubinin-Radushkevich, Freundlich, Langmuir, Temkin, and adsorption models all fit the MB adsorption well, with correlation coefficients reaching about 0.9997. Nitric acid was found to be the best desorbing agent, with a desorption efficiency of about 99%.

Environment remediation is one of the primary goals of sustainable development and anthropogenic activities, and the use of fuels in various industrial processes through combustion has led to an increase in CO₂ as well as big damage to the atmosphere by the greenhouse effect. Biochar has been used for the capture of carbon dioxide due to its high surface area. In this study, we obtained biochar from soursop seeds. The materials were synthesized by pyrolysis of precursor materials and chemical activation with chlorides of Ca and Mg at a concentration of 5% w/v. The effect of the defatting process of the soursop seeds on the obtained carbon was also researched. The absorbed solids were characterized through thermogravimetric analysis, X-ray diffraction, and CO₂ adsorption, followed by infrared spectroscopy, N₂-physisorption, CO₂-physisorption, CO₂, XPS, DRIFTS and TPD of NH₃. The type of activating agent and pretreatment conditions used were more favorable than the defatted process at obtaining carbons with N₂ surface areas between 26 and 220 m²g⁻¹. The biochars were analyzed by CO₂ surface area to describe the microporous framework, and the solid with the best CO₂ surface area was the one with the highest CO₂ adsorption. According to the statistical analyses conducted, the evaluated models Langmuir, Freundlich, and Redlich-Peterson presented good fits to the experimental data. However, the Redlich-Peterson model showed the lowest values for the residual variance, which were of the order of 0.001 or less in all cases based on the CO₂ adsorption isotherms on the studied activated carbons. However, the carbons obtained by defatting showed favorable hydrophilic behavior along with adsorption capacities in the bioremediation process and affinity towards of this GHG.

Direct capture of CO(_2) from ambient air is technically feasible today, with commercial units already in operation. A demonstrated technology for achieving direct air capture (DAC) is chemical separation of CO(_2) in a steam-assisted temperature-vacuum swing adsorption (S-TVSA) process. However, the potential to develop scalable solutions remains high, requiring a detailed understanding of the impact of both process design and operation on the performance of the DAC unit. Here, we address this knowledge gap by presenting a state-of-the-art process simulation tool for the purification of CO(_2) from ambient air by a 5-step S-TVSA process. By considering the benchmark adsorbent APDES-NFC, we conduct multi-objective productivity/energy usage optimization of the DAC unit, subject to the requirement of producing a high purity CO(_2) product ((ge 95)%). For the base case scenario, we find a maximum productivity of Pr(_{max } = 6.20) kg/m(^3)/day and a minimum specific equivalent work of W(_{text {EQ},min } = 1.66) MJ/kg. While in reasonable agreement with published data, our results indicate that the description of both competitive adsorption and adsorption kinetics are key factors in introducing uncertainty in process model predictions. We also demonstrate that the application of formal optimization techniques, rather than design heuristics, is central to reliably assess the process performance limits. We identity that system designs employing moderate CO(_2) sorption kinetics and contactors with low length-to-radius ratios yield the best performance in terms of system productivity. Finally, we find that moderate-high ambient relative humidities (50–75%) offer significantly favourable performance, and that a wide range of feed temperatures (5–30 (^circ)C) can be accommodated via process optimization without a significant impact on performance.

With the advent of industrialization and other anthropogenic activities, water sources are being contaminated incrementally. Groundwater contaminated by fluoride has been a major global concern for public health in recent years. Various types of materials have been employed for the removal of contaminants from water. Among all, biochar has gained attention in recent times. Biochar is a carbon-rich and environmentally friendly pollutant adsorbent important in remediating inorganic contaminants like fluoride from water. In the current study, Bryophyllum pinnatum-raw biochar and activated biochar doped with aluminum were prepared from the leaves of the Bryophyllum pinnatum (B. pinnatum) plant. The removal efficiency of raw/pristine biochar (RB) and Bryophyllum pinnatum-activated biochar (BAB) was investigated by treating both biochars with fluoride-contaminated water. The biochar was characterized using FTIR, FESEM-EDX, XRD, BET, and pH_pzc techniques, which showed that the positive charges and adsorption sites were created due to the effective loading of the metal hydroxide on the biochar surface during BAB formation which played a significant role in defluoridation. To investigate the effect of different factors on the percentage of fluoride removal, batch tests were carried out. Kinetic and isotherm models were also applied to evaluate the mode of action and mechanistic approach. The results revealed that BAB exhibited a higher fluoride removal efficiency of 92% compared to RB and followed the pseudo-second-order model and Langmuir model showing chemisorption. Thus, the prepared activated biochar holds a good potential to be used as a sorbent for defluoridation.

The wastewater generated from the industrial activities are considered as one of the prime sources of water contamination. The yearly production of synthetic dyes are ~ 700 tons worldwide. Synthetic dyes have detrimental effects on the human as well as animal health. Therefore, there is an urgent need to treat the water containing synthetic dyes. Dye treatment methods can be divided in to three categories namely; chemical, physical, and biological. The chemical procedure includes; photocatalytic degradation, ozonation, fenton reagent, and aerobic and anaerobic degradation are the examples of the biological procedures. However, the physical procedures consists of filtration/coagulation, adsorption, ion exchange etc. Further, these techniques may have its own drawbacks including generation of hazardous sludge and expensive to operate along with high maintenance cost. The most appealing techinque for abatement of dye from the contaminated water is adsorption owing to its ecofriendly, flexibility, affordability, sustainability, and abundant availability of raw materials to produce adsorbents. It has been noticed that over 80% of dye adsorption processes on adsorbent surfaces were endothermic in nature which means the adsorption processes were self-sustaining in terms of energy consumption. In present review paper, the discussion has been focused on the removal of anionic dyes from water using low-cost biochar adsorbents which is not reported in any previous review papers. Further, it will significantly help to the budding researchers to develop continuous water treatment system (in column mode), if wish to work of anionic dyes remediation from water.

The presence of heavy metal ions in water bodies constitutes a significant environmental hazard. The development of sustainable and cost-effective adsorbent materials for their removal is an urgent priority. In alignment with this critical objective, the present study explores the potential of a novel composite material for water remediation. This composite, fabricated from biochar and magnesium ferrite nanoparticles, targets the removal of hexavalent chromium and divalent nickel. While prior research has explored the application of rice husk as an adsorbent, no investigation, to our knowledge, has examined the potential of magnesium ferrite-rice husk composites for this purpose. Initial screening identified the biochar-magnesium ferrite composite (pre-calcination) as the most effective adsorbent. This composite displayed a superior surface area (151 m²/g) compared to calcined magnesium ferrite (91 m²/g) and achieved exceptional removal efficiencies for both chromium (50 mg/g) and nickel (54 mg/g). Optimal chromium removal occurred at pH 1 with a 110-minute contact time, while nickel favored a pH of 6 and the same contact time. The adsorption process was characterized as physisorption and endothermic. Notably, the composite exhibited efficient regeneration (82% for nickel and 90% for chromium) using simple acid/base solutions. The BJH analysis of pore characteristics indicated an average pore diameter of 1.5365 nm and a total pore volume of 0.17 cm³/g. The research findings demonstrate the composite’s effectiveness as a sustainable adsorbent for capturing heavy metal ions from water.

Graphical Abstract