Adsorption最新文献

Water pollution is currently a critical global issue. Various research groups have developed active adsorbent materials. This study aims to enhance the adsorption of water pollutants, particularly fluoride, by modifying the electronic structure of red soil through in-situ chemical oxidative polymerization techniques. The synthesized materials were characterized using techniques including powder XRD, FT-IR, UV spectroscopy, and Conductometer, followed by testing their adsorption performance. The XRD analysis revealed that while the crystal structures of embedded red soil remained amorphous, polyaniline (PANI) and PANI/red soil (RS) nanoparticles became polycrystalline. The maximum adsorption capacity (qmax) of fluoride ions by PANI/RS was determined to be 9.35 mg/g. Optimization experiments showed that PANI/RS exhibited maximum adsorption performance for fluoride ions under specific conditions: pH 4.0, a contact time of 50 min, temperature of 35 °C, and an initial concentration of 15 mg/L with 2 mg of adsorbent, achieving a removal efficiency of 99.9%. Both Langmuir and Freundlich isotherm models demonstrated a good fit with the experimental data, with R² values of 0.94 and 0.95, respectively. This suggests that PANI/RS is an effective adsorbent material for removing fluoride ions from wastewater. Overall, PANI/RS outperformed red soil alone, demonstrating potential for practical application in water treatment processes.

We prepared guggul gum-based hydrogel (GgG-cl-poly(AA)) through a free radical graft copolymerization mechanism in this work. The preparation was carried out using ammonium persulfate as an initiator, acrylic acid as the monomer, and N, N′-methylenebisacrylamide as the crosslinker. The synthesized hydrogel’s swelling capacity and equilibrium swelling ratio were thoroughly investigated by optimizing various reaction parameters: reaction time, solvent volume, microwave power, crosslinker amount, initiator concentration, and monomer concentration. The swelling results demonstrated that the synthesized hydrogel can attain a maximum percentage swelling of 980% within 3 h in an aqueous solution. The prepared hydrogel sample was characterized using Fourier transform infrared, X-ray diffraction, scanning electron microscopy, nuclear magnetic resonance, and thermogravimetric analysis. The prepared hydrogel was studied for water retention behavior in the soil, water absorbance in the open air at room temperature, reswelling studies, and resistive swelling studies in various salt solutions at different temperatures and pH values. Notably, the crosslinked hydrogel exhibited a reduced swelling capacity across various salt solutions compared to the aqueous solutions. The biodegradation studies were examined in both soil burial and vermicomposting methods for two months, revealing a maximum biodegradation of 95.65% through the vermicomposting method and 87.7% through the soil burial method. The results indicate that the crosslinked hydrogel based on guggul gum is a potential candidate for various agricultural applications.

Use of renewable waste material for water treatment is an area of interest. An attempt has been made for preparation of Dairy industry waste Ghee residue (GR) based biogenic adsorbent for removal of dye present in water/waste water. This novel approach contributes in valorisation of dairy industry by- product Ghee residue. The ghee residue was first converted into carbon and processed with the titanium precursor and rare earth metal. This combination yields GR-C/TiO₂/Eu³⁺ adsorbent. A series of adsorbing material was prepared by differing loading of Eu³⁺ keeping ratio of RG-C and TiO₂ constant. Synthesized adsorbents were subjected to characterization studies such as X-Ray Diffraction (XRD) spectroscopy, Brunauer Emmett Teller-Surface Area (BET-SA), Scanning Electron Microscopy (SEM), Fourier Transformed Infra Red spectroscopy (FTIR) etc. XRD pattern shows formation of crystalline anatase phase of TiO₂ with average particle size of 34.9494 nm. SEM image also confirms irregular morphology with particles in nanometer range. BET-surface area of GR-C/TiO₂/Eu³⁺ (1%) was found to be 53.633 m²/g with total pore volume = 8.555e^− 02 cc/g for pores smaller than 18330.1 Å (Radius) at P/Po = 0.99948 and average pore radius was found to be 3.19022e^+ 01 Å indicating mesoporosity of material. Synthesized adsorbents were studied for dye adsorption and GR-C/TiO₂/Eu³⁺ (1%) shows quick and complete removal of 5ppm Methyl orange dye in contact time of less than three minutes at 30-32^oC with the adsorbent dose of 75 mg/10mL. The high adsorption property is attributed to presence of crystalline nanostructured TiO₂ and Eu³⁺ on to the biogenic carbon framework. Langmuir adsorption isotherm data indicates monolayer adsorption with R² value of 0.97. ΔG^o values are in the range of -12.81 to -17.77 KJ mol^− 1 indicating spontaneous adsorption process.

Expandable clay minerals play a pivotal role in the geological sequestration of greenhouse gases due to their contribution to storage capacity and caprock integrity. The charge-balancing cations in the interlayer space are known to influence carbon dioxide adsorption. The present study investigated the general adsorption behaviour and characteristics of montmorillonite towards CO₂ adsorption at temperatures above critical point, typical to geological sequestration. Modelling on the excess isotherm and absolute isotherm was used to compare the variation of the adsorption behaviour of sodium, potassium and calcium montmorillonite. Excess isotherm modelling using the monolayer Ono-Kondo (O-K) model successfully captured the experimental adsorption. The lateral interaction of the adsorbed molecules on the montmorillonite surface, a variable with the type of cation, remarkably affected the strength of adsorption. The derived adsorbed phase density data confirmed the onset of swelling in montmorillonite at pressures below the critical point. Additionally, the study comprehended the influence of approximations used to derive the absolute isotherm from the experimental isotherm and investigated the validity of common theoretical models to represent adsorption. The study recommended the application of Dubinin-Astakhov (D-A) isotherm with reciprocal van der Waals density approximation or liquid density approximation to model the adsorption of CO₂ on montmorillonite.

This work prepared a class of starch hydrogel with and without lignin from sugarcane bagasse (5% wt.) and trisodium citrate as a crosslinking agent. The physical and chemical properties of the hydrogels were characterized by Fourier-transformed infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), and X-ray diffractometry (XRD) techniques. Besides, the swelling degree and the pH of zero point charge (pH_zpc) were evaluated. Hydrogels were tested for the adsorption of potentially toxic elements (PTEs) and dye (methylene blue) by chromatography and UV-vis, respectively. FTIR confirmed that the reticulation of the starch structure successfully occurred, while the inclusion of lignin promoted new interactions that increased pore size, swelling degree, and pH_zpc of the developed hydrogels. The adsorption of cationic metals at pH < pHzpc showed low removal but presented complete adsorption of oxyanion chromium. Moreover, the adsorption of methylene blue presented removal higher than 90%, further enhanced by lignin presence, which presented an adsorption capacity of 99.4 mg.g⁻¹ at 70 min. The hydrogels presented a better fit to the Freundlich isotherm model, indicating that removal is favorable. Thus, using lignin in the hydrogels can enhance their performance and be an alternative to developing new eco-friendly materials.

Desulfurization of organosulfur compounds in petrochemical fuels is mainly limited by diffusion in porous solids. Design and optimization of such heterogeneous process need basic knowledge of molecular diffusion inside porous solids. In this work, molecular dynamics method was applied to study the intrinsic pore diffusion and surface diffusion of some common organosulfur compounds of thiophene, benzothiophene and dibenzothiophene in silica pores. Based on the molecular dynamics data, the effects of temperature and pore size on the intrinsic pore diffusion and surface diffusion were investigated by an established mathematic model considering the molecular size effect on diffusion. It was found that the widely used Knudsen diffusion model might overestimate the pore diffusion as much as a few dozens folds, but could be improved by incorporating molecular interaction and molecular size effect into diffusion model. The proportion of mass transfer by surface diffusion in total mass transfer in different pores was estimated. The results exhibited herein convey some basic instruction not only for design pores of porous solids used in hydrodesulfurization or in adsorption desulfurization, but also for optimization of operation conditions for desulfurization processes.

This study synthesized chitosan-alginate-polyvinylpyrrolidone and applied it for Cr(VI) removal. Characterization was carried out using FTIR, TGA, N₂ adsorption, ¹H NMR, and FE-SEM. FTIR spectra show peaks at 1415 cm^− 1, 1323 cm^− 1, 1029 cm^− 1, and 448 cm^− 1, which are COO, C-N, C-O, and N-C = O groups. The surface area of CsAgPVP was 20.42 m²/g. The pore size of CsAgPVP was 5.36 nm. Field emission shows the C, O, N, and Na. The optimum conditions CsAgPVP dor adsorption Cr(VI) were 50 ppm, 360 min, and pH 4. It uses adsorption isotherm and kinetic to show the Langmuir model and pseudo-second-order. The CsAgPVP adsorption process is assumed homogeneous and considered as chemisorption. Adsorption capacity shows 208.67 mg/g. It uses a regeneration study of removal percentage up to 90% in the fourth cycle. The removal percentage in real sample mine wastewater and waste acid laboratories was 80% and 72%.

Highly efficient removal of tetracycline antibiotic residue from aqueous solution was demonstrated by a novel, cost effective and environmentally friendly adsorbent consisting in composite polymeric beads of sodium alginate, chitosan and polyvinyl pyrrolidone, doped with equal ratio of sulfonated graphene oxide and sulfonated titania, fabricated via simple blending method using calcium chloride as a crosslinker. The adsorption parameters of beads amount, initial tetracycline concentration, adsorption time and solution pH were investigated. Furthermore, adsorption time, beads amount, and the initial tetracycline concentration were optimized using the response surface methodology model. Pseudo-second-order kinetic equation was fitted to the adsorption process’ kinetics. It was discovered that the electrostatic attraction and hydrogen bonding, which primarily contribute to the noticeably enhanced adsorption ability, are the essential factors driving the adsorption mechanism. The maximum antibiotic adsorption capacity of the nanocomposite beads reached 357 mg/g.