Preparation Of New Adsorbent Research Articles

Monomer Symmetry-Regulated Defect Engineering: In Situ Preparation of Functionalized Covalent Organic Frameworks for Highly Efficient Capture and Separation of Carbon Dioxide

Developing crystalline porous materials with highly efficient CO2 selective adsorption capacity is one of the key challenges to carbon capture and storage (CCS). In current studies, much more attention has been paid to the crystalline and porous properties of crystalline porous materials for CCS, while the defects, which are unavoidable and ubiquitous, are relatively neglected. Herein, for the first time, we propose a monomer-symmetry regulation strategy for directional defect release to achieve in situ functionalization of COFs while exposing uniformly distributed defect-aldehyde groups as functionalization sites for selective CO2 capture. The regulated defective COFs possess high crystallinity, good structural stability, and a large number of organized and functionalized aldehyde sites, which exhibit one of the highest selective separation values of all COF sorbing materials in CO2/N2 selective adsorption (128.9 cm3/g at 273 K and 1 bar, selectivity: 45.8 from IAST). This work not only provides a new strategy for defect regulation and in situ functionalization of COFs but also provides a valuable approach in the design and preparation of new adsorbents for CO2 adsorption and CO2/N2 selective separation.

Removal of chlorobenzene by adsorption from aqueous solutions on the HDTMA-bentonites as a function of HDTMA/CEC ratio

In this work an Algerian natural bentonite was used in the preparation of new adsorbents by impregnation with different mass ratios of hexadecyltrimethylammonium bromide (HDTMA) surfactant. The HDTMA-bentonites adsorbents were prepared according to the HDTMA/bentonite cation exchange capacity (CEC) ratios (HDTMA/CEC). Five HDTMA/CEC ratios (25%, 50%, 100%, 150% and 200%) were used to investigate the effects on the physicochemical characteristics and the adsorptive power of these clays. The characteristics of these adsorbents were studied by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The adsorptive power of these clays was studied by batch adsorption of chlorobenzene from aqueous solutions. FTIR and TGA spectra confirm the modification of bentonites by intercalation with HDTMA. XRD spectra of these adsorbents exhibited interlayer spacings from 13 to 20 Å, with maximum interlayer spacing of 20 Å corresponding to the adsorbent with 100% HDTMA/CEC ratio. Adsorption experiments of chlorobenzene indicate that pseudo first order model was suitable for describing the kinetic results. Regarding the equilibrium results, both Langmuir and Freundlich isotherms were fitted well. The adsorbent impregnated with 100% HDTMA/CEC ratio, shows a high percentage of chlorobenzene removal compared to the other adsorbents.

Silica Gel Impregnated by Deep Eutectic Solvents for Adsorptive Removal of BTEX from Gas Streams.

The paper presents the preparation of new adsorbents based on silica gel (SiO2) impregnated with deep eutectic solvents (DESs) to increase benzene, toluene, ethylbenzene, and p-xylene (BTEX) adsorption efficiency from gas streams. The DESs were synthesized by means of choline chloride, tetrapropylammonium bromide, levulinic acid, lactic acid, and phenol. The physico-chemical properties of new sorbent materials, including surface morphology and structures, as well as porosity, were studied by means of thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller analysis. The effect of DESs type, flow rate, and initial concentration of BTEX were also investigated followed by regeneration and reusability of adsorbents. The results indicate that SiO2 impregnated with tetrapropylammonium bromide and lactic acid in a 1:2 molar ratio have great potential for the removal of BTEX from gas streams. Its adsorption capacity was higher than the pure SiO2 and other developed SiO2-DES adsorbents. This result can be explained by the specific interaction between DESs and BTEX, i.e., hydrogen bonds interaction.

Bonding of crown ethers to α-zirconium phosphate—Novel layered adsorbent for radioactive strontium separation

Searching for new efficient, selective, and stable, adsorbents for 90Srgenerated in the nuclear fuel cycle remains important. In the last year, 18 crown 6ether and its derivatives have been intensively studied as highly efficient ion-exchangers for removal of 90Sr. However, one of the main problems for further application of these expensive macrocyclic ligands is loss in solid-liquid media due to their solubility. To overcome this problem, in this work, we have developed a new organic – inorganic layer α-ZrP composite by intercalation of 4-amino-benzo-18 crown 6. This new α-ZrP composite (AM-ZrP) not only inherits the advantages of 4-amino-benzo-18 crown 6 and α-ZrP, exhibiting excellent stability under acid and radioactive conditions, but also efficiently decreases the loss of valuable4-amino-benzo-18 crown 6 in the adsorption process. Furthermore, the preparation process for AM-ZrP is simple and it can be easily produced on a large-scale. Remarkably, having a pore size matching4-amino-benzo-18 crown 6, AM-ZrP shows high selectivity for capturing Sr2+ from complicated mixed solutions. The maximum adsorption capacity for Sr2+ onto AM-ZrP is 320.16 mg·g−1, which is about five times that of neat α-ZrP. Itsurpasses most other inorganic adsorbents, which can be attributed to the much higher number of adsorption sites and the wide interlayer spacing of α-ZrP after interactionwith4-amino-benzo-18 crown 6. Our present work not only poses a new way to promote crown ether compounds and α-ZrP materials, furthering their application in nuclear wastewater disposal, but also develops a new way of thinking about the design and preparation of new adsorbents for removal of difficult-to-capture ions from nuclear wastewater.

Integration of phosphoric acid onto radiation grafted poly (2,3-epoxypropyl methacrylate) -PP/PE non-woven fabrics aimed copper adsorbent via response surface method

This study focuses on preparation of new adsorbent for copper by radiation induced grafting (RIG) of 2,3-epoxypropyl methacrylate (EMPA) onto PP/PE non-woven fabric (NWF) with subsequent functionalization with phosphoric acid (PA). The density of phosphoric acid incorporated onto EMPA-g-NWF was tuned by reaction parameters optimization such as PA concentration, reaction temperature, reaction time and EMPA grafting yield by using response surface method (RSM) engaging Box-Behnken design (BBD). Maximum PA density of 2.0 mmol/g−1 was estimated at optimum reaction parameter of 45.50% PA concentration, 70 °C reaction temperature, 2.76 h reaction time and 132.68% grafting yield. The deviation between optimum experimental and projected phosphoric acid density was taken into consideration, in order to verify the consistency of RSM in predicting the yield and optimizing the functionalization reaction parameters. The PA-functionalized EMPA-g-NWF was assessed with X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric (TGA), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-energy dispersive x-ray (SEM-EDX) to examine the crystallinity, chemical composition, thermal stability and morphology, and respectively. The preliminary study on adsorption of copper was carried out with PA-functionalized EMPA-g-NWF at different conditions such as different initial copper concentration, PA density and contact time. The maximum adsorption was obtained at pH of 4. The adsorption capacity increases as the PA density increases and maximum adsorption obtained at 2.5 mmol/g-ad of PA density. The adsorption results obtained was very promising and suggested PA-functionalized EMPA-g-NWF as a suitable candidate for copper removal.

Preparation of bio-inspired trimethoxysilyl group terminated poly(1-vinylimidazole)-modified-chitosan composite for adsorption of chromium (VI) ions.

Chitosan and poly(1-vinylimidazole) are both potential adsorbents to remove Cr(VI). Here, we designed the preparation of new adsorbents by combining chitosan and poly(1-vinylimidazole) to get the synergistic effect for the removal of hexavalent chromium. Trimethoxysilyl group terminated poly(1-vinylimidazole)-modified-chitosan composite was successfully synthesized by one-step free radical polymerization based on the grafting backbone of chitosan and vinylimidazole. The resulting adsorbents were used for the removal of Cr(VI) ions from the aqueous solution. The modified chitosan composite was characterized by ATR, FTIR, BET isotherm studies, elemental analysis, TGA, DSC, FE-SEM, and EDX. ATR. FTIR results confirmed the presence of the imidazole group in modified chitosan. The adsorption results were described by the Langmuir isotherm model with a maximum adsorption capacity of 196.1 mg/g for modified chitosan, however, the chitosan yielded 151.5 mg/g. It has been observed that the adsorption of chromium fitted better with the pseudo-second-order kinetics. The modified chitosan composite exhibited greater adsorption capacity than chitosan for hexavalent chromium and has potential application for Cr(VI) removal from aqueous solution containing other common ions with regeneration ability. This novel approach of modifying chitosan with telomerized poly(1-vinyl imidazole) offers potential application in wastewater treatment of different industries releasing Cr (VI).

Cellulose paper grafted with polyamines as powerful adsorbent for heavy metals

The preparation of new adsorbents for heavy metals consisting of cellulose paper grafted with polyamine moieties is described. The tosylation of pristine cellulose paper allowed the subsequent displacement of the tosylated leaving groups with either ethylenediamine or spermine provided the corresponding cellulose-based polyaminated adsorbents Cell-Ed and Cell-Sperm, respectively. Optimizations related to the influence of experimental conditions (time and pH) on the adsorption processes associated to detailed studies devoted to the understanding of the mechanism of adsorption through kinetic experiments and isotherm modeling provided a rational understanding for the removal Cu(II) and Pb(II). Interestingly, Cell-Sperm also displayed outstanding adsorption properties for other metal cations such as Cd(II), Zn(II) and Fe(II).

Adsorbent ability of lignin-based activated carbons for the removal of p-nitrophenol from aqueous solutions

This paper reports the p-nitrophenol (PNP) removal from aqueous solutions by adsorption onto active carbons (ACs). Nine ACs were prepared from acid-precipitated eucalyptus kraft lignin following a two-step process consisting in CO2 partial gasification (750–850°C) after carbonization (350–800°C) in N2 atmosphere. The amount adsorbed ranged from 1 to 4.4mmol/g, and it is related to the initial concentration of adsorbate, temperature, pH, burn off of the activated carbons, and contact time. The equilibrium results were fitted by the Temkin, Dubinin-Radushkevich, and Guggenheim-Anderson-de Boer equations. The main thermodynamic magnitudes were estimated as well, and their values indicated that the adsorption processes were spontaneous and exothermic. The kinetic study showed that the processes are of apparent second order related to the concentrations of the empty active sites on the ACs surface. The values of the effective diffusivities have been calculated and they have suggested that the internal diffusion controls the net mass transfer. The results obtained in the present work can be for the benefit of the preparation of new adsorbents, as well as the primary design of the adsorption equipment with separation or environmental purposes.

Application of hydroxyapatite and cement kiln dust mixture in adsorption of lead ions from aqueous solution

This study describes the preparation of new adsorbent by hydroxyapatite and cement kiln dust as raw materials. In the first part of investigation the adsorption capacity of hydroxyapatite and dust powders were separately studied by measuring the lead concentration in the aqueous solution. Thereafter the mixed powders containing different proportions of hydroxyapatite and dust were shaped by a laboratory single screw extruder in the cylindrical form and the adsorption capacity, porosity of samples and the compressive strength were measured according to standard methods. Regardless the composition used in the purification, the solution did not remain transparent when the adsorbent was prepared with dust only and the distinguishable fine particles were suspended in the lead solution. From visual observations, the solution was clear when the same amounts of hydroxyapatite and dust were used in the preparation of porous media. In order to evaluate the mechanical reliability of extruded samples, the compressive strength data of adsorbents were statistically analyzed by Weibull theory. The results clearly indicated that Weibull modulus of porous media is not affected by hydroxyapatite but the strength increases two times compared to the bed which is manufactured by using dust only. The finding results were confirmed by the observation of the fracture surface of adsorbents with a scanning electron microscopy.

Equilibrium and Kinetic Study of Congo Red Adsorption onto Lignin-Based Activated Carbons

The adsorption of Congo Red (CR) from aqueous solutions has been studied using various activated carbons prepared by us from eucalyptus kraft lignin. The adsorption isotherms were complex; nevertheless their data were fitted to the Langmuir and BET models. ΔG values suggested spontaneous nature of the adsorption processes. The high amounts adsorbed were studied as a function of the operating variables (pH, temperature) as well as the specific surface properties (zero-point charge, burn-off, and porosity) of the activated carbons. The diffusion coefficients have been estimated on the basis of an internal diffusion controlling mechanism for the net adsorption rate. Therefore, the obtained results in the present study should be of utility for the preparation of new adsorbents and they should make a contribution to design the adsorption equipment. Technical, economical, and environmental concerns have been considered in the purpose of the present study for water purification where that is polluted by anionic dyes.

Immobilization of oxime derivative on silica gel for the preparation of new adsorbent

A new silica gel compound modified 4,4′-oxy-bis(chlorophenylglyoxime) (CPGO) was synthesized and characterized by infrared spectroscopy, elemental analysis and thermogravimetric analysis. The sorption capacity of such a matrix towards Co(II), Ni(II) and Cu(II) from aqueous solutions was studied. The optimum pH values for the separation of these divalent cations on the sorbent were 5.0, 6.0 and 6.0 for Cu, Co and Ni, respectively. The process of metal separation was followed by batch method, and fitted to a Langmuir and Freundlich sorption isotherms. The maximum sorption capacities (0.055, 0.042, and 0.034 mmol g −1) were found from the Langmuir equation and the enthalpies of binding were 44.96, 71.63, and 68.14 kJ mol −1 for Cu, Co and Ni, respectively. The other thermodynamic parameters calculated from the adsorption results were used to explain the mechanism of the adsorption. For example, the Gibbs free energies of binding agree with the spontaneity of the proposed reaction between cations and basic centers.

Removal of Zn2+ from Electroplating Wastewater Using Modified Wood Sawdust and Sugarcane Bagasse

This paper describes the preparation of new adsorbents derived from sugarcane bagasse and wood sawdust Manilkara sp. to remove zinc II ions from electroplating wastewater. The first part deals with the chemical modification of sugarcane bagasse and wood sawdust, using succinic anhydride to introduce carboxylic acid functions into the material. The obtained materials modified sugarcane bagasse MB2 and modified wood sawdust MS2 were then characterized by infrared spectroscopy IR and used in adsorption experi- ments. The adsorption experiments evaluates Zn 2+ removal from aqueous single metal solution and real electroplating wastewater on both batch and continuous experiments using fixed-bed columns prepared in laboratorial scale with the obtained adsorbents. Adsorption isotherms were then developed using Langmuir model and the Thomas kinetic model. The calculated Zn 2+ adsorption capacities were found to be 145 mg/g for MS2 and 125 mg/g for MB2 in single metal aqueous solution, whereas for the industrial wastewater these values were 61 mg/g for MS2 and 55 mg/g for MB2.

Removal of Zn2+from Electroplating Wastewater Using Modified Wood Sawdust and Sugarcane Bagasse

This paper describes the preparation of new adsorbents derived from sugarcane bagasse and wood sawdust (Manilkara sp.) to remove zinc (II) ions from electroplating wastewater. The first part deals with the chemical modification of sugarcane bagasse and wood sawdust, using succinic anhydride to introduce carboxylic acid functions into the material. The obtained materials (modified sugarcane bagasse MB2 and modified wood sawdust MS2) were then characterized by infrared spectroscopy (IR) and used in adsorption experiments. The adsorption experiments evaluates Zn2+ removal from aqueous single metal solution and real electroplating wastewater on both batch and continuous experiments using fixed-bed columns prepared in laboratorial scale with the obtained adsorbents. Adsorption isotherms were then developed using Langmuir model and the Thomas kinetic model. The calculated Zn2+ adsorption capacities were found to be 145mg∕g for MS2 and 125mg∕g for MB2 in single metal aqueous solution, whereas for the industrial wastewater these values were 61mg∕g for MS2 and 55mg∕g for MB2.

Adsorption of poly(4-vinylpyridine) onto bentonites

The preparation of new adsorbents based on the coating of a poly(4-vinylpyridine) (P 4VP) polymer onto industrial bentonites was investigated. Two ways of synthesis were investigated, using dibromohexane (DBH) or its absence as a difunctional quaternizing agent in order to fasten the polymer by cross-linking. Several parameters (reagents ratio, type of bentonite, chemical stability in liquid media) were studied. Qualitative (IR and RMN spectroscopies) and quantitative (thermogravimetric) analyses of the samples were carried out.