Development Of Effective Adsorbents Research Articles

Ultralight crystalline hybrid composite material for highly efficient sequestration of radioiodine

Considering the importance of sustainable nuclear energy, effective management of radioactive nuclear waste, such as sequestration of radioiodine has inflicted a significant research attention in recent years. Despite the fact that materials have been reported for the adsorption of iodine, development of effective adsorbent with significantly improved segregation properties for widespread practical applications still remain exceedingly difficult due to lack of proper design strategies. Herein, utilizing unique hybridization synthetic strategy, a composite crystalline aerogel material has been fabricated by covalent stepping of an amino-functionalized stable cationic discrete metal-organic polyhedra with dual-pore containing imine-functionalized covalent organic framework. The ultralight hybrid composite exhibits large surface area with hierarchical macro-micro porosity and multifunctional binding sites, which collectively interact with iodine. The developed nano-adsorbent demonstrate ultrahigh vapor and aqueous-phase iodine adsorption capacities of 9.98 g.g−1 and 4.74 g.g−1, respectively, in static conditions with fast adsorption kinetics, high retention efficiency, reusability and recovery.

New insights into the interactions between Pb(II) and fruit waste biosorbent.

Fruit waste is a sustainable biosorbent for heavy metal removal from wastewater. Elucidation of adsorption mechanism is imperative for the process control and development of effective adsorbents. In this study, watermelon rind (WR) exhibited selective and efficient Pb(II) adsorption with a maximum uptake of 230.5mg/g at pH 5.0. The WR-packed bed column showed high Pb(II) uptake and robust durability over 10 adsorption-desorption cycles with long breakthrough time of 8-13h (89-144 bed volume), and 95% of sequestered Pb(II) was rapidly desorbed in 1-2h by 0.05M HCl. Spectroscopic characterization by FTIR and XPS identified hydroxyl, carboxyl, amine, and ether groups as the binding sites for Pb(II) via the binding force of complexation. Physicochemical analysis showed that ion exchange with Mg2+ and Ca2+ accounted for 19% of Pb(II) adsorption by WR; electrostatic attraction and microprecipitation jointly contributed. Quantum chemistry simulation verified the interactions between Pb(II) and binding sites and revealed carboxyl was the preferential functional group. The findings corroborate the applicability of WR in scale-up Pb(II) removal/recovery from wastewater and elaborate the mechanisms of Pb(II) adsorption by the WR biosorbent. This also provides insights into the behavior of heavy metals in other liquid/solid interfaces.

Metal-Organic Framework-Based Materials for Adsorption and Detection of Uranium(VI) from Aqueous Solution.

The steady supply of uranium resources and the reduction or elimination of the ecological and human health hazards of wastewater containing uranium make the recovery and detection of uranium in water greatly important. Thus, the development of effective adsorbents and sensors has received growing attention. Metal–organic frameworks (MOFs) possessing fascinating characteristics such as high surface area, high porosity, adjustable pore size, and luminescence have been widely used for either uranium adsorption or sensing. Now pertinent research has transited slowly into simultaneous uranium adsorption and detection. In this review, the progress on the research of MOF-based materials used for both adsorption and detection of uranium in water is first summarized. The adsorption mechanisms between uranium species in aqueous solution and MOF-based materials are elaborated by macroscopic batch experiments combined with microscopic spectral technology. Moreover, the application of MOF-based materials as uranium sensors is focused on their typical structures, sensing mechanisms, and the representative examples. Furthermore, the bifunctional MOF-based materials used for simultaneous detection and adsorption of U(VI) from aqueous solution are introduced. Finally, we also discuss the challenges and perspectives of MOF-based materials for uranium adsorption and detection to provide a useful inspiration and significant reference for further developing better adsorbents and sensors for uranium containment and detection.

Facile preparation of hydroxyl‑rich mesoporous magnesium silicate with excellent adsorption performance

The pollution of heavy metal ions and dyes in water pose a significant threat to the ecological environment and organismal health, and the development of effective adsorbents has attracted greatly attention. In the present work, hydroxyl‑rich mesoporous magnesium silicate (HMMS) with a high specific surface area of 472.9 m2/g was synthesized by a facile microwave-assisted solvothermal method for adsorption of Pb(II) ions and cationic dye methylene blue (MB) from water. HMMS particles were formed by the stack of nano-sized crystal and dense pores were formed between them. Adsorption experiments showed that HMMS exhibited fast adsorption speed and excellent adsorption capacity for Pb(II) ions (449.8 mg/g) and MB (467.3 mg/g). After six cycles, the adsorption performance of HMMS still remained above 92%. The adsorption data of HMMS for Pb(II) ions and MB were both well-fitted by the Langmuir isotherm model and pseudo-second-order kinetic model. Adsorption carried out at different initial pH values and FTIR analysis demonstrated that the adsorption mechanism of HMMS for Pb(II) ions and MB was the synergistic effect of electrostatic attraction and hydroxyl bonding. This work demonstrated that HMMS has significant potential in practical wastewater treatment.

Application of micro–meso hierarchical porous carbon for toluene adsorption treatment

Organic waste gases from petrochemical industry cause air pollution. Due to the environmental effects of refractory organic gas, the development of effective adsorbent is imperative. The micro–meso hierarchical porous carbon with high surface area was synthesised by the hard-template method. With MCM-41 as template, this material was prepared using phenolic resin as carbon source. Dynamic adsorption performance of toluene on micro–meso hierarchical porous carbon was studied by gas chromatographic techniques. Effects of toluene initial concentration, temperature and bed height on adsorption capacity were also researched. The results showed that when toluene concentration was 1750 mg/m3, equilibrium amount of toluene adsorbed was 358.8 mg/g by micro–meso hierarchical porous carbon, 79.41 mg/g by MCM-41. The adsorption capacity increased with the increase of initial concentration and bed height, while the adsorption capacity decreased along with the increase of temperature. Due to strong toluene adsorption capacity, this micro–meso hierarchical porous carbon manifests profound theoretical and practical significance in petrochemical organic waste gas treatment.

Nanoadsorbent of Organic Compounds Based on Two- and Three-Dimensional Mesocylinder Monoliths

The considerable contamination of the aqueous environment by organic pollutants still requires the development of effective adsorbents for removal of these compounds. The current work reports the applicability of hexagonal and cubic aluminosilica monoliths with macro-and meso-cylinder pore structures and aluminium contents with 19 ≤ Si/Al ≥ 1 as effective adsorbents for removal of organic pollutants such as aniline compounds from an aqueous solution. A simple, reproducible, and one-pot synthesis strategy was used to achieve a realistic control over a wide range of mesophase geometries, cylindrical-like pores, and relatively high surface area, yet maintains the long-range structural ordering of aluminosilica monoliths. To better understand the role of the geometry and nanoscale pore orientation of mesostructures, theoretical models have been developed. In addition, the atomic charge distribution in the interior structures was investigated to give insight about the effect of active site surfaces in the enhancement of the adsorption process. The coordination and location of aluminium sites in the frameworks play a key role in the generation of the surface acidity of aluminosilica monoliths, which enhanced the adsorption capacity of the organic pollutants. Our experimental results suggest that the acidity of the adsorbents significantly increased with increasing amounts of aluminium species in the pore framework walls. The natural surfaces of acidic active sites of monoliths strongly induced the removal and adsorption of toxic aromatic amines from wastewater. The relative adsorption affinity of the mesocylinder adsorbent for organic pollutants was decreased in the order of p-nitroaniline < o-aminophenol < p-chloroaniline < aniline. In addition, the thermodynamic studies indicated that these adsorbent monoliths with macroand meso-cylinder pore cavities show promise for the spontaneous removal of organic containments from aqueous water. Finally, we believe our adsorption model will open a new avenue in the development of simple and effective strategy for removal of pollutants and wastewater treatment.