Facile Preparation of Novel Ion-Imprinted Polymers for Selective Extraction of Br(I) Ions from Aqueous Solution

A novel crosslinked chitosan material modified by quaternary ammonium group for efficient adsorption of bromide ions from wastewater

Recovering bromide ions from wastewater can not only alleviate the shortage of bromine resources but also solve the problem of bromine pollution. However, there is no efficient method for selective extraction of bromide ions from bromine-containing wastewater up to now. In this paper, chitosan was acidified into a gel to extend its molecular chain, modified by quaternary ammonium salt functional groups, and then crosslinked to obtain a new adsorption material. The prepared adsorbents were characterized by FT-IR, SEM, XPS and TGA. The effects of adsorption time, pH value, adsorbent dosage, coexisting anions, reusability on the adsorption behavior of bromide ions were studied. Under the optimum adsorption conditions, the saturated adsorption capacity of the adsorbent was 38.21 mg·g-1 at the temperature of 298 K and pH of 7. In addition, batch adsorption experiments showed that the adsorption of bromide ions was better consistent with pseudo-second-order kinetic model and Langmuir model, which could also further clarify the adsorption process mechanism. The mechanism of adsorption behavior of bromide ions on quaternary ammonium-modified chitosan was based on ion exchange. This work provides a new possibility for the recovery of bromide ions from wastewater.

Pyridine-N-Anchored Ag Strategy Facilitated Br- Adsorption via Ultrahigh Exposure and Coordination Unsaturation of Ag

Traditional adsorbents using silver nanoparticles demonstrated exceptional adsorption capacities for Br-. However, the majority of the adsorption sites in silver nanoparticles are situated on their surfaces, limiting the interaction of internal atoms with Br-. Therefore, we synthesized Ag/UiO-bpy MOF by utilizing the two pyridine nitrogen atoms in the ligand to anchor silver. So each silver atom was effectively exposed. Besides, owing to the coordinatively unsaturated state of the silver atoms, they exhibited a stronger adsorption affinity for Br-. As a result, Ag/UiO-bpy demonstrated an exceptional Br- adsorption capacity of 362.6 mg/g. Notably, the adsorption capacity with respect to silver was 2083.9 mg/gAg, which surpasses all previously reported values in the literature. Furthermore, Ag/UiO-bpy exhibited rapid kinetics and exceptional selectivity in Br- adsorption experiments. This work not only fabricated a Br- adsorbent with a high adsorption capacity but also proposed a new and innovative strategy for the subsequent preparation of Br- adsorbents.

In Situ Growth of MOF from Wood Aerogel toward Bromide Ion Adsorption in Simulated Saline Water

Utilizing metal-organic framework (MOF) materials for the extraction of bromide ions (Br-) from aqueous solutions, as an alternative to chlorine gas oxidation technology, holds promising potential for future applications. However, the limitations of powdered MOFs, such as low utilization efficiency, ease of aggregation in water, and challenging recovery processes, have hindered their practical application. Shaping MOF materials into application-oriented forms represents an effective but challenging approach to address these drawbacks. In this work, a novel Ag-UiO-66-(OH)2@delignified wood cellulose aerogel (CA) adsorbent is synthesized using an oil bath impregnation method, involving the deposition of UiO-66-(OH)2 nanoparticles onto CA and the uniform dispersion of Ag0 nanoparticles across its surface. CA, characterized by the intertwined cellulose nanofiber structure and a highly hydrophilic surface, serves as an ideal substrate for the uniform growth of UiO-66-(OH)2 nanoparticles, which, in turn, spontaneously reduce Ag+ to form distributed Ag0 nanoparticles due to the abundant hydroxyl groups provided. Leveraging the well-defined biological structure of CA, which offers excellent mass transfer channels, and the highly dispersed Ag adsorption sites, Ag-UiO-(OH)2/CA exhibits remarkable adsorption capacity (642 mg/gAg) under optimized conditions. Furthermore, an integrated device is constructed by interconnecting Ag-UiO-(OH)2/CA adsorbents in series, affirming its potential application in the continuous recovery of Br-. This study not only presents an efficient Ag-UiO-(OH)2/CA adsorbent for Br- recovery but also sheds light on the extraction of other valuable elements from various liquid ores.

Preparation and Application Progress of Imprinted Polymers

Due to the specific recognition performance, imprinted polymers have been widely investigated and applied in the field of separation and detection. Based on the introduction of the imprinting principles, the classification of imprinted polymers (bulk imprinting, surface imprinting, and epitope imprinting) are summarized according to their structure first. Secondly, the preparation methods of imprinted polymers are summarized in detail, including traditional thermal polymerization, novel radiation polymerization, and green polymerization. Then, the practical applications of imprinted polymers for the selective recognition of different substrates, such as metal ions, organic molecules, and biological macromolecules, are systematically summarized. Finally, the existing problems in its preparation and application are summarized, and its prospects have been prospected.

Bio-inspired fabrication of Ester-functionalized imprinted composite membrane for rapid and high-efficient recovery of lithium ion from seawater

Lithium ion (Li⁺) is one of the important sustainable resource and it's urgently demanded to develop high-selectivity and high-efficient method to extract of Li⁺ from seawater. Hence, we propose the ester-functionalized ion-imprinted membrane (IIMs) with high selectivity and stability for the rebinding and separation of Li⁺ in aqueous medium via ion imprinted technology and membrane separation technology. In this work, the hydrophilic polydimethylsiloxane membranes (PDMS) are synthesized by self-polymerization of dopamine (DA) in aqueous solution, resulting in the fabrication of dense poly-dopamine (PDA) layer on the surface of PDMS (PDMS-PDA). In view of weak bonding forces (such as hydrogen bond, ionic bond and Van der Waals' force) between traditional imprinted polymer and ligand, the ester groups are formed between modified PDMS-PDA and ligand by surface grafting. The obtained Li⁺ imprinted membranes (Li-IIMs) have a suitable cavity and high adsorption capacity toward Li⁺ which reveal a high rebinding capacity (50.872 mg g^-1) toward Li⁺ based on ample rebinding sites and strong affinity force. The superior relative selectivity coefficients (α_Na/Li, α_K/Li and α_Rb/Li are 1.71, 4.56 and 3.80, respectively) can be also achieved. The selectivity factors of Li-IIMs for Na⁺, K⁺ and Rb⁺ are estimated to be 2.52, 2.8 and 3.03 times larger than Li⁺ non-imprinted membranes (Li-NIMs), which imply the superior selectivity of Li-IIMs toward Li⁺. The regeneration ability of Li-IIMs is observed by systematic batch experiments. In summary, it can be concluded that the rebinding capacities of Li-IIMs is slightly decrease after eluting process, owing to the Li-IIMs with outstanding stability performance. Presentation of the method pave a fine prospect for coming true the long-term use of imprinted membrane.