Bioinspired construction of magnetic nano stirring rods with radially aligned dual mesopores and intrinsic rapid adsorption of palladium

Quaternized Fe3O4@chitosan nanoparticles for efficient and selective isolation of heparin

Heparin, a highly sulfated polysaccharide, is industrially produced for clinical applications. To realize highly efficient and selective adsorption of heparin from complex biological components (e.g., proteins, nucleic acids) remains a challenge in the isolation process. This study reported a simple and green approach to fabricate heparin adsorbent of quaternized Fe3O4@chitosan nanoparticles (QFCNs) by using the natural polysaccharides of chitosan coated and cross-linked with glutaraldehyde on the Fe3O4 and further quaternized using glycidyltrimethylammonium chloride. The effects of adsorbent type, pH, initial heparin concentration, and temperature on the adsorption performance were investigated. The QFCNs demonstrated a high adsorption efficiency of 90.02 % and a remarkable adsorption capacity of 33.04 mg g-1, surpassing the performance of previously reported adsorbents, and the adsorption process was found to be more closely aligned with the pseudo-first-order model, Langmuir and Sips isotherm model. Furthermore, the QCNFs exhibited a distinct selectivity for heparin in the presence of BSA at pH 7.0 in 0.3 mol L-1 of NaCl. The adsorption capacity of QFCNs was 1.63 times that of the commercial Amberlite FPA98Cl resin in the adsorption process of crude heparin, and the purity of the crude heparin was enhanced from 37.10 % to 78.10 %. Besides, the adsorption capacity remained at an acceptable level after five cycles. The X-ray photoelectron spectroscopy results elucidated the heparin adsorption follows the mechanism of the electrostatic attraction with the quaternary ammonium groups of QCNFs. QFCNs could become an ideal adsorbent for the selective capture of heparin and other negatively charged natural polysaccharides, offering high efficiency, environmental friendliness, and facile recyclability.

Fabrication of superporous cryogels with amidoxime chelation sites and customizable 3D printing for targeted palladium recovery from secondary resources

Recovering precious metals such as palladium from secondary resources faces significant challenges, including the scarcity of efficient adsorbents capable of withstanding harsh acidic conditions and needing materials with high selectivity, mechanical stability, and scalability. In response to these challenges, we developed highly porous cryogels functionalized with sulfonic and amidoxime groups, achieving a unique combination of hydrophilicity, flexibility, and selectivity for Pd(II) ions. Using a redox cryopolymerization method, these cryogels attained a gel fraction of 100 % and a maximum adsorption capacity of 425.3 mg g-1 at 318 K, as the Langmuir isotherm model fitted. This work also combined 3D printing technology with cryopolymerization to create a highly selective, high mechanical strength and customizable shape adsorption material, overcoming traditional adsorption materials' limitations in acid conditions. This innovative combination fills the gap in selective palladium recovery in customizable super macroporous materials, offering a sustainable solution for precious metal recovery and setting a foundation for broader applications in adsorption separation.

Physical-Chemical Coupling Coassembly Approach to Branched Magnetic Mesoporous Nanochains with Adjustable Surface Roughness

Self-assembly processes triggered by physical or chemical driving forces have been applied to fabricate hierarchical materials with subtle nanostructures. However, various physicochemical processes often interfere with each other, and their precise control has remained a great challenge. Here, in this paper, a rational synthesis of 1D magnetite-chain and mesoporous-silica-nanorod (Fe3O4&mSiO2) branched magnetic nanochains via a physical-chemical coupling coassembly approach is reported. Magnetic-field-induced assembly of magnetite Fe3O4 nanoparticles and isotropic/anisotropic assembly of mesoporous silica are coupled to obtain the delicate 1D branched magnetic mesoporous nanochains. The nanochains with a length of 2-3 µm in length are composed of aligned Fe3O4@mSiO2 nanospheres with a diameter of 150 nm and sticked-out 300 nm long mSiO2 branches. By properly coordinating the multiple assembly processes, the density and length of mSiO2 branches can well be adjusted. Because of the unique rough surface and length in correspondence to bacteria, the designed 1D Fe3O4&mSiO2 branched magnetic nanochains show strong bacterial adhesion and pressuring ability, performing bacterial inhibition over 60% at a low concentration (15 µg mL-1). This cooperative coassembly strategy deepens the understanding of the micro-nanoscale assembly process and lays a foundation for the preparation of the assembly with adjustable surface structures and the subsequent construction of complex multilevel structures.

Manganese dioxide decorated kiwi peel powder for efficient removal of lead from aqueous solutions, blood and Traditional Chinese Medicine extracts

For human health and environment safety, it is of great significance to develop novel materials with high effectiveness for removal of lead from not only aqueous solutions but also human body and traditional Chinese medicines. Here, functional kiwi peel composite, manganese dioxide decorated kiwi peel powder (MKPP), is proposed for the removal of Pb2+ effectively. The adsorption of Pb2+ in aqueous solution is a highly selective and endothermic process and kinetically follows a pseudo-second-order model, which can reach equilibrium with the capacity of 192.7 mg/g within 10 min. Comprehensive factors of hydration energy, charge-to-radius ratio and softness of Pb2+ make a stronger affinity between MKPP and Pb2+. The possible adsorption mechanism involves covalent bond, electrostatic force and chelation, etc. MKPP can be efficiently regenerated and reused with high adsorption efficiency after five cycles. Besides, MKPP can remove over 97% of Pb2+ from real water samples. MKPP can also alleviate lead poisoning to a certain extent and make the Pb level of TCM extract meet the safety standard. This work highlights that MKPP is a promising adsorbent for the removal of Pb2+ and provides an efficient strategy for reusing kiwi peel as well as dealing with the problem of Pb pollution.

An Aryl-ether-linked Covalent Organic Framework Modified with Thioamide Groups for Selective Extraction of Palladium from Strong Acid Solutions

Efficient adsorption of palladium ions from acid nuclear waste solution is crucial for ensuring the safety of vitrification process for radioactive waste. However, the limited stability and selectivity of most current adsorbents hinder their practical applications under strong acid and intense radiation conditions. Herein, to address these limitations, we designed and synthesized an aryl-ether-linked covalent organic framework (COF-316-DM) grafted dimethylthiocarbamoyl groups on the pore walls. This unique structure endows COF-316-DM with high stability and exceptional palladium capture capacity. The robust polyarylether linkage enables COF-316-DM to withstand irradiation doses of 200 or 400 kGy of β/γ ray. Furthermore, COF-316-DM demonstrates fast adsorption kinetics, high adsorption capacity (147 mg g-1 ), and excellent reusability in 4 M nitric acid. Moreover, COF-316-DM exhibits remarkable selectivity for palladium ions in the presence of 17 interference ions, simulating high level liquid waste scenario. The superior adsorption performance can be attributed to the strong binding affinity between the thioamide groups and Pd2+ ions, as confirmed by the comprehensive analysis of FT-IR and XPS spectra. Our findings highlight the potential of COFs with robust linkers and tailored functional groups for efficient and selective capture of metal ions, even in harsh environmental conditions.

Comparison of Salvianolic Acid A Adsorption by Phenylboronic-Acid-Functionalized Montmorillonites with Different Intercalators

Due to its success in treating cardio-cerebrovascular illnesses, salvianolic acid A (SAA) from Salvia miltiorrhiza is of major importance for effective acquisition. For the adsorption of salvianolic acid, cationic polyelectrolytes, and amino-terminated silane intercalated with phenylboronic-acid-functionalized montmorillonites, known as phenylboronic-acid-functionalized montmorillonites with PEI (PMP) and phenylboronic-acid-functionalized montmorillonites with KH550 (PMK), respectively, were produced. In this paper, detailed comparisons of the SAA adsorption performance and morphology of two adsorbents were performed. PMP showed a higher adsorption efficiency (>88%) over a wide pH range. PMK showed less pH-dependent SAA adsorption with a faster adsorption kinetic fitting in a pseudo-second-order model. For both PMP and PMK, the SAA adsorption processes were endothermic. Additionally, it was clearer how temperature affected PMP adsorption. PMK has a higher adsorption selectivity. This study demonstrates how the type of intercalator can be seen to have an impact on adsorption behavior through various structural variations and offers an alternative suggestion for establishing a dependable method for the synthesis of functional montmorillonite from the intercalator's perspective.