Complexation of Hg(II) ions with a functionalized adsorbent: A thermodynamic and kinetic approach

Synthesis of furan-modified cationic cellulose for stereo-specific imprinting and separation of S-indacrinone via Diels-Alder reaction

This study introduces a novel approach for the separation of indacrinone (IC) enantiomers, crucial in treating edema, hypertension, and hyperuricemia. A cationic biopolymer from furan-2-ylmethylhydrazine-cellulose (FUH-CE), derived from cyanoethyl cellulose (CEC), serving as a substrate in molecular imprinting. A key innovation is the use of the Diels-Alder reaction for efficient cross-linking with bis(maleimido)ethane (BME). This chemical strategy resulted in molecularly imprinted microparticles with high selectivity for the S-IC enantiomer, which can be eluted by adjusting the solution's pH. Extensive characterization confirmed the chemical modifications and selective binding efficacy of these biopolymers. Utilizing separation columns, our method achieved an impressive chiral resolution of (±)-IC, with an enantiomeric excess (ee) of 95 % for R-IC during the loading phase and 97 % for S-IC during elution. Under optimized conditions, the biopolymer demonstrated a maximum binding capacity of 131 mg/g at pH 6. This advanced approach represents a significant advancement in chiral separation technology, offering a robust and efficient technique for the selective isolation of enantiomers. This method not only enhances potential targeted therapeutic applications but also provides a scalable solution for industrial chiral separations.

Ion-imprinted aminoguanidine-chitosan for selective recognition of lanthanum (III) from wastewater

Developing a sorbent for the removal of La3+ ions from wastewater offers significant environmental and economic advantages. This study employed an ion-imprinting process to integrate La3+ ions into a newly developed derivative of aminoguanidine-chitosan (AGCS), synthesized via an innovative method. The process initiated with the modification of chitosan by attaching cyanoacetyl groups through amide bonds, yielding cyanoacetyl chitosan (CAC). This derivative underwent further modification with aminoguanidine to produce the chelating AGCS biopolymer. The binding of La3+ ions to AGCS occurred through imprinting and cross-linking with epichlorohydrin (ECH), followed by the extraction of La3+, resulting in the La3+ ion-imprinted sorbent (La-AGCS). Structural confirmation of these chitosan derivatives was established through elemental analysis, FTIR, and NMR. SEM analysis revealed that La-AGCS exhibited a more porous structure compared to the smoother non-imprinted polymer (NIP). La-AGCS demonstrated superior La3+ capture capability, with a maximum capacity of 286 ± 1 mg/g. The adsorption process, fitting the Langmuir and pseudo-second-order models, indicated a primary chemisorption mechanism. Moreover, La-AGCS displayed excellent selectivity for La3+, exhibiting selectivity coefficients ranging from 4 to 13 against other metals. This study underscores a strategic approach in designing advanced materials tailored for La3+ removal, capitalizing on specific chelator properties and ion-imprinting technology.

Mercury abatement in the environment: Insights from industrial emissions and fates in the environment

Mercury's neurotoxic effects have prompted the development of advanced control and remediation methods to meet stringent measures for industries with high-mercury feedstocks. Industries with significant Hg emissions, including artisanal and small-scale gold mining (ASGM)-789.2 Mg year-1, coal combustion-564.1 Mg year-1, waste combustion-316.1 Mg year-1, cement production-224.5 Mg year-1, and non-ferrous metals smelting-204.1 Mg year-1, use oxidants and adsorbents capture Hg from waste streams. Oxidizing agents such as O3, Cl2, HCl, CaBr2, CaCl2, and NH4Cl oxidize Hg0 to Hg2+ for easier adsorption. To functionalize adsorbents, carbonaceous ones use S, SO2, and Na2S, metal-based adsorbents use dimercaprol, and polymer-based adsorbents are grafted with acrylonitrile and hydroxylamine hydrochloride. Adsorption capacities span 0.2-85.6 mg g-1 for carbonaceous, 0.5-14.8 mg g-1 for metal-based, and 168.1-1216 mg g-1 for polymer-based adsorbents. Assessing Hg contamination in soils and sediments uses bioindicators and stable isotopes. Remediation approaches include heat treatment, chemical stabilization and immobilization, and phytoremediation techniques when contamination exceeds thresholds. Achieving a substantially Hg-free ecosystem remains a formidable challenge, chiefly due to the ASGM industry, policy gaps, and Hg persistence. Nevertheless, improvements in adsorbent technologies hold potential.

Preparation of magnetic hydrochar derived from iron-rich Phytolacca acinosa Roxb. for Cd removal

Considering that hyperaccumulators can accumulate high concentrations of iron salt, they can successfully obtain magnetic hydrochar from iron-rich hyperaccumulators. In this study, iron-rich biomass was obtained by irrigating Phytolacca acinosa Roxb. using iron salt. Magnetic nano-Fe₃O₄ hydrochar was prepared from iron-rich Phytolacca acinosa Roxb. via hydrothermal carbonization to remove Cd. The characterization results showed that the synthesized magnetic nanoparticles had an average size of 2.62 ± 0.56 nm and N elements were doped into magnetic nano-Fe₃O₄ hydrochar with abundant oxygenic groups. Cd adsorption on magnetic nano-Fe₃O₄ hydrochar was better fitted using the Langmuir isotherm and the pseudo-second-order kinetic model. The maximum adsorption capacity was 246.6 mg g^-1 of Cd. The research confirmed that Cd adsorption was controlled by multiple mechanisms from the jar test, transmission electron microscopy mapping, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. CdCO₃ crystals can be formed after adsorption, indicating that surface precipitation played an important role in Cd adsorption. The abundance of O atoms and the doping of N atoms on the hydrochar surface were conducive to Cd adsorption, indicating that the mechanisms were related to surface complexation and electrostatic attraction. In addition, the significant decrease in Na⁺ content after Cd adsorption illustrated that ion exchange had a non-negligible effect on Cd adsorption. This study not only provides a strategy for preparing magnetic nano-Fe₃O₄ hydrochar derived from iron-rich plants but also verifies multiple Cd adsorption mechanisms using magnetic nano-Fe₃O₄ hydrochar.