Analyzing ab initio infrared spectra and electronic properties of polyethylenimine water complexes in the solid state

Engineering a sustainable cadmium sulfide/polyethyleneimine-functionalized biochar/chitosan composite for effective chromium adsorption: optimization, co-interfering anions, and mechanisms

A novel eco-friendly adsorbent was fabricated by mixing mushroom-derived cadmium sulfide and polyethyleneimine-functionalized biochar that was fabricated from coffee waste with a chitosan biopolymer. The green-synthesized CdS/PEI-BC/CTS composite was analyzed using several characterization methods to identify its morphological, compositional, and structural characteristics. In addition, the adsorption property of the composite was investigated for hexavalent chromium as a model for anionic heavy metals. The best adsorption conditions to efficiently adsorb Cr(vi) onto CdS/PEI-BC/CTS were scrutinized in the batch mode. The experimental results elucidated that the higher adsorption efficacy for Cr(vi) was 97.89% at pH = 3, Cr(vi) concentration = 50 mg L-1, CdS/PEI-BC/CTS dose = 0.01 g, and temperature = 20 °C. The impact of co-interfering anionic species on Cr(vi) adsorption was identified in simulated wastewater. The recycling property of the CdS/PEI-BC/CTS composite was assessed for ten runs to ensure the applicability of the green composite. The adsorption mechanism and interaction types were proposed on the basis of kinetic and isotherm studies, along with analysis tools. The mechanistic study proposed that the Cr(vi) adsorption onto CdS/PEI-BC/CTS occurred via chemical and physical pathways, including protonation, electrostatic interactions, reduction, and coordination bonds.

Water-soluble iron oxide nanoparticles with high stability and selective surface functionality

The water dispensability and stability of high quality iron oxide nanoparticles synthesized in organic solvents are major issues for biomedical and biological applications. In this paper, a versatile approach for preparing water-soluble iron oxide nanoparticles with great stability and selective surface functionality (-COOH, -NH(2), or -SH) was demonstrated. The hydrophobic nanoparticles were first synthesized by the thermal decomposition of an iron oleate complex in organic solvent. Subsequently, the hydrophobic coatings of nanoparticles were replaced with poly(acrylic acid) , polyethylenimine, or glutathione, yielding charged nanoparticles in aqueous solution. Two parameters were found to be critical for obtaining highly stable nanoparticle dispersions: the original coating and the surfactant-to-nanoparticle ratio. These charged nanoparticles exhibited different stabilities in biological buffers, which were directly influenced by the surface coatings. This report will provide significant practical value in exploring the biological or biomedical applications of iron oxide nanoparticles.