Extraction and separation feasibility of cerium (III) and lanthanum (III) from aqueous solution using modified graphite adsorbent

Facile synthesis of eco-friendly alginate-chitosan bio-adsorbent for critical raw materials adsorption: A comprehensive study

Sustainable management of critical raw materials is of paramount importance to ensure a steady supply and reduce environmental impact. The application of newly synthesized and environmentally friendly ALG@CS material as a bio-adsorbent for the effective rare earth elements removal from aqueous solution has been presented. The synthesized material underwent FTIR, XPS, EDX, and SEM analysis to determine its suitability for metal uptake. To evaluate the adsorption capacity of ALG@CS for rare earth elements several factors were taken into consideration. These factors included alginate:chitosan ratios, bead size, pH level, composite mass, interaction time, metal ion concentration, and temperature, being all varied during the batch mode evaluation process. Under the optimal conditions, the maximum adsorption capacities were found to be 145.90 mg La(III)/g, 168.44 mg Ce(III)/g, 132.51 mg Pr(III)/g, 128.40 mg Nd(III)/g, 154.36 mg Sm(III)/g, and 165.10 mg Ho(III)/g. The equilibrium data fits well with non-linear three-parameter Sips and Redlich-Peterson isotherm models. The PSO model finds the highest process suitability. The synthesized ALG@CS bio-adsorbent showed excellent regenerative capacity in ten cycles, making it a suitable adsorbent for rare earth elements uptake. The unique bio-adsorbents combination allows for efficient critical raw materials adsorption providing a promising solution for their recovery and recycling.

Intervention-Free Graphitization of Carbon Microspheres from a Non-Graphitizing Polymer at Low Temperature: Nanopores as Dynamic Nanoreactors

Graphitizability of organic precursors is the topic of numerous investigations due to the wide applications of graphitic materials in the industry and emerging technologies of supercapacitors, batteries, etc. Most polymers, such as polydivinyl benzene (PDVB) are classified as non-graphitizings that do not convert to Graphite even after heating to 3000℃. Here, for the first time, the development of graphitic structure in the hierarchal porous sulfonated-PDVB microspheres without employing specific equipment or additives like metal catalysts, organic ingredients, or graphite particles, at 1100°C is reported. The abnormal additive-free graphitic structure formation is confirmed by Raman spectroscopy (ID/IG = 0.87), high-resolution transmission electron microscopy (HRTEM), and selected area diffraction patterns (SAED), as well as x-ray diffraction patterns (XRD), while preservation of aromatic compounds from the carbonization is detected by Fourier transform infrared (FTIR) analysis. Polymer evolution from room temperature to 1100°C is also studied by FTIR, Raman spectroscopy, and XRD techniques. Based on the obtained results, it is suggested that the hierarchal and complicated ink-bottle pore network with a high surface area besides super micropores in the sulfonated-PDVB microspheres has served as nano-sized reaction media. These pores, hereafter referred as "dynamic nanoreactors", are expected to have confined the in-situ produced thermal decomposition products containing broken bond benzene rings, while changing dimensionally and structurally during the designed carbonization regime. This confinement has led to the benzene rings fusion at 250°C, a remarkable extension of them at 450°C, their growth to graphene sheets at 900°C and finally, the stacking of curved graphene layers at 1100°C. The results of this research put stress on the capability of nanopores as nanoreactors to facilitate reactions of decomposition products at low temperatures and ambient pressures to form stacked layers of graphene; A transformation that normally requires catalysts and very high pressures for only specific polyaromatic hydrocarbons.

Effect of Lanthanum Sorption on the Behavior of Rarely Crosslinked Acidic and Basic Polymer Hydrogels during Remote Interaction

This present study is targeted at the complex investigation of the behavior of interpolymer systems based on acidic rarely crosslinked polymeric hydrogels (polyacrylic acid hydrogel (hPAA); polymethacrylic acid hydrogel (hPMAA)) and basic rarely crosslinked polymeric hydrogels (poly-4-vinylpyridine hydrogel (hP4VP), specifically the poly-2-methyl-5-vinylpyridine hydrogel (hP2M5VP)) either in an aqueous medium or lanthanum nitrate solution. We found that the transition of the polymeric hydrogels in the developed interpolymer systems (hPAA-hP4VP, hPMAA-hP4VP, hPAA-hP2M5VP, and hPMAA-hP2M5VP) into highly ionized states leads to significant changes in electrochemical, conformational, and sorption properties of the initial macromolecules. The subsequent mutual activation effect demonstrates strong swelling of both hydrogels in the systems. The sorption efficiency of lanthanum by the interpolymer systems is 94.51% (33%hPAA:67%hP4VP), 90.80% (17%hPMAA-83%hP4VP), 91.55% (67%hPAA:33%hP2M5VP), and 90.10% (50%hPMAA:50%hP2M5VP). An advantage of the interpolymer systems (compared to individual polymeric hydrogels) is the strong growth of their sorption properties (up to 35%) due to high ionization states. Interpolymer systems can be considered new-generation sorbents for further application in the industry for highly effective sorption of rare earth metals.