Enhancement of Cerium Sorption onto Urea-Functionalized Magnetite Chitosan Microparticles by Sorbent Sulfonation—Application to Ore Leachate

The recovery of strategic metals such as rare earth elements (REEs) requires the development of new sorbents with high sorption capacities and selectivity. The bi-functionality of sorbents showed a remarkable capacity for the enhancement of binding properties. This work compares the sorption properties of magnetic chitosan (MC, prepared by dispersion of hydrothermally precipitated magnetite microparticles (synthesized through Fe(II)/Fe(III) precursors) into chitosan solution and crosslinking with glutaraldehyde) with those of the urea derivative (MC-UR) and its sulfonated derivative (MC-UR/S) for cerium (as an example of REEs). The sorbents were characterized by FTIR, TGA, elemental analysis, SEM-EDX, TEM, VSM, and titration. In a second step, the effect of pH (optimum at pH 5), the uptake kinetics (fitted by the pseudo-first-order rate equation), the sorption isotherms (modeled by the Langmuir equation) are investigated. The successive modifications of magnetic chitosan increases the maximum sorption capacity from 0.28 to 0.845 and 1.25 mmol Ce g⁻¹ (MC, MC-UR, and MC-UR/S, respectively). The bi-functionalization strongly increases the selectivity of the sorbent for Ce(III) through multi-component equimolar solutions (especially at pH 4). The functionalization notably increases the stability at recycling (for at least 5 cycles), using 0.2 M HCl for the complete desorption of cerium from the loaded sorbent. The bi-functionalized sorbent was successfully tested for the recovery of cerium from pre-treated acidic leachates, recovered from low-grade cerium-bearing Egyptian ore.     

Synthesis and Spectroscopic Characterization of Novel Aryl-Dithiofluorophosphonate Derivatives and X-Ray Studies of [(4-CH3OC6H4)(F)P(S)S−][PH4P+]

Abstract

Potassium and tetraphenylphosphonium salts of novel aryldithiofluorophosphonic acids were synthesized. Lawesson's Reagent was allowed to react with KF in acetonitrile to yield the potassium salt of p-methoxyphenyldithiofluorophosphonic acid. Treatment of the latter with tetraphenylphosphonium chloride resulted in the formation of the tetraphenylphosphonium salt. The structures of the compounds were elucidated by FTIR, ¹H, ¹³C, ¹⁹F, and ³¹P NMR spectroscopy as well as by ESI-mass spectrometry. The molecular and crystal structure of the tetraphenylphosphonium salt, determined by single crystal X-ray diffraction, is also presented.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Microwave-assisted synthesis and crystal structure of some novel 1,2,4-oxadiazol-5-ylmethyl-1,2,3-triazoles

Microwave-assisted 1,3-dipolar cycloaddition of 5-azidomethyl 3-aryl-substituted 1,2,4-oxadiazoles to electron-deficient alkyne; phenyl propiolic acid affords a series of 1,2,3-triazole derivatives carrying 3-p-substitutedphenyl-1,2,4-oxadiazolyl methyl unit. The structures of all the cycloadducts were elucidated by IR, NMR (¹H, ¹³C, 2D), MASS (low and high resolution) spectra, X-ray diffraction data, and physical characteristics (melting points and R_f values).     

ELECTRO-MAGNETO-THERMOELASTIC PLANE WAVES IN MICROPOLAR SOLID INVOLVING TWO TEMPERATURES

<正>The model of equations of micropolar generalized magneto-thermoelasticity is introduced within the context of the theory of two temperatures generalized thermoelasticity and we consider a problem of an isotropic homogeneous micropolar medium taking into account the heat effects and allowing the magnetic field effects.A plane wave analysis is employed to obtain the exact formulas of the two temperatures(conductive and mechanical),displacement components, micro-rotation components,stresses,couple stresses,induced electric current,electric field and magnetic field.Arbitrary application is chosen to enable us to get the complete solution.The considered variables are presented graphically and discussions are made for the results.     

Commutativity for a certain class of rings

We discuss the commutativity of certain rings with unity 1 and one-sideds-unital rings under each of the following conditions:x ^r [x ^s ,y]=±[x,y ^t ]x ⁿ x ^r [x ^s ,y]=±x ⁿ [x,y ^t ]x ^r [x ^s ,y]=±[x,y ^t ]y ^m , andx ^r [x ^s ,y]=±y ^m [x,y ^t ], wherer, n, andm are non-negative integers andt>1,s are positive integers such that eithers, t are relatively prime ors[x,y]=0 implies [x,y]=0. Further, we improve the result of [6, Theorem 3] and reprove several recent results.     

Structure of low-density nanoporous dielectrics revealed by low-vacuum electron microscopy and small-angle X-ray scattering

Aerogels (AGs) are ultralow-density nanoporous solids that have numerous potential applications. However, as most AGs are strong insulators with poor mechanical properties, direct studies of the complex nanoporous structure of AGs by methods such as atomic force and conventional scanning electron microscopy (SEM) have not proven feasible. Here, we use low-vacuum SEM to image directly the ligament and pore size and shape distributions of representative AGs over a wide range of length scales (approximately 100-105 nm). The structural information obtained is used for unambiguous, real-space interpretation of small-angle X-ray scattering curves for these complex nanoporous systems. Low-vacuum SEM permits imaging of both cross-sections and skin layers of AG monoliths. Images of skin layers reveal the presence of microcracks, which alter the properties of cast monolithic AGs.