Adding MgO nanoparticles to hydroxyapatite–PLLA nanocomposites for improved bone tissue engineering applications

The hydroxyapatite was successfully synthesized, characterized, and used as an alternative low-cost adsorbent material to study the adsorption behavior of La(III) and Eu(III) ions from nitrate aqueous solutions as a function of contact time, initial metal ion concentration, pH, and temperature by using a bath technique. The kinetic data correspond very well to the pseudo-second-order equation, and in both cases the uptake was affected by intraparticle diffusion. Isotherm adsorption data were well fitted by the Freundlich model equation with <path id="x1D45B" d="M495 86q-46 -47 -87 -72.5t-63 -25.5q-43 0 -16 107l49 210q7 34 8 50.5t-3 21t-13 4.5q-35 0 -109.5 -72.5t-115.5 -140.5q-21 -75 -38 -159q-50 -10 -76 -21l-6 8l84 340q8 35 -4 35q-17 0 -67 -46l-15 26q44 44 85.5 70.5t64.5 26.5q35 0 10 -103l-24 -98h2
q42 56 97 103.5t96 71.5q46 26 74 26q9 0 16 -2.5t14 -11.5t9.5 -24.5t-1 -44t-13.5 -68.5q-30 -117 -47 -200q-4 -19 -3.5 -25t6.5 -6q21 0 70 48z" /> , indicating a multilayer and cooperative-type adsorption. Thermodynamic parameters for the adsorption systems were determinated at 293, 303, 313, and 323 K. These parameters show that adsorptions of La(III) and Eu(III) ions on hydroxyapatite are endothermic and spontaneous processes. The adsorption was found to follow the order Eu(III) > La(III) and is dependent on ion concentration, pH, and temperature.

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Adsorption Behaviour of La(III) and Eu(III) Ions from Aqueous Solutions by Hydroxyapatite: Kinetic, Isotherm, and Thermodynamic Studies

Chromium (VI) is an important heavy metal commonly found in tannery wastewater. In order to manage this type of environmental pollution, there needs to be a better understanding of Cr(VI) adsorption mechanisms. This article reviews the recent usage of various adsorbents to adsorb Cr(VI) from wastewater. The paper provides an overview of the removal capacity of numerous adsorbents in terms of Cr(VI) speciation, empirical modeling, surface complexation model (SCM) and spectroscopic measurements carried out by a wide number of researchers. Special emphasis was given to summarise various proposed Cr(VI) adsorption mechanism. It has been noted that Cr(VI) adsorption has been studied using a wide range of adsorbent materials with adsorption capacity from low to higher depending several factors including the nature and type of adsorbent, surface property of adsorbent, surface modification, pre-treatment of substrate, coexisting substrate and experimental conditions (equilibration time, solution pH, initial Cr(VI) concentration, ionic strength). Cr(VI) adsorption was highly dependent on solution pH and Cr(VI) adsorbed strongly in acidic pH while it exhibited weak or no adsorption in alkaline pH condition. Cr(VI) adsorption data has been studied using proton stoichiometry, kinetic, Langmuir, Freundlich, and surface complexation model (SCM). Adsorption data commonly fitted with a pseudo-second-order (PS2) kinetic model and Langmuir equation. Cr(VI) adsorbed typically by inner-sphere Cr(VI) complex at pH below 6.0 and by outer-sphere Cr(VI) complex above pH 6.0. Proton stoichiometry indicated that more than one reaction was involved in Cr(VI) adsorption. This review can be a centrepiece of researchers who wish to work on Cr(VI) adsorption. This study will shed new light on the understanding Cr(VI) adsorption onto the substrate at the water-solid interface and develop high-performance substrate to remove pollutants efficiently from wastewater.

Recent innovative research on chromium (VI) adsorption mechanism

Recent developments in the field of biomaterials for tissue engineering open up new opportunities for regenerative therapy and prevention of progression of osteo-articular damage/impairment. A key advancement was the discovery of the regenerative activity of a group of physiologically occurring high-energy polymers, inorganic polyphosphates (polyP). These bio-polymers, in suitable bioinspired formulations, turned out to be capable of inducing proliferation and differentiation of mesenchymal stem cells into osteogenic or chondrogenic lineages through differential gene expression (morphogenetic activity). Unprecedented is the property of these biopolymers to deliver high-energy phosphate in the extracellular space to promote anabolic processes including extracellular matrix synthesis in bradytrophic tissues such as cartilage and mineralized bone. This review summarizes the biological effects of these unique bio-polymers, not yet met by other biomaterials and depending on their specific formulation as smart amorphous nanoparticles/microparticles with different counterions. In addition, polyP in combination with other, hydrogel-forming polymers provides the basis for the fabrication of hardenable bio-inks applicable in additive manufacturing/3D printing and 3D cell bioprinting of regeneratively active patient-specific osteo-articular implants. The future prospects of this innovative technology are discussed.

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Amorphous polyphosphate, a smart bioinspired nano-/bio-material for bone and cartilage regeneration: towards a new paradigm in tissue engineering

Fluoride removal from groundwater by limestone treatment in presence of phosphoric acid.

Calcium phosphate with hydroxyapatite structure was synthesized and its ability to adsorb Cr(VI) from aqueous solution is presented. XRD, BET, IR, TGA, SEM and EDS techniques were used to characterize the obtained material. A pure phase was obtained through a simple synthesis process. The specific surface area of the synthesized powder was found to be 64.5 m 2 g -1 . The X-ray diffraction pattern shows that the calcium phosphate formed was nanocrystalline with an average grain size of approximately 75 nm. A fast adsorption was observed and in less than 24 h it was found that 2.41 x 10 -4 meq g -1 of Cr(VI) ions were adsorbed on calcium phosphate. Desorption experiments showed that Cr(VI) adsorption decreased to 2.23 x 10 -4 meq g -1 of calcium phosphate. This behavior is a consequence of partial dehydration of the synthesized material. Calcium phosphate can be effectively used for removing Cr(VI) from aqueous solutions in treatment processes of metal wastes.

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Síntesis y caracterización de fosfato de calcio y su relación con las propiedades de adsorción del Cr(VI)

Polypropylene (PP) grafted with dimethylaminoethyl- methacrylate (DMAEMA), was prepared by irradiation with a 60 Co γ source. The obtained PP-g-DMAEMA was used to study the Cr(VI) ion adsorption as a function of contact time, initial pH, initial concen- tration of metal ion and temperature. Chromium adsorption data on PP-g-DMAEMA at various initial concentration fit well the Freundlich and Langmuir isotherms. The maximum adsorption capacity (amax) was found to be 0.3103 × 0 -4 mol g -1 . The thermodynamic parameters ΔH 0 , ΔG 0 and ΔS 0 were estimated showing the adsorption process to

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Adsorption of chromium(VI) on radiation grafted N,N-dimethylaminoethylmethacrylate onto polypropylene, from aqueous solutions

In order to select a treatment method for the final disposition of ion-exchange res ins used in nuclear power plants, a thermal study of styrene-divinylbenzene resins based on sulfonic and ammonium quaternary groups was carried out to determine their mode of decomposition as well as their relative thermal stability using thermogravimetric analysis (TGA) The Kissinger differential method was used to calculate thermal activation energy Infrared spectroscopy (IR) was used to characterize the resin degradation steps The resins undergo thermal degradation from 373 to 770 K through a dehydration (331 K), followed by a chemical decomposition Anionic resins decompose releasing tertiary amines (453 K and Ea = 10406 kJmol –1 ) while cationic resins decompose releasing sulfur compounds (610 K and Ea = 144 kJmol –1 ) Depolymerization of cationic (667 K and Ea = 270 kJmol –1 ) and anionic (707 K and Ea = 2287 kJmol –1 ) resins was evaluated by IR identification of aliphatic and aromatic

/pdf/termodegradacion-de-resinas-agotadas-de-intercambio-ionico-2rocjw3ke3.pdf

Juan Bonifacio-Martínez

Papers

Síntesis y caracterización de fosfato de calcio y su relación con las propiedades de adsorción del Cr(VI)

Adsorption of chromium(VI) on radiation grafted N,N-dimethylaminoethylmethacrylate onto polypropylene, from aqueous solutions

Termodegradación de resinas agotadas de intercambio iónico de lecho mixto

Synthetic alkaline-earth hydroxyapatites: Influence of their structural, textural, and morphological properties over Co ion adsorption capacity