Removal-concentration of pollutant metal-ions by water-soluble polymers in conjunction with double emulsion systems: A new hybrid method of membrane-based separation

Efficacy of Alkaline-Treated Soy Waste Biomass for the Removal of Heavy-Metal Ions and Opportunities for Their Recovery

In this study, soy waste biomass (SW) resulting from oil extraction was treated with alkaline solution, and the obtained material (Na-SW) was used as biosorbent for the removal of Pb(II), Cd(II), and Zn(II) ions from aqueous media. The performance of this biosorbent was examined in batch systems, at different initial metal ion concentrations and contact times (pH 3.4; 5 g of biosorbent/L). Isotherm and kinetic modeling was used to calculate the equilibrium and kinetics of the biosorption processes. The maximum biosorption capacity, calculated from the Langmuir isotherm model, followed the order Zn(II) (0.49 mmol/g) > Cd(II) (0.41 mmol/g) ≈ Pb(II) (0.40 mmol/g), while the kinetics of biosorption processes fit the pseudo-second-order model. Three cycles of biosorption/desorption were performed to estimate the reusability of Na-SW biosorbent, and the regeneration efficiency was higher than 97% in all cases. The practical applicability of Na-SW biosorbent in treating of wastewater contaminated with Pb(II), Cd(II), and Zn(II) ions was examined using simulated wastewater samples, and the main quality characteristics of the effluents obtained after treatment were evaluated. All these aspects highlight the potential applicability of Na-SW for large-scale wastewater treatment.

Preparation of pectin/poly(m-phenylenediamine) microsphere and its application for Pb2+ removal

Novel pectin/poly(m-phenylenediamine) (P/PmPDA) microspheres with different content of PmPDA were prepared by assembling PmPDA on the surface of pectin microsphere. The successful preparation was confirmed by the results of Fourier Transform Infrared spectra (FTIR), scanning electron microscopy (SEM) and elemental analysis. Compared with pectin microsphere, the Pb²⁺ adsorption performance of P/PmPDA microspheres was significantly improved. The results of batch adsorption experiments were in good agreement with the Langmuir isotherm model for Pb²⁺ adsorption, indicating the adsorption was monolayer. The maximum adsorption capacity of Pb²⁺ was found to be 390.9 mg/g. The kinetic adsorption process was well described by the pseudo-second-order model and chemical adsorption dominated the adsorption process. The potential mechanisms of Pb²⁺ adsorption were speculated as ion exchange and chelation, which were supported by X-ray photoelectron spectroscopy (XPS). The P/PmPDA microspheres showed good recyclability after five adsorption/desorption cycles. All these results indicated the potential of P/PmPDA microspheres for removing Pb²⁺.

Effect of Copolymer Structure on Rare-Earth-Element Chelation Thermodynamics

Rare-earth elements (REEs) are crucial to modern technology, leading to a high demand for materials capable of REE extraction and purification. Metal-chelating polymers (e.g., polycarboxylic acids, polyamines, and others) are particularly useful in these applications due to their synthetic accessibility and high selectivity. Copolymers with varied mole fractions of acrylic acid and methyl acrylate are synthesized and isothermal titration calorimetry (ITC) to measure the thermodynamics of REE binding for each material is used. Across a series of copolymer compositions, entropically driven binding thermodynamics (∆G, ∆H, and ∆S) that appear to be independent of χ_{Acrylic Acid} are found. ITC stoichiometry data reveal that each copolymer requires between four and five repeat units to bind each REE. These data suggest that alterations in the copolymer structure do not affect the overall binding thermodynamics of REEs to these copolymers.

Equilibrium and Kinetics Studies of Metal Ions Biosorption on Alginate Extracted from Marine Red Algae Biomass (Callithamnion corymbosum sp.)

Biosorption is a viable alternative that can be used to remove heavy metal ions from aqueous effluents, as long as the biosorbent used is cost-effective and efficient. To highlight this aspect in this study, alginate extracted from marine red algae biomass (Callithamnion corymbosum sp.) was used as biosorbent for the removal of Cu(II), Co(II) and Zn(II) ions from aqueous media. Biosorption studies were performed in a batch system, and the biosorptive performances of the alginate were examined as function of initial solution pH, biosorbent dosage, contact time, initial metal ions concentration and temperature. The optimal experimental conditions were found: initial solution pH of 4.4, a biosorbent dose of 2.0 g/L and a temperature of 22 °C, when over 88% of Cu(II), 76% of Co(II) and 81% of Zn(II) are removed by biosorption. The modeling of the obtained experimental data show that the Langmuir isotherm model and pseudo-second kinetic model well describe the biosorption processes of studied metal ions. The maximum biosorption capacity (q_max, mg/g) increases in the order: Cu(II) (64.52 mg/g) > Zn(II) (37.04 mg/g) > Co(II) (18.79 mg/g), while the minimum time required to reach the equilibrium is 60 min. Moreover, the regeneration efficiency of alginate is higher than 97% when a 10⁻¹ N HNO₃ solution is used as desorption agent for the recovery of Cu(II), Co(II) and Zn(II) ions. All these characteristics demonstrate that the alginate extracted from marine algae has promising applications in the decontamination of industrial effluent containing metal ions.

Enhancing trans-Resveratrol loading capacity by forcing W1/O/W2 emulsions up to its colloidal stability limit

Trans-Resveratrol (3, 5, 4'-trihydroxystilbene) is a naturally occurring polyphenol easily oxidizable and extremely photosensitive with a short biological half-life that must be encapsulated to maintain its beneficial properties on the human body. The aim of this work is to increase the amount of resveratrol encapsulated using concentrated double water-in-oil-in-water (W₁/O/W₂) emulsions, making these systems more interesting as ingredient for functional food products and/or pharmaceutical formulations. The concentration of the inner emulsion (W₁/O) for several external (W₁O/W₂) ratios was optimized in terms of encapsulation efficiency (EE), colloidal stability and rheological behaviour. W₁/O emulsions formulated with ratios of 30/70 and 40/60 were used to obtain double emulsions (with ratios of 20/80 up to 80/20 of W₁O/W₂). Trans-Resveratrol EE increased up to 90 % when the most concentrated double emulsions were prepared for both W₁/O ratios tested. The maximum resveratrol concentrations on double emulsions were 10.8 mg/L and 14.4 mg/L when 30/70 and 40/60 of W₁/O ratios were used, respectively. However, longer time stability was found for double high internal phase emulsions (W₁O/W₂) with a ratio of 30/70 of W₁/O. The double emulsion formulated with a 80/20 W₁O/W₂ volumetric ratio together with 30/70 of W₁/O seems suitable to be used as ingredient for pharmaceutical and food devices/products due to its high colloidal stability, clearly pseudoplastic and elastic behaviour, high EE and large trans-Resveratrol carrier capacity.

Lignocellulosic fraction of the pericarps of the acorns of Quercus suber and Quercus ilex: isolation, characterization, and biosorption studies in the removal of copper from aqueous solutions

Pericarps of Algerian Quercus ilex (Q. ilex) and Quercus suber (Q. suber) were used as copper adsorbents in artificially contaminated solutions. Exposing accessible lignocellulosic binding sites enhanced adsorption. The lignocellulosic fractions of Q. suber and Q. ilex (36.47±9.1 and 47.66±9.3, respectively) were characterized by FTIR before and after adsorption. The aim was to identify the functional groups adsorbing Cu(II). SEM/EDX determined lignocellulose surface morphology and composition. The amount of adsorbent-bound Cu(II) increased with initial [Cu(II)]. Cu(II) adsorption range was 23.59–48.06 mg.g−1 for Q. Suber and 22.56–38.19 mg.g−1 for Q. ilex when [Cu(II)] was 100–500 mg.L−1. Adsorption isotherms and Langmuir and Freundlich models of the Q. suber and Q. ilex lignocellulosic fractions indicated natural Cu(II)adsorption capacities (Qmax) of 53.76 mg.g−1 and 36.06 mg.g−1 and KF of 5.9 mg.g−1 and 7.43 mg.g−1, respectively.

Valorisation possibilities of exhausted biosorbents loaded with metal ions - A review

Biosorption is considered one of the most promising methods for removal of metal ions from aqueous effluents, due to its low-cost and eco-friendly characteristics. However, the exhausted biosorbents loaded with metal ions, obtained at the end of biosorption processes, are still a problem which should be solved to increase the applicability of biosorption on an industrial scale. In this study are examined three possibilities for the valorisation of exhausted biosorbents loaded with metal ions, namely: (i) regeneration and reuse of biosorbents in multiple biosorption cycles, (ii) the use of exhausted biosorbents as fertilizers for soils poor in essential microelements, and (iii) the pyrolysis of exhausted biosorbents, under well defined conditions. The main advantages and disadvantages of each valorisation possibility are reviewed in order to find the best way to use these cheap materials in accordance with the principles of the circular economy and thereby contributing to the development of sustainable biosorption technology.

Controllable promotion of chondrocyte adhesion and growth on PVA hydrogels by controlled release of TGF-β1 from porous PLGA microspheres

Poly(vinyl alcohol) (PVA) hydrogels have been candidate materials for cartilage tissue engineering. However, the cell non-adhesive nature of PVA hydrogels has been a limit. In this paper, the cell adhesion and growth on PVA hydrogels were promoted by compositing with transform growth factor-β1 (TGF-β1) loaded porous poly(D,L-lactide-co-glycolide) (PLGA) microspheres. The porous microspheres were fabricated by a modified double emulsion method with bovine serum albumin (BSA) as porogen. The average pore size of microspheres was manipulated by changing the BSA/PLGA ratio. Such controllable porous structures effectively influenced the encapsulation efficiency (Eencaps) and release profile of TGF-β1. By compositing PVA hydrogels with such TGF-β1-loaded PLGA microspheres, chondrocyte adhesion and proliferation were significantly promoted in a controllable manner, as confirmed by fluorescent imaging and quantitative CCK-8 assay. That is, the chondrocyte proliferation was favored by using PLGA microspheres with high Eencaps of TGF-β1 or by increasing the PLGA microsphere content in the hydrogels. These results demonstrated a facile method to improve the cell adhesion and growth on the intrinsically cell non-adhesive PVA hydrogels, which may find applications in cartilage substitution.