Equilibrium, Thermodynamic, Reuse, and Selectivity Studies for the Bioadsorption of Lanthanum onto Sericin/Alginate/Poly(vinyl alcohol) Particles

Innovative Green Alginate-Cellulose Composite for Light Lanthanides: Experimental Design and Comprehensive Studies on Kinetics, Equilibrium, Thermodynamics, and Reusability

Nowadays, there is a great interest in efficient adsorbent development due to the recent demand for lanthanides, which are widely used in high-tech technology. Alginates, owing to their natural occurrence, gel formation capability, and safety, could be promising feasible adsorbents for lanthanide removal. This study proposes the alginate-cellulose composite as an ecological, sustainable adsorbent for light lanthanide sorption. The structure, morphology, qualitative and quantitative compositions, average diameter, and pHpzc of the composite were discussed in great detail. Using the batch approach, sorption trials were performed to evaluate the metal sorption performance. The maximum lanthanide accumulation was attained at pH 5.0 and a dosage of 0.05 g. The uptake kinetics are successfully explained by the Ho and McKay model, whereas the equilibrium data is best represented by the Langmuir equation. The presence of Cl-, NO3 -, SO4 2-, Ni(II), and Co(II) did not have any impact on the adsorption capacity. In turn, the presence of Fe(III) ions led to a 15 % reduction in the adsorption. The lanthanide ions were eluted from the adsorbent following the treatment with 0.1 M HNO3. The adsorbent retained over 95 % of its initial adsorption capacity after 6 series of sorption/desorption studies.

Cerium biosorption onto alginate/vermiculite-based particles functionalized with ionic imprinting: Kinetics, equilibrium, thermodynamic, and reuse studies

Cerium is an essential element for several applications in industry, therefore, recovering it from secondary sources is a promising strategy from an economic and environmental perspective. For this purpose, biosorption is a low-cost and effective alternative. The present work evaluated the recovery of Ce³⁺ from aqueous solutions using alginate/vermiculite-based particles (ALEV) functionalized by ionic imprinting. From the kinetic assays, it was verified that the uptake of Ce³⁺ followed the pseudo-second-order model and was mainly controlled by external diffusion. The Langmuir model better described the equilibrium data, and a maximum biosorption capacity of 0.671 mmol/g at 45 °C was attained. The evaluation of the thermodynamic quantities revealed that the process occurs spontaneously and endothermically. The particles reuse and Ce³⁺ recovery were achieved using 0.1 mol/L HCl or 1.0 mol/L CaCl₂ solutions for up to four cycles of biosorption/desorption. The biosorbent was characterized before and posted Ce³⁺ biosorption to investigate the morphology, textural properties, crystallinity, thermal resistance, composition, and functional groups of the biosorbent.

Biosorption of rare-earth and toxic metals from aqueous medium using different alternative biosorbents: evaluation of metallic affinity

Currently, the world faces difficulties related to the quantity and quality of water because of industrial expansion, population growth, and urbanization intensification. Biosorption is considered a promising technology that can be applied to remove toxic metals (TMs) and rare-earth metals (REMs) in wastewater at low concentrations, due to its efficiency and low cost. In this work, we investigated different non-conventional biosorbents to remove metallic ions (TMs and REMs) in biosorptive affinity tests. Metallic affinity assays among lanthanum and different biosorbents showed that greater affinities were found for sericin-alginate beads crosslinked with polyvinyl alcohol (SAPVA) (0.280 mmol/g) and polyethylene glycol diglycidyl ether (SAPEG) (0.277 mmol/g), expanded vermiculite (0.281 mmol/g), Sargassum filipendula seaweed (0.287 mmol/g), and seaweed biomass waste (0.289 mmol/g). Among the biosorbents evaluated, SAPVA and SAPEG beads, besides to sericin-alginate beads crosslinked with proanthocyanidins (SAPAs) were selected for affinity assays with other REMs and TMs. Compared to other particles, SAPVA beads showed higher potential for biosorption by REMs with the following order of affinity: Yb³⁺ > Dy³⁺ > Nd³⁺ > Ce³⁺ > La³⁺. Additionally, the biosorptive affinity of TMs by SAPVA beads followed the order: Al³⁺ > Cr³⁺ > Pb²⁺ > Cu²⁺ > Cd²⁺ > Zn²⁺ > Ni²⁺.

Cell Immobilization Using Alginate-Based Beads as a Protective Technique against Stressful Conditions of Hydrolysates for 2G Ethanol Production

The development of biorefineries brings the necessity of an efficient consumption of all sugars released from biomasses, including xylose. In addition, the presence of inhibitors in biomass hydrolysates is one of the main challenges in bioprocess feasibility. In this study, the application of Ca-alginate hybrid gels in the immobilization of xylose-consuming recombinant yeast was explored with the aim of improving the tolerance of inhibitors. The recombinant yeast Saccharomyces cerevisiae GSE16-T18SI.1 (T18) was immobilized in Ca-alginate and Ca-alginate–chitosan hybrid beads, and its performance on xylose fermentation was evaluated in terms of tolerance to different acetic acid concentrations (0–12 g/L) and repeated batches of crude sugarcane bagasse hemicellulose hydrolysate. The use of the hybrid gel improved yeast performance in the presence of 12 g/L of acetic acid, achieving 1.13 g/L/h of productivity and reaching 75% of the theoretical ethanol yield, with an improvement of 32% in the xylose consumption rate (1:1 V_beads/V_medium, 35 °C, 150 rpm and pH 5.2). The use of hybrid alginate–chitosan gel also led to better yeast performance at crude hydrolysate, yielding one more batch than the pure-alginate beads. These results demonstrate the potential of a hybrid gel as an approach that could increase 2G ethanol productivity and allow cell recycling for a longer period.