Browsing by Author "Contreras-Porcia, L."

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    Enhancing the Biosorption Capacity of Macrocystis pyrifera: Effects of Acid and Alkali Pretreatments on Recalcitrant Organic Pollutants Removal
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025) Varas, M.; Castro-Rojas, J.; Contreras-Porcia, L.; Ureta-Zanartu, M.S.; Blanco, E.; Escalona, N.; Muñoz, E.; Garrido Ramirezm, E.
    © 2025 by the authors.The effects of acid and alkali pretreatments on the physicochemical and textural properties of Macrocystis pyrifera were evaluated to assess its potential for removing recalcitrant organic pollutants from aquatic systems. Untreated (UB), acid-pretreated (ACPB), and alkali-pretreated (ALPB) seaweed biomass were characterized using SEM, FTIR-ATR, N2 adsorption–desorption, and potentiometric titrations. Adsorption isotherms and kinetic studies, using methylene blue (MB) as a model pollutant, were conducted to evaluate removal performance. All biosorbents exhibited Langmuir behavior, with maximum adsorption capacities of 333 mg g−1 (UB), 189 mg g−1 (ACPB), and 526 mg g−1 (ALPB). FTIR-ATR and SEM analyses revealed that alkali pretreatment increased the abundance of hydroxyl, carboxylate, and sulfonated functional groups on the seaweed cell walls, along with greater porosity and surface roughness, resulting in enhanced MB adsorption. In contrast, acid pretreatment increased the exposure of carboxylic, amine, and amide functional groups, reducing the electrostatic interactions. The adsorption energy values further supported this, while the intra-particle diffusion model indicated a two-step process involving MB diffusion onto the seaweed surface, followed by diffusion into internal pores. These findings highlight the potential application of Macrocystis pyrifera-based biosorbents in the treatment of wastewater containing recalcitrant organic pollutants.
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    Enhancing the Biosorption Capacity of Macrocystis pyrifera: Effects of Acid and Alkali Pretreatments on Recalcitrant Organic Pollutants Removal
    (Elsevier, 2025) Varas, M.; Castro-Rojas, J.; Contreras-Porcia, L.; Ureta-Zanartu, M.S.; Blanco, E.; Escalona, N.; Muñoz, E.; Garrido Ramirezm, E.
    © 2025 by the authors.The effects of acid and alkali pretreatments on the physicochemical and textural properties of Macrocystis pyrifera were evaluated to assess its potential for removing recalcitrant organic pollutants from aquatic systems. Untreated (UB), acid-pretreated (ACPB), and alkali-pretreated (ALPB) seaweed biomass were characterized using SEM, FTIR-ATR, N2 adsorption–desorption, and potentiometric titrations. Adsorption isotherms and kinetic studies, using methylene blue (MB) as a model pollutant, were conducted to evaluate removal performance. All biosorbents exhibited Langmuir behavior, with maximum adsorption capacities of 333 mg g−1 (UB), 189 mg g−1 (ACPB), and 526 mg g−1 (ALPB). FTIR-ATR and SEM analyses revealed that alkali pretreatment increased the abundance of hydroxyl, carboxylate, and sulfonated functional groups on the seaweed cell walls, along with greater porosity and surface roughness, resulting in enhanced MB adsorption. In contrast, acid pretreatment increased the exposure of carboxylic, amine, and amide functional groups, reducing the electrostatic interactions. The adsorption energy values further supported this, while the intra-particle diffusion model indicated a two-step process involving MB diffusion onto the seaweed surface, followed by diffusion into internal pores. These findings highlight the potential application of Macrocystis pyrifera-based biosorbents in the treatment of wastewater containing recalcitrant organic pollutants.
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    Physiological plasticity of Dictyota kunthii (Phaeophyceae) to copper excess
    (2014) Sordet, C.; Contreras-Porcia, L.; Lovazzano, C.; Goulitquer, S.; Andrade, S.; Potin, P.; Correa, J. A.
    The brown alga Dictyota kunthii is one of the dominant species in the coastal areas of northern Chile affected by copper enrichment due to accumulated mining wastes. To assess its physiological plasticity in handling copper-mediated oxidative stress, 4-days copper exposure (ca. 100 mu g/L) experiments were conducted with individuals from a copper impacted area and compared with the responses of plants from a non-impacted site. Several biochemical parameters were then evaluated and compared between populations. Results showed that individuals from the copper-impacted population normally displayed higher levels of copper content and antioxidant enzymes activity (catalase (CAT), ascorbate peroxidase (AP), dehydroascorbate reductase (DHAR), glutathione peroxidase (GP) and peroxiredoxins (PRX)). After copper exposure, antioxidant enzyme activity increased significantly in plants from the two selected sites. In addition, we found that copper-mediated oxidative stress was associated with a reduction of glutathione reductase (GR) activity. Moreover, metabolic profiling of extracellular metabolites from both populations showed a significant change after plants were exposed to copper excess in comparison with controls, strongly suggesting a copper-induced release of metabolites. The copper-binding capacity of those exudates was determined by anodic stripping voltammetry (ASV) and revealed an increased ligand capacity of the medium with plants exposed to copper excess. Results indicated that D. kunthii, regardless their origin, counteracts copper excess by various mechanisms, including metal accumulation, activation of CAT, AP, DHAR, GP and PRX, and an induced release of Cu binding compounds. Thus, plasticity in copper tolerance in D. kunthii seems constitutive, and the occurrence of a copper-tolerant ecotype seems unlikely. (C) 2014 Elsevier B.V. All rights reserved.