# Removal of As from Tambo River Using Sodium Alginate from Lessonia trabeculata (Aracanto)

## TL;DR

This study shows that sodium alginate from a brown seaweed can effectively remove arsenic from contaminated river water in Peru.

## Contribution

The novel use of sodium alginate from Lessonia trabeculata for arsenic removal in a contaminated river is demonstrated.

## Key findings

- Sodium alginate from Lessonia trabeculata achieved 99% arsenic removal at 48 hours with a 1.0 g/L dose.
- The biosorbent outperformed industrial alginate in arsenic adsorption capacity and efficiency.
- Langmuir and Freundlich isotherms confirmed favorable adsorption, indicating potential for large-scale application.

## Abstract

Arsenic (As) contamination in the Tambo River (Perú), linked to mining activities and volcanic eruptions, poses significant health and agricultural risks. This study evaluated sodium alginate extracted from the brown macroalgae Lessonia trabeculata (LT) as a biosorbent for As removal. Water samples from three river points revealed As concentrations up to 0.309 mg/L, exceeding regulatory limits (0.1 mg/L). Sodium alginate was obtained via a simplified alkaline method, yielding an average of 21.44% (w/w relative to dry algae biomass) and characterized by Fourier Transform Infrared Spectroscopy (FTIR), showing structural similarity to industrial alginate (A1). Biosorption assays under simulated environmental conditions (neutral pH, 20 °C) demonstrated that LT alginate (A2) reduced As by 99% at 48 h with a 1.0 g/L dose, outperforming A1. Langmuir (qmax = 0.0012 mmol/g; b = 506.9 L/mg) and Freundlich (n = 1.94) isotherms confirmed favorable adsorption, while kinetics followed a Pseudo-Second-Order Model, suggesting physisorption. These results highlight LT alginate as a sustainable and scalable solution for remediating As-contaminated water, promoting the conservation of a vulnerable marine resource. This study underscores the potential of algal biopolymers in bioremediation strategies aligned with environmental and socioeconomic needs.