Uptake of Phosphorus from an Acidic Kraft Pulp Industrial Effluent Using Magnetic Nanoparticles

Global population growth and industrialization have increased the demand for natural resources, notably phosphorus, which is essential for agricultural and industrial applications. However, the scarcity of phosphorus and its environmental ramifications require innovative solutions for its removal and reuse. This study assesses cobalt ferrite nanoparticles' efficacy in removing phosphorus from kraft pulp effluents. Comprehensive sampling was conducted at various paper pulp facilities utilizing Eucalyptus globulus and the kraft pulp process. Variables, such as pH, temperature, sorbent dose, and initial phosphorus concentration, were investigated. Experiments were performed on streams containing 5, 25, and 45 mg/L phosphorus. At 5 mg/L, the nanoparticles achieved up to 93% P removal at pH 6, 60 °C, and 1.0 g/L nanoparticles. Kinetic studies suggested that the adsorption process conforms to the pseudo-second-order model, indicative of chemisorption. For streams with concentrations of 25 and 45 mg/L, the nanoparticles maintained a rapid adsorption process, achieving 96% removal. The Elovich model aptly described the kinetics, reaffirming chemisorption as the predominant mechanism. Comparative analyses revealed that the nanoparticles outperformed Phoslock (a commercial lanthanum phosphorus sorbent), particularly at shorter contact times and at pH values of 3 and 6. Desorption studies yielded optimal results using a binary solution of NaOH (0.1 mol/L) and Ca-(OH)₂ (1 mol/L), allowing four cycles maintaining high performances. These findings underline the potential of this technology in effluent treatment, where the reusability of nanoparticles offers a cost-effective strategy for environmental remediation and sustainable water and phosphorus management.