Uso de escamas de peixe como adsorvente natural para glifosato

Abstract

The growing use of agrochemicals in modern agriculture has generated a significant environmental impact, highlighted by the contamination of water resources by Glyphosate, the most widely applied herbicide globally. The search for low-cost and environmentally sustainable solutions for environmental remediation is therefore urgent. This study evaluated the technical feasibility of fish scales, a residue from the fishing industry, as a precursor for an adsorbent used in the removal of Glyphosate from aqueous solutions. The material was tested in its in natura and calcined (activated carbon) forms, and the adsorption process was optimized through the Rotational Central Composite Design (RCCD), by varying the Adsorbent Mass and Contact Time. The calcined adsorbent demonstrated superiority due to the reorganization of its hydroxyapatite matrix, which acts as a structural template, promoting an increase in surface area and porosity. The regression model obtained for the calcined material showed no lack of fit (p=0.9868), confirming the internal consistency of the data. Experimental results indicated the high effectiveness of the calcined adsorbent, which achieved a maximum efficiency of over 98.32% in four tests, resulting in residual Glyphosate concentrations below the Limit of Quantification (LQ) of the Ion Chromatograph. The Adsorbent Mass variable was identified as the factor of greatest influence, with maximum removal achieved at the lowest masses tested. The predominant mechanism is electrostatic attraction, favored by the solution's pH condition being lower than the material's Point of Zero Charge. It is concluded that the calcined fish scale adsorbent is a technically viable, environmentally sustainable, and highly competitive potential alternative for treating contaminated water.