Hidrogéis de alginato utilizados no tratamento de águas residuárias contendo corante verde malaquita

Abstract

The dyeing process is the process that produces most wastewater from all other industrial textile processes, with major environmental impact. New methods to treat these effluents have been studied to mitigate these impacts. In this work, it was proposed the use of the adsorption method, using the sodium alginate hydrogel (beads) crosslinked with Ca2+ ions as adsorbent agent. The hydrogel was applied in the treatment of wastewater containing malachite green dye and it was characterized by thermogravimetric analysis (TGA/DTG) and differential scanning calorimetry (DSC). Factors that may change the adsorption capacity, such as pH, adsorbent weight and initial dye concentration in aqueous solution were investigated. Langmuir and Freundlich isotherms were applied to the experimental results, in order to obtain the adsorption mechanism. The Langmuir isotherm adjusted to the experimental data (R = 0.9873), predicting a maximum adsorption capacity (qmax) of 16.91 mg of dye per gram of hydrogel, i.e., qmax = 16.91 mg g-1. In this case, the alginate beads can adsorb malachite green dye from aqueous solutions, allowing reuse of the water.