Adsorção de corantes reativos "vermelho e azul s-matrix 150" utilizando cinzas do carvão da pirólise do Rennisetwm RurRnremm

Abstract

Global industrial expansion and growth have contributed to the formation of new categories of organic pollutants, such as: pesticides hygiene products, surfactants, pharmaceuticals, and dyes. These pollutants are regularly found in aquatic environments through industrial effluent discharges, causing toxicity to the environment and the species that inhabit them. Industrial dyes contain various organic groups, such as azo and anthraquinones. These groups are toxic to living beings, and some are therefore carcinogenic upon prolonged exposure. In this context, this study produced biochar ash from the pyrolysis process of elephant grass for the adsorption of individual dyes, such as Bezaktiv red S-matrix 150 and blue S-matrix 150. This adsorbent was modified through a physical process in which it was placed in an oven at 800°C for 5 hours and then chemically treated with 3.5M NaOH. The adsorbents were subsequently characterized using XRD, XRF, FTIR, SEM, and EDS. The adsorption process was performed in batch mode, in wich adsorbents being tested on raw and chemically treated ash. For the batch process, the following variables were studied: adsorbent mass and nature, dye concentration, pH, temperature, and adsorption time. The results were analyzed by obtaining adsorption isotherms based on the Langmuir and Freundlich models, investigating pseudo-first- and second-order kinetics, and identifying the controlling mechanism using the Weber–Morris equation and the Elovich kinetic model. Finally, the experiments were performed with synthetic solutions of both dyes, simulating a real effluent. Subsequently, it was determined through the results obtained that the best adsorbent studied was the ashes produced only with heat treatment, in which they obtained a removal percentage of 96.75% in the red dye s-matrix 150 and in the blue dye s-matrix 150 a percentage of 88.75%. For commercial activated carbon, removal percentages were obtained in the order of approximately 85% for the red dye s-matrix 150 and approximately 100% for the blue dye s-matrix 150.