Adsorption of cationic and anionic dyes using chemically modified activated carbon from agricultural waste

Abstract Methylene blue (MB), a cationic dye, and Congo red (CR), an anionic dye, were adsorbed from aqueous solution using activated carbons that were prepared from date pits (date pits AC) biomass. These adsorbents’ surface chemistry was described using a variety of analytical methods, and the corresponding adsorption interactions were examined using the findings. The adsorption mechanism was discussed based on adsorption isotherm, kinetic, and surface characterization results. In order to assess the adsorption behaviour of the biomass, batch adsorption studies were carried out and a number of parameters, including pH, initial concentration of the adsorbates, adsorbent dose, time, and temperature, were optimized. Results showed that the maximal uptakes of MB were 833 mg g −1 at pH between 5.5 to 10 and 743 mg g −1 for MB and CR at pH between 2 and 4.5 respectively. The pseudo-second-order model provided the best fit to the kinetic data, indicating that chemisorption may play a role in the adsorption process for both MB and CR dyes. The findings demonstrated that the inexpensive biomass-derived adsorbent has the potential to effectively remove both cationic and anionic dyes from wastewater.