Peach seed shell and Aspergillus oryzae as adsorbents for the uptake of acid violet 90 dye from wastewater

In this study, Aspergillus oryzae (A. Oryzae) biomass and waste peach seed shells (PPSS) were used to create alternative and effective adsorbents. Acid Violet 90 (AVD) dye was removed from wastewater using the as-prepared adsorbents. Different process variables like pH (2–11), contact period (0–180 min), and adsorbent mass (0.2–2.0 g/L) were examined. The solution pH had a synergistic effect on the improved removal of AVD and the optimal adsorption removal for the PPSS and the A. Oryzae adsorbent occurred at pH 2.0 and pH 5.0, respectively. The findings demonstrated that, in comparison to A. Oryzae, PPSS reported a greater AVD adsorption (mg/g). The equilibrium time for the adsorption process was attained within 180 min for both adsorbents. The adsorption kinetics modelling results showed a good fit with pseudo-second-order kinetics, for both adsorbents, with average R² values of 0.999 (for PPSS) and 0.997 (for A. Oryzae). Similarly, the isotherm modelling results confirmed the good fitting of the Langmuir isotherm model for A. Oryzae (R² = 0.999) and the Freundlich model for PPSS (R² = 0.997). The maximum adsorption capacity (q_max) of 55.0 and 94.92 mg/g was recorded for A. Oryzae and PPSS, respectively. Mechanistic investigation of the present system suggests that both intraparticle diffusion and surface sorption mechanisms control the adsorption rate. As agro materials, both adsorbents are composed of mostly oxygen-based surface functional groups like the –OH, –C = O, -C-O-C, and multiple carbon-carbon bonds, all contributed to the synergistic mechanism interaction between the adsorbent and AVD dye in this study. This study, therefore, revealed that the PPSS and A. Oryzae may be very helpful for removing anionic dye from contaminated wastewater, indicating its potential for useful application in the removal of other major pollutants.