Steam-activated sawdust efficiency in treating wastewater contaminated by heavy metals and phenolic compounds

Abstract

This research study encompasses the utilization of new adsorbents fabricated from pine sawdust for the adsorption of heavy metals and phenol from simulated industrial wastewater. Batch trials are conducted to evaluate the activity of these adsorbents for a possible substitution of the costly commercial adsorbents. The maximum adsorption capacities are evaluated and linked to the physicochemical characteristics of the adsorbents. The maximum monolayer adsorption capacity (qmax) of the adsorbents corresponds to the specific surface area of the adsorbents. The adsorbents with the larger specific surface area have shown higher qmax estimates (phenol adsorption is an exception). The highest amount of the phenol pollutant adsorbed by steam-activated sawdust (SAS) is 10.0 mg/g. The performance of SAS is found to be of the same order as the commercial activated carbon for the removal of Pb and Zn. Equilibrium data for the metal removal are in concordance with the Freundlich adsorption isotherm, whereas the phenol elimination has satisfied the Langmuir adsorption isotherm model. Kinetic data are fitted to Lagergren pseudo-first-order, pseudo-second-order, and the intraparticle diffusion models. Thus, kinetic parameters, rate constants, equilibrium adsorption capacities, and related correlation coefficients for each kinetic model are determined and discussed. The results suggest that the adsorption of Cr follows pseudo-second-order kinetics, indicating chemisorption for the tested adsorbents such that the intraparticle diffusion is not the only step that controls the overall process for Cr adsorption. At the end of this study, the production cost of the SAS adsorbent is estimated ($52 per kg) and compared to the cost of the commercial AC adsorbent in the industrial sector which has a great variation ($80–300 per kg) based on size and location plant. The results of this study can be used for the design of a suitable ecological control procedure to mitigate the harmful effects of industrial wastewater.