Abstract
The present study investigated the dynamics of batch adsorption of manganese onto bone char by using two distinct mathematical formulations: the diffusion model and the shrinking core model. Both models assumed spherical particles and adequately described the transient behavior of metal adsorption under changing operating conditions. Comparatively, the diffusion model described the manganese adsorption better at distinct particle sizes even when small particles were used (dp ≤ 0.147 mm); the shrinking core model proved to be more reliable when larger adsorbent particles were used (dp > 0.147 mm), and it described experimental data better at changing solid-liquid ratios. Manganese adsorption was favored when: (i) smaller adsorbing particles were used due to the increase in the contact area and easier access to reacting sites of the char; however, such an effect proved to be limited to dp ≤ 0.147 mm, and (ii) higher solid-liquid ratios were used due to the increase in the available reacting sites. External and intraparticle mass transfer dependences on particle size and solid-liquid ratio were also investigated, and results corroborated with prior investigations found in the literature.
Highlights
The treatment of industrial effluents containing dissolved metals is commonly done using chemical precipitation, which is a relatively simple operation and an efficient method to attend to legal requirements
Experimental results obtained by Moreno et al (2010) and Sicupira et al (2014) using acid rock drainage (ARD) effluents revealed that manganese adsorption onto bone char followed satisfactorily the Langmuir equilibrium isotherm, with a value of qm between 22 and 30 mg g-1
In an attempt to evaluate the dynamics of manganese adsorption onto bone char and to identify the main phenomena that affect the process as a whole, two distinct models were developed in the present paper
Summary
The treatment of industrial effluents containing dissolved metals is commonly done using chemical precipitation, which is a relatively simple operation and an efficient method to attend to legal requirements. The method, is not advantageous in the treatment of sulfuric aqueous solutions containing manganese, as is the case of acid rock drainage (ARD) effluents generated in the southeastern region of Brazil, because manganese presents high solubility within a wide range of pH (Bamforth et al, 2006). The precipitation of manganese may occur at high pH values of approximately 10-11. The quantity and the toxicity of the sludge will depend on the type and concentration of the dissolved metals. It may result in a costly operation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
