Effective removal of Hg2+ from aqueous solutions and seawater by Malva sylvestris

This paper introduces a biomaterial prepared from Malva sylvestris for environmental remediation and medicine treatment purposes. The effects of pH (2-12), adsorbent dose (0.1-1.25mg/L), Hg2+ concentration (5-15mg/L), and contact time (3-60min) were studied on the removal of Hg2+ from aqueous phase. The results were compared with powder of charcoal tablet, a medicine drug. At pH solution of 8, over 96% removal of 10mg/L Hg2+ was obtained for a M. sylvestris powder (MSP) dose of 1.5mg/L after a 40min contact time; while for these conditions only 60% of Hg2+ was removed by charcoal tablet powder (CTP). The Langmuir model was the best fit for the experimental data, which attains a maximum adsorption capacity of 602 and 389mg/g for MSP and CTP, respectively. Surface analyses (Fourier transform infrared, scanning electron microscopy, Brunauer, Emmet, and Teller, and X-ray photoelectron spectroscopy) of the MSP were also performed. The co-adsorption study indicated that the Hg2+ adsorption by MSP was 33% increased by addition of 2mg/L ceftriaxone antibiotic. The MSP had acceptable performance after four times recycling. The MSP could be used to remove Hg2+ ions from seawater. Accordingly, the finding of this work suggests that the prepared adsorbent, MSP, is an efficient, no-cost, and promising biomaterial for the removal of Hg2+ ion from liquid phase and could be substituted for charcoal tablets in medicine.