This study aims to investigate the effi ciency of magnesium oxide nanoparticles (MON) in vitro for the removal of lead (II) and chromium (VI) from aqueous environments. The effects of various parameters such as contact time (15 to 280 min), pH (3, 5, 7 and 9), the initial concentration of lead/chromium (10, 20, 30.40 and 50 mg/L), absorbent dose (0.3, 0.5 and 0.8 g/L), and shaking speed (150 to 350 rpm) was investigated. The parameters were optimized by varying one parameter at a time and keeping other parameters constant. The maximum removal effi ciency of MON for lead (II) and chromium (VI) was achieved at contact time 280 min, pH 9, initial concentration of lead/chromium 10 mg/L, adsorbent dose 0.8 g/L, and shaking speed 250 rpm. The results also indicated that MON convert the Pb²⁺ to Pb⁰ and Cr⁶⁺ to Cr³⁺ during the removal process. The adsorption of lead (II) and chromium (VI) follows the Langmuir isotherms, therefore the adsorption was of a physical nature.

The objective of the present study was to investigate the potential use of applying polythiophene coating on magnetic Fe₃O₄ nanoparticles for the enhancement of asphaltene adsorption. Two stages of experimental were conducted. In the first stage, the ability of coated nanoparticles for asphaltene adsorption in synthetic asphaltene-toluene solution was evaluated. The effects of parameters such as nanoparticles concentration, initial concentration of asphaltene, and temperature were studied. In the second stage, the performance of the coated nanoparticles for the adsorption of asphaltene from crude oil was investigated under atmospheric pressure and a pressure-volume-temperature (PVT) apparatus was utilized for simulated reservoir conditions. Fe₃O₄ and Fe₃O₄-PT MNPs were synthesized using an effective co-precipitation method. The results of the first-stage tests indicated that the maximum adsorption capacity values for Fe₃O₄ and Fe₃O₄-PT MNPs were 0.79 and 1.09 mg m⁻², respectively. The optimum value of nanoparticles concentration was approximately determined as 10 g L⁻¹. According to the adsorption isotherms and kinetics, the Langmuir and pseudo-second-order Lagergren models were consistent with the experimental data, respectively. The average adsorption efficiencies for Fe₃O₄-PT and Fe₃O₄ MNPs were 78.98 and 65.94%, respectively. The results of the performed experiments on crude oil showed that Fe₃O₄-PT MNPs could adsorb asphaltenes from crude oil in a similar trend as synthetic asphaltene-toluene solution.