Continuous fixed-bed adsorption of Mo(VI) from aqueous solutions by Mo(VI)-IIP: Breakthrough curves analysis and mathematical modeling

Column adsorption of biological oxygen demand, chemical oxygen demand and total organic carbon from wastewater by magnetite nanoparticles-zeolite A composite

“…Also, the removal efficiency of the adsorbate was observed to decrease from 99.96 to 99.75% for BOD, 99.88 to 99.60% for COD and 99.87 to 99.50% for TOC. The trend of this result may be ascribed to the rapid saturation of the active sites of the adsorbent at a higher amount of inlet adsorbate concentration which was also supported by other researchers [ 56 , 80 ]. However, the length of the mass transfer zone increased from 3.97 to 4.49 cm for BOD, 4.12–4.41 cm for COD and 3.75–4.38 cm for TOC, while the adsorption capacity also increased from 67.42 to 155.48 mg/g for BOD, 66.10–101.66 mg/g for COD and 60.44–119.60 mg/g for TOC, respectively.…”

“…The trend of this result indicates that a larger amount of BOD, COD and TOC are leaving the bed column without being captured before attaining adsorption equilibrium due to insufficient contact between the adsorbate and adsorbent at a higher flow rate. Other researchers noticed similar observations too [ 79 , 80 ]. On the other hand, the decrease in the adsorption capacity is an indication that the lower flow rate was favourable, thereby increasing the adsorption capacity due to the larger contact time for the interaction of adsorbent-adsorbate and extended intraparticle diffusion of the adsorbate onto the adsorbent surface [ 56 , 60 , 81 ].…”

“…As such, the fast attainment of the breakthrough time and exhaustion time may be attributable to the increased diffusion of adsorbed molecules which enhanced the completion of the adsorption cycle at a reduced time [ 77 ]. However, at lower adsorbate inlet concentrations that produced a lower concentration gradient, slower transport was observed due to a decline in the mass transfer coefficient and diffusion coefficient [ 80 , 83 ].

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Feasibility Study of Benzene Dehydration through an Adsorption Process: Isotherm Determination, Kinetics, and Fixed-Bed Column Studies

“…As the concentration of water decreased in test D-5 when compared to that of test D-4, the value of k Th increased, whereas that of q 0 indicated an opposite trend (Table ). This may be attributed to the higher driving force in the case of test D-4 because of a higher concentration gradient . It is expected that by increasing the flow rate, an additional amount of water in the benzene solution would bring into contact with the adsorbent which could increase the amount of water adsorbed onto the height of the unit bed .…”

“…This may be attributed to the higher driving force in the case of test D-4 because of a higher concentration gradient. 66 It is expected that by increasing the flow rate, an additional amount of water in the benzene solution would bring into contact with the adsorbent which could increase the amount of water adsorbed onto the height of the unit bed. 67 This is in accordance with the obtained trend for q 0 (equilibrium adsorption amount of water) in Table 7.…”