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Browsing Earth Sciences by Subject "Adsorption isotherms"

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    Kinetics, adsorption isotherms, thermodynamics, and desorption studies of cadmium removal from aqueous solutions using bamboo sawdust/rice husk biochar
    (Springer, 2022) Kwikima, Muhajir Mussa; Chebude, Yonas; Meshesha, Beteley Tekola
    The adsorption mechanisms of Cd2+ removal from synthetic water using blended biochar from bamboo sawdust (BSD) and rice husk (RH) feedstocks at BSD/RH ratios 1:1, 1:3, and 3:1 were investigated. The equilibrium isotherms (Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich) and kinetics (pseudo-first order, pseudo-second order, Elovich, and intra-particle diffusion kinetic adsorption models) and thermodynamics were examined. The BSD/RH biochar ratio of 1:1, 1:3, and 3:1 produced the Cd2+ removal of 99.2%, 98.3%, and 97.24% respectively. The adsorption investigation found insignificant differences in removal efficiency across the biochar ratio combinations. Furthermore, the equilibrium isotherm analyses for the BSD/RH ratio of 3:1 and 1:1 are best described by in favor of the Freundlich model, whereas for BSD/RH biochar ratio of 1:3 best matched the Langmuir model. The thermodynamic study revealed that the process is non-spontaneous, endothermic, and dominated by the physisorption mechanism. Generally, physisorption was discovered to be the dominant process controlling the Cd2+ removal from the solution.
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    Kinetics, adsorption isotherms, thermodynamics, and desorption studies of cadmium removal from aqueous solutions using bamboo sawdust/rice husk biochar
    (Springer Nature, 2022) Kwikima, Muhajir Mussa; Chebude, Yonas; Meshesha, Beteley Tekola
    The adsorption mechanisms of Cd2+ removal from synthetic water using blended biochar from bamboo sawdust (BSD) and rice husk (RH) feedstocks at BSD/RH ratios 1:1, 1:3, and 3:1 were investigated. The equilibrium isotherms (Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich) and kinetics (pseudo-first order, pseudo-second order, Elovich, and intra-particle diffusion kinetic adsorption models) and thermodynamics were examined. The BSD/RH biochar ratio of 1:1, 1:3, and 3:1 produced the Cd2+ removal of 99.2%, 98.3%, and 97.24% respectively. The adsorption investigation found insignificant differences in removal efficiency across the biochar ratio combinations. Furthermore, the equilibrium isotherm analyses for the BSD/RH ratio of 3:1 and 1:1 are best described by in favor of the Freundlich model, whereas for BSD/RH biochar ratio of 1:3 best matched the Langmuir model. The thermodynamic study revealed that the process is non-spontaneous, endothermic, and dominated by the physisorption mechanism. Generally, physisorption was discovered to be the dominant process controlling the Cd2+ removal from the solution.
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    Standardizing defluoridation of community waters using bone char
    (2017) Mbabaye, G. K.; Mtalo, F.; Minja, R. J.; Legonda, I.
    Different bone char (BC) preparation methods affect the physical chemical properties and therefore the capacity to remove fluoride. Fluoride removal capacities of BC prepared at three controlled temperatures, with particle grain sizes of 250–500 μm, 500–1,000 μm and 1,000–1,800 μm were determined in column experiments with an initial fluoride concentration of 8.55 mg/L. The sorbent was calcined at 400°C, 500°C and 600°C. BC calcined at 400°C had better fluoride removal performance compared to those calcined at 500°C and 600°C due to decreased pore volume and surface area as the calcination temperature was increased. There was a reduced mass transfer effect to the adsorption sites in pores as the BC particle size was increased. The equilibrium adsorptions Langmuir and Freundlich isotherms were tested. For the Langmuir equilibrium adsorption isotherm, maximum monolayer coverage (Q) was determined to be 3.512 mg/g, and the value of the separation factor (r) obtained was 0.1394 indicating favorable adsorption as it lies between 0 and 1. The Freundlich governing equilibrium adsorption isotherm model gave a value of 1/n equal to 0.445. This indicates a favorable adsorption process, since the bond energies increase with surface density of the adsorbent.