Browsing by Author "Chebude, Yonas"

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    Cadmium removal from aqueous solution by blended bamboo sawdust/rice-husk biochar; optimization of influencing parameters
    (Taylor & Francis, 2022) Kwikima, Muhajir Mussa; Chebude, Yonas; Meshesha, Beteley Tekola
    This study attempted to investigate the adsorptive potential of blended bamboo (Oxytenanthera abyssinica) sawdust/rice husk (BSD/RH) at a ratio of 1:1 carbonized at 400 °C for the sorption of cadmium ions from synthetic solutions in batch mode. The Box-Behnken Design in response surface methodology (RSM) was used to achieve the best removal efficiency and adsorption capacity of the biochar. With a p-value of 0.0001, the initial Cd2+ concentration and adsorbent dose were discovered to be the most significant parameters controlling the adsorption capacity and removal efficiency of Cd2+ from the solution. At a pH of 8.95, ionic strength of 0.020 mol/L KNO3, a contact time of 15 min, an initial concentration of 200 mg/L, and an adsorbent dose of 0.5 g, the optimum Cd2+ removal and adsorption capacity of 99.97% and 358.65 mg/g, respectively, were obtained. The optimized conditions were later used to determine the removal efficiency and adsorption capacity of pristine biochars of rice husk and bamboo sawdust, which were found to be 79.8% and 83.7%, respectively. This finding indicates the potential for using biosorbent derived from blended feedstock materials to remove heavy metals such as cadmium.
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    Enhancement of agrosoil cd2+ immobilization efficiency through incubation with bamboo sawdust/rice husk biochar blends: the effect of carbonization temperature and blending ratio
    (2023) Kwikima, Muhajir Mussa; Chebude, Yonas; Meshesha, Beteley Tekola
    Thermal modification of blended feedstocks has recently gained popularity, due to its importance in improving biochar yield and features, such as pore structure and adding extra functional groups than pristine ones and thus improving adsorption effectiveness against a range of pollutants. In this study, the biochar made up of blended bamboo sawdust and rice husk has been investigated on its effectiveness on Cd2+ sorption processes controlling the accessibility and mobility of this metal in agro-soil. In a set of batch experiments, the effect of a 10% w/w biochar (carbonized at 400°C and 700°C) to soil ratio at various blending ratios (1:1, 1:3, and 3:1) on the adsorption and desorption characteristics of Cd2+ in agricultural clay soil incubated for 60 days was investigated. The adsorption kinetics and isotherms were also studied to examine adsorption mechanism at pH of 8, initial solute concentration 200 mg/L, ionic strength of 0.01 M (NaNO3), Contact time of 180 min, and adsorbent dosage of 0.1 g. For adsorption kinetics, pseudo-first order, pseudo-second order, elovich, and intra-particle diffusion models were fitted, while Langmuir, Freundlich, Temkin, and Dubinin Radushkevich models were fitted in isotherm study. According to the findings, increasing the carbonization temperature (400–700°C) boosted the effectiveness of cadmium removal substantially (70–96%), the best adsorption capacity of 130 mg/g was obtained at 700°C. Meanwhile, the removal efficiency of biochar blending ratios was not significantly different. Similarly, as the carbonization temperature was increased, the rate of Cd2+ adsorption increased dramatically, whereas the rate of Cd2+ desorption dropped. Langmuir isotherm adsorption model and Pseudo-second order kinetic model were found to fit best (R2 = 0.99) on isotherm and kinetics studies, respectively. It can be concluded that employing blended feedstock biochar could improve soil immobilization efficiency for Cd2+ in agricultural fields.
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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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    Potentials of agricultural wastes as the ultimate alternative adsorbent for cadmium removal from wastewater. A review
    (Elsevier, 2021) Kwikima, Muhajir Mussa; Mateso, Said; Chebude, Yonas
    The removal/recovery of cadmium from wastewaters by conventional technologies is proving expensive due to the non-renewability of the materials used and the high costs of both operation and materials. Biosorption using agricultural wastes is emerging as a method that offers economical alternate biological materials to save the purpose. Functional groups like carboxyl, hydroxyl, sulphydryl, and amido present in these Agricultural waste-based biosorbents (AWB) make it possible for them to attach Cd2+ from waters. This review article discusses the potential use of different AWBs for the removal of cadmium in terms of their adsorption effiffifficiencies, variable inflfluencing factors, and pre-treatment methods. The literature studies consulted signpost that AWBs have equal and even greater adsorption capabilities in some cases compared to conventional adsorbents. Initial concentration, pH, ionic strength, co-ions, biosorbent dosage, temperature, and particle size of AWBs significantly determine the biosorption potential for Cd2+ removal. Furthermore, physical and chemical pre-treatments of AWBs bring remarkable improvement in Cd2+ uptake capacity, but some chemical additives have been found to have negative impacts on aquatic life. Nevertheless, there are some gaps observed, which require further study, such as (i) searching for pre-treatment chemicals with maximum adsorption potential enhancement with minimal impact on aquatic lives, (ii) developing the most cost-effective modifification methods, and (iii) assessing AWBs under real wastewater systems. The study moreover recommends that the extensive use of AWBs should not jeopardize food security.
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    Process optimization of cadmium adsorption on blended bamboo saw dust/rice-husk from aqueous solution using the response surface methodology
    (Springer Nature, 2022) Kwikima, Muhajir Mussa; Chebude, Yonas; Meshesha, Beteley Tekola
    Blending two or more feedstocks to enhance the adsorptive capacity of adsorbent materials for pollutant removal in aqueous systems has recently gained more attention. In this article, the adsorptive capability of blended bamboo (Oxytenanthera abyssinica) sawdust/rice husk (BSD/RH) at a ratio of 1:1 for the sorption of cadmium ions from aqueous solutions in batch mode was studied. The key process variable parameters; initial Cd2+ concentration (20–200 mg/L), initial solution pH (5–9), ionic strength (0.001–0.02 mol/L of KNO3), adsorbent dose (1–3 g), and contact time (15–180 min) were optimized to achieve maximum removal efficiency by employing the Box–Behnken design in response surface methodology. Results showed that; all variable operating parameters were significant in the removal process of Cd2+ from the solution by BSD/RH adsorbent, initial Cd2+ concentration, and adsorbent dosage being the most significant. The optimum Cd2+ removal of 90.56% and 88.97% of predicted and experimental respectively, were obtained at the pH (8.9), ionic strength (0.012 mol/L), contact time (125.93 min), and adsorbent dose (1.99 g). The optimized conditions were later used to study the Cd2+ removal efficiency of individual rice husk and bamboo sawdust and found 61.43 and 69.68% respectively. This observation signpost the potential of utilizing the biosorbent derived from blended feedstocks materials on removing heavy metals as cadmium