Browsing by Author "Hiruy, A.M."

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    Nano-Clay and Iron Impregnated Clay Nanocomposite for Cu2+ and Pb2+ Ions Removal from Aqueous Solutions
    (SAGE Publications Ltd, 2022) Tarekegn, M.M.; Mohan Balakrishnan, R.M.; Hiruy, A.M.; Hussen, A.H.; Maanyam, H.S.
    Several physicochemical techniques have been widely studied for heavy metals removal despite most of them are associated with challenges of higher cost, accessibility, and complex technical feasibility. In this study, nano-sorbent materials were developed from a naturally available clay matrices and its heavy metals (Cu2+ and Pb2+) removal capacity was tested at its pristine and iron impregnated form. Both top to down and borohydride reduction methods were used to produce the nano-sorbents. The nano-sorbents were characterized by XRD, XRF, SEM, FTIR, BET, and TGA/DGA. The sorption was studied in batch experiments. The surface area, pore-volume, and pore diameter of nano-clay were found 43.49 m2/g, 0.104 cm3/g, and 2.81 nm, respectively while iron impregnated nano-clay has shown a surface area (73.11 m2/g), pore-volume (0.153 m3/g), and pore diameter (3.83 nm). Both nanoparticles have shown a mesoporous nature. The highest Cu2+ and Pb2+ removal capacity of nano-clay was 99.2% (~11.9 mg/g) and 99.6% (~11.95 mg/g), respectively. Whereas, the iron impregnated nano-clay has achieved the highest Cu2+ and Pb2+ removal efficiency 99.8% (~11.97 mg/g) and 99.7% (11.96 mg/g), respectively. The highest Cu2+ adsorption efficiency of iron impregnated nanoclay was achieved at pH 5.0, adsorbent dose 0.83 g/L, contact time 150 minutes, and Cu2+ initial concentration 4 ppm while its highest Pb2+ adsorption activity was achieved at pH 5.0, contact time (90 minutes), Pb2+ initial concentration (6 ppm), and the adsorbent dose (0.67 g/L). Whereas, the Cu2+ adsorption using nano-clay was highest at pH 5.0, contact time (180 minutes), adsorbent dose (1.0 g/L), and Cu2+ initial concentration (2 ppm). While, pH 5.0, contact time (90 minutes), adsorbent dose (0.83 g/L), and Pb2+ initial concentration (4 ppm) was found to the conditions of highest Pb2+ removal. In all cases, the pseudo-second-order kinetics indicated the presence of chemisorption. Langmuir adsorption characteristics has been reflected on Pb2+ and Cu2+ removal activities of the nanoclay and iron impregnated nanoclay, respectively. Whereas, Freundlich isotherm model was better fitted for Cu2+ adsorption activity of the nanoclay. The −ΔG (<−20 KJ/mol), +ΔH°, and +ΔS° have shown a spontaneous and endothermic adsorption activity with a high level of adsorbents disorder. In general, the result of iron impregnated nano-clay has shown a promising result for the removal of Cu2+ and Pb2+ aqueous solution. © The Author(s) 2022.
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    Removal of methylene blue dye using nano zerovalent iron, nanoclay and iron impregnated nanoclay-a comparative study
    (Royal Society of Chemistry, 2021) Tarekegn, M.M.; Mohan Balakrishnan, R.M.; Hiruy, A.M.; Hussen, A.H.
    There has been an increasing challenge from the emission of methylene blue (MB) dye-containing wastewater and its management methods in industry. The sorption process is one conventionally used method. In this study, nanoclay, nano zero valent iron (nZVI), and iron impregnated nanoclay were prepared and studied for the removal of MB dye in batch mode. The effects of operating parameters like pH, dye concentration, sorbent dosage, and contact time were investigated and optimized. The nZVI, nanoclay, and iron impregnated nanoclay sorbents showed zeta potentials of -32.1, -53.4, and -40.7 mV, respectively. All the nano adsorbents were crystalline. The nanoclay was characterized by an average surface area, pore volume and pore diameter of 43.49 m2 g-1, 0.104 cm3 g-1 and 2.806 nm, respectively. nZVI showed a surface area of 47.125 m2 g-1, pore volume of 0.119 cm3 g-1, and pore diameter of 3.291 nm. And iron impregnated nanoclay showed a surface area of 73.110 m2 g-1 with a pore volume of 15 cm3 g-1 and a pore diameter size of 3.83 nm. A Langmuir EXT nitrogen gas adsorption isotherm (R2 ? 0.99) was the best fit. The thermodynamics parameters, such as ?G° (-12.64 to -0.63 kJ mol-1), ?H° (+0.1 to +62.15 kJ mol-1) and ?S° (+0.10 to +0.22 kJ mol-1), confirmed that a spontaneous and endothermic adsorption process took place at a high rate of disorder. Iron impregnated nanoclay showed higher negative Gibbs free energy (-12.64 kJ mol-1), higher enthalpy change (+62.5 kJ mol-1) and entropy (+0.22 kJ mol-1) and gave a better MB removal performance. In addition, the lower negative heat of enthalpy for all adsorptions proved the dominance of physisorption. The methylene blue adsorption isotherm on nZVI and nanoclay showed the best fit with the Freundlich isotherm model with correlation coefficients (R2) ?0.98 and 0.99, respectively. Whereas the Langmuir adsorption isotherm was the best fit for iron impregnated nanoclay (R2 ? 0.98). The adsorption activities of nZVI, nanoclay and iron impregnated nanoclay were fitted to a pseudo-second-order kinetic model with correlation coefficients (R2) of 0.999, 0.997 and 0.983, respectively. The optimal pH 7.0 (RE: 99.1 ± 0.73%), initial MB concentration 40 ppm (RE: 99.9 ± 0.03%), contact time 120 min (RE: 99.9 ± 0.9%), and adsorbent dose 80 (99.9 ± 0.03%) were obtained for iron impregnated nanoclay. The optimal operational parameters of nanoclay and nZVI, respectively, were pH 11.0 and 13.0, initial MB concentration 20 and 20 ppm, adsorbent dose 100 and 140 mg, and contact time 120 and 140 min. In general, iron impregnated nanoclay has shown promising cationic dye adsorbance for industrial applications; but a recyclability test is suggested before scale-up. © The Royal Society of Chemistry.