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Effect of (a, b) adsorbent dosage on the adsorption performance of CMB and CB, respectively, and (c, d) initial metal concentration (experimental conditions: initial pH = 6.0 ± 0.1, T = 298 K, and contact time = 120 min. Error bars indicate standard deviations for duplicate measurements)

Effect of (a, b) adsorbent dosage on the adsorption performance of CMB and CB, respectively, and (c, d) initial metal concentration (experimental conditions: initial pH = 6.0 ± 0.1, T = 298 K, and contact time = 120 min. Error bars indicate standard deviations for duplicate measurements)

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The use of banana peel as a sustainable and low-cost precursor for the fabrication of effective biochar was exploited. Here, calcined magnetic biochar (CMB) was fabricated and characterized. CMB possesses surface acidic functional groups (-OH and COO −), porous structures, high saturation magnetization (39.55 emu/g), and larger surface area than th...

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... It is concluded that in the case of MB and SO dye adsorption, the % removal efficiency was enhanced from 89 to ~ 96%, 86 to 97.9%. This is because of the enhancement in the surface area of the adsorbent, which provides additional functional groups and more active sorption sites (Oladipo 2019). In case of CV dye, the % removal efficiency was increased from 95.77 to 98.27% by increasing the adsorbent loading from 0.005 to 0.01 g. ...
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... The FTIR spectrum of bio-sorbent ( Fig. 2b) at 3416 cm −1 corresponds to the -OH of hydroxyl functional groups. The peak at 1743 cm −1 is probably related to the stretching vibration of carboxyl groups or C=O of lipids (Oladipo et al. 2019;Toumi et al. 2018b). The band at 1380 cm −1 is attributed to the symmetrical stretching vibration CH 2 (Allwar, 2020). ...
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... Unfortunately, few studies have been carried out to evaluate the effectiveness of Fe-BC composites on Hg 2+ elimination. For example, banana peels were treated with Fe salts to produce Fe-modified BC (500 °C) for the efficient removal of Hg 2+ (Oladipo et al. 2019). The porous structures, abundance of active functional groups, high magnetization (39.55 emu g −1 ), and high specific surface of 323.2 m 2 g −1 , promoted Hg 2+ sorption (83.4 mg g −1 ) by the modified BC over the original BC (45.5 mg g −1 ) at pH 6.0. ...
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... The FTIR spectrum of bio-sorbent ( Fig. 2b) at 3416 cm −1 corresponds to the -OH of hydroxyl functional groups. The peak at 1743 cm −1 is probably related to the stretching vibration of carboxyl groups or C=O of lipids (Oladipo et al. 2019;Toumi et al. 2018b). The band at 1380 cm −1 is attributed to the symmetrical stretching vibration CH 2 (Allwar, 2020). ...
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Olive oil mill wastewater (OMWW) poses an undeniable environmental problem due to its high organic loads and phenolic compounds (PCs) content. This study determined the optimal conditions for preparing a new bio-sorbent from olive pomace (OP) and the adsorptive treatment of OMWW by this bio-sorbent. The activation reaction was performed with hydrogen peroxide. The results of the combination effect optimization of the three preparation variables: the activation temperature (°C) X 1 , the activation time (min) X 2 and the impregnation ratio X 3 , are presented by the response surface methodology (RSM). The maximum adsorption capacity was obtained at activation time 300 min, temperature 80 °C and ratio equal to 6.2:1. The bio-sorbent was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffractometer (XRD). The adsorption process performance of this bio-sorbent was examined in batch and fixed-bed columns. An adsorption capacity of 446 mg g ⁻¹ has been achieved for 4000 mg L ⁻¹ concentration of PCs. The adsorption isotherm and kinetics were consistent with the Langmuir and pseudo-second-order models. Therefore, the Thomas model best fit the fixed bed column experimental data. The bio-sorbent gave a high desorption percentage of PCs, which was above 70% using HCl (0.1M).
... Kinetic parameters for adsorption of Cr(VI) onto TT-GMH and CT-GMH. χ = jq e,exp − q e,the j/q e,the , where q e,exp and q e,the are the equilibrium and theoretical adsorption capacity of adsorbents according the model, respectively[46]. ...
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This study reports the efficacy of adsorbents synthesized by thermal (TT-GMH) and chemical (CT-GMH) modification of great millet husk (GMH) for the treatment of synthetic wastewater containing Cr(VI). The chemical modification of raw GMH was done by concentrated H2SO4 to increase the porosity and heterogeneity on the surface. The comparative investigations of physicochemical properties of synthesized adsorbents were examined by point of zero charge (pHpzc), BET surface area, SEMEDX, FTIR, and XRD analyses. The results revealed that CT-GMH had around three times higher surface area and more porous structure as compared to TT-GMH. The adsorption experiments were executed in batch mode to examine the impact of parameters governing the adsorption process. For Cr(VI) solution of 25 mg/L, adsorbent dose of 4 g/L, temperature of 25° C, and shaking speed of 150 RPM, the maximum removal for TT-GMH was attained at pH 1 and contact time 150 min, while for CT-GMH, maximum removal was attained at pH 2 and contact time 120 min. The experimental results fitted to the rate kinetic equations showed that for both TT-GMH and CT-GMH, adsorbents followed the quasi-second-order kinetic model during the adsorption process. Further, results revealed that the adsorption process was endothermic and Sips isotherm model was followed for both TT-GMH and CT-GMH. Based on the Sips isotherm, maximum uptake capacity for TT-GMH and CTGMH was noted to be 16 and 22.21 mg/g, respectively. Among the tested mass transfer models, liquid film diffusion model was followed during the adsorption process of both the adsorbents. The desorption study revealed that TT-GMH and CT-GMH give 69.45% and 74.48% removal, respectively, up to six cycles.
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The conventional waste management practices dispose or incinerate agricultural and forestry waste, contributing to the environmental pollution while misusing biomass, a valuable resource with a great potential of reuse. In fact, cultivation of agricultural crops and harvesting generate an abundant amount of waste (e.g., stones, shells, straw) that can be used for wastewater treatment. Waste biomass may be used as: (i) an adsorbent in its original, raw form, following ambient drying and grinding; (ii) modified bio-based sorbents; or (iii) a source material for the synthesis of activated carbon adsorbents through carbonization. Despite the numerous publications in this field examining the removal of a wide range of target pollutants (metals, metalloids, dyes, pesticides, as well as emerging contaminants) by several materials, more realistic studies are still required to evaluate the potential to remove residual compounds in complex matrices, by testing natural matrices, i.e., environmental samples without spiking the target compounds. This perspective paper highlights how an integrated-engineering approach may help solving environmental-pollution issues related to water, solid waste, and air pollution. Chiefly, the application of locally produced bio-waste as an adsorbent for wastewater treatment tackles water contamination, decreases the overall amount of agricultural waste, and reduces the potential gas emissions caused by waste transportation, treatment and/or disposal.
... Science of the Total Environment 799 (2021) 149500 electronegativity (2.0) showed more competitive adsorption as compared to Cu(II) and Zn(II). Also, the antagonistic effect of Hg(II) on Cu (II) was reported as adsorption capacity reduced significantly in the presence of high Hg(II) concentration in the ternary system (Oladipo et al., 2019). The affinity of an adsorbent for metals Pb(II), Cd(II) and Ni(II) was reported to be strongly related to the electronegativity of the ions. ...
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