The presence of heavy metals in polluted water is known not only to cause severe harm to marine organisms, but also to terrestrial plants and animals including human beings. This research applied low-cost and environmentally benign adsorbent primed from waste orange peel (OP) for the removal of Cd(II) ions from aqueous solution via batch adsorption process. The surface properties of the orange peel powder were studied using scanning electron microscopy (SEM), X-ray spectroscopy (XRD) and Fourier transform infrared spectroscopy (FT-IR). Operational conditions like temperature, contact time, sorbent dosage, solution pH and initial adsorbate concentration were investigated. The utmost uptake of Cd(II) ion was obtained at a contact time of 120 min, initial metal concentration of 240 mg/L, adsorbent dosage of 0.04 g/L, temperature of 45 °C and solution pH of 5.5. Equilibrium results showed that the orange peel adsorbent has an adsorption capacity of 128.23 mg/g as obtained from the Langmuir isotherm. The adsorption kinetics data followed a pseudo-first-order kinetic model with correlation coefficient (R2) > 0.9 and low standard % error values. The adsorption process was found to be endothermic in nature with enthalpy of 0.0046 kJ mol−1 and entropy of-636.865 Jmol−1K−1. Results from the optimization study indicated that higher adsorbent dosage and lower Cd(II) ion concentration increased the percentage of Cd(II) ion removal. Thus, orange peel could be used in the removal of Cd(II) ion from aqueous solutions.
This study presents the preparation, characterization, and formaldehyde (HCHO) adsorption performance of hybrid mixed-metal oxide (MMO)− coated latex composites for indoor air quality control. The hybrid MMO−latex composites were prepared by coating a thin layer of TiO 2 /SiO 2 particles onto a latex polymer film using polypropylene glycol (PPG) to aid in uniform deposition of MMO particles via hydrogen bonding, while also providing additional active sites for HCHO adsorption. The effect of PPG content on the HCHO removal performance of the composites in terms of capture capacity and kinetics were systematically investigated. The indoor chamber tests indicated that the HCHO adsorption capacity and kinetics of the composite thin film increased by 36% and 63%, respectively, compared to those of its MMO-incorporated latex analogue under identical conditions. Moreover, our results indicated that upon increasing the PPG content from 0 to 90 wt %, the HCHO adsorption capacity and rate were significantly enhanced from 0.36 to 0.57 mmol/g and 0.01 to 0.14 h −1 , respectively, due to increased affinity and better accessibility to the adsorption active sites in the thin films with uniformly deposited MMO particles. The increase in the humidity level from 45 to 80% RH was also found to promote the rate of HCHO capture by 50%. The findings of this work demonstrate that hybrid MMO−coated latex composites have superior HCHO adsorptive performance compared to their incorporated MMO−latex analogues.
Metal−organic frameworks (MOFs) often exhibit an exceptional adsorption-based separation performance for a variety of gases, ions, and liquids. While most radioactive iodine removal studies focus on the capture of radioactive iodine from off-gas streams, few studies have systematically investigated the effect of structure−property relationships of MOFs on iodine removal performance in the presence of interfering ions in liquid solutions. Herein, we investigated the iodide ion (I − ) adsorption performance of two model MOFs (e.g., Ni-MOF-74 and Zr-UiO-66) in liquid phase as a function of iodine concentration (e.g., 0.125 to 0.25 and 0.50 mmol/ L) and adsorption temperature (e.g., 25 to 40 and 60 °C), and in the presence of interfering ions such as Cl − and CO 3 2− through batch-mode experiments. Under identical experimental conditions, Ni-MOF-74 outperformed Zr-UiO-66 in immobilizing iodine from the solution by achieving a maximum iodine removal efficiency of 97% at 60 °C. The results showed that the presence of other interfering ions marginally affects the iodine removal efficiency (e.g., capacity and rate of iodine capture) over both MOF adsorbents. The adsorption kinetics was found to be controlled by multiple transport processes encompassing external surface adsorption, intraparticle diffusion, and final equilibrium. Moreover, the leach test results revealed 8 and 12% iodine release from Ni-MOF-74 and Zr-UiO-66, respectively, at 25 °C after 48 h aging. This study establishes guiding principles for sustainable removal of iodine in the presence of Cl − and CO 3 2− species in cyclohexane.
The presence of heavy metals in polluted water is known not only to cause stern harm to marine organisms but also to terrestial plants and animals including human beings. This research applied low-cost and environmental benign adsorbent primed from waste orange peel (OP) in the removal of Cd(II) ions from aqueous solution via the batch process. The surface properties of the orange peel powder was studied using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (XRD) and Fourier transform infrared spectroscopy FT-IR). Operational conditions like temperature, contact time, sorbent dosage, solution pH and initial adsorbate concentration were investigated. The utmost uptake of Cd(II) ion was obtained at the contact time of 120 min, initial metal concentration of 240 mg/L, adsorbent dosage of 0.04 g/L, temperature of 45 °C and solution pH of 5.5 on the adsorption of Cd(II) ion. Equilibrium results showed that the orange peel adsorbent has an adsorption capacity of 27.916 mg/g as obtained from the Langmuir isotherm. The adsorption kinetics data followed a Pseudo-first-order kinetic model with correlation coefficient (R2) > 0.9 and low standard % error values. The adsorption process was found to be spontaneous, feasible and with enthalpy of 0.0046 kJ mol− 1 and entropy of -636.865 Jmol− 1K− 1 respectively. Results from the optimization study indicated that higher adsorbent dosage and lower Cd(II) ion concentration increased the percentage of Cd (II) ion removal. Thus, orange peel could be used in the removal of Cd(II) ion from aqueous solutions.
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