Removal of uranium(VI) from aqueous solutions and nuclear industry effluents using humic acid-immobilized zirconium-pillared clay

In this study, the iron-pillared clay nanocatalyst (ICN) was employed as a nanocatalyst for decolorization of methylene blue (MB) in aqueous solutions without hydrogen peroxide. The changes in clay structure after the incorporation of iron-oxide particles was studied with the help of XRD analytical data. The SEM micrographs showed higher heterogeneous structure of ICN compared to pristine clay and the specific surface area of ICN (82.54 m2/g) is considerably higher than the unmodified clay (63.41 m2/g). Further, the EDX analytical data indicate the successful incorporation of iron-oxide into bentonite clay. Batch experiments showed that ICN could degrade MB within pH 3.0 to 11.0 and it is efficient even at higher concentrations. The degradation is very fast and more than 90% is removed within 30 mins. A small amount of ICN is effective for degradation of MB and the reusability test showed that ICN can be reuse for several times for the degradation of MB in aqueous solutions. The effect of scavengers studies indicate that the ·OH radicals generated from the ICN are responsible in the degradation of MB. This study indicates that ICN must be low cost and environmentally friendly active nanocatalyst for degradation of MB present in aquatic environment.

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Humic Acid Functionalized - Silver Nanoparticles as Nanosensor for Colorimetric Detection of Copper (II) Ions in Aqueous Solutions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.831.142 ◽

2020 ◽

Vol 831 ◽

pp. 142-150

Author(s):

Edgar Clyde R. Lopez ◽

Michael Angelo Zafra ◽

Jon Nyner L. Gavan ◽

Emil David A. Villena ◽

Francis Eric P. Almaquer ◽

...

Keyword(s):

Silver Nanoparticles ◽

Humic Acid ◽

Aqueous Solutions ◽

Limit Of Detection ◽

Colorimetric Detection ◽

Hydrodynamic Diameter ◽

Limit Of Quantification ◽

Local Surface Plasmon Resonance ◽

Optical Absorbance ◽

Absorbance Spectra

Humic acid - functionalized silver nanoparticles (HA-AgNPs) were successfully synthesized and used to detect Cu (II) ions in aqueous solutions. The HA-AgNPs was shown to have an average hydrodynamic diameter of 101.4 nm and a polydispersity index of 0.447. The absorbance spectra of HA-AgNPs showed the characteristic local surface plasmon resonance (LSPR) peak of AgNPs at 408.3 nm. Addition of Cu (II) in the HA-AgNPs led to their agglomeration as evidenced by the change in their surface morphology and their corresponding optical absorbance spectra. The synthesized HA-AgNPs showed a strong linear response for Cu (II) concentrations in the range of 0.00 – 1.25 mM with a limit of detection (LoD) of 4.4428 ± 0.1091 mg L-1, a limit of quantification (LoQ) of 14.8094 ± 0.3636 mg L-1, and a limit of blank (LoB) of 0.1214 ± 0.0065 mg L-1. Statistical analysis showed that this calibration curve could be used to quantify Cu (II) concentrations within a 95% confidence level. Furthermore, HA-AgNPs was found to be selective for Cu (II) detection based on the selectivity study against common metal ions found in drinking water. This shows that the synthesized HA-AgNPs can be used as an environment-friendly colorimetric nanosensor for rapid and point-of-need quantification of Cu (II) ions in aqueous media.

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