Sunlight-induced photoreduction of Cr(VI) to Cr(III) in wastewater by nitrogen-phosphorus-doped carbon dots

Bhati, Anshu; Anand, Satyesh Raj; Saini, Deepika; Gunture,; Sonkar, Sumit Kumar

doi:10.1038/s41545-019-0036-z

Cited by 94 publications

(59 citation statements)

References 63 publications

(67 reference statements)

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“…Numerous technologies have been applied for the removal of Cr(VI) from aqueous solutions such as adsorption (Gupta et al 2013), reduction (Bhati et al 2019), ion exchange (Rengaraj et al 2001) and membrane processes (Zolfaghari and Kargar 2019). The adsorption process is one of the most frequently encountered techniques for the removal of Cr(VI).…”

Section: Introductionmentioning

confidence: 99%

Preparation of cationic surfactant-modified kaolin for enhanced adsorption of hexavalent chromium from aqueous solution

Belachew

Hinsene

2019

Appl Water Sci

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In the current work, we have reported a cationic surfactant-modified Ethiopian kaolin for improved adsorption of Cr(VI) from aqueous solution. The raw kaolin was modified by treating with CTAB to enhance the adsorption properties. The crystal structure and vibrational analysis of CTAB-kaolin were investigated by Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (p-XRD) techniques. The successful modification of kaolin by CTAB through intercalation and coating was investigated by XRD and FTIR. p-XRD confirms the raw kaolin obtained from Belesa, Tigo kebele is kaolinite mineral. The study has also focused on the application of kaolin-CTAB for adsorption of hexavalent chromium. The percent removal of Cr(VI) was investigated at different parameters such as pH, contact time, concentration of Cr(VI) and adsorbent dosage. CTAB-kaolin shows 99% removal of Cr(VI) at the adsorption equilibrium (time = 180 min, 100 mg CTAB-kaolin, 10 ppm/100 ml). The Langmuir and Freundlich isotherm models were used to investigate the adsorption process of chromium onto kaolin-CTAB composites. The equilibrium data obeyed Langmuir model than Freundlich, which shows that the adsorption process proceeds through monolayer adsorption and maximum adsorption capacity was found to be Q o = 22.72 mg/g. The pseudo-second-order kinetics model is found to be well fitted than Pseudo-first-order kinetics, which implies that the adsorption mechanism more favors electrostatic interaction between chromium and kaolin-CTAB composites. In conclusion, CTAB-kaolin was found to be a promising adsorbent for the efficient removal of Cr(VI) from the aqueous solution.

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Section: Introductionmentioning

confidence: 99%

Preparation of cationic surfactant-modified kaolin for enhanced adsorption of hexavalent chromium from aqueous solution

Belachew

Hinsene

2019

Appl Water Sci

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“…A merge graph of absorption and fluorescence spectra of NPCDs is shown in Figure 1 A. The absorption spectra exhibited two bands at ~275 nm (π-π*) and ~320 nm (n-π*) due to the emergence of C=C and C=N/O/P groups, respectively 20 , 39 , 40 . The fluorescence spectra of NPCDs showed excitation wavelength-dependent spectra (340-520 nm) with emissions in the blue-green region (Max.…”

Section: Resultsmentioning

confidence: 99%

“…with N, B, P etc. ), individually 18 , 19 or multiple 20 - 22 and sometimes its self-doping 23 , 24 . Doping of N and P considerably improves the chemical activity and physicochemical properties of CDs due to the generation of the new surficial active sites in terms of surface defects that can improve their optical properties 25 .…”

Section: Introductionmentioning

confidence: 99%

Multifunctional N-P-doped carbon dots for regulation of apoptosis and autophagy in B16F10 melanoma cancer cells and in vitro imaging applications

et al. 2020

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Rationale: The present study reports the multifunctional anticancer activity against B16F10 melanoma cancer cells and the bioimaging ability of fluorescent nitrogen-phosphorous-doped carbon dots (NPCDs). Methods: The NPCDs were synthesized using a single-step, thermal treatment and were characterized by TEM, XPS, fluorescence and UV-Vis spectroscopy, and FTIR analysis. The anticancer efficacy of NPCDs was confirmed by using cell viability assay, morphological evaluation, fluorescent live-dead cell assay, mitochondrial potential assay, ROS production, RT-PCR, western-blot analysis, siRNA transfection, and cellular bioimaging ability. Results: The NPCDs inhibited the proliferation of B16F10 melanoma cancer cells after 24 h of treatment and induced apoptosis, as confirmed by the presence of fragmented nuclei, reduced mitochondrial membrane potential, and elevated levels of reactive oxygen species. The NPCDs treatment further elevated the levels of pro-apoptotic factors and down-regulated the level of Bcl2 (B-cell lymphoma 2) that weakened the mitochondrial membrane, and activated proteases such as caspases. Treatment with NPCDs also resulted in dose-dependent cell cycle arrest, as indicated by reduced cyclin-dependent kinase (CDK)-2, -4, and -6 protein levels and an enhanced level of p21. More importantly, the NPCDs induced the activation of autophagy by upregulating the protein expression levels of LC3-II and ATG-5 (autophagy-related-5) and by downregulating p62 level, validated by knockdown of ATG-5. Additionally, owing to their excellent luminescence property, these NPCDs were also applicable in cellular bioimaging, as evidenced by the microscopic fluorescence imaging of B16F10 melanoma cells. Conclusion: Based on these findings, we conclude that our newly synthesized NPCDs induced cell cycle arrest, autophagy, and apoptosis in B16F10 melanoma cells and presented good cellular bioimaging capability.

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“…In addition, a portion of electrons located on the surface of the ZnO react with the adsorbed oxygen to produce •O 2 − , which ultimately produces hydrogen peroxide (H 2 O 2 ) (Equations 4and 5). Cr 6+ is reduced to Cr 3+ in acidic solution due to the strong reducibility of H 2 O 2 [45]. The overall reaction process is illustrated by the following equations:…”

Section: Mechanism For Photocatalytic Cr(vi) Reductionmentioning

confidence: 99%

Facile Synthesis of Heterojunctioned ZnO/Bi2S3 Nanocomposites for Enhanced Photocatalytic Reduction of Aqueous Cr(VI) under Visible-Light Irradiation

Yuan

Feng

et al. 2019

Catalysts

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Heterojunctioned ZnO/Bi2S3 nanocomposites were prepared via a facile solvothermal method. The obtained photocatalysts were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and Photoelectrochemical and Photoluminescence spectroscopy (PL), respectively. The results showed that ZnO/Bi2S3 composites exhibited the sandwiched-like structure, where ZnO nanoparticles were randomly embedded between Bi2S3 nanoflakes. The performance of photocatalytic Cr(VI) reduction under visible light indicated that ZnO/Bi2S3 composites exhibited high-efficiency photocatalytic activity in comparison with either Bi2S3 or ZnO. The 5%-ZnO/Bi2S3 photocatalyst removed 96% of Cr(VI) within 120 min at 20 mg/L initial concentration of Cr(VI). The enhanced performance of ZnO/Bi2S3 photocatalysts could be ascribed to the increased light harvesting and the effective separation and transfer of the photogenerated charge carriers across the heterojunction interface of the ZnO/Bi2S3 composite. This work could pave the way for the design of new hetero-structured materials and has great potential in environmental remediation.

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Sunlight-induced photoreduction of Cr(VI) to Cr(III) in wastewater by nitrogen-phosphorus-doped carbon dots

Cited by 94 publications

References 63 publications

Preparation of cationic surfactant-modified kaolin for enhanced adsorption of hexavalent chromium from aqueous solution

Preparation of cationic surfactant-modified kaolin for enhanced adsorption of hexavalent chromium from aqueous solution

Multifunctional N-P-doped carbon dots for regulation of apoptosis and autophagy in B16F10 melanoma cancer cells and in vitro imaging applications

Facile Synthesis of Heterojunctioned ZnO/Bi2S3 Nanocomposites for Enhanced Photocatalytic Reduction of Aqueous Cr(VI) under Visible-Light Irradiation

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