Potential Applications of Nanomaterials in Wastewater Treatment

Over the last few decades, nanotechnologies have gained a great deal of attention, and various nanomaterials and techniques have been developed for water remediation. This study deals with the adsorption of Naphthol green B onto the magnetite nanoparticles synthetized by the coprecipitation method at the laboratory temperature. According to the obtained results, the sorption process is obvious only at the acidic condition when the pH of solution decreases to pH level 3. According to nonlinear fit of experimental data, the sorption of the Naphthol green B onto magnetite nanoparticles is assumed as multilayer, while the Freundlich model fits better (96.158 %) than the Langmuir model does (55.941 %).

Synthetic Wastewater Treatment using Agro-Based Adsorbents

This study was undertaken to determine the treatment a binary mixture of dye wastewater (containing Naphthol Green B) and the sugar industry wastewater for removal of color. The specific treatment in the current research consists of adsorption using low-cost adsorbents and microfiltration using Whatman-41 microfilters. Considerations of this treatment process are to take the samples using batch adsorption and avoid coagulation with further dilution. Numerous runs are made, with the ideal waste samples prepared in the laboratory. As a 1st step in the study, different dye concentrations are considered using different concentrations of sugar wastewater. Samples are treated with 3 different Agro-based low-cost adsorbents (orange peel, peanut hull, and Powdered Activated Carbon (PAC)). Transmittance values for Naphthol Green B after treatment with orange peel and peanut hull are 83.12 % and 76.98 % respectively. Peanut hull has the highest transmittance of 76.98 % with < 425 µm size. Orange peel contributes to the highest transmittance of 83.12 % with a 2 g dosage. The values of transmittance after treatment with PAC are taken as the datum for the comparison of adsorption performance after treatment using orange peel and peanut hull. Peanut hull has the highest Non-Purgeable Organic Carbon (NPOC) measurement of 37.86 mg/L when mixed with 600 ppm of sugar wastewater. Similarly, when mixed with 600 ppm of sugar wastewater, orange peel contributes to the NPOC value of 35.06 mg/L. These treated samples using low-cost adsorbents can be considered as pre-treated wastewater that can be sent to municipal wastewater treatment plants. HIGHLIGHTS Orange Peel and Peanut Hull are the Agro-based low-cost adsorbents for color removal Wastewater treated with Peanut Hull has high Non-Purgeable Organic Carbon measurement Peanut hull has the highest transmittance of 76.98 % with < 425µm size Orange peel contributes to the highest transmittance of 83.12 % with a 2 g dosage Powdered Activated Carbon is considered as a reference adsorbent in this study GRAPHICAL ABSTRACT

Photocatalytic Degradation of Naphthol Green B Dye Using Coupled CdS-ZnMoO4 in UV-A Light Irradiation

At present, nanotechnology field development makes a major role in photocatalysis. CdS-ZnMoO4 (36.6 wt%) coupled nanophotocatalyst is synthesized using facile hydrothermal method. The CdSZnMoO4 catalyst shows superior photocatalytic activity in the Naphthol Green B (NGB) dye degradation in UV-A (365 nm) light irradiation. XRD analysis reveals the monoclinic structure of ZnMoO4, cubic structure of CdS. PL shows lesser the recombination (e−–h+) rate of electron–hole pair formation. UV-Vis-DRS reveals an increase in absorption in entire visible region while loading with CdS. SEM images indicate that CdS-ZnMoO4 has nanofibrous structure. EDS reveal that Cd and S are present on the ZnMoO4 surface. ECM indicates the division of homogeneity in elements. SAED pattern of HR-TEM images proved high crystalline properties of the catalyst. XPS reveals the different oxidation states and term-symbols of Cd, S, Zn, Mo and O in this catalyst with corresponding binding energies. CdS-ZnMoO4 (18.5 m2g−1) has a higher surface area compared to ZnMoO4 (10.8 m2g−1). Current densities obtained from CV reveals the higher cyclic movement of electrons (electrochemical activity) of CdS-ZnMoO4. An effective parameters for photodegradability of NGB dye by CdS-ZnMoO4 was analyzed.

Utilization of Mixed Naphthol Green B and Janus Green B Dyes as Photosensitier in Photogalvanic Cell for Solar Energy Conversion and Storage

In this work, a new dye-sensitized solar cell (DSSC) was prepared using naphthol green B and Janus green B as photosensitizers and EDTA as reductant. A 210 μA of photocurrent and 1018 mV of photo-potential were generated using these dyes. The fill factor of 0.40, a conversion efficiency was observed to be 1.0028% and the power or maximum output of cell was calculated to be 213.78 μW. Because of the storage capacity in a cell, a DSSC can be used for a total of 180 min in dark. The properties of mixed photosensitize system EDTA-NGB-JGB were characterized and evaluated by UV-visible, fluorosencemeter, FESEM and XRD analysis. The photocurrent generation mechanism in photogalvanic cell was also discussed