Evaluation of scrap metallic waste electrode materials for the application in electrocoagulation treatment of wastewater

Microwave-Prepared Quantum Dots and Their Potential Applications as Adsorbents and Chemosensors

A combination of different eco-friendly materials prepared promising fluorescent quantum dots (QDs) through the one-step process using the microwave heating of urea with cellulose, chitosan, and biochar. Characterizations of the prepared QDs, including the investigation of their structure by infrared spectroscopy, Raman analysis, X-ray diffraction, thermal gravimetric analysis, morphology, and optical properties, were performed. The results showed that QDs possess a small size, high UV absorption, and excitation wavelength-dependent fluorescence. The prepared QDs were also tested for metal ions removal from aqueous solutions. The adsorption at different contact times was investigated to optimize the adsorption efficiency of the prepared QDs. All QDs were found to be an ideal sorbent for Cr(II), Cu(II), Mn(II), and Pb(II). From the data, Cr(II) was more highly adsorbed than other metal ions. The results of the kinetic investigation showed that the pseudo-second-order kinetic model fit the adsorption process effectively. In addition, the fluorescence spectra of QDs were changed after the adsorption of metal ions; hence, the prepared QDs could be utilized in environmental sectors such as wastewater pollution detection, adsorption, and chemical sensing applications.

An economical electrocoagulation process of a hazardous anionic azo dye wastewater with the combination of recycled electrodes and solar energy

The energy and electrode costs are the restrictions of applying electrocoagulation (EC) in wastewater treatment and many attempts have been made to decrease these costs. In this study, an economical EC was investigated to treat a hazardous anionic azo dye wastewater (DW) that threatens the environment and human health. Firstly, an electrode for EC process was produced from recycled aluminum cans (RACs) by remelting in an induction melting furnace. The performance of the RAC electrodes in the EC was evaluated for COD, color removal, and the EC operating parameters such as initial pH, current density (CD), and electrolysis time. Response surface methodology which is based on central composite design (RSM-CCD) was used for the optimization of the process parameters which were found to be pH 3.96, CD 15 mA/cm², and electrolysis time 45 min. The maximum COD and color removal values were determined as 98.87% and 99.07%, respectively. The characterization of electrodes and the EC sludge was conducted by XRD, SEM, and EDS analyses for the optimum variables. In addition, the corrosion test was conducted to determine the theoretical lifetime of the electrodes. The results showed that the RAC electrodes show an extended lifetime as compared to their counterparts. Secondly, the energy cost required to treat DW in the EC was aimed to decrease by using solar panels (PV), and the optimum number of PV for the EC was determined by the MATLAB/Simulink. Consequently, the EC with low treatment cost was proposed for the treatment of DW. An economical and efficient EC process for waste management and energy policies was investigated in the present study which will be instrumental in the emergence of new understandings.