The ability of aluminum coagulant extracted from red earth to treat Terasil Red R (disperse) and Cibacron Red R (reactive) synthetic dye wastewater was studied. The effects of extractant concentration, soil-to-volume of extractant ratio, and the types of extracting agents (NaOH vs. KCl) on the concentration of aluminum extracted were also investigated. In addition, the efficiency of extracted aluminum was compared with aluminum sulfate, in terms of its capability to reduce the chemical oxygen demand (COD) and to remove synthetic color. Factorial design was applied to determine the effect of selected factors on the amount of aluminum extracted from red earth (i.e., pH, dose of coagulant, type of coagulant on COD reduction, and color removal). It was found that only selected factors exhibited a significant effect on the amount of aluminum extracted from red earth. It was also determined that all factors and their interactions exhibited a significant effect on COD reduction and color removal when applying the extracted aluminum in a standard coagulation process. The results were also compared to aluminum sulfate. Furthermore, NaOH was found to be a better extractant of aluminum in red earth than KCl. Therefore, the best extracting conditions for both extractants were as follows: 2 M NaOH and in a 1:5 (soil/volume of extractant) ratio; 1 M KCl and 1:5 ratio. In treating synthetic dye wastewater, the extracted coagulant showed comparable treatment efficiency to the commercial coagulant. The extracted coagulant was able to reduce the COD of the dispersed dye by 85% and to remove 99% of the color of the dispersed dye, whereas the commercial coagulant reduced 90% of the COD and removed 99% of the color of the dispersed dye. Additionally, the extracted coagulant was able to reduce the COD of the reactive dye by 73% and to remove 99% of the color of the reactive dye. However, the commercial coagulant managed to reduce the COD of the reactive dye by 94% and to remove 96% of the color for the reactive dye.
In this work, polymers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-triphenylamine] with side chains containing: pyrene (C1), diphenyl (C2), naphthalene (C3), and isopropyl (C6) structures were synthesized via a Suzuki coupling reaction. The structures were verified using NMR and cyclic voltammetry measurements provide the HOMO and LUMO of the polymers. The polymer with pyrene (C1) and naphthalene (C3) produced photoluminescence in the green while the polymer with the side chain containing diphenyl (C2) and isopropyl (C6) produce dual emission peaks of blue-green photoluminescence (PL). In order to examine the electroluminescence properties of the polymers, the solutions were spin-coated onto patterned ITO anode, dried, and subsequently coated with an Al cathode layer to form pristine single layer polymer LEDs. The results are compared to a standard PFO sample. The electroluminescence spectra resemble the PL spectra for C1 and C3. The devices of C2, C3, and C6 exhibit voltage-dependent EL. An additional red emission peak was detected for C2 and C6, resulting in spectra with peaks at 435 nm, 490 nm, and 625 nm. The effects of the side chains on the spectral characteristics of the polymer are discussed.