Cationic oxides and dioxides of modified sugarcane bagasse beads with applications as low-cost sorbents for direct red 28 dye

The direct red 28 (DR28) dye contamination in wastewater blocks the transmission of light into the water body resulting in the inability to photosynthesize by aquatic life. In addition, it is difficult to break down and persist in the environment, and it is also harmful to aquatic life and water quality because of its aromatic structure. Thus, wastewater contaminated with dyes is required to treat before releasing into the water body. Sugarcane bagasse beads (SBB), sugarcane bagasse modified with titanium dioxide beads (SBBT), sugarcane bagasse modified with magnesium oxide beads (SBBM), sugarcane bagasse modified with aluminum oxide beads (SBBA), and sugarcane bagasse modified with zinc oxide beads (SBBZ) for DR28 dye removal in aqueous solution, and they were characterized with several techniques of BET, FESEM-FIB, EDX, FT-IR, and the point of zero charges (pHpzc). Their DR28 dye removal efficiencies were examined through batch tests, adsorption isotherms, and kinetics. SBBM had the highest specific surface area and pore volume, whereas its pore size was the smallest among other materials. The surfaces of SBB, SBBM, SBBT, and SBBA were scaly sheet surfaces with an irregular shape, whereas SBBZ was a coarse surface. Oxygen, carbon, calcium, chloride, sodium, O-H, C-H, C=O, C=C, and C-O-C were found in all materials. The pHpzc of SBB, SBBT, SBBM, SBBA, and SBBZ were 6.57, 7.31, 10.11, 7.25, and 7.77. All materials could adsorb DR28 dye at 50 mg/L by more than 81%, and SBBM had the highest DR28 dye removal efficiency of 94.27%. Langmuir model was an appropriate model for SBB, whereas Freundlich model was a suitable model for other materials. A pseudo-second-order kinetic model well described their adsorption mechanisms. Their adsorptions of the DR28 dye were endothermic and spontaneous. Therefore, they were potential materials for adsorbing DR28 dye, especially SBBM.

Comparative Reactive Blue 4 Dye Removal by Lemon Peel Bead Doping with Iron(III) Oxide-Hydroxide and Zinc Oxide

The increasing concern of dye contamination in wastewater results in the toxicity of aquatic life and water quality, so wastewater treatment is required to treat the low water quality standard for safety purposes. Lemon peel beads-doped iron(III) oxide-hydroxide (LBF) and lemon peel beads-doped zinc oxide (LBZ) were synthesized and characterized to investigate their crystalline structure, surface morphology, chemical compositions, chemical functional groups, and ζ potentials by X-ray diffraction, field emission scanning electron microscopy and focused ion beam, energy dispersive X-ray spectroscopy, Fourier transform infrared, and zetasizer techniques. Their effects of dose, contact time, temperature, pH, and concentration for reactive blue 4 (RB4) dye removal efficiencies were investigated by batch experiments, and their adsorption isotherms, kinetics, and desorption experiments were also studied. LBF and LBZ demonstrated semicrystalline structures, and their surface morphologies had a spherical shape with coarse surfaces. Five main elements of carbon (C), oxygen (O), calcium (Ca), chlorine (Cl), and sodium (Na) and six main function groups of O-H, C≡N, C=C, C-OH, C-O-C, and C-H were detected in both materials. The results of ζ potential demonstrated that both LBF and LBZ had negative charges on the surface at all pH values, and their surfaces increased more of the negative charge with the addition of the pH value from 2-12. For batch tests, the RB4 dye removal efficiencies of LBF and LBZ were 83.55 and 66.64%, respectively, so LBF demonstrated a higher RB4 dye removal efficiency than LBZ. As a result, the addition of iron(III) oxide-hydroxide helped in improving the material efficiency more than zinc oxide. In addition, both LBF and LBZ could be reused in more than five cycles for RB4 dye removal of more than 41%. The Freundlich model was a good explanation for their adsorption patterns relating to physiochemical adsorption, and a pseudo-second-order kinetic model was a well-fitted model for explaining their adsorption mechanism correlating to the chemisorption process with heterogeneous adsorption. Therefore, LBF was a potential adsorbent to further apply for RB4 dye removal in industrial applications.

Modified Alginate Beads with Ethanol Extraction of Cratoxylum formosum and Polygonum odoratum for Antibacterial Activities

Bacteria contaminations in water are concerned as environmental effects including human health, so water treatment is required before use. Although using extracted plant is interesting because of their good chemical compounds for bacterial inhibitions, no study has applied the extracted plant in bead materials for disinfection in wastewater. The current research attempted to extract Cratoxylum formosum and Polygonum odoratum for the synthesis of C. formosum beads (CFB) and P. odoratum beads (POB), and their antibacterial efficiencies were investigated by agar diffusion tests, antibacterial batch tests, adsorption isotherm and kinetics, and material reusability. C. formosum and P. odoratum leaves were ethanol-extracted, and their bead materials (CFB and POB) were synthesized. Furthermore, their characterizations of surface area, chemical compositions, and chemical functional groups were investigated. For field emission scanning electron microscopy and focused ion beam (FESEM-FIB) analysis, CFB and POB had spherical shapes with coarse surfaces. Energy-dispersive X-ray spectrometry (EDX) analysis of CFB and POB illustrated five main chemical compositions, which were carbon (C), oxygen (O), calcium (Ca), chlorine (Cl), and sodium (Na), whereas Fourier transform infrared (FTIR) spectroscopy analysis identified seven main chemical functional groups, which were O-H, C-H, C=O, C=C, N-H, C-O, and C-Cl. Agar diffusion tests confirmed the abilities of CFB and POB to inhibit both Staphylococcus aureus and Escherichia coli, and batch experiments examined high antibacterial efficiencies of CFB of almost 100% on both bacterial types. The adsorption isotherm of CFB corresponded to the Freundlich model, which is related to the physiochemical adsorption process with multilayer or heterogeneous adsorption, and the adsorption kinetics of CFB was correlated to the pseudo-second-order kinetic model, which involved chemisorption relating to physiochemical interaction. Moreover, the desorption experiment confirmed the reusability of CFB. Therefore, CFB is a potential material to possibly apply for disinfection of wastewater.