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This research aimed to study the degradation of Methyl Orange Dyes (MOD) and Methylene Blue Dyes (MBD) in different pH solutions using ZnO and ZnO/MOP-CTAB materials under UV light. Medan Orange Peel (MOP) materials which modified by CTAB was added to ZnO which aimed to improve ZnO ability for MOD and MBD dyestuffs degradation. This research was conducted in the dark and the light methods by adding ZnO and ZnO / MOP-CTAB materials to the MOD and MBD with various pH solutions, which was at pH 2, 4, 6, 8, and 10. The characterization results showed that ZnO/MOP-CTAB had better character than ZnO, with BET characterization results showed ZnO/MOP-CTAB had surface area of 36.07 m2/g which larger than ZnO, and DRUV results obtained narrower band gap energy value of 3.15 eV. The XRD results showed that the addition of MOP-CTAB modifications into ZnO did not affect crystal structure of wurtzite with hexagonal shape. SEM photographs showed that the surface of ZnO/MOP-CTAB was more homogeneous than ZnO. The results of the pH variation treatment of MOD and MBD solutions showed that ZnO/MOP-CTAB was better than ZnO for dyestuffs degradation in dark and light methods. In the bright method with UV light assistance, the optimum result of MOD degradation by ZnO/MOP-CTAB occurred at acidic pH of 2 at 50th minute of 79%, while using ZnO obtained at the 40th minutes of 49%. In MBD degradation, optimum results were obtained by ZnO/MOP-CTAB at pH 10 at the 40th minutes by 90%, while in ZnO by 83%. The reaction kinetics that occurred in dyestuffs with pH variations in both the dark and the light methods followed the pseudo-second-order reaction kinetics. [ABSTRACT FROM AUTHOR]

Methyl Orange (MO) is one of the dyestuffs that are often used in the textile industry. MO itself has non-biodegradable anionic properties and has the potential to cause hypersensitivity allergies, thus it potentially been dangerous, especially for aquatic environment. One of the methods which often used is photodegradation method. Photodegradation was a method that was easy to implement and relatively affordable. Additionally, dyes could be more easily decomposed into simpler components with the intention that being safer for the environment. This research aimed to degrade MO using ZnO composited with orange peel (OP) which had been modified with cetyltrimethylammonium bromide (CTAB) addition. CTAB itself served as template to increase surface area of the ZnO material, thereby increasing their photocatalytic activities. ZnO, ZnO/OP, and ZnO/OP-CTAB were characterized using FTIR, XRD, SEM-EDX, BET and DR-UV. The results showed that ZnO/OP-CTAB degraded MO more than both ZnO/OP and ZnO. It was achieved optimum condition for without UV irradiation method in 40 minutes treatment, where ZnO/OP-CTAB was able to degrade MO by 48% whereas ZnO/OP and ZnO were only by 40% and 28%, respectively. In with UV irradiation method the optimum condition was achieved for 50 minutes, which ZnO/OP-CTAB succeeded in degrading MO by 78% while ZnO/OP was 74%. This treatment gave different results for ZnO, which ZnO gave optimum performance with %removal of 40% for 40 minutes treatment. Based on the reaction kinetics, it was known that the photodegradation reaction of MO by ZnO, ZnO/OP, and ZnO/OP-CTAB followed the pseudo-second-order reaction kinetics model. [ABSTRACT FROM AUTHOR]

Several alkali metalss (AM) are doped into ZnO nanoclusters (Zn12O12 NCs) has been studied in geometry optimization, energy and electronic properties by using density functional theory (DFT). It has been proven that adding alkali metal is an effective way to decrease energy gap to 0.985. The minimum energy gap of HOMO-LUMO is Rb-doped ZnO, and the energy gap is 3.040 eV. The Rb-doped Zn12O12 NCs was then tested on MB dye to obtain adsorption energy (Eads). The Eads of -224.7 kcal / mol are obtained from calculations using DFT. The results show the AM doped ZnONCs is a promising application materials in the MB photodegradation. [ABSTRACT FROM AUTHOR]