The increasing growth of the textile industry does not only provide benefits in the economic sector but also has the potential to damage the environment, because it generates the dye wastewater which is hard to eliminate. Procion red is one of the synthetic textile dyes that is toxic to the aquatic environment and it needs to be processed properly. The photocatalytic method of processing dye wastewater is the most effective, because it can remove the harmful pollutants in the dye wastewater. This study aimed to prepare and characterize the ZnO-Zeolite nanocomposites for photocatalytic applications tested with a 50 mg/L procion red dye sample. The nanocomposites consisted of the ZnO semiconductors and synthetic zeolite adsorbents prepared by using the sol-gel method. The dye degradation test was carried out under the irradiation conditions with ultraviolet (UV) lamp. Apart from the ZnO-Zeolite nanocomposite, testing was also carried out with the synthetic zeolite and ZnO. The results of SEM-EDX and XRD characterization proved that the nanocomposite forming components were ZnO and zeolite and could be seen from the resulting peaks. BET showed that the surface area value of the ZnO-Zeolite nanocomposite increased to 95.98 m 2 /g, the pore size of the ZnO-Zeolite nanocomposite was 4.42 nm, and the total pore volume was 0.08 cm³/g. The obtained average crystalline size of ZnO-Zeolite nanocomposite was 32.87 nm. The percentage of dye degradation using the ZnO-Zeolite nanocomposite for 120 minutes has reached 90.42%.

The development of textile factories has had a significant impact on the environment because dye wastewater is difficult to degrade. The handling of textile wastewater usually involves the adsorption method, in which pollutants only transfer to another phase. As an alternative solution, a photodegradation method was developed using photocatalyst material assisted by ultraviolet irradiation. In this photodegradation method, dye substances are broken down into components that are simpler and safer for the environment. The possibility of using sunlight as a radiation source makes this a particularly promising method for countries such as Indonesia. Procion red, one of the most commonly utilized synthetic dyes in the home textile or Batik industry, was used as a model pollutant in this study. The objectives of the present research were to synthesize and characterize a nano-photocatalyst of ZnO-natural zeolite with the capacity to degrade Procion red. This nano-photocatalyst was synthesized using the sol-gel method, by which Zn(CH3COO)2 2H2O was used as a precursor and combined with natural zeolite to increase its photocatalytic ability. The nano-photocatalyst was characterized using X-ray diffraction (XRD), scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDX), and Brunauer-Emmett-Teller (BET). The activity of nano-photocatalyst ZnO-natural zeolite was compared to ZnO alone and natural zeolite alone in terms of its ability to degrade Procion red. An average photocatalyst crystallite diameter of 82 nm was achieved, proving that a nano-sized photocatalyst of ZnO-natural zeolite was successfully synthesized. BET characterization showed that nanophotocatalyst ZnO-natural zeolite had a specific surface area of 14.84 m 2 /g, a pore size of 32.71 nm, and a pore volume of 0.12 cm 2 /g. A peak Procion red degradation percentage of 96.23% was obtained using nano-photocatalyst ZnO-natural zeolite after 120 minutes of irradiation under sunlight applied to a Procion red concentration of 50 ppm.

Heavy metal is a type of metal that has a high density and high toxicity when consumed by living things, especially humans. To prevent the impact of environmental pollution, optimal handling of wastewater containing heavy metals is required, including the wastewater from laboratories. This research aimed to study the effect of pH, catalyst dose, and irradiation time on the reduction of Copper (Cu), Iron (Fe), and Lead (Pb) heavy metals and their application to laboratory wastewater treatment. Among the Advanced Oxidation Processes (AOPs) methods, photocatalysis was chosen to reduce the level of Cu, Fe, and Pb heavy metals where zinc oxide (ZnO) is used as a photocatalyst and the sunlight as a light source. To determine the effect of pH, catalyst dose, and time on the reduction of heavy metal levels, firstly, this research used the synthetic wastewater containing Cu, Fe, or Pb heavy metals. On the basis of the experimental results, it is concluded that the pH value, catalyst dose, and time affect the photocatalytic process, decreasing the levels of Cu, Fe, and Pb metals. The optimum pH value obtained for Cu was at pH 7-8, for Fe it was at pH 6, and for Pb it was at pH 8; in turn, the metal removal percentages were 99.46, 99.91, and 99.70%, respectively. In the photocatalysis of synthetic wastewater, high removal percentage of more than 99% was achieved by using 0.1 g/L catalyst. The optimum decrease of metals occurred in the first 15 minutes of solar irradiation where the removal percentage was close to 100%. In this study, the application of ZnO photocatalyst under solar irradiation can reduce the heavy metals content in the laboratory wastewater by almost 100%, which meets the environmental quality standard for Cu, Fe, and Pb.

No abstract

In this paper, the photocatalytic degradation of procion red dye, one of the most frequently used dyes in the textile industry, was studied. The objective of the research is to study the ZnO-Zeolite nanocomposite application to degrade procion red dye by using different irradiation sources. The adsorption isotherm was also investigated. The ZnO-Zeolite nanocomposite was prepared by a sol-gel process. Photodegradation test was applied under the sunlight irradiation, ultraviolet (UV) lamp, and in a darkroom. The dye degradation was also examined by the synthetic zeolite and ZnO for a comparison. Another objective of this study is to analyse the appropriate adsorption isotherm to describe the degradation process of procion red dye by using ZnO-Zeolite nanocomposite. The adsorption ability of the nanocomposite was described by Langmuir and Freundlich isotherms. The adsorption of the nanocomposite was reported to depend on the degradation time. The highest photodegradation result of 98.24 % was achieved by irradiating 50 mg/l of procion red dye under the sunlight for 120 minutes. The result showed that the Langmuir adsorption isotherm was the appropriate adsorption equation for the degradation process of procion red dye by using ZnO-Zeolite nanocomposite with R2 value of 0.995.