We report a modification of the liquid-phase exfoliation (LPE) method in order to produce reduced graphene oxide (rGO) material by varying the heating temperature. The rGO was obtained by dissolving graphite powder into a surfactant solution and then heated by varying the heating temperature. There is an intercalation process on the graphene layers as the heating temperature was increased. The rGO material were tested using UV-vis, FTIR, Raman spectroscopies, and conductivity measurement based on Ohm principles.

Background: This study aims to study the mixing of graphite with water irradiated by X-ray (low energy gamma ray) towards the formation of graphene oxide (GO). Materials & Methods: The graphite is obtained from Zinc-Carbon (ZnC) battery wastes. This is a simple alternative technique in synthesizing GO based on X-ray irradiation without involving additional chemicals. X-ray irradiation is conducted upon 10 ml of distilled water using 20 kV of X-ray with irradiation time variation of 3 and 4 hours. The X-ray irradiation towards the distilled water causes radiolysis to occur in the water. The graphite solution consists of 0.6 grams of graphite in 100 ml of distilled water. The GO is formed by mixing the X-ray irradiated water with 5 drops of the graphite solution. The sample solutions obtained are shaken several times and left to settle for a night. The samples are then characterized using UV-Visible (UV-Vis) and Fourier transform infra-red (FTIR) spectroscopies, and tunneling electron microscopy (TEM), whereas scanning electron microscope and energy dispersive X-ray (SEM-EDX) characterization is done by coating the sample on glass slides. Results: The UV-Vis characterization results show a red shift of absorbance peaks from 234.5 nm to 244.5 nm as the time of irradiation is increased. These peaks indicate the formation of GO in the samples. The FTIR characterization results indicate that there are functional groups of OH, C = C, and C - O in the samples, which also show the existence of GO. The SEM images show the surface morphology of the sample, which resembles smooth-quadrilateral lump of clays, and the EDX result shows that the sample is composed of 2.86%, 54.02%, 11.62%, 2.2%, 26.23%, and 3.06% of carbon, oxygen, sodium, magnesium, silicon, and calcium atoms, respectively. The occurrence of carbon and oxygen atoms verifies further the formation of GO in the samples. Conclusion: Finally, the TEM result shows few-layers of GO materials supported by the electron diffraction pattern showing hexagonal structure of the GO.

The aim of this research is to determine the effect of micro-sized carbon material mass variation from coconut shell leftovers or wastes reinforced with filter paper towards Fe filtration of Mataram canal water. Preparation and synthesis of the micro-sized carbon material are conducted via liquid sonication exfoliation (LSE) method using two main type of equipments, i.e.: a blender and a self-custom made piezoelectric-based ultrasonication apparatus, and then incorporated into a simple filtration apparatus. UV-Vis spectroscopy characterization is done on the micro-sized carbon material solution, while atomic absorption spectroscopy (AAS) is done on samples of Mataram canal water before and after Fe filtration with a mass variation of the micro-sized carbon material. The UV-Vis results show that increasing the mass of the micro-sized carbon material increases the absorbance values at the same wavelength. The AAS results confirm that the greater the mass of the micro-sized carbon material the smaller the Fe content inside the water samples after filtration. The lowest Fe content of 0.016 ppm is obtained for 3 grams of the micro-sized carbon material.

Graphite exfoliation has been the main mechanism to produce graphene material and its derivatives, such as graphene oxide (GO) and reduced GO (rGO). This study was aimed to exfoliate graphite using MnO2 paste in Zinc-Carbon (ZnC) battery wastes via audio sonication in X-ray irradiated water. The exfoliated graphite (EG) sample was then characterized using UV-Vis spectrophotometry, FTIR spectroscopy, XRD, and SEM. The EG sample was utilized as an additive for producing sponge with heat-induced volumetric-shrinkage resistance property. The irradiated water was obtained by exposing X-ray radiation upon distilled water. The graphite and K2MnO4 were mixed in the irradiated water followed by audio sonication accompanied by stirring and heating. The K2MnO4 was obtained from the MnO2 paste added with KOH. The UV-Vis results showed a shouldering peak at 271 nm indicating that the graphite was succesfully exfoliated. The FTIR test showed the presence of hydroxyl, C-O, CO2, N-O, and C=C functional groups. The XRD showed a peak at 12° for the EG sample similar to the XRD peak of GO. The SEM images showed layers of graphene flakes. The threshold temperature values of the sponge, sponge with EG (sponge+EG), and sponge with graphite (sponge+graphite) were 399.20, 271.03, and 414.82 °C, respectively. The sponge+EG underwent less volume shrinkage compared to ordinary sponge and sponge+graphite, which confirms its volume shrinkage resistant upon heating. HIGHLIGHTS We have exfoliated graphite using MnO2 paste obtained from ZnC battery wastes via audio sonication in X-ray irradiated water The UV-Vis characterization of the exfoliated graphite shows a shouldering peak at 271 nm. The FTIR test shows the presence of hydroxyl, C-O, CO2, N-O, and C=C functional groups. The XRD diffractogram shows a peak at 12° of an amorphous material. Finally, the SEM image shows layers of graphene flakes The exfoliated graphite is used as an additive to produce a volume-shrinkage resistant sponge, which underwent less volume shrinkage compared to ordinary sponge and sponge with graphite GRAPHICAL ABSTRACT

This study aims to synthesis micro-sized carbon material from coconut shell leftovers or wastes using piezoelectric-based ultrasonication in liquid phase. The micro-sized carbon material produced is then utilized as a filtration material for Mataram canal water in Yogyakarta. This study begins with synthesizing the micro-sized carbon material by mixing i) mashed coconut shells, ii) 100 ml distilled water, and iii) 2 grams of detergent into a blender. The aforementioned materials are blended with mixing time variation of 30 minutes and 60 minutes. The resulted solution is left alone for a night and then ultrasonicated for 4 hours. The solution is then characterized using UV-Vis spectrophotometer. The sediments obtained from the carbon materials are characterized using X-ray diffraction (XRD) for each mixing time variation whereas scanning electron microscopy (SEM) is conducted upon the micro-sized carbon material with 60 minutes mixing time. The solution and the sediment is poured onto a filter paper, heated until dry, and fitted to a simple filtration device. Water from Mataram canal is used to test the Fe filtration ability of the micro-sized carbon material. The water samples before and after filtration are characterized using atomic absorption spectroscopy (AAS). The UV-Vis results show that increasing the mixing time of material, increases the absorbance value. Based on XRD results the synthesized micro-sized carbon material from coconut shell has an amorphous phase. The SEM result at 60 minutes of mixing time looks like an irregular bulk material with sizes of about 1 $\mu$m to 12 $\mu$m with thicknesses of around 0.6 $\mu$m to 0.8 $\mu$m. The AAS results indicate that the longer the mixing time, the lower the Fe content in the water samples after filtration.