Key Engineering Materials Vol. 920

Abstract: In this research, iron modified activated carbon (FeAC) was prepared through chemical activation method to enhance the adsorption potential of activated carbon (AC) towards the removal of Reactive Blue 19 (RB 19) dye in batik wastewater and aqueous solution. The adsorbents were characterized by various characterization techniques while the industrial wastewater and aqueous solution were characterized using UV-Vis spectroscopy and chemical oxygen demand (COD) analysis. The effects of various parameters such as adsorbent dosage, amount of H₂O₂, contact time, initial RB 19 dye concentration, pH and the reusability of the adsorbent in the presence and absence of 30 % w/w H₂O₂ were investigated. In the presence of H₂O₂, FeAC exhibited the highest removal efficiencies ( > 90.0 %) for RB 19 dye in both industrial wastewater and aqueous solution using 0.2 g adsorbent, 10 mL of 30 % w/w H₂O₂ and at ambient pH within 480 minutes compared to the AC and FeAC alone.

Abstract: Glass fiber reinforced plastics (GFRP) are composite materials with high strength and flame retardancy, and the disposal process is expensive to cause illegal dumping. Therefore, new recycling technology of waste GFRP is desired. In this study, recycling of waste GFRP via pyrolysis with sodium hydroxide (NaOH) under an inert atmosphere using microwave heating was attempted by carbonization of resin and conversion of glass fiber into soluble sodium silicate. The pyrolysis behavior of GFRP, the characteristics of the obtained residue, and the silica extraction into the solution were compared for microwave heating and conventional heating. In both heatings, the carbonization of the resin and the conversion of the glass fiber into soluble sodium silicate were confirmed by pyrolysis with NaOH, and the sample after the pyrolysis treatment can be pulverized into a powdery residue by washing the solution without mechanical crushing. In comparison with conventional heating, microwave heating could reduce the time for heat treatment (41.3% reduction), to reduce the energy consumption (75% reduction), suggesting that microwave heating can provide more efficient treatment.

Abstract: Plastic waste will potentially cause serious environmental problems. In this study aluminum-plasticspackaging waste is recycled into pellets for alternative fuel. Plastic waste is pelletized using an extruder with temperature variations of 140°C, 160°C and 180°C. Then, the calorific value, moisture content, density and compressive strength of the pellet were measured. The calorific value of the pellet is 38.79 mJ/ Kg. The density value shows good results because it exceeds the standard density for pellet solid fuel of more than 600 kg/m³. Meanwhile, the compressive strength exceeding the specified standard and experiencing an increase from each temperature variant. The economic feasibility analysis shows an NPV of Rp. 3.249.934.093. IRR 28.16%, B/CR 1.617 and PP 5.84 years. From these data, it indicates that the aluminum foil plastic pellet business is possible to be implemented.

Abstract: The environmental problem that often occurs in coal mining is acid mine drainage which can pose a serious threat to human health, animals and ecological systems. Acid mine drainage contains heavy metal contaminants such as iron and manganese. The purpose of this study was to determine the adsorption equilibrium carried out using natural zeolite adsorbents type mordenite from Klaten, Central Java. The application of natural zeolite with a volume of 100 mL synthetic acid mine drainage with concentrations of Fe 41.97 mg/L, Mn 21.75 mg/L and variations in dose of natural zeolite (2, 4, 6, 8, and 10 grams). The highest percent removal was at a dose of 10 grams of zeolite resulted in % removal of 97.94 % for Fe and 67.81 % for Mn. The results obtained using Langmuir and Freundlich adsorption isotherms. The results followed the Freundlich isotherm model with an adsorption parameters K_f = 0.427 mg/g, R² = 0.991, n = 1.610 Fe metal and Mn metal adsorption parameters are K_f = 0.006 mg/g, R² = 0.9971, and n = 0.578

Abstract: This study reports the removal of cadmium ions in aqueous solution as the artificial waste using natural zeolite as the adsorbent. Natural zeolite was characterized by using XRD (X – Ray Diffraction) and XRF (X-Ray fluorescence) analysis. The XRD results show that the natural zeolite derived from Klaten, Jawa Tengah, is mordenite type and the XRF results show that Si/Al ratio is 5.688 % (medium). A batch adsorption method is carried out at room temperature varied adsorbent dose. Equilibrium of adsorption data were analyzed using the Langmuir and Freundlich isotherm model. The values of the parameters constants for the Langmuir equation were qmax = -2.301 mg/g and KL = -1.00067 while the Freundlich equation were Kf = 3.999 and n = 0.845. It was found that the Freundlich adsorption model is better than the Langmuir isotherm model with high coefficient of determination. In this study, the removal efficiency for Cd2+ was 99.4 % for adsorbent dose of 70 g/L. It can be concluded that the natural zeolite of mordenite type is a very potential adsorbent for removal Cd2+. Therefore, the utilization of zeolite should to be encouraged in a larger scale especially in the environmental application.

Abstract: The waste of palm sugar fiber from the home industry of glass noodles reaches 25 tons/day and has not been used economically regardless of the content of its cellulose about 52%. With the high content of cellulose, palm sugar fiber can be synthesized as a functional adsorbent to overcome the environmental issues that arise. The synthesis of nanofiber was carried out in several steps including washing the sample to remove dirt, synthesizing using a chemical approach (NaOH, HCl, NaClO₂, and CH₃COOH), and modifying the nanofiber surface with 3% and 5% cobalt oxide. The characterization showed that palm sugar fiber was successfully transformed into nanofiber based on XRD, FTIR, dan SEM results. The removal of dye waste was observed, showing that the adsorption capacity of nanofiber modified with 5% cobalt oxide calcined at 400 °C for 2 hours was suitable for methylene blue removal compared to congo red up to 9.162 mg/g. The adsorption followed the pseudo-second-order kinetic model with Langmuir adsorption isotherm.

Abstract: This research paper describes the effect of hydrogen peroxide concentrations (0; 1; 3; 5 and 7 wt%) on fluorescence properties of carbon dots (CDs) from high-density polyethylene (HDPE) plastic. Synthesis of CDs has been carried out using modified pyrolysis and hydrothermal methods. The CDs obtained were characterized by FTIR, XRD, UV-Visible and fluorescence spectrophotometer. Based on UV-Visible spectra, the maximum wavelength of carbon dot ranges from 287 to 291 nm, indicating there is an π -π* electron transition belonging to the core site (C=C), then the absorption widens to 400 nm which indicated n-π* electron transition relating to the CDs surface functional group (carbonyl, hydroxyl, and carboxyl). The use of hydrogen peroxide (5 wt%) can produce CDs with the best fluorescence properties based on fluorescence spectra. CDs has a structure like graphite which is rich in functional groups on its surface. The photocatalytic activity of carbon dot has been tested and it showed that CDs can degrade methylene blue (MB) dye under visible light (80.3%).

Abstract: The development of smart materials have a significant impact on sample preparation and preconcentration methods. Ferrofluid or magnetic fluids (FF) are smart colloidal suspensions of single domain magnetic nanoparticles in a polar or non-polar liquid carrier. In this study, graphene oxide magnetite (GO@Fe₃O₄) and deep eutectic solvent-based choline chloride and ethylene glycol as a carrier liquid were utilized to form GO@Fe₃O₄-DES FF. The synthesised GO@Fe₃O₄-DES FF was characterized using FTIR, SEM, TEM and vibrating sample magnetometer (VSM). GO@Fe₃O₄-DES FF was further developed for the application of GO@Fe₃O₄-DES FF-liquid phase microextraction (LPME) for enrofloxacin as test compound. Several parameters such as type of FF composition and volume, extraction time, desorption solvent volume, desorption time and solution pH were optimised and analysed using HPLC-UV. Under optimum conditions, the developed GO@Fe₃O₄-DES FF-LPME method showed good linearity, R² ≥ 0.9921, repeatability, RSD 0.57 – 9.40 %. The developed GO@Fe₃O₄-DES FF-LPME method was applied for the determination of enrofloxacin in water samples from Langat River Basin, Selangor and the recovery of 71.6 – 112.3% was obtained. In conclusion, the developed GO@Fe₃O₄-DES FF-LPME method for the determination of enrofloxacin showed excellent sensitivity and precision and may be an excellent alternative method for the extraction on water samples.

Abstract: This study aims to evaluate the feasibility of the yttrium recovery from compact fluorescent lamp waste using methyltrioctylammonium peanut oil ([N_1,8,8,8][PO]) compared to methyltrioctylammonium naphthenic acid ([N_1,8,8,8][NA]) and tetraoctylphosphonium oleate ([P_8,8,8,8][Oleate]) on a large scale. Based on the techno-economic analysis, the process was feasible on a large scale commercially due to changes in economic parameters such as gross profit margin (GPM), payback period (PBP), break-even point (BEP), break even capacity (BEC), cumulative net present value (CNPV), profitability index (PI), internal rate return (IRR), and return on investment (ROI) tend to be positive with the greatest profit when using [P_8,8,8,8][Oleate] compared to [N_1,8,8,8][NA] and [N_1,8,8,8][PO] under ideal conditions and the use of [N_1,8,8,8][PO] can still be profitable under non-ideal conditions with certain fluctuation limits.

Abstract: Waste from plastic products can be considered complex materials, making recycling a challenge. PET and LDPE are common type of plastic that is easily found in garbage pile. This research was conducted to study the potential of plastic waste conversion into solid fuel to reduce the accumulation of this waste in the environment. The conversion method is to use an extruder. An economic analysis was performed to measure the feasibility of this recycling method. PET and LDPE plastic waste were recycled into pellets using simple heated-extruder equipment after being shredded into small flakes. The extruder temperature was varied at 120^OC, 130^OC, 140^OC, 150^OC, 160^OC, and 180^OC. The optimum temperature for LDPE pellets is 120^OC, and PET pellets is 130^OC. The highest density LDPE pellets is 966.7 kg/m³, and PET pellets is 1320 kg/m³. The highest compressive strength LDPE pellets is 1041.1 kg/m², and PET pellets is 615.2 kg/m². The calorific value of the recycled LDPE and PET pellets is 43.52 mJ/kg and 27.26 mJ/kg, respectively. The moisture value in each plastic pellet did not change significantly by temperature difference. Meanwhile, the economic feasibility analysis shows an NPV of Rp4,394,049,079; IRR of 25.18%; B/CR of 1.465; and PP of 5.95 years.