Vol. 1 No. 2 (2023): July

The adsorption features of rice husk biochar (BC) have been improved by structure refinement due to being composited with manganese oxide (MnO). The composite material formed under low energy (temperature) was identified by X-ray Diffraction (XRD), Fourier Transform Infra-red (FTIR), and Brunauer-Emmet-Teller (BET) Surface Area instrumentation. The composite of BC/MnO analysis of XRD was specialized at 9.48° (110) and 31.42° (111). Functional group investigation of FTIR on BC/MnO composite was detected at 349 cm^-1 and 401 cm^-1 as manganese oxide vibration on biochar. The improvement in specific surface area is evidenced by BET surface area analysis, with the highest result at 96.047 m²/g. Several analyses on the adsorption work concluded that malachite green adsorption on BC/MnO composite follows the pseudo-second-order model and the Freundlich scheme under spontaneous reaction. Additionally, calculation in adsorption parameters resulted in an adsorption maximum capacity of about 79.365 mg/g with regeneration effectiveness up to 48.170% at the final of the seventh cycle.

Peel of duku fruit (Lansium domesticum) was prepared into hydrochar by using hydrothermal carbonation method at heating time variation of 8, 10, 12, 24 hours and temperature variation of 200 and 250°C. X-Ray Diffraction (XRD), Fourier Transform Infra Red (FT-IR), Brunauer Emmet Teller (BET) and Scanning Electron Microscope (SEM) analyses were conducted to determine at what time and temperature variations the adsorbent had the best adsorption quality. Based on the characteristics of the adsorbent, it can be seen that the best hydrochar is at 12 hours and at a temperature of 200°C. X-Ray Diffraction (XRD) analysis showed the presence of diffraction peaks at angles of 15.7° and 22.79° Fourier Transform Infra Red (FT-IR) analysis obtained explained that there were peaks of vibration peaks namely -OH, -CH, =CH, C=O, C=C aromatic and aliphatic. Brunauer Emmet Teller (BET) analysis can be seen that the increase in surface area on duku fruit peel (Lansium domesticum) and hydrochar at 200°C from 12.343 m² /g to 22.635 m² /g. Scanning Electron Microscope (SEM) analysis shows that the surface peel of duku fruit (Lansium domesticum) material has a clumped surface morphology in the same phase or also called aggregation, while the hydrochar tends to have an irregular shape or can be called heterogeneous morphology.

Malachite green dye in industrial wastewater can be removed by the adsorption method. The adsorbents used in the adsorption method were Ni-Cr LDH, microcrystalline cellulose, and Ni Cr LDH/microcrystalline cellulose composite. Regeneration process of malachite green dye with the Ni-Cr/microcrystalline cellulose adsorbent resulted in the adsorbent having the highest percent adsorbed when compared to Ni-Cr LDH and microcrystalline cellulose adsorbents. This is proof that Ni-Cr/microcrystalline cellulose LDH composite adsorbent can be used repeatedly as much as five cycles. Ni-Cr LDH material and Ni-Cr/microcrystalline cellulose LDH composite were synthesized by the coprecipitation method and were successfully carried out by XRD characterization to see the stability of the structure. The results of XRD characterization of Ni-Cr/microcrystalline cellulose composite showed peaks at diffraction angles of 11°(003), and 60°(110) which are typical regions of LDH and at diffraction angle of 22°(020) which is a typical area of microcrystalline cellulose material. Ni-Cr LDH, microcrystalline cellulose and Ni-Cr/microcrystalline cellulose get optimum pH at 7 with wavelength malachite green at 618.8 nm, kinetic equation following PSO and isotherm following Freundlich with capacity maximum until 129.870 mg.g⁻¹. FT-IR spectra display groups found in LDH and composites including O-H, NO₃⁻, M-O also microcrystalline cellulose have groups C-O and C-H. SEM characterization found out the biggest particle size is 1,954 µm as much as 72 and EDX composite material contains elements of O, C, Ni, Cr, Na, and N.

In this study, hydrocarbons were obtained through the hydrothermal carbonization synthesis method. The XRD data of the cellulose sample revealed 2θ angles of 15.46°, 22.34°, and 34.36°, indicating that the cellulose sample under investigation had an amorphous structure. The XRD data of the hydrocarbon sample showed a 2θ angle of 25.72°, indicating the presence of graphitic carbon. The FTIR spectra of both cellulose and hydrocarbon exhibited similarities at wave numbers 3394 cm-1, 2893 cm-1, 1662 cm-1, 1000-1200 cm-1, and 847 cm-1. BET analysis revealed that the hydrocarbon material surface area measured was 7.366 m²/g, measured pore volume for the entire sample was 0.008 cc/g, and the average size of the pores was 3.189 nm. The optimal pH variation for cellulose was at pH 10, with an adsorption capacity of 10.75 mg/g, on the other hand, was tested at pH 6 and demonstrated an adsorption capacity of 12.74 mg/g. The adsorption kinetics model for both adsorbents was PSO, and the adsorption isotherm model was Freundlich. Cellulose exhibited a maximum adsorption capacity of 35.336 mg/g, while hydrochar demonstrated a maximum adsorption capacity of 21.008 mg/g. It is noteworthy that both adsorbents were capable of being reused for up to five cycles.

Material NiAl-K₃[α-PW₁₂O₄₀], NiAl-K₄[α-SiW₁₂O₄₀], ZnAl-K₄[α-SiW₁₂O₄₀] and ZnAl-K₃[α-PW₁₂O₄₀] were created. FTIR, XRD and SEM were used to characterize the substance. The findings of the successfully completed synthesis showed that peak diffraction angle for NiAl-LDH were at 11.58°, 23.18°, 35.01°, 39.41°, 46.70°, 60.94°, and 62.26° and diffraction at 10.29°, 20.07°, 34.02°, and 60.16° for ZnAl-LDH. The composite material LDH-polyoxometalate NiAl-PW₁₂O₄₀ that was at angles 10.76°, 26.59°, 30.8° and 63.1° and 8.61°, 25.27°, 33.8°, 66.34° for ZnAl-plyoxometalate. The typical polyoxometalate band on the composite material’s FTIR spectrum proved tha intecalation of the substance. SEM examination revealed the aggregat for nearly all intercalated and synthesized materials.