Vol. 1 No. 1 (2023): March

Biochar derived from rice husk was successfully prepared with the pyrolysis method. X-Ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Thermogravimetry analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis confirmed biochar. The results indicate that biochar is amorphous carbon. Functional groups on biochar include -OH, C-H, C-O, C=C, and C-O. The surface area of biochar of 72.252 m²/g with a pore size of 3.334 nm which is classified as mesoporous material. Biochar was used as an adsorbent on the congo red (CR) and procion red MX-5B (PR) dyes with adsorption capacities of 42.918 and 84.034 mg/g, respectively. The equilibrium adsorption occurred at 120 minutes. The adsorption isotherm and kinetics both followed the Langmuir isotherm and Pseudo Second Order (PSO), respectively. CR and PR adsorption process using biochar by physisorption and chemisorption with interactions that occur include hydrogen interactions, physical interactions, π-π interactions, and electrostatic interactions.

Synthesis of Zn-Al and Zn-Cr LDHs in this research was successfully carried out. The sucsessfully results can be seen from the XRD characterization which displays diffraction angles at 10 and 60 which indicates the presence of layered structures and anions. FT-IR data displays the presence of nitrate groups at wavenumber 1381 cm⁻¹. BET data shows surface area of Zn-Al and Zn-Cr at 1.965, 31.638 m²/g, corresponding. pHpzc determination of Zn-Al material gets a pH below pHpzc which is 6.2 while Zn-Cr is at pHpzc which is 7.6. Able of Zn (Al/Cr) as adsorbent to adsorp Pb(II) was investigated through several parameters such as kinetics, isotherms, thermodynamics. Kinetic Adsorption for Zn-Al inclined follow PSO, while Zn-Cr follow PFO. Isotherm parameter for Zn-Al and Zn-Cr is Freundlich with a maximum adsorption capacity 74.127 mg/L, and 27.027 mg/L. Thermodynamic process shows that Zn-Al and Zn-Cr LDHs take place in endothermic and spontaneously.

The layered double hydroxide-based material features of Ca/Al have improved according to the adsorption capacity and structure stabilization by transforming into composite Ca/Al-graphite. The composite was synthesized by co-precipitation method, and the chemical structure was characterized using X-ray Diffraction (XRD), Fourier Transform Infra-red (FT-IR), Brunauer Emmet-Teller (BET) Surface Area, and Thermo-Gravimetry Differential Analyse (TG-DTA). The XRD analysis of Ca/Al-Graphite composite was noticed in 10.205°(003), 18.083°(012), 20.45°(004), 26.532°(002), 44.52°(101), 54.52°(004), and 77.38°(006). The TG-DTA analysis of the composite was noticed at 100°C as water molecule decomposition, 270°C as nitrate decomposition, and 700 and 760°C as graphite decomposition to the oxide form. BET surface area analysis of Ca/Al-Graphite composite achieved the highest surface area at 16.795 m²/g. According to the kinetic parameter, the adsorption of direct orange to composite follows the pseudo-second-order model. The isotherm parameter of direct orange adsorption onto the composite followed the Langmuir model and occurred spontaneously and endothermically. The regeneration study proved the composite effective in 3 cycles by adsorption percentage at the third cycle reached 73.559%.

Rice husk, a green adsorbent, was used for procion red adsorption. Analysis with BET, XRD, FTIR, and SEM confirmed the formation of rice husk. The results indicate that rice husk is more porous and has a rougher surface. The surface of the rice husk has a non-uniform shape and uneven morphology. The pore of rice husk is critical to the adsorption process of procion red. The procion red will enter the pore of the rice husk to make an interaction. The rice husk has a surface area, pore volume, and pore diameter of 7.08 m²/g, 0.011 cc/g, and 3.14 nm, respectively. The vibrational peak at 3448 1620, 1103, and 794 cm⁻¹. the XRD powder patterns of rice husk characterization diffraction peak at 2θ 23°. Rice husk’s adsorption system for procion red removal follows PSO kinetic and Freundlich isotherm models with a maximal removal capacity of 158.730 mg/g. This study sheds light on the effectiveness of rice husk as an adsorbent for procion red contaminants.

Graphene oxide materials were successfully synthesized using the Hummer method with XRD, FTIR, and BET characterization results. Graphene oxide material was used as malachite green dye adsorbent. The surface area of graphene oxide material and the maximum adsorption capacity were 157.360 m²/g and 106.383 mg/g. The selectivity process of graphene oxide material to the three dyes showed the most effective malachite green dye. The optimum pH of adsorption was obtained at pH 4. The optimum time of adsorption occurred at 120 minutes and the kinetics model followed PSO. The isotherm data followed Langmuir isotherm and the adsorption process was endoetrmic and spontaneous. The regeneration results showed the ability up to five cycles with a decrease of 40.019% from 96.698% to 56.679%.