Title Science and Technology Indonesia e-ISSN:2580-4391 p-ISSN:2580-4405 Vol. 8, No. 2, April 2023 Research Paper Interlayer Modification of West Java Natural Bentonite as Hazardous Dye Rhodamine B Adsorption Satria Jaya Priatna1, Yusuf Mathiinul Hakim2, Sahrul Wibyan3, Siti Sailah4, Risfidian Mohadi1,2* 1Department of Soil Science, Sriwijaya University, Indralaya, 30862, South Sumatera, Indonesia2Graduate School, Faculty of Mathematics and Natural Sciences, Sriwijaya University, Palembang, 30139, Indonesia3Department of Chemistry, Faculty of Mathematics and Natural Sciences, Sriwijaya University, Indralaya, 30862, South Sumatera, Indonesia4Department of Physics, Faculty of Mathematics and Natural Sciences, Sriwijaya University, Palembang, 30139, Indonesia *Corresponding author: risfidian.mohadi@unsri.ac.id AbstractThis work reports the modification of West Java natural bentonite as an effective adsorbent for rhodamine B dye. The modificationwas finished by sodium intercalation at room temperature to get low-energy preparation. Characterization of bentonite-modifiedadsorbent was used SEM, XRD, FTIR, and BET analysis. The material pore size and surface area were increased by 0.303 nm and178.710 m2/g on Na-bentonite. The adsorption mechanism conformed well with the Freundlich isotherm model and pseudo-second-order kinetics equations. The adsorption process by thermodynamic analysis was endothermic and advantageous. Under theoptimum condition of pH 6 (confirmed by pHpzc), initial dye concentration of 125 mg/L, and the adsorbent dosage of 0.09 g for 65minutes, the Na-bentonite has a larger adsorption capacity (Qm) of 142.86 mg/g, while the different adsorbent dosages of 0.11 g for75 minutes, the adsorption capacity of natural bentonite (Qm) reaches 140.85 mg/g. This work provides a method for establishinga low-energy preparation adsorbent of bentonite-based on Na-intercalant as a low-cost and valuable adsorbent for waste dyeremoval. KeywordsBentonite, Intercalation, Low Temperature, Adsorption, Rhodamine B Received: 3 October 2022, Accepted: 23 January 2023 https://doi.org/10.26554/sti.2023.8.2.160-169 1. INTRODUCTION In recent years, environmental contamination has become a crucial issue due to the massive disposal of industrial waste (Asgari et al., 2021; Soleimani et al., 2022). Massive wastewater disposed of led to contamination in the ecosystem (Kamarehie et al., 2020; Rahmani et al., 2022). Coloring products are widely used in the food, cosmetics, pharmaceuticals, paints, and textiles industries (Laysandra et al., 2017) . It was estimated that 7x105 tons of dye waste are produced annually (AL Tufaily and Al Qadi, 2016; Mohammad et al., 2019). Rhodamine B (RhB) is a basic cationic dye with complex structures shown in Figure 1. In some cases, long-term ex- posure to RhB likely triggers temporary skin, and mucous membrane irritation, until the mutagenic effect (Laysandra et al., 2017) . Several works provide techniques to detach the pollutants such as precipitation, osmotic reverse, floccula- tion/coagulation, electrodialysis, and adsorption (Dotto et al., 2019; Giraldo et al., 2022; Xie et al., 2022). Adsorption be- comes the most efficient due to the organics, toxic metals, and dye contaminants binding to the solid adsorbent. Those stable contaminants bonded physically or chemically at the adsorbent surface (Chai et al., 2020; Mohammad et al., 2019). Potential low-cost adsorbents that provide adsorption features are zeo- lites, limestone, silica gel, chitosan, dolomite, activated carbon, and bentonite/clay. Nowadays, the layered material of alumina-silicate ben- tonite has gained popularity as a low-cost adsorbent due to its abundance and high potency to enhance adsorbing capacity. The limitation of natural bentonite due to its rigid structure and the negative charge that is only sensitive to removing cationic dyes have encouraged researchers to modify the bentonite structure (Ding et al., 2018) . However, the intercalation of natural bentonite by cationic exchange assisted by calcination to increase the adsorption capacity is favorable (Srikacha et al., 2022) . However, the intercalation step may need a longer preparation time of 3 h to 10 days, moreover calcination pro- cess of more than 300°C to change the bentonite structure could trigger a collapse of the bentonite structure (Bouras et al., 2007; Leodopoulos et al., 2015). Recently, Islam and Mostafa https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.160-169&domain=pdf https://doi.org/10.26554/sti.2023.8.2.160-169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Figure 1. Chemical Structure of RhB Dye (2022) studied the natural sodium bentonite adsorption ca- pacity towards methylene blue by an adsorption capacity of 25.19 mg/g. According to Shattar and Foo (2022) , activa- tion bentonite assisted by sodium salt under heating of 70°C gives removal of methylene blue with an adsorption capacity of 318.38 mg/g. The intercalation process becomes a challenge in bentonite modification. The rigid characteristics of the bentonite struc- ture block the intercalation of another molecule. Sodium in- tercalation, as the preliminary step, becomes the favorable solution. The opening interlayer process to insert the inter- calant need some energy that uses heat and pressure. High energy insertion is the challenge to discover a new method of the intercalating molecule to increase the interlayer bentonite. According to the report of Lin et al. (2007) , intercalation via intermolecular force becomes an effective method for inserting molecules in low temperatures to decrease energy consump- tion. This work aims to intercalate the West Java natural ben- tonite by saturated sodium salt solution under the natural am- biance of low-temperature preparation to get intramolecular force in inserting the intercalant and evaluate its removal capac- ity on RhB from aqueous solutions. Sodium salt was chosen because it is non-toxic to essential substances in the environ- ment and has a high cationic exchange capacity in bentonite surfaces (Alexandru, 2011) . The bentonite-modified charac- terization used SEM, XRD, FTIR, and BET to analyze physic- ochemical structural changes. The adsorption mechanism of RhB was carried out with optimization of the operational con- dition by pHpzc, variations in time, the dosage of adsorbent, temperature, and initial concentration. 2. EXPERIMENTAL SECTION 2.1 Chemicals and Instrumentation The natural bentonite was obtained from West Java with pu- rification. Chemicals in a pure grade, such as sodium chloride (NaCl), sodium hydroxide (NaOH), silver nitrate (AgNO3), hydrochloric acid (HCl), and rhodamine B (RhB) dye, were purchased from Sigma-Aldrich and directly used without purifi- cation. Instrumentation such as X-Ray Diffractometer (XRD) type Rigaku Mini-flex600, Fourier Transfer Infra-Red (FTIR) type Perkin-Elmer UATR Spectrum two, UV-Vis Spectropho- tometer type Orion AquaMate 8000, Scanning Electron Mi- croscope Energy Dispersive Spectrometer (SEM-EDS) type JEOL JSM 6510-LA, and Surface Area Analyzer using Quan- tachrome ASIQ-win based on BET method calculation. 2.2 Bentonite Intercalation The natural bentonite was modified by the cationic exchange methods at room temperature of 25°C: 100 g of natural ben- tonite dissolved in 333 mL of saturated NaCl and stirred for 2 hours. Then the mixture was added with distilled water (by two times the mixture volume) and continued stirring for 10 min- utes. The bentonite mixture was precipitated and repeatedly added with 333 mL saturated NaCl, then mixed for 2 hours. It was washed three times with boiled distilled water, and the precipitate was oven-dried at 200ºC for 12 hours. It is noticed as Na-bentonite. 2.3 Optimization of Operational Condition The pHpzc (point zero charges) was determined by adding 0.02 g of adsorbent into 20 mL of 0.1 M NaCl solution and adjusted to pH of 2, 3, 4, 5, 6, 7, 8, 9, 10 using 0.1 M of NaOH and HCl solution. The mixture was stirred for 3 hours, and the final pH of the filtrate was measured using a pH meter to graph the pHpzc state. 2.4 Adsorption Studies The effect of adsorption time was studied by varying the time adsorption at 5, 15, 25, 35, 45, 55, 65, 75, and 85 minutes. The composition of the adsorption process is 0.01 g of adsor- bent into 50 mL of 30 mg/L RhB dyes. The effect of adsorbent dosages was studied by variation of adsorbent dosages at 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, and 0.13 g. The effect of tem- perature and concentration adsorption was conducted on the adsorption of RhB using various temperatures and initial con- centrations at 30, 40, 50, 60, and 70°C, with the concentration of RhB 25, 50, 75, 100, and 125 mg/L. 2.5 Analysis of Mechanism Adsorption Adsorption kinetics of this experiment conducted by Wu et al. (2021) for pseudo-first order and pseudo-second order kinetic models are shown in Equation 1 and 2, respectively: ln(qe − qt) = lnqe − tK1 (1) t qt = 1 q2e + t qe (2) Where K1 is the rate constant of pseudo-first order (min−1), K2 is the constant rate of pseudo-second order (g.mg−1min−1), t for time, then qe and qt are capacity adsorption at equilibrium © 2023 The Authors. Page 161 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 and specific time, respectively. The Langmuir and Freundlich adsorption isotherm were analyzed to know the adsorption isotherm of this experiment according to Sahnoun et al. (2018) by the equation, respectively: Ce qe = 1 qmaxKL + Ce qmax (3) lnqe = lnKF + lnCe n (4) Where qe is the capacity equilibrium of adsorbent (mg/g), Ce is the concentration equilibrium after adsorption (mg/L), qmax is the capacity maximum of adsorption (mg/g), KL is constant of Langmuir adsorption (L/mg), then Kf and n are constant of Freundlich adsorption (L/g). Furthermore, the thermodynamic parameters can be analyzed by following equa- tions (Dotto et al., 2019) : ΔG = −RTlnKd (5) ΔG = ΔH −TΔS (6) lnKd = ΔS R − ΔH RT (7) Where ΔG° is the value of free energy Gibbs (kJ/mol), ΔH° is the enthalpy change of adsorption (kJ/mol), ΔS° is adsorp- tion entropy change (kJ/mol.K), R is the standard gas constant (8.324 kJ/mol), T is temperature reaction (K), and Kd is the equilibrium constant. 3. RESULT AND DISCUSSION 3.1 Characterization of Adsorbents The morphologies of modified bentonite were observed us- ing SEM techniques in Figure 2 shows a massive quantity of lamellar particles with unshaped aggregated and rough particles attached to the surface area, especially in modified bentonite in Figure 2b (Mahmoodi, 2015) . Aggregate and rough parti- cles may be impurities from zeolite, while according to Figure 2a, the flake’s structures are considered montmorillonite(Jiang et al., 2021) . According to Figure 2b, lamellar structures in Na- bentonite present numerous small particles attached. Those phenomena showed that cation exchange significantly reduced impurities, confirmed by detailed EDX data in Table 1. The intercalation process affected the removal of the Ti substance. The composition and structural changes are reflected by XRD analysis in Figure 3. The basal spacing of the bentonite- modified adsorbents is 8.06 nm and corresponds to the d001 peak, the value of 2\ about 20°, noticed as montmorillonite. Figure 2. SEM Image of (a) Natural Bentonite (b) Na-bentonite The sodium-intercalated did not change significantly due to low interaction binding and the size particle of sodium identic to the previous cation in the interlayer. Unfortunately, the sodium intercalation has affected the cationic exchange, and it is confirmed from Figure 3 that the peak positions of all adsorbents are similar (He et al., 2022) . According to the data of XRD, the crystal size of natural bentonite and Na-bentonite are 4.35 nm and 8.06 nm, respectively. Modifying bentonite assisted by sodium intercalation between interlayers increases the montmorillonite composition, layer space, and adsorption capacity by providing the cationic exchange field. According to JCPDS data No. 24-0495 shows that 2\ at around 20°, 35°, 55°, and 63° are montmorillonite compounds. Then, for 2\ at about 26° are quartz compounds, while at 2\ around 28° are compounds composed of Al, Si, and O (Reza et al., 2015) . Figure 3. XRD Patterns of (a) Natural Bentonite and (b) Na-bentonite Bentonite, as layered material, has several functional groups that influence adsorption. The FT-IR spectrums of bentonite- modified are displayed in Figure 4. The composition of OH octahedra stretching vibrations at the surface layer is indicated by a peak at 3380 cm−1 . A peak indicates the H-O-H vibra- tions of the water molecule at 1632 cm−1 . The layer structures of bentonite were confirmed by stretching vibrations of Si-O- © 2023 The Authors. Page 162 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Table 1. EDX Data of Bentonite-modified Adsorbent Element Natural bentonite (%W) Na-bentonite (%W) O 57.88 54.83 Si 22.17 22.86 C 13.02 10.77 Al 3.32 4.21 Fe 1.34 1.42 Mg 0.71 0.69 Cu 0.62 1.10 Ca 0.27 1.59 K 0.26 0.48 Na 0.23 0.84 Ti 0.17 - Table 2. The Analysis of BET Surface Area, Pore Diameter, and Pore Volume of the Natural Bentonite and Na-bentonite Adsorbent BET Surface Area (m2/g) Pore Diameter (nm) Pore Volume (cm3/g) Natural bentonite 61.791 4.678 0.144 Na-bentonite 178.710 3.401 0.303 Si from the peak at 1028 cm−1 and vibrations of Al-O-Al from the peak at 791 cm−1 (Castellini et al., 2017) . The peak at 518 and 459 cm−1 is ascribed to the cation vibration on the layer structure of bentonite. The difference in peak sharp- ness affected vibration intensity due to sodium salt intercalant power binding at the surface interlayers, thus giving additional functional groups between interlayers (Yang et al., 2022) . The textural characteristics of natural bentonite and the intercalated one were characterized via the N2 adsorption- desorption method at 77.35 K. Detailed result was plotted in the graph of N2 adsorption-desorption isotherm characteris- tics in Figure 5. The isotherm trend from the natural bentonite and Na-bentonite behave in the same condition that fits into the type IV according to Braunnauer-Deming-Deming-Teller (BDTT) classification (Mu’azu et al., 2018) . The overlapping of adsorption-desorption points occurred at the low relative pressure; thus fit with the H3 type of hysteresis loop that initi- ated at a relative pressure (P/P0) around 0.42. The emerging features are grouped as the characteristic of the mesopore lay- ered material (Tong et al., 2018; Yurdakal et al., 2019). The precise surface area value calculated using the BET model on natural and Na-bentonite is tabulated in Table 2. In this case, the specific surface area of bentonite-intercalated Na+ was differently higher than the natural one. It assumed that sodium intercalations’ effectivity significantly impacts the active surface of adsorbent-adsorbate interaction in multiple quan- tities and generates additional mesopores (Javed et al., 2018) . Despite the decreasing pore diameter, the pore volume was increasing due to the enormous size of intercalate, thus pro- moting the adsorption process (Ain et al., 2020; Mohammed and Isra’a, 2018). Figure 4. FT-IR Spectrums of (a) Natural Bentonite and (b) Na-bentonite 3.2 Optimization of Operational Conditions The pHpzc of bentonite-based adsorbent was plotted by Al Ma- liky et al. (2021) in Figure 6, which turned out to be 4.35 for natural bentonite and 5 for Na-bentonite provides an acid medium for adsorption of dyes. The role of pHpzc is to de- termine the influence of pH range on the active site of the surface adsorbent. The value of pH > pHpzc induces optimum adsorption of cationic dyes due to negative charge increases on adsorbent (Kanwal et al., 2022) . RhB has a positive charge in the solvent, then tends to adsorb at a higher pH value than the pHpzc condition (Ribeiro dos Santos et al., 2019) . It is appropriate for the experiment due to the optimum adsorption © 2023 The Authors. Page 163 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Table 3. Adsorption Kinetic Model Model Parameter Adsorbent Adsorbent Kinetics Adsorption Natural bentonite Na-bentonite Qe (mg/g) 102.49 119.22 Pseudo First Order k1 0.062 0.058 R2 0.926 0.883 Qe (mg/g) 102.49 102.49 Pseudo Second Order k2 0.006 0.007 R2 0.9975 0.9978 Table 4. Parameter of Isotherm Adsorption of RhB on the Bentonite-modified Adsorbent Adsorbent Isotherm Model Parameter Adsorption Temperature (°C) 30 40 50 60 70 Langmuir Qm 140.85 133.33 138.89 125 123.46 KL 0.023 0.033 0.034 0.057 0.114 Natural Bentonite R2 0.930 0.913 0.914 0.919 0.809 Freundlich n 1.506 1.641 1.647 1.808 2.244 KF 4.827 6.193 6.427 7.984 12.159 R2 0.995 0.991 0.991 0.987 0.946 Langmuir Qm 142.86 136.99 140.85 138.89 140.85 KL 0.035 0.054 0.063 0.078 0.107 Na-bentonite R2 0.972 0.994 0.994 0.991 0.994 Freundlich n 1.536 1.648 1.687 1.720 1.783 KF 5.725 7.037 7.628 8.093 8.978 R2 0.993 0.998 0.997 0.996 0.997 of RhB occurring at pH 6 based on preliminary laboratory screening. 3.3 Effect of Adsorption Time The effect of variations in the contact time of bentonite-based adsorbent on RhB is seen in Figure 7. Figure 7 shows that the equilibrium adsorption time of RhB on natural bentonite reaches 75 minutes, while the equilibrium time on Na-bentonite reaches 65 minutes. According to the literature, the calculated data of adsorption was gained using pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic equations (Mohadi et al., 2022) . The results of kinetic data adsorption on variation time adsorption are shown in Table 3. Based on Table 3, the kinetic data shows that the linear re- gression value (R2) of the pseudo-second-order (PSO) tends to be closer to 1 value than to the pseudo-first-order (PFO) kinetic model, so it concluded that RhB adsorption in bentonite-based adsorbent follows the PSO model kinetics. It suggested that adsorption tends to occur by chemisorption, then the adsorp- tion equilibrium rate is affected by the adsorbent and adsorbate composition (Shattar and Foo, 2022) . 3.4 Effect of Adsorbent Dosage Effect of variation dosages adsorption was prepared under room temperatures, pH = 6, adsorption time of 65 minutes for nat- ural bentonite and 75 minutes for Na-bentonite. Figure 8 shows the adsorption rate for 30 mg/L RhB with a variation of bentonite-modified adsorbent dosages, where variation dosages were used from 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, and 0.13 g. Based on Figure 8, the equilibrium of adsorption rate of the natural bentonite and Na-bentonite occurred at 0.11 g and 0.09 g, respectively, with insignificant increases at adsorbent dosages of more than 0.11g. The insignificant increase is related to the restricted concentration of dye that can be adsorbed and the agglomeration in bentonite adsorbent (Khan et al., 2012) . 3.5 Effect of Concentration and Adsorption Temperature According to Figure 9, the increases in adsorption temperature will cause a decrease in the adsorbate adsorbed for the RhB dye. Otherwise, the concentration increases are affected by RhB adsorbed. Data in Tables 4 and 5 were used to determine the adsorption isotherm model using the Langmuir and Freundlich equation based on (Sahnoun et al., 2018) . The data of the Langmuir and Freundlich isotherm calculation are shown in Table 4. According to Huang et al. (2017) , the Langmuir isotherm model ascribed that adsorption occurs by the monolayer con- formation on the surface of the adsorbent, thus not having inter- actions between molecules of adsorbate, while the Freundlich © 2023 The Authors. Page 164 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Table 5. Adsorption Thermodynamic Parameter Data on Natural Bentonite Consentration (mg/L) Temperature (K) Qe (mg/g) ΔH (kJ/mol) ΔS ( J/K.mol) ΔG (kJ/mol) 303 18.188 -2.218 313 19.233 -2.917 25 323 19.442 18.96 0.070 -3.616 333 20.278 -4.315 343 22.055 -5.014 303 31.568 -1.348 313 32.892 -1.599 50 323 33.380 6.24 0.025 -1.849 333 34.147 -2.099 343 34.983 -2.350 303 45.784 -1.117 313 46.411 -1.259 75 323 47.038 3.19 0.014 -1.401 333 47.874 -1.543 343 48.293 -1.685 303 58.536 -0.877 313 60.487 -1.062 100 323 61.463 4.72 0.018 -1.246 333 62.299 -1.431 343 64.111 -1.616 303 69.861 -0.590 313 71.777 -0.740 125 323 72.823 3.95 0.015 -0.890 333 73.171 -1.039 343 76.133 -1.189 Figure 5. N2 Adsorption-Desorption Properties isotherm ascribed that the adsorbent is supported multilayer and heterogeneous adsorption, thus adsorption process occurs by physical. Based on Table 4, the Freundlich isotherm model shows a linear regression value (R2) closer to the value 1 than the Langmuir isotherm model for RhB adsorption, indicating Figure 6. The pHpzc of (a) Natural Bentonite and (b) Na-bentonite that RhB adsorptions are spread heterogeneously (Xing et al., 2015) . The dimensions of the exponent 1/n state the favorable interaction between adsorbent-adsorbate. Adsorption will be beneficial if n > 1. In this study, the adsorption of RhB is easy due to an n value higher than 1 (Annadurai et al., 2000) . Furthermore, according to Huang et al. (2017) calculation © 2023 The Authors. Page 165 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Table 6. Adsorption Thermodynamic Parameter Data on Na-Bentonite Concentration (mg/L) Temperature (K) Qe (mg/g) ΔH (kJ/mol) ΔS ( J/K.mol) ΔG (kJ/mol) 303 18.710 -2.747 313 19.616 -3.131 25 323 19.965 8.88 0.038 -3.515 333 20.174 -3.898 343 20.627 -4.282 303 43.742 -2.094 313 44.648 -2.379 50 323 44.997 6.54 0.028 -2.664 333 45.206 -2.949 343 45.659 -3.234 303 49.861 -1.720 313 50.592 -1.893 75 323 51.428 3.50 0.017 -2.065 333 51.951 -2.237 343 52.474 -2.410 303 61.324 -1.188 313 62.996 -1.328 100 323 63.554 3.06 0.014 -1.468 333 63.972 -1.609 343 64.947 -1.749 303 72.474 -0.822 313 74.216 -0.964 125 323 75.610 3.47 0.014 -1.105 333 76.133 -1.247 343 77.526 -1.388 Figure 7. Effect of Contact Time Adsorption on (a) Natural Bentonite and (b) Na-bentonite Figure 8. Effect of Adsorbent Dosage on (a) Natural Bentonite and (b) Na-bentonite © 2023 The Authors. Page 166 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Table 7. Comparative of Adsorption Capacity on Rhodamine B in Different Adsorbent Bentonite Adsorbate Adsorption Capacity (mg/g) Optimum Time (minutes) References Na-bentonite RhB 142.86 65 This study Bentonite-CTA-DAPTMS RhB 0.98 5 de Morais Pinos et al. (2022) 𝛾- Fe2O3/montmorillonite RhB 45.08 60 Fatimah et al. (2022) Beta zeolite SiO2/Al2O3 RhB 27.97 60 Cheng et al. (2018) 𝛼-Al2O3 RhB 52 30 Yen Doan et al. (2020) Figure 9. Effect of Temperature and Concentration Adsorption of RhB on (a) Natural Bentonite and (b) Na-bentonite Figure 10. Mechanism Interaction Proposed of RhB Adsorption Bentonite-modified of thermodynamic parameters can provide data (ΔG°), (ΔS°), and (ΔH°). The detail of the thermodynamic parameter data is shown in Tables 4 and 5 . The calculation results for ΔG° value are negative on each adsorbent; thus, the value decreased with increasing adsorption temperature. A negative value of ΔG° indicates that the RhB adsorption process is beneficial and spontaneously occurs He et al. (2022) , and the adsorption is better at high temperatures. The ΔH° value showed a range of 18.96 kJ/mol to 3.95 kJ/mol was related to the tendency of RhB adsorption to occur by physical adsorption and en- dothermic based on a positive ΔH° value, thus supporting the isotherm adsorption analysis. The adsorption mechanism of RhB into bentonite-modified adsorbent visualized in Figure 10. Physisorption as dominant mechanism take a apart in ben- tonite negative charge of surface, then the cation exchange of RhB into interlayer bentonite has reduce the sodium ion in the interlayer structure (Selvam et al., 2008) . Another result is the positive value of ΔS°, which is related to the irregularity of the particles during adsorption increases due to the adsorbent- liquid interaction between the bentonite-based adsorbent and RhB (Mahmoodi, 2014) . 4. CONCLUSION In summary, the new route modification of natural bentonite imported from West Java of Indonesia was completed using cation exchange of sodium salt-intercalant under low room temperature of 25°C to develop efficient and low energy pre- pared adsorbent to remove RhB dyes in an aqueous solution. The bentonite-modified was characterized by several character- ization techniques, indicating the sodium was intercalated on the interlayer bentonite. The adsorption study proved that Na- bentonite effectively removed the RhB with adsorption capacity (Qm) reached 142.86 mg/g for Na-bentonite by physisorption and spontaneously endothermic occurred. 5. ACKNOWLEDGMENT The research of this article was funded by DIPA of Public Service Agency of Universitas Sriwijaya 2022. SP DIPA- 23.17.2.677515 /2022, On Desember 13, 2021. Under the Rectors Decree 0017/UN9.3. 1 /SK.LP2M.PT/2022, On Juni 15, 2022. REFERENCES Ain, Q. U., U. Rasheed, M. Yaseen, H. Zhang, R. He, and Z. Tong (2020). Fabrication of Magnetically Separable 3-acrylamidopropyltrimethylammonium Chloride Interca- lated Bentonite Composite for the Efficient Adsorption of Cationic and Anionic Dyes. Applied Surface Science, 514; 145929 Al Maliky, E. A., H. A. Gzar, and M. G. Al Azawy (2021). Determination of Point of Zero Charge (PZC) of Concrete Particles Adsorbents. IOP Conference Series: Materials Science and Engineering, 1184(1); 012004 AL Tufaily, M. and Z. Al Qadi (2016). Preparation and Utiliza- tion of Corncob Activated Carbon for Dyes Removal from Aqueous Solutions: Batch and Continuous Study. Journal of Babylon University/Engineering Sciences, 2(3); 24 © 2023 The Authors. Page 167 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Alexandru, I. (2011). The Role Of Sodium In the Body Stantin. In Balneo-Research Journal, 2(3); 23–25 Annadurai, G., S. Rajesh Babu, K. Mahesh, and T. Muruge- san (2000). Adsorption and Bio-degradation of Phenol by Chitosan-immobilized Pseudomonas Putida (NICM 2174). Bioprocess Engineering, 22(6); 493–501 Asgari, G., A. Seid Mohammadi, A. Rahmani, M. T. Samadi, M. Salari, S. Alizadeh, and D. Nematollahi (2021). Diuron Degradation using Three-dimensional Electro-peroxone (3D/E-peroxone) Process in the Presence of TiO2/GAC: Application for Real Wastewater and Optimization using RSM-CCD and ANN-GA Approaches. Chemosphere, 266; 129179 Bouras, O., J. C. Bollinger, M. Baudu, and H. Khalaf (2007). Adsorption of Diuron and its Degradation Products from Aqueous Solution by Surfactant-modified Pillared Clays. Applied Clay Science, 37(3-4); 240–250 Castellini, E., D. Malferrari, F. Bernini, M. F. Brigatti, G. R. Castro, L. Medici, A. Mucci, and M. Borsari (2017). Baseline Studies of the Clay Minerals Society Source Clay Montmo- rillonite STx-1b. Clays and Clay Minerals, 65(4); 220–233 Chai, J. B., P. I. Au, N. M. Mubarak, M. Khalid, W. P. Q. Ng, P. Jagadish, R. Walvekar, and E. C. Abdullah (2020). Ad- sorption of Heavy Metal from Industrial Wastewater Onto Low-cost Malaysian Kaolin Clay–based Adsorbent. Environ- mental Science and Pollution Research, 27(12); 13949–13962 Cheng, Z. L., Y. x. Li, and Z. Liu (2018). Study on Adsorption of Rhodamine B Onto Beta Zeolites by Tuning SiO2/Al2O3 Ratio. Ecotoxicology and Environmental Safety, 148; 585–592 de Morais Pinos, J. Y., L. B. de Melo, S. D. de Souza, L. Marçal, and E. H. de Faria (2022). Bentonite Functionalized with Amine Groups by the Sol-gel Route as Efficient Adsorbent of Rhodamine-B and Nickel (II). Applied Clay Science, 223; 106494 Ding, F., M. Gao, T. Shen, H. Zeng, and Y. Xiang (2018). Comparative Study of Organo-vermiculite, Organo- montmorillonite and Organo-silica Nanosheets Function- alized by An Ether-spacer-containing Gemini Surfactant: Congo Red Adsorption and Wettability. Chemical Engineer- ing Journal, 349; 388–396 Dotto, J., M. R. Fagundes-Klen, M. T. Veit, S. M. Palacio, and R. Bergamasco (2019). Performance of Different Co- agulants In the Coagulation/flocculation Process of Textile Wastewater. Journal of Cleaner Production, 208; 656–665 Fatimah, I., G. Purwiandono, A. Hidayat, S. Sagadevan, and A. Kamari (2022). Mechanistic Insight Into the Adsorption and Photocatalytic Activity of a Magnetically Separable 𝛾- Fe2O3/Montmorillonite Nanocomposite for Rhodamine B Removal. Chemical Physics Letters, 792; 139410 Giraldo, S., N. Y. Acelas, R. Ocampo Pérez, E. Padilla Ortega, E. Flórez, C. A. Franco, F. B. Cortés, and A. Forgionny (2022). Application of Orange Peel Waste as Adsorbent for Methylene Blue and Cd2+ Simultaneous Remediation. Molecules, 27(16); 5105 He, H., K. Chai, T. Wu, Z. Qiu, S. Wang, and J. Hong (2022). Adsorption of Rhodamine B from Simulated Waste Water onto Kaolin-Bentonite Composites. Materials, 15(12); 4058 Huang, Z., Y. Li, W. Chen, J. Shi, N. Zhang, X. Wang, Z. Li, L. Gao, and Y. Zhang (2017). Modified Bentonite Adsorp- tion of Organic Pollutants of Dye Wastewater. Materials Chemistry and Physics, 202; 266–276 Islam, M. and M. Mostafa (2022). Adsorption Kinetics, Isotherms and Thermodynamic Studies of Methyl Blue in Textile Dye Effluent on Natural Clay Adsorbent. Sustainable Water Resources Management, 8(2); 1–12 Javed, S. H., A. Zahir, A. Khan, S. Afzal, and M. Mansha (2018). Adsorption of Mordant Red 73 Dye on Acid Acti- vated Bentonite: Kinetics and Thermodynamic Study. Jour- nal of Molecular Liquids, 254; 398–405 Jiang, K., K. Liu, Q. Peng, and M. Zhou (2021). Adsorption of Pb (II) and Zn (II) Ions on Humus-like Substances Modified Montmorillonite. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 631; 127706 Kamarehie, B., A. Jafari, M. Ghaderpoori, F. Azimi, M. Fari- dan, K. Sharafi, F. Ahmadi, and M. A. Karami (2020). Quali- tative and Quantitative Analysis of Municipal Solid Waste In Iran For Implementation of Best Waste Management Prac- tice: A Systematic Review and Meta-analysis. Environmental Science and Pollution Research, 27(30); 37514–37526 Kanwal, A., R. Rehman, and M. Imran (2022). Adsorptive Detoxification of Congo Red and Brilliant Green Dyes Us- ing Chemically Processed Brassica Oleracea Biowaste from Waste Water. Adsorption Science & Technology, 2022; 1–14 Khan, T. A., S. Dahiya, and I. Ali (2012). Use of Kaolinite as Adsorbent: Equilibrium, Dynamics and Thermodynamic Studies on the Adsorption of Rhodamine B From Aqueous Solution. Applied Clay Science, 69; 58–66 Laysandra, L., M. W. M. K. Sari, F. E. Soetaredjo, K. Foe, J. N. Putro, A. Kurniawan, Y. H. Ju, and S. Ismadji (2017). Adsorption and Photocatalytic Performance of Bentonite- titanium Dioxide Composites for Methylene Blue and Rho- damine B Decoloration. Heliyon, 3(12); e00488 Leodopoulos, C., D. Doulia, and K. Gimouhopoulos (2015). Adsorption of Cationic Dyes Onto Bentonite. Separation & Purification Reviews, 44(1); 74–107 Lin, J. J., Y. M. Chen, and M. H. Yu (2007). Hydrogen-bond Driven Intercalation of Synthetic Fluorinated Mica by Poly (oxypropylene)-amidoamine Salts. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 302(1-3); 162–167 Mahmoodi, N. M. (2014). Dendrimer Functionalized Nanoar- chitecture: Synthesis and Binary System Dye Removal. Jour- nal of the Taiwan Institute of Chemical Engineers, 45(4); 2008– 2020 Mahmoodi, N. M. (2015). Manganese Ferrite Nanoparticle: Synthesis, Characterization, and Photocatalytic Dye Degra- dation Ability. Desalination and Water Treatment, 53(1); 84– 90 Mohadi, R., E. S. Fitri, and N. R. Palapa (2022). Unique Adsorption Properties of Cationic Dyes Malachite Green and Rhodamine-B on Longan (Dimocarpus Longan) Peel. © 2023 The Authors. Page 168 of 169 Priatna et. al. Science and Technology Indonesia, 8 (2023) 160-169 Science and Technology Indonesia, 7(1); 115–125 Mohammad, A. T., A. S. Abdulhameed, and A. H. Jawad (2019). Box-Behnken Design to Optimize the Synthesis of New Crosslinked Chitosan-glyoxal/TiO2 Nanocomposite: Methyl Orange Adsorption and Mechanism Studies. Inter- national Journal of Biological Macromolecules, 129; 98–109 Mohammed, A. A. and S. S. Isra’a (2018). Bentonite Coated with Magnetite Fe3O4 Nanoparticles as A Novel Adsorbent for Copper (ii) Ions Removal From Water/wastewater. En- vironmental Technology & Innovation, 10; 162–174 Mu’azu, N. D., N. Jarrah, T. S. Kazeem, M. Zubair, and M. Al Harthi (2018). Bentonite-layered Double Hydrox- ide Composite for Enhanced Aqueous Adsorption of Eri- ochrome Black T. Applied Clay Science, 161; 23–34 Rahmani, A. R., N. Navidjouy, M. Rahimnejad, S. Alizadeh, M. R. Samarghandi, and D. Nematollahi (2022). Ef- fect Of Different Concentrations of Substrate In Microbial Fuel Cells Toward Bioenergy Recovery and Simultaneous Wastewater Treatment. Environmental Technology, 43(1); 1–9 Reza, E. M., J. P. Bueno, F. E. Arreola, L. A. Arellano, J. P. Robles, R. N. Mendoza, and A. H. Macías (2015). Organobentonites with Crystalline Layer Separation Used for Adsorption In Water Treatment. Handbook of Research on Diverse Applications of Nanotechnology in Biomedicine, Chemistry, and Engineering, 3; 496–517 Ribeiro dos Santos, F., H. C. de Oliveira Bruno, and L. Zela- yaran Melgar (2019). Use of Bentonite Calcined Clay As An Adsorbent: Equilibrium and Thermodynamic Study of Rho- damine B Adsorption In Aqueous Solution. Environmental Science and Pollution Research, 26(28); 28622–28632 Sahnoun, S., M. Boutahala, C. Tiar, and A. Kahoul (2018). Adsorption of Tartrazine From An Aqueous Solution by Oc- tadecyltrimethylammonium Bromide-modified Bentonite: Kinetics and Isotherm Modeling. Comptes Rendus Chimie, 21(3-4); 391–398 Selvam, P. P., S. Preethi, P. Basakaralingam, N. Thinakaran, A. Sivasamy, and S. Sivanesan (2008). Removal of Rho- damine B from Aqueous Solution by Adsorption Onto Sodium Montmorillonite. Journal of Hazardous Materials, 155(1-2); 39–44 Shattar, S. F. A. and K. Y. Foo (2022). Sodium Salt-assisted Low Temperature Activation of Bentonite For the Adsorp- tive Removal of Methylene Blue. Scientific Reports, 12(1); 1–12 Soleimani, H., O. Nasri, M. Ghoochani, A. Azhdarpoor, M. Dehghani, M. Radfard, M. Darvishmotevalli, V. Oskoei, and M. Heydari (2022). Groundwater Quality Evaluation and Risk Assessment of Nitrate Using Monte Carlo Simula- tion and Sensitivity Analysis In Rural Areas of Divandarreh County, Kurdistan Province, Iran. International Journal of Environmental Analytical Chemistry, 102(10); 2213–2231 Srikacha, N., M. Sriuttha, L. Neeratanaphan, C. Saiyasom- bat, and B. Tengjaroensakul (2022). The Improvement of Natural Thai Bentonite Modified with Cationic Surfactants on Hexavalent Chromium Adsorption from an Aqueous Solution. Adsorption Science & Technology, 2022; 1–15 Tong, D. S., C. W. Wu, M. O. Adebajo, G. C. Jin, W. H. Yu, S. F. Ji, and C. H. Zhou (2018). Adsorption of Methy- lene Blue From Aqueous Solution Onto Porous Cellulose- derived Carbon/montmorillonite Nanocomposites. Applied Clay Science, 161; 256–264 Wu, Z., W. Deng, S. Tang, E. Ruiz Hitzky, J. Luo, and X. Wang (2021). Pod-inspired MXene/porous Carbon Mi- crospheres with Ultrahigh Adsorption Capacity Towards Crystal Violet. Chemical Engineering Journal, 426; 130776 Xie, L. Q., X. Y. Jiang, and J. G. Yu (2022). A Novel Low- Cost Bio-Sorbent Prepared from Crisp Persimmon Peel by Low-Temperature Pyrolysis for Adsorption of Organic Dyes. Molecules, 27(16); 5160 Xing, X., G. Lv, W. Zhu, C. He, L. Liao, L. Mei, Z. Li, and G. Li (2015). The Binding Energy Between the Interlayer Cations and Montmorillonite Layers and Its Influence On Pb2+ Adsorption. Applied Clay Science, 112; 117–122 Yang, D., F. Cheng, L. Chang, and D. Wu (2022). Sodium Modification of Low Quality Natural Bentonite as Enhanced Lead Ion Adsorbent. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 651; 129753 Yen Doan, T. H., T. P. Minh Chu, T. D. Dinh, T. H. Nguyen, T. C. Tu Vo, N. M. Nguyen, B. H. Nguyen, and T. D. Pham (2020). Adsorptive Removal of Rhodamine B Using Novel Adsorbent-based Surfactant-modified Alpha Alumina Nanoparticles. Journal of Analytical Methods in Chemistry, 2020; 1–8 Yurdakal, S., C. Garlisi, L. Özcan, M. Bellardita, and G. Palmisano (2019). (Photo) Catalyst Characterization Techniques: Adsorption Isotherms and BET, SEM, FTIR, UV–Vis, Photoluminescence, and Electrochemical Charac- terizations. Heterogeneous Photocatalysis, 4; 87–152 © 2023 The Authors. Page 169 of 169 INTRODUCTION EXPERIMENTAL SECTION Chemicals and Instrumentation Bentonite Intercalation Optimization of Operational Condition Adsorption Studies Analysis of Mechanism Adsorption RESULT AND DISCUSSION Characterization of Adsorbents Optimization of Operational Conditions Effect of Adsorption Time Effect of Adsorbent Dosage Effect of Concentration and Adsorption Temperature CONCLUSION ACKNOWLEDGMENT