Science and Technology Indonesia e-ISSN:2580-4391 p-ISSN:2580-4405 Vol.
No.
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* 1 Department of Soil Science.
Sriwijaya University.
Indralaya, 30862.
South Sumatera.
Indonesia 2 Graduate School.
Faculty of Mathematics and Natural Sciences.
Sriwijaya University.
Palembang, 30139.
Indonesia 3 Department of Chemistry.
Faculty of Mathematics and Natural Sciences.
Sriwijaya University.
Indralaya, 30862.
South Sumatera.
Indonesia 4 Department of Physics.
Faculty of Mathematics and Natural Sciences.
Sriwijaya University.
Palembang, 30139.
Indonesia *Corresponding author: risfidian.
mohadi@unsri.
Abstract This work reports the modification of West Java natural bentonite as an effective adsorbent for rhodamine B dye.
The modification was finished by sodium intercalation at room temperature to get low-energy preparation.
Characterization of bentonite-modified adsorbent was used SEM.
XRD.
FTIR, and BET analysis.
The material pore size and surface area were increased by 0.
303 nm and 710 m2 /g on Na-bentonite.
The adsorption mechanism conformed well with the Freundlich isotherm model and pseudo-secondorder kinetics equations.
The adsorption process by thermodynamic analysis was endothermic and advantageous.
Under the optimum condition of pH 6 .
onfirmed by pHpz.
, initial dye concentration of 125 mg/L, and the adsorbent dosage of 0.
09 g for 65 minutes, the Na-bentonite has a larger adsorption capacity (Q.
86 mg/g, while the different adsorbent dosages of 0.
11 g for 75 minutes, the adsorption capacity of natural bentonite (Q.
85 mg/g.
This work provides a method for establishing a low-energy preparation adsorbent of bentonite-based on Na-intercalant as a low-cost and valuable adsorbent for waste dye Keywords Bentonite.
Intercalation.
Low Temperature.
Adsorption.
Rhodamine B Received: 3 October 2022.
Accepted: 23 January 2023 https://doi.
org/10.
26554/sti.
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.
, 2.
Massive wastewater disposed of led to contamination in the ecosystem (Kamarehie et al.
, 2020.
Rahmani et al.
, 2.
Coloring products are widely used in the food, cosmetics, pharmaceuticals, paints, and textiles industries (Laysandra et al.
, 2.
It was estimated that 7x105 tons of dye waste are produced annually (AL Tufaily and Al Qadi, 2016.
Mohammad et al.
, 2.
Rhodamine B (RhB) is a basic cationic dye with complex structures shown in Figure 1.
In some cases, long-term exposure to RhB likely triggers temporary skin, and mucous membrane irritation, until the mutagenic effect (Laysandra et al.
, 2.
Several works provide techniques to detach the pollutants such as precipitation, osmotic reverse, flocculation/coagulation, electrodialysis, and adsorption (Dotto et al.
Giraldo et al.
, 2022.
Xie et al.
, 2.
Adsorption becomes 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.
, 2.
Potential low-cost adsorbents that provide adsorption features are zeolites, limestone, silica gel, chitosan, dolomite, activated carbon, and bentonite/clay.
Nowadays, the layered material of alumina-silicate bentonite 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.
, 2.
However, the intercalation of natural bentonite by cationic exchange assisted by calcination to increase the adsorption capacity is favorable (Srikacha et al.
However, the intercalation step may need a longer preparation time of 3 h to 10 days, moreover calcination process of more than 300AC to change the bentonite structure could trigger a collapse of the bentonite structure (Bouras et al.
Leodopoulos et al.
, 2.
Recently.
Islam and Mostafa Priatna et.
Science and Technology Indonesia, 8 .
160-169 Instrumentation such as X-Ray Diffractometer (XRD) type Rigaku Mini-flex600.
Fourier Transfer Infra-Red (FTIR) type Perkin-Elmer UATR Spectrum two.
UV-Vis Spectrophotometer type Orion AquaMate 8000.
Scanning Electron Microscope Energy Dispersive Spectrometer (SEM-EDS) type JEOL JSM 6510-LA, and Surface Area Analyzer using Quantachrome ASIQ-win based on BET method calculation.
Figure 1.
Chemical Structure of RhB Dye .
studied the natural sodium bentonite adsorption capacity towards methylene blue by an adsorption capacity of 19 mg/g.
According to Shattar and Foo .
, activation bentonite assisted by sodium salt under heating of 70AC gives removal of methylene blue with an adsorption capacity 38 mg/g.
The intercalation process becomes a challenge in bentonite The rigid characteristics of the bentonite structure block the intercalation of another molecule.
Sodium intercalation, as the preliminary step, becomes the favorable The opening interlayer process to insert the intercalant 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.
, intercalation via intermolecular force becomes an effective method for inserting molecules in low temperatures to decrease energy consumption.
This work aims to intercalate the West Java natural bentonite by saturated sodium salt solution under the natural ambiance of low-temperature preparation to get intramolecular force in inserting the intercalant and evaluate its removal capacity on RhB from aqueous solutions.
Sodium salt was chosen because it is non-toxic to essential substances in the environment and has a high cationic exchange capacity in bentonite surfaces (Alexandru, 2.
The bentonite-modified characterization used SEM.
XRD.
FTIR, and BET to analyze physicochemical structural changes.
The adsorption mechanism of RhB was carried out with optimization of the operational condition by pHpzc, variations in time, the dosage of adsorbent, temperature, and initial concentration.
2 Bentonite Intercalation The natural bentonite was modified by the cationic exchange methods at room temperature of 25AC: 100 g of natural bentonite dissolved in 333 mL of saturated NaCl and stirred for 2 Then the mixture was added with distilled water .
y two times the mixture volum.
and continued stirring for 10 minutes.
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 200AC for 12 hours.
It is noticed as Na-bentonite.
3 Optimization of Operational Condition The pHpzc .
oint zero charge.
was determined by adding 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.
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 adsorbent into 50 mL of 30 mg/L RhB dyes.
The effect of adsorbent dosages was studied by variation of adsorbent dosages at 0.
03, 0.
05, 0.
07, 0.
09, 0.
11, and 0.
13 g.
The effect of temperature and concentration adsorption was conducted on the adsorption of RhB using various temperatures and initial concentrations at 30, 40, 50, 60, and 70AC, with the concentration of RhB 25, 50, 75, 100, and 125 mg/L.
5 Analysis of Mechanism Adsorption Adsorption kinetics of this experiment conducted by Wu et al.
for pseudo-first order and pseudo-second order kinetic models are shown in Equation 1 and 2, respectively:
e Oe q.
= lnqe Oe tK1
= 2
qt qe qe
EXPERIMENTAL SECTION
1 Chemicals and Instrumentation The natural bentonite was obtained from West Java with purification.
Chemicals in a pure grade, such as sodium chloride (NaC.
, sodium hydroxide (NaOH), silver nitrate (AgNO.
, hydrochloric acid (HC.
, and rhodamine B (RhB) dye, were purchased from Sigma-Aldrich and directly used without purifi- A 2023 The Authors.
Where K1 is the rate constant of pseudo-first order .
inOe1 ).
K2 is the constant rate of pseudo-second order .
mgOe1 minOe1 ), t for time, then qe and qt are capacity adsorption at equilibrium Page 161 of 169 Science and Technology Indonesia, 8 .
160-169 Priatna et.
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.
by the equation, respectively:
qmax KL qmax Figure 2.
SEM Image of .
Natural Bentonite .
lnqe = lnKF Where qe is the capacity equilibrium of adsorbent .
Ce is the concentration equilibrium after adsorption .
g/L), qmax is the capacity maximum of adsorption .
KL is constant of Langmuir adsorption (L/m.
, then K f and n are constant of Freundlich adsorption (L/.
Furthermore, the thermodynamic parameters can be analyzed by following equations (Dotto et al.
, 2.
iG = OeRT lnKd iG = iH Oe T iS .
iS iH lnKd = 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.
, 2.
According to the data of XRD, the crystal size of natural bentonite and Na-bentonite 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 2yuE at around 20A, 35A, 55A, and 63A are montmorillonite compounds.
Then, for 2yuE at about 26A are quartz compounds, while at 2yuE around 28A are compounds composed of Al.
Si, and O (Reza et al.
, 2.
Where iGA is the value of free energy Gibbs .
J/mo.
, iHA is the enthalpy change of adsorption .
J/mo.
, iSA is adsorption entropy change .
J/mol.
K).
R is the standard gas constant .
324 kJ/mo.
T is temperature reaction (K), and Kd is the equilibrium constant.
RESULT AND DISCUSSION
1 Characterization of Adsorbents The morphologies of modified bentonite were observed using 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, 2.
Aggregate and rough particles may be impurities from zeolite, while according to Figure 2a, the flakeAos structures are considered montmorillonite(Jiang et al.
, 2.
According to Figure 2b, lamellar structures in Nabentonite 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 bentonitemodified adsorbents is 8.
06 nm and corresponds to the d001 peak, the value of 2yuE about 20A, noticed as montmorillonite.
A 2023 The Authors.
Figure 3.
XRD Patterns of .
Natural Bentonite and .
Na-bentonite Bentonite, as layered material, has several functional groups that influence adsorption.
The FT-IR spectrums of bentonitemodified are displayed in Figure 4.
The composition of OH octahedra stretching vibrations at the surface layer is indicated by a peak at 3380 cmOe1 .
A peak indicates the H-O-H vibrations of the water molecule at 1632 cmOe1 .
The layer structures of bentonite were confirmed by stretching vibrations of Si-OPage 162 of 169 Science and Technology Indonesia, 8 .
160-169 Priatna et.
Table 1.
EDX Data of Bentonite-modified Adsorbent Element Natural bentonite (%W) Na-bentonite (%W) Table 2.
The Analysis of BET Surface Area.
Pore Diameter, and Pore Volume of the Natural Bentonite and Na-bentonite Adsorbent BET Surface Area .
2 /.
Pore Diameter .
Pore Volume .
m3 /.
Natural bentonite Na-bentonite Si from the peak at 1028 cmOe1 and vibrations of Al-O-Al from the peak at 791 cmOe1 (Castellini et al.
, 2.
The peak at 518 and 459 cmOe1 is ascribed to the cation vibration on the layer structure of bentonite.
The difference in peak sharpness affected vibration intensity due to sodium salt intercalant power binding at the surface interlayers, thus giving additional functional groups between interlayers (Yang et al.
, 2.
The textural characteristics of natural bentonite and the intercalated one were characterized via the N2 adsorptiondesorption method at 77.
35 K.
Detailed result was plotted in the graph of N2 adsorption-desorption isotherm characteristics 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 (MuAoazu et al.
, 2.
The overlapping of adsorption-desorption points occurred at the low relative thus fit with the H3 type of hysteresis loop that initiated at a relative pressure (P/P.
The emerging features are grouped as the characteristic of the mesopore layered material (Tong et al.
, 2018.
Yurdakal et al.
, 2.
The precise surface area value calculated using the BET model on natural and Na-bentonite is tabulated in Table 2.
this case, the specific surface area of bentonite-intercalated Na was differently higher than the natural one.
It assumed that sodium intercalationsAo effectivity significantly impacts the active surface of adsorbent-adsorbate interaction in multiple quantities and generates additional mesopores (Javed et al.
, 2.
Despite the decreasing pore diameter, the pore volume was increasing due to the enormous size of intercalate, thus promoting the adsorption process (Ain et al.
, 2020.
Mohammed and IsraAoa, 2.
A 2023 The Authors.
Figure 4.
FT-IR Spectrums of .
Natural Bentonite and .
Na-bentonite 2 Optimization of Operational Conditions The pHpzc of bentonite-based adsorbent was plotted by Al Maliky et al.
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 determine 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.
, 2.
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.
, 2.
It is appropriate for the experiment due to the optimum adsorption Page 163 of 169 Science and Technology Indonesia, 8 .
160-169 Priatna et.
Table 3.
Adsorption Kinetic Model Model Kinetics Adsorption Pseudo First Order Pseudo Second Order Parameter Adsorbent Natural bentonite Adsorbent Na-bentonite Qe .
Qe .
Table 4.
Parameter of Isotherm Adsorption of RhB on the Bentonite-modified Adsorbent Adsorbent Natural Bentonite Isotherm Model Parameter Adsorption Langmuir Freundlich Langmuir Na-bentonite Freundlich of RhB occurring at pH 6 based on preliminary laboratory 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.
, 2.
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 regression 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 adsorption equilibrium rate is affected by the adsorbent and adsorbate composition (Shattar and Foo, 2.
4 Effect of Adsorbent Dosage Effect of variation dosages adsorption was prepared under room temperatures, pH = 6, adsorption time of 65 minutes for natA 2023 The Authors.
Temperature (AC) 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.
g, respectively, with insignificant increases at adsorbent dosages of more than 0.
The insignificant increase is related to the restricted concentration of dye that can be adsorbed and the agglomeration in bentonite adsorbent (Khan et al.
, 2.
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 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.
, 2.
The data of the Langmuir and Freundlich isotherm calculation are shown in Table 4.
According to Huang et al.
, the Langmuir isotherm model ascribed that adsorption occurs by the monolayer conformation on the surface of the adsorbent, thus not having interactions between molecules of adsorbate, while the Freundlich Page 164 of 169 Science and Technology Indonesia, 8 .
160-169 Priatna et.
Table 5.
Adsorption Thermodynamic Parameter Data on Natural Bentonite Consentration .
g/L) Temperature (K) Qe .
iH .
J/mo.
iS (J/K.
iG .
J/mo.
Figure 6.
The pHpzc of .
Natural Bentonite and .
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 A 2023 The Authors.
Na-bentonite that RhB adsorptions are spread heterogeneously (Xing et al.
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.
, 2.
Furthermore, according to Huang et al.
calculation Page 165 of 169 Science and Technology Indonesia, 8 .
160-169 Priatna et.
Table 6.
Adsorption Thermodynamic Parameter Data on Na-Bentonite Concentration .
g/L) Temperature (K) Qe .
Figure 7.
Effect of Contact Time Adsorption on .
Natural Bentonite and .
Na-bentonite A 2023 The Authors.
iH .
J/mo.
iS (J/K.
iG .
J/mo.
Figure 8.
Effect of Adsorbent Dosage on .
Natural Bentonite and .
Na-bentonite Page 166 of 169 Science and Technology Indonesia, 8 .
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Table 7.
Comparative of Adsorption Capacity on Rhodamine B in Different Adsorbent Bentonite Adsorbate Adsorption Capacity .
Optimum Time .
References Na-bentonite Bentonite-CTA-DAPTMS yu- Fe2O3/montmorillonite Beta zeolite SiO2/Al2O3 yu-Al2O3 RhB RhB RhB RhB RhB This study de Morais Pinos et al.
Fatimah et al.
Cheng et al.
Yen Doan et al.
Physisorption as dominant mechanism take a apart in bentonite 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.
, 2.
Another result is the positive value of iSA, which is related to the irregularity of the particles during adsorption increases due to the adsorbentliquid interaction between the bentonite-based adsorbent and RhB (Mahmoodi, 2.
Figure 9.
Effect of Temperature and Concentration Adsorption of RhB on .
Natural Bentonite and .
Na-bentonite 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 25AC to develop efficient and low energy prepared adsorbent to remove RhB dyes in an aqueous solution.
The bentonite-modified was characterized by several characterization techniques, indicating the sodium was intercalated on the interlayer bentonite.
The adsorption study proved that Nabentonite effectively removed the RhB with adsorption capacity (Q.
86 mg/g for Na-bentonite by physisorption and spontaneously endothermic occurred.
ACKNOWLEDGMENT
Figure 10.
Mechanism Interaction Proposed of RhB Adsorption Bentonite-modified The research of this article was funded by DIPA of Public Service Agency of Universitas Sriwijaya 2022.
SP DIPA23.
677515 /2022.
On Desember 13, 2021.
Under the Rectors Decree 0017/UN9.
1 /SK.
LP2M.
PT/2022.
On Juni 15, 2022.
REFERENCES