Modification of Java bentonite assists by the multi-step intercalation of sodium and ammonium ions under low-temperature preparation. The adsorbent was examined to remove rhodamine B and methylene blue dyes in an aqueous solvent. The analysis of structural changes conducted by XRD analysis showed the peak shifting from 19.89° to 16.1° and specific peak spectra FTIR of 2846.93 cm-1 due to increase basal spacing from ammonium intercalation. The total capacities of NH-bentonite, Na-bentonite, and Natural Bentonite adsorption to rhodamine B were 192.308 mg/g, 136.936 mg/g, and 116.279 mg/g, respectively, under acidic conditions. Furthermore, the total capacities of NH-bentonite, Na-bentonite, and Natural Bentonite adsorption to methylene blue were 270.27 mg/g, 158.73 mg/g, and 136.986 mg/g, respectively, under alkaline conditions. The adsorption mechanism described that the rhodamine B and methylene blue removal occurred endothermically, was feasible, and adhered to the kinetics model of pseudo-second-order and Langmuir isotherm. It concluded that the modified Java Bentonite from multi-step intercalation is affordable and effective as wastewater treatment.
Improving the selectivity of photocatalysis of LDH pristine (MgAl-LDH) and LDH composite (MgAl-SiW12O40] and MgAl-[PW12O40]) was synthesized and used for degraded malachite green (MG). The effects of the amount of catalyst, pH value, and reaction times on degradation performance were discussed. MG degraded better composites than LDH pristine. The results indicated that MgAl-LDH was successfully synthesized by showing the peak diffractions at angles 10.39°(003), 20.17°(006), and 34.8°(009). Both kinds of attained MgAl-[SiW12O40] and MgAl-[PW12O40] had the typical structure of LDH that proved by appeared diffraction at 2θ angles 7.73°, 28.6°, 35.6° for MgAl-[PW12O40] and at 2θ angles 8.61°, 24.27°, 34.96° and 66.34° for MgAl-[SiW12O40]. The FTIR result indicates materials used for fifth regeneration, which confirmed the LDH composite structure. The photodegradation activity of MG for pristine MgAl LDH (56.1%), composites MgAl-Pw (84.6%) and MgAl-Si (87.8%), respectively. The successful ability of photodegradation process by the percentage of degradation on material LDH-polyoxometalate composite showed the increasing of photodegradation catalytic and the regeneration ability of LDH pristine.
The synthesis and characterization of layered double hydroxide (LDH) and intercalated polyoxometalate were presented.. The growth of polyoxometalate on Ni/Mg layered double hydroxide for degradation procion red (PR) was reported. The degradation parameters and organic dye removal efficiency of Zn/Mg-LDH and both composite LDH-polyoxometalate were determined by considering factors such as pH of dye solution, catalyst dosage, and time as variables of degradation. X-Ray, FTIR, and SEM spectroscopy confirmed the layered double hydroxide structure. XRD and FTIR analysis confirmed the single-phase of the as-made and polyoxometalate intercalated LDH. SEM images show the formation of aggregates of small various sizes. The catalytic activity of the material was evaluated in the degradation of PR as a model pollutant. The result showed that MgAl-SiW12O40 has a good degradation capacity for PR as compared to MgAl-PW12O40, ZnAl-SiW12O40, and ZnAl-PW12O40. The result shows that the LDH composite presents stability and has good photocatalytic activities toward the reduction of methylene blue. The materials utilized for the fifth regeneration are indicated by the FTIR results, which verified the LDH composite structure. The photodegradation process of procion red for immaculate ZnAl-LDH, MgAl-LDH, ZnAl-[PW12O40], ZnAl-[SiW12O40], MgAl-[PW12O40], MgAl-[SiW12O40] amounted to 68%, 70%, 56%, 79%, 74%, and 80%, respectively. The capacity of LDH-polyoxometalate composite material to successfully photodegrade, as measured by the percentage of degradation, revealed an increase in photodegradation catalysis and the ability of LDH to regenerate.
In this work, hydrochar using to modified nickel aluminum layered double hydroxide (hydrochar@NiAl LDH). The collected data by XRD indicate that 2θ of material at 11.38°, 22.90°, 35.20°, and 61.60°. The FTIR spectrum of hydrochar@NiAl LDH at wavenumber 3448, 1650, 1500–1600, 1348, 1056, and 500–800 cm-1. NiAl LDH and hydrochar have surface areas of 3.288 m2/g and 7.366 m2/g, respectively. The precursors enhance the composite’s surface area by 11.879 m2/g. NiAl LDH, hydrochar, and hydrochar@NiAl LDH have optimal pH values of 3, 6, and 6 respectively. The adsorption process is determined by the kinetic model of pseudo-second order and the model of Freundlich isotherm. NiAl LDH, hydrochar, and hydrochar@NiAl LDH had respective maximum adsorption capacities of 25.445, 21.008, and 25.773 mg/g. The increase in regeneration cycles decreases the percentage of adsorbed.
This study aimed to determine the adsorption capacity of rhodamine-B (Rh-B) and methylene blue (MB) on Mg/Cr-Ni adsorbents. The Mg/Cr-Ni adsorbent was synthesized by the coprecipitation method. The results of the characterization of Mg/Cr-Ni using XRD analysis showed the formation of oxides at an angle of 2θ = 31.726°, 33°, and 45.44°. The surface area of Mg/Cr-Ni is 23.139 m2/g. The adsorption capacity test for Mg/Cr-Ni for Rh-B and MB were 85.470 mg/g and 166.667 mg/g, respectively. The adsorption kinetics model followed the pseudo second order (PSO). The adsorption process is endothermic and occurs spontaneously at any temperature. Mg/CrNi showed stability in the adsorption process of Rh-B and MB for 5 regeneration cycles.
The preparation of the CaAl/HC composite was carried out with a supporting material in the form of hydrochar from duku skin. The success of the preparation was demonstrated by XRD, FT-IR, and BET analysis. The diffractogram of CaAl/HC showed diffraction peaks at 2θ = 10.16° (003), 18.0° (002), 20.15° (006) and 65.4° (110). The diffraction showed similarity to diffraction in CaAl and hydrochar double layer hydroxyl. The FT-IR spectrum of CaAl/HC also showed similarity to the CaAl/HC double layer hydroxyl at 3448, 1635, and 1381 cm-1. The characteristic spectrum of the hydrochar also appeared in CaAl/HC at 20.15. BET analysis showed an increase in the surface area of CaAl/HC before modification of 11.842 m2/g and increased to 22.635 m2/g of CaAl/HC. The ability of CaAl/HC as an adsorbent is determined through several parameters including selectivity, regeneration, isotherm, and thermodynamics. The results of dye selectivity showed that CaAl/HC was more likely to absorb MR dyes in a mixture of dyes (DG, MO, PR, MR, CR, and DR). The regeneration results showed the ability of CaAl/HC which lasted up to 73.26% in the fifth cycle.
Bioadsorbent preparation from rambutan peel applied as adsorbent was characterized using FT-IR, SEM-EDS, BET and TG-DTA analysis. FTIR analysis showed the presence of specific cellulose compounds in the rambutan peel bioadsorbent, the rambutan peel bioadsorbent was amorphous, there were wavy and uneven pores in the morphology of the rambutan peel and had the highest elemental content of 74.3%, the surface area of the rambutan peel was 1.22 cm/g. The adsorption process was applied to malachite green, congo red, and procion red dyes with parameters such as pH, kinetics, isotherm and thermodynamics. Based on kinetic parameters, the adsorption process of malachite green, congo red, and procion red using rambutan peel tends to follow the pseudo second order kinetic model. The adsorption capacity achieved was 182.40 mg/g in procion red, 6.24 mg/g in congo red, and 11.73 mg/g in malachite green. The adsorption process takes place spontaneously which is indicated by a negative Gibs free energy value.
MgAl-LDH was directly impregnated with biochar to fabricate MgAl-Biochar (MgAl/BC) and applied to remove methyl orange (MO) and methyl red (MR). The XRD, BET, FTIR, TG-DTA and SEM analyses were conducted to characterize the prepared material. The result of XRD characterization diffraction peaks at 11.47, 22.86, 34.69, and 61.6 shows that the precursor was successfully transformed to MgAl-BC. The FT-IR analysis at vibration 1010, 1381,3447 and 1635 cm-1 illustrated that the composite was well formed. The BET analysis showed that the Surface area of the MgAl-BC composite was 111.404 m2/g which was larger than that of the precursor, equal to 23.15 m2/g. The kinetic model of the adsorption study both MR and MO were fitted to PSO and followed the Langmuir model with adsorption capacities for MR 142.857 mg/g and MO 128.205 mg/g. The regeneration study of composite indicated higher efficiency than the pristine and show good stability of adsorption process in five cycles.
Layered double hydroxide (LDH) can be used as an adsorbent to remove pollutants from aqueous solutions, but it drawbacks where the structure is easily damaged so that it cannot be reused in the adsorption process and has a low adsorption capacity. This can be overcome through the development of layered double hydroxide material composited with chitosan support material. In addition to untilizing waste, chitosan is selected as supporting material in the layered double hydroxide modification process, because it is cheap, has high selectivity, and is biodegradable. In this study, the adsorbent was applied in the process of removing Congo Red (CR). The LDH modification process using chitosan was successfully carried out, as seen from XRD analysis which resembled the base material (Mg-Al) and support (CT), the BET analysis which showed an increase in surface area, as well as from the large adsorption capacity value and the regeneration process which tends to be stable after compositing is done.
The development of studies on layered double hydroxide (LDH) material as a photocatalyst for the degradation of dye pollutants continues to increase. LDH is an anionic clay, which is a natural or synthetic mixed metal hydroxide. Pristine LDH is written as M2+/M3+ LDH, (M is metal ion). This study prepared pristine Mg/Al LDH and Zn/Al LDH composited with metal oxide TiO2 and ZnO, respectively. Composite is denoted by M2+/M3+ -metal oxide. The coprecipitation method used was accompanied by calcination of the composite at a temperature 300 °C that was not high. The prepared composites were morphologically characterized by SEM. The materials that had been used until the fifth cycle of regeneration were characterized by XRD and FTIR which still indicated the presence of LDH-metal oxide composite structure. The materials degraded cationic dyes namely rhodamine-B (RhB) and methylene blue (MB). RhB degraded better than MB by pristine LDH and composites. The percent degradation of RhB for pristine Mg/Al LDH, composites Mg/Al-TiO2 and Mg/Al-ZnO were 53.1%, 59.8%, 62.8%, respectively. The percent RhB degradation for pristine Zn/Al LDH, composites Zn/Al-TiO2 and Zn/Al-ZnO were 51.4%, 58.5%, 58.9%, respectively. The percentage of degradation indicates that the LDH-metal oxide composite has succeeded in increasing the photodegradation catalytic ability and the regeneration ability of LDH pristine.
Development of Zn/Al layered double hydroxide by intercalation using polyoxometalate (POM) K4 [α-SiW12O40] to Zn/Al-POM was investigated. The success of the modification is evidenced by the XRD, FT-IR, and BET characterization data. XRD characterization showed an increase in the interlayer distance from 8.59 Å in Zn/Al LDHs to 10.26 Å in Zn/Al-POM. This success is also supported by the FT-IR data with the appearance of vibrations around 779–979 cm-1 which indicates the vibration of the polyoxometalate compound in Zn/Al-POM. Other supporting data in the form of BET also prove an increase in surface area from 1.968 m2/g in Zn/Al LDHs to 14.042 m2/g Zn/Al-POM. The ability of Zn/Al-POM as an adsorbent is proven through several parameters such as kinetics, isotherm, thermodynamics, and regeneration for Cd2+, Pb2+, Ni2+, and Co2+. Adsorption kinetics showed that Zn/Al-POM was more likely to follow the pseudo-second-order adsorption kinetics model for Cd2+, Pb2+, Ni2+, and Co2+. The results of determining the adsorption isotherm parameters of Zn/Al-POM tend to follow the Freundlich isotherm model with a maximum adsorption capacity of 74.13 mg/g on Pb2+. The regeneration process showed that Zn/Al-POM was more resistant than Zn/Al LDHs up to 3 cycles. It was proven that Zn/Al-POM was able to survive in the last cycle up to 69.19% on Ni2+.
Mg/Cr layered double hydroxide (LDH) has been successfully synthesized by means of the coprecipitation method followed by the intercalation process using oxalate to form Mg/Cr-oxalate. The materials were characterized using XRD, BET, and FTIR and then applied as an adsorbent of anionic dyes i.e. methyl red (MR) and methyl orange (MO). MR and MO adsorption was studied through variations of adsorption time, concentration, temperature, desorption process, and adsorbent regeneration. The XRD characterization results showed an increase in the interlayer distance from 7.62 Å to 11.35 Å after the intercalation process. The increase of interlayer space of Mg/Cr-oxalate is also equal to the BET data, which shows an increase in surface area from 21.511 m2/g to 49.270 m2/g. The kinetics and isotherm parameters of MR and MO adsorption using Mg/Cr LDH and Mg/Cr-oxalate showed the same results following the PFO kinetics model and Langmuir isotherm model with R2 close to one. Mg/Cr LDH has the adsorption capacity for MR and MO up to 61.728 mg/g 54.645 mg/g, respectively. In turn, the highest adsorption capacity is achieved by Mg/Cr-oxalate for MR adsorption at 81.235 mg/g and MO at 71.429 mg/g. The thermodynamic parameters of MR and MO adsorption using Mg/Cr LDH and Mg/Cr-oxalate indicate that the adsorption process is endothermic and spontaneous.
In this study, NiAl-LDH was modified with hydrochar using the NiAl-Hydrochar composite coprecipitation method. Materials were characterized by XRD and FT-IR analysis. XRD diffractogram and FT-IR spectra show that the NiAl-Hydrochar composite material has the characteristics of the precursors. NiAl- Hydrochar composite materials have a large adsorption capacity to adsorb cationic dyes. The adsorption follows the Langmuir adsorption isotherm model with the maximum capacity (Qmax) of the NiAl-Hydrochar composite material reaching 256.410 mg/g for malachite green and the adsorption process takes place spontaneously and endothermically. The regeneration process of NiAl-Hydrochar composites was more stable and the decrease was not significant (>70%). The selectivity of the dye mixture showed that the adsorbent was more selective for malachite green dye compared to methylene blue and rhodamine-B.
Zn/Cr and Zn/Cr layered double hydroxides (LDHs) intercalated with Keggin ion [α-SiW12O40]4-were successfully synthesized at room temperature and pH value of 10. The synthesized materials were characterized by means of the XRD, BET, and FT-IR analyses and used as an adsorbent iron(II). The adsorption process was investigated by studying pH, the kinetics, and thermodynamic properties of the adsorption process. The results showed the interlayer Zn/Cr LDHs was 7.53 Å and increase to 10.26 Å on Zn/Cr LDHs intercalated with Keggin ion [α-SiW12O40]4-. The BET analysis showed that the pore volume of both materials increased from 0.063 cm3 g-1 to 0.163 cm3 g-1. The pH point zero charge measurement for the Zn/Cr LDHs material was 10 while LDHs Zn/Cr intercalated with Keggin ion [α-SiW12O40]4- was 8. Zn/Cr LDHs intercalated with Keggin ion [α-SiW12O40]4- has higher adsorption capacity than Zn/Cr LDHs without intercalation. Desorption of iron (III) was successfully conducted using HCl as reagent showing the involvement of ion exchange in the adsorption.
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