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%.

NiAl-LDH and ZnAl-LDH intercalated polyoxometalate K4 [SiW12O40] and K3 [PW12O40] were synthesized to form composite NiAl-[SiW12O40], NiAl-[PW12O40], ZnAl-[SiW12O40], and ZnAl-[PW12O40]. The physicochemical properties of the materials were characterized by XRD, FTIR, SEM, and UV-DRS. The material used for degraded Rhodamine B (RhB) as a cation dye. The results successfully synthesized by showed the peak diffractions angles at 11.63°, 23.13°, and 35.16° for NiAl-LDH and diffractions at 10.39°, 20.17°, 34.6° and 60.52°for ZnAl-LDH. The LDH typical structure of the composite materials NiAl-[SiW12O40] and NiAl-[PW12O40] was demonstrated by apparent diffraction at 2???? angles of 10.76°, 26.59°, 30.8°, and 63.11° for NiAl [PW12O40], 2???? angles at 8.26°, 11.34°, 29°, and 35.1° for NiAl-[SiW12O40], 7.73°, 28.6° and 35.6° for ZnAl-[PW12O40], and 8.61°, 25.27°, 34.96° and 66.34° for ZnAl-[SiW12O40]. The materials were characterized as an advanced catalyst to improve photocatalytic activity for RhB elimination under visible light sources. The intercalation of polyoxometalate [SiW12O40]4- and [PW12O40]3- into LDH could enhance the degradation cationic dye of RhB. Intercalation improved the photodegradation performance determined under UV-Vis irradiation conditions which composite NiAl-LDH was better than ZnAl-LDH composite. It was present by the %degradation RhB performances NiAl-LDH, ZnAl-LDH, NiAl-[SiW12O40], NiAl-[PW12O40], ZnAl-[SiW12O40], and ZnAl-[PW12O40] were 91.48%, 88.59%, and 88.41%, and 87.87%, respectively. The %degradation for NiAl-LDH and ZnAl-LDH was 68.94% and 65.76%. Recovery and reusability experiment of the catalyst demonstrated by degradation percentage that the LDH intercalated polyoxometalate has a great photocatalytic ability.

Composites based on layered double hydroxide with polyoxometalate K3[-PW12O40] and K4[-SiW12O40] were synthesized to form NiAl-[SiW12O40] and NiAl-[PW12O40]. The materials were characterized by XRD, FTIR, SEM, and UV-DRS and were then applied as a photocatalyst to degrade MG. The effects of catalyst loading, pH value, and contact times on photodegradation performance were carried out in this study. The results indicated that        NiAl-LDH was successfully synthesized by showing the peak diffractions at angles 11.63°, 23.13°, and 35.16°. Both kinds of attained NiAl-[SiW12O40] and NiAl-[PW12O40] had typical structures of LDH that were proved by appearing diffraction at 2θ angles 10.76°, 26.59°, 30.8°, and 63.11° for NiAl-[PW12O40] and at 2θ angles 8.26°, 11.34°, 29°, and 35.1° for NiAl-[SiW12O40]. The materials used for the fifth regeneration were characterized by FTIR, which still presents characteristics of LDH structure. The photocatalyst was applied for the first time to degrade MG. The decrease of band gap on NiAl pristine than LDH composite from 4.76 eV to 3.22 eV for NiAl-[SiW12O40] and 3.78 eV for NiAl-[PW12O40] respectively, was presented by DR-UV analysis. LDH composite shows improved degradation photocatalytic performance in comparison with LDH pristine. It was present by the %degradation MG performances were 68.94% for NiAl LDH, 84.51% for NiAl-[PW12O40]), and 88.91% for NiAl-[SiW12O40]. The degradation percentage indicates that the LDH-polyoxometalate composite has succeeded in increasing the ability of photodegradation catalytic and the regeneration ability of LDH pristine. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The modification catalysts of layered double hydroxide (LDH) with polyoxometalate based on Keggin type were prepared and characterized using X-Ray, FTIR, and SEM to confirm the layered double hydroxide structure. Intercalation was successfully synthesized and showed a heterogeneous aggregate resulted from SEM analysis. The degradation parameters of LDH pristine and LDH composite were determined by observing a number of factors such as pH, catalyst weight, and degradation time. The modification material resulted by preparation material LDH and polyoxometalate (POM) successfully resulted in the lower band gap value compared to material pristine LDH allowing LDH polyoxometalate as photocatalysts to show good photocatalytic activities. The NiAl-SiW12O40 material had the highest percentage of degradation removing Congo Red up to 86% degradation when compared to another composite material, yet it was still significantly better than LDH pristine. The result showed that the LDH composite presented excellent photocatalytic activity in reducing Congo Red.

The synthesis and characterization of M2+/Al (M2+=Ni, Mg) layered double hydroxide (LDH) and intercalated polyoxometalate is presented. We have reported the growth of polyoxometalate on Ni/Mg layered double hydroxide for degradation methylene blue (MB). By considering variables such as pH of dye solution, dye concentration, and time as degradation variables, the efficiency of organic dye degradation and degradation parameters of M2+/Al (M2+ = Ni, Mg) LDH and both composite LDH-polyoxometalate has been identified. X-Ray Diffraction (XRD), Fourier Transform Infra Red (FTIR), Scanning Electron Microscope (SEM), and Ultra Violet Diffuse Reflectance Spectroscopy (UV-DRS) 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 material’s photodegradation was assessed through methylene blue (MB) degradation process. The result showed that NiAl-Si has a good degradation capacity for MB as compared to NiAl-Pw, MgAl-Si, and MgAl-PW. The result shows that LDH composite presents stability and has good photocatalytic activities toward the reduction of methylene blue. The FTIR measurement confirming the LDH composite structure reveals the materials used in the fifth regeneration. The activity of MB photodegradation pristine were NiAl (45%), MgAl (43%), NiAl-Pw (78%), NiAl-Si (85%), MgAl-Pw (58%), and MgAl-Si (75%), respectively. The LDH-polyoxometalate composite material’s capacity to successfully photodegrade, as measured by the percentage of degradation, revealed an increase in photodegradation catalysis and the ability of the LDH to regenerate. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).