Wyniki wyszukiwania - Biblioteka Nauki

1

Layered Double Hydroxide/Chitosan Composite (Mg-Al/CT) as a Selective Adsorbent in Congo Red Adsorption from Aqueous Solution

100%

Mohadi R. , Siregar P. M. S. B. N. , Palapa N. R. , Taher T. , Lesbani A.

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2022

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tom Vol. 23, iss. 2

144--152

EN

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.

2

Stearate modification of Layered Double Hydroxide (LDH) for Polyurethane Elastomeric Nanocomposites

100%

Kumar S. , Das C. K.

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tom T. 14, nr 4

15-22

EN

Layered Double Hydroxide (LDH) is a class of inorganic clay materials having layered structure in which anions are accommodated between the positively charged metal hydroxide layers. An increasing interest exists, because this class of materials can be used as catalysts, photo catalysts, catalysts supports, anion exchangers and as nanofillers in polymer composites, etc. LDHs with easily exchangeable interlayer ionic species have tremendous potential as novel fillers for polymers composites. Due to a low interlayer space and hydrophilic nature they hardly disperse in polymer matrices. After suitable modification by anions, LDHs can be successfully dispersed at nanoscale in a wide range of polymers. LDHs as a nanofillers improve the flame retardancy and barrier properties of polymer composites. In the present work Mg/Al based LDH was modified by the regeneration method. Modified LDH samples were characterized by XRD, FTIR, HRTEM, SEM and FESEM. XRD results indicate that anionic moiety was introduced into the gallery space and acts as pillar increasing the gallery height, what is evident by increased interlayer spacing. FTIR studies of modified LDH samples corroborated the presence of anionic moiety. From FESEM study it was observed, that after modification of LDH, platelet morphology is completely different from that, which was recorded for pure LDH with hexagonal structure. This modified LDH is well exfoliated in polyurethane polymer matrix with improved mechanical properties.

PL

Dwuwarstwowe hydroksyzwiązki (LDH) stanowią grupę nieorganicznych materiałów mineralnych, w których aniony umiejscowione są pomiędzy dodatnio naładowanymi warstwami wodorotlenków metali. Zainteresowanie tymi związkami ciągle wzrasta, ponieważ mogą być one stosowane jako katalizatory lub ich nośniki, fotokatalizatory, wymienniki jonowe oraz jako nanonapełniacze w kompozytach polimerowych. LDH, ze względu na łatwość wymiany jonów w warstwie pośredniej, ma ogromny potencjał jako nowy napełniacz kompozytów polimerowych. Jednak ze względu na niewielkie odległości między warstwami i hydrofilową naturę trudno jest zdyspergować je w ośrodku polimerowym. Jest to możliwe dopiero po odpowiedniej modyfikacji i wymianie anionów w warstwie pośredniej. LDH jako nanonapełniacze zwiększają odporność kompozytów polimerowych na palenie i poprawiają ich właściwości barierowe. W niniejszym artykule omówiono wyniki modyfikacji LDH, opartego na związkach magnezu i glinu, z wykorzystaniem metody regeneracji. Zmodyfikowane hydroksyzwiązki scharakteryzowano wykorzystując analizę XRD, FTIR, HRTEM, SEM i FESEM. Wyniki dyfrakcji rentgenowskiej (XRD) wskazują, że nastąpiła wymiana anionowych fragmentów struktury, a nowo wprowadzone ugrupowania rozpychają warstwy metaliczne, o czym dowodnie świadczy zwiększenie przestrzeni międzywarstwowej. Analiza widm FTIR potwierdziła obecność nowych ugrupowań. Na podstawie badań FESEM stwierdzono, że po modyfikacji całkowicie zmieniła się morfologia LDH. Modyfikowane hydroksyzwiązki były dobrze eksfoliowane w matrycy poliuretanowej, co skutkowało poprawą właściwości mechanicznych kompozytów.

3

Pamoate intercalated Zn-Al layered double hydroxide for the formation of layered organic-inorganic intercalate

100%

Hussein M. Z. , Jubri Z. B. , Zainal Z. , Yahya A. H.

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tom Vol. 22, No. 1

57--67

EN

A layered organic-inorganic intercalate was prepared by the self-assembly technique using pamoate (PA) as an organic guest in the Zn-Al layered double hydroxide inorganic host (ZAPAN). Various concentrations of PA, ranging from 0.01 to 0.04 M, were used to prepare the intercalated compound with a constant 4:1 ratio of Zn:Al in the mother liquor. The concentration of PA of 0.02 M at pH 7 was found to give a well-ordered nanolayered organic-inorganic hybrid structure. As a result of successful intercalation of PA anion into the Zn-Al inorganic layered double hydroxide (LDH), the expansion of interlayer spacing to 18 A was observed in the PXRD diffractogram of the intercalated compound, compared to 9 A for the Zn-Al LDH with nitrate as the counter anion (ZANIL). FTIR study shows that the intercalated compound resembled the spectra of PA and ZANIL, thus indicating the presence of both functional groups in ZAPAN. It was also found that the BET surface area increased from 6 m2/g to 90 m2/g for ZANIL and ZAPAN, respectively. The pore texture of the resulting materials was also changed as the result of the intercalation and the expansion of the basal spacing together with pore formation between the crystallite during the formation of the resulting layered intercalated compound.

4

Dielectric properties of Bi-substituted LDHs synthesized by co-precipitation and sol-gel methods

88%

Sokol D. , Ivanov M. , Salak A. N. , Grigalaitis R. , Banys J. , Kareiva A.

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tom Vol. 37, No. 2

190--195

EN

Magnesium-aluminum-bismuth layered double hydroxides (Mg3Al1-xBix; LDHs) were prepared using both coprecipitation and sol-gel methods. For the preparation of Mg/Al/Bi LDH by the co-precipitation method, the appropriate amounts of dissolved starting materials (Al(NO3)3·9H2O, Mg(NO3)2·6H2O and Bi(NO3)3·5H2O) were mixed with a solution of NaHCO3:NaOH. In the sol-gel processing, the precursor Mg–Al–Bi–O gels were synthesized using the same starting materials and ethylene glycol as complexing agent. The mixed-metal oxides obtained by subsequent heating of Mg–Al–Bi–O gels at 650 °C were reconstructed to Mg3Al1-xBix LDHs in water at 80 °C. All the synthesized products were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and dielectric measurements.

5

Polyoxometalate Intercalated Layered Double Hydroxide for Degradation of Procion Red

88%

Hanifah Y. , Mohadi R. , Mardiyanto , Lesbani A.

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tom Vol. 24, iss. 6

109--116

EN

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.

6

Oxalate Intercalated Mg/Cr Layered Double Hydroxide as Adsorbent of Methyl Red and Methyl Orange from Aqueous Solution

75%

Badri A. F. , Juleanti N. , Palapa N. R. , Hanifah Y. , Mohadi R. , Mardiyanto , Lesbani A.

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tom Vol. 22, iss. 3

71--81

EN

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.