Hemant Mittal

Gum ghatti and Fe3O4 magnetic nanoparticles based nanocomposites for the effective adsorption of rhodamine B

This article reports the development of a new nanocomposite using gum ghatti crosslinked with poly(acrylic acid-co-acrylamide) reinforced with iron oxide magnetic nanoparticles. The nanocomposite was characterized through BET, FT-IR, XRD, SEM-EDX, TGA and TEM and applied for the removal of RhB. Different optimized adsorption parameters were adsorbent dose (0.8 g/L) and pH (7.0). The adsorption isotherm data was used to study Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich isotherm models. The value of correlation coefficient confirmed the applicability of Langmuir isotherm model with maximum adsorption efficiency of 654.87 mg/g. The adsorption kinetics data showed pseudo second order reaction. Thermodynamic studies showed that the adsorption process was endothermic and spontaneous. Moreover, the adsorbent was successfully utilized for successive three cycles for the adsorption-desorption of RhB.

The adsorption of Pb2+ and Cu2+ onto gum ghatti-grafted poly(acrylamide-co-acrylonitrile) biodegradable hydrogel: isotherms and kinetic models.

A biodegradable hydrogel polymer of gum ghatti (Gg) with a copolymer mixture of acrylamide (AAm) and acrylonitrile (AN) was synthesized using the free-radical graft copolymerization technique. The effect of graft copolymerization on the surface area of Gg was studied using BET analyses. The graft copolymerization of Gg with poly(AAm-co-AN) was characterized using Fourier transform infrared spectroscopy, CHN analysis, thermogravimetric analysis, atomic force microscopy, and scanning electron microscopy. The adsorption of Pb(2+) and Cu(2+) from aqueous solution using the Gg-cl-P(AAm-co-AN) hydrogel polymer was studied in batch mode. The adsorption process was found to be highly pH dependent, and the maximum adsorption efficiency was observed at pH 5.0 for both metal ions. The adsorption isotherm data were analyzed by applying five different isotherm models, namely, the Langmuir, Freundlich, Temkin, Flory-Huggins, and Dubinin-Kaganer-Radushkevich isothermal models. The Langmuir model was found to fit well with the experimental isotherm data, with a maximum adsorption capacity of 384.6 and 203.7 mg/g for Pb(2+) and Cu(2+), respectively. The metal ion-adsorption process was found to be controlled by the pseudo-second-order rate model. The Gg-cl-P(AAm-co-AN) hydrogel polymer retained its original adsorption capacity for three successive cycles of adsorption-desorption. In summary, the potential for remediating industrial wastewater polluted by metal ions using the biodegradable Gg-cl-P(AAm-co-AN) hydrogel polymer has been demonstrated.

Flocculation and adsorption properties of biodegradable gum-ghatti-grafted poly(acrylamide-co-methacrylic acid) hydrogels.

This study reports the microwave-assisted synthesis of gum-ghatti (Gg)-grafted poly(acrylamide-co-methacrylic acid) (AAm-co-MAA) hydrogels for the development of biodegradable flocculants and adsorbents. The synthesized hydrogels were characterized using TGA, FTIR and SEM. TGA studies revealed that the synthesized hydrogels were thermally more stable than pristine Gg and exhibited maximum swelling capacity of 1959% at 60°C in neutral pH. The optimal Gg-cl-P(AAm-co-MAA) hydrogel was successfully employed for the removal of saline water from various petroleum fraction-saline emulsions. The maximum flocculation efficiency was achieved in an acidic clay suspension with a 15 mg polymer dose at 40°C. Moreover, the synthesized hydrogel adsorbed 94% and 75% of Pb(2+) and Cu(2+), respectively, from aqueous solutions. Finally, the Gg-cl-P(AAm-co-MAA) hydrogel could be degraded completely within 50 days. In summary, the Gg-cl-P(AAm-co-MAA) hydrogel was demonstrated to have potential for use as flocculants and heavy metal absorbents for industrial waste water treatment.

Synthesis and flocculation properties of gum ghatti and poly (acrylamide-co-acrylonitrile) based biodegradable hydrogels

This article reports the development of biodegradable flocculants based on graft co-polymers of gum ghatti (Gg) and a mixture of acrylamide and acrylonitrile co-monomers (AAm-co-AN). The hydrogel polymer exhibited an excellent swelling capacity of 921% in neutral medium at 60°C. The polymer was used to remove saline water from various petroleum fraction-saline water emulsions. The flocculation characteristics of the hydrogel polymer were studied in turbid kaolin solution as a function of the amount of polymer and the solution temperature and pH. Biodegradation studies of hydrogel polymer were conducted using the soil composting method, and the degradation process was constantly monitored using scanning electron microscopy and Fourier transform infrared spectroscopy techniques. The results demonstrated an 89.47% degradation of the polymer after 60 days. Finally, the hydrogel polymer adsorbed 98% of cationic dyes from the aqueous solutions.

Biosorption potential of Gum ghatti-g-poly(acrylic acid) and susceptibility to biodegradation by B. subtilis

This article reports the biosorption potential of Gum ghatti (Gg)-grafted-acrylic acid (AA) polymer and its susceptibility to biodegradation by Bacillus subtilis (BS) in two different liquid media, i.e. phosphate buffered saline (PBS) and mineral salt medium (MSM). The progress of biodegradation was monitored after every 15 days using FT-IR and SEM techniques. The degradation of the polymer was further evidenced by a loss of weight of 23.2% and 27% in BS-MSM and BS-PBS, respectively, after 60 days. The AA-grafted polymer was then utilized for the removal of Pb(II) and Cu(II) from aqueous solution. The adsorption isotherm data were studied using Langmuir, Freundlich, Temkin, Flory-Huggins and Dubinin-Kaganer-Radushkevich isothermal models. High values of correlation coefficients confirmed the applicability of Langmuir isotherm model used to determine the adsorption capacity of the AA-grafted polymer. The maximum adsorption capacity was found to be 84.74 mg/g for Cu(II) and 310.55 mg/g for Pb(II). Kinetic data were evaluated using pseudo first order, pseudo second order, Elovich, intraparticle diffusion and liquid film diffusion models. The experimental kinetic data fitted well with the pseudo second order rate model.

Effect of functionalization on the adsorption capacity of cellulose for the removal of methyl violet

In this research paper a comparative study has been carried out for the removal of methyl violet dye using unfunctionalized and functionalized cellulose. The functionalization was achieved through esterification of cellulose with furan-2,5-dione. The functionalization of the cellulose was evidenced using BET, FT-IR, SEM and TGA. The adsorption isotherm data was fitted using different isotherm models like Langmuir, Freundlich, Temkin, Flory-Huggins and Dubinin-Kaganer-Radushkevich models and found to follow Langmuir and Temkin isotherm models with high value of correlation coefficients. Functionalized cellulose (106.38 mg g(-1)) showed higher dye removal capability than unfunctionalized cellulose (43.668 mg g(-1)). The kinetics of adsorption was investigated using pseudo first order, second order, Elovich, liquid film diffusion and intra-particle diffusion models. The mechanism of adsorption was found to follow pseudo second order rate equation. Thermodynamic studies showed that the adsorption process was endothermic and spontaneous.

Synthesis of Crosslinked Networks of Gum ghatti with Different Vinyl Monomer Mixtures and Effect of Ionic Strength of Various Cations on its Swelling Behavior

A series of pH, temperature, and electrical stimulus sensitive novel hydrogels of Gum ghatti (Gg) with vinyl monomer mixtures of acrylamide (AAm) with acrylic acid (AA), acrylonitrile (AN), and methacrylic acid (MAA) using potassium persulphate-ascorbic acid redox pair as an initiator and N,N’-methylene-bis-acrylamide (MBA) as a crosslinker was synthesized using a free radical polymerization process. Initially, different reaction parameters for the graft copolymerization and crosslinking of Gum ghatti with AAm and MBA were optimized. Afterwards, optimization of AA, AN, and MAA in combination with preoptimized AAm was carried out. Synthesized products were characterized by FT-IR, SEM, XRD, and TGA/DTA/DTG. Swelling behavior of hydrogels was investigated in deionized water as a function of time, temperature, and pH of swelling medium. Moreover, hydrogels have been found to exhibit cationic charge-dependent swelling in different salt solutions of Na+, Ba2+, Fe3+, and Sn4+. The order of swelling was found to be Na+>Ba2+>Fe3+>Sn4+.

Effective removal of cationic dyes from aqueous solution using gum ghatti-based biodegradable hydrogel

Biodegradable hydrogels of gum ghatti (Gg) with a co-polymer mixture of acrylamide (AAm) and methacrylic acid (MAA) (termed as Gg-cl-P(AAm-co-MAA)) were synthesised by microwave-assisted free radical graft co-polymerisation technique. The hydrogel polymer was characterized by FTIR, SEM, and Brunauer-Emmett-Teller techniques. The Gg-cl-P(AAm-co-MAA) hydrogel was studied as an adsorbent for the removal of methylene blue (MB) and methyl violet (MV) from aqueous solutions. Adsorption of both the dyes followed pseudo-second-order kinetics and Langmuir adsorption isotherm models. The hydrogel polymer adsorbed 98% of MB and 95% of MV from aqueous solution. The Gg-cl-P(AAm-co-MAA) maintained its original sorption capacity for three cycles of adsorption-desorption. Furthermore, the hydrogel polymer degraded fully within 50 days in soil compost. In summary, the Gg-cl-P(AAm-co-MAA) hydrogel could be a potential adsorbent for the remediation of dyes from industrial wastewater.

Adsorption of methyl violet from aqueous solution using gum xanthan/Fe3O4 based nanocomposite hydrogel

This research paper reports the utilization of gum xanthan-grafted-polyacrylic acid and Fe3O4 magnetic nanoparticles based nanocomposite hydrogel (NCH) for the highly effective adsorption of methyl violet (MV) from aqueous solution. Synthesized NCH was characterized using various techniques, such as FTIR, XRD, SEM-EDS, TEM and BET. Adsorption behavior of NCH was studied for the adsorption of MV and it was found to remove 99% dye from the solution. Adsorption process followed Langmuir isotherm model (qe=642mg/g) and pseudo-second-order kinetics model. Thermodynamic studies suggested that the adsorption process was endothermic and spontaneous. Moreover, the adsorbent was successfully utilized for successive five cycles of adsorption-desorption.

Synthesis, characterization and photoluminescence properties of Ce3+-doped ZnO-nanophosphors

The present study involves the synthesis of Ce3+ doped ZnO nanophosphors by the zinc nitrate and cerium nitrate co-precipitation method. The synthesized nanophosphors were characterized with respect to their crystal structure, crystal morphology, particle size and photoluminescence (PL) properties using X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), transmission electron microscopy (TEM)/Energy-dispersive X-ray spectroscopy (EDS) and PL-spectroscopy respectively. XRD results revealed that ZnO nanophosphors are single phase and cubic type structures. Further, PL spectra of ZnO:Ce3+ nanophosphors showed green emission because of the charge transfer at single occupied oxygen vacancies with ZnO holes and red emission due to the cerium ion transitions. Intensity and fine structure of the Ce3+ luminescence and its temperature dependence are strongly influenced by the doping conditions. The formation of ZnO:Ce3+ nanophosphors was confirmed by Fourier transform infrared (FTIR) and XRD spectra.