Radha Tomar

Biological and medicinal properties of grapes and their bioactive constituents: an update.

The grape is one of the most valued conventional fruits, worldwide. Although most of the parts of the grapevine are useful, primarily, the grape is considered as a source of unique natural products not only for the development of valuable medicines against a number of diseases, but also for manufacturing various industrial products. Over the last few decades, apart from the chemistry of grape compounds, considerable progress has been made towards exploring the biological activities of various grape-derived constituents. Today, it is well established that in addition to serving as food, the grape is a major source of several phytochemicals. The main biologically active and well-characterized constituent from the grape is resveratrol, which is known for various medicinal properties in human diseases. This review discusses the roles of various grape-derived phytochemicals in relation to various diseases.

Medicinal and biological potential of pumpkin: an updated review

The use of herbal remedies individually or in combination with standard medicines has been used in various medical treatises for the cure of different diseases. Pumpkin is one of the well-known edible plants and has substantial medicinal properties due to the presence of unique natural edible substances. It contains several phyto-constituents belonging to the categories of alkaloids, flavonoids, and palmitic, oleic and linoleic acids. Various important medicinal properties including anti-diabetic, antioxidant, anti-carcinogenic, anti-inflammatory and others have been well documented. The purpose of the present article is to discuss various medicinal and biological potentials of pumpkin that can impart further research developments with this plant for human health benefits.

Synthesis and characterization of an analogue of heulandite: sorption applications for thorium(IV), europium(III), samarium(II) and iron(III) recovery from aqueous waste.

The synthesis of needle/fibrous particles of analogue of heulandite with particle diameter of 0.08 microm, length 4-8 microm and high specific surface area (478 m(2) g(-1)) with cation exchange capacity (3.27 mequiv g(-1)) have been achieved. The heulandite needles were obtained by using inorganic salts as a source for silicon and aluminum in the hydrothermal synthesis of the material. Alkalinity of the medium played an important role in the formation of heulandite fibers, as it affects the nucleation rate of zeolite synthesis. The analogue of heulandite was characterized using spectroscopic, thermal analysis, scanning and adsorption techniques. After mechanical grinding of crystals of heulandite, obtained powder was used for the study of radionuclide recovery from aqueous waste. The adsorption experiments were carried out under batch process with, pH of medium, amount of sorbent, time of contact between sorbate and sorbent, metal ion concentration and temperature as the variables. The adsorption was strongly dependent on pH of the medium and the uptake of all the metal ions increased from pH 1.0 to 9.0 and the maximum sorption was noticed in the pH range of 5.0-7.0. The optimum condition for these metal ions (Th(IV), Eu(III), Sm(II), and Fe(III)) sorption on self synthesized analogue of heulandite was; 0.001 N metal ion concentration, equilibration time of 4 h, 100 mg sorbent dose and 313-323 K temperature. This sorption process is fit to both Langmuir and Freundlich sorption isotherm. Thermodynamic studies predict the endothermic and spontaneous nature of the same.

Synthesis and morphological studies of nanocrystalline MOR type zeolite material

A number of nanosize mordenite (MOR) analogues with particle size ranging from 5 to 50 nm were synthesized by the hydrothermal method. The effect of various growth parameters like: alkalinity of the medium, type of silica source, etc. on crystal morphology and the crystal size of MOR type of zeolites was investigated. Specific surface and micropore volume were investigated by the Brunauer-Emmett-Teller (BET) method. XRD, SEM, TEM studies indicate nanosize growth of the MOR type crystals. Electron diffraction patterns confirm the crystalline nature of the nanoparticles and the results of their indexing prove that the material is MOR. These synthesized materials show microporous as well mesoporous character. In the case of MOR material synthesized using sodium silicate, it was found that an increase in the alkalinity of the medium led to changes in the morphology and crystal size of the material. For low concentrations of NaOH, the crystallites were spherical in shape whereas at high concentrations, they were in the shape of nanorods of diameter 25 to 50 nm. The morphology of the MOR material synthesized using tetraethyl orthosilicate (TEOS), on the other hand, did not change when the NaOH concentration was increased beyond 2.0 molar.

Synthesis and surfactant modification of clinoptilolite and montmorillonite for the removal of nitrate and preparation of slow release nitrogen fertilizer

This article introduces the synthesis of clinoptilolite and montmorillonite, and their surfactant modification by using solutions of hexadecyltrimethylammonium bromide (CH(3)(CH(2))(15)N(Br)(CH(3))(3), HDTMAB) and dioctadecyldimethylammonium bromide ((CH(3)(CH(2))(17))(2)N(Br)(CH(3))(2), DODMAB). The feasibility of using surfactant modified silicates (SMSs) as a potential adsorbent for nitrate and for slow release of nutrient has been investigated. Adsorption isotherms of NO(3)(-) on SMSs have been measured at aqueous concentration of 160-280 mg L(-1). The SMSs show much higher adsorption capacity than the unmodified materials as determined by Langmuir adsorption isotherm. The surfactant modification and increased surfactant loading concentration enhance the nitrate anion retaining capacity of silicates (montmorillonite (16.05 mg g(-1))<clinoptilolite (30.58 mg g(-1))<DODMAB loaded clinoptilolite (75.19 mg g(-1))<DODMAB loaded montmorillonite (76.92 mg g(-1))<HDTMAB loaded montmorillonite (80.65 mg g(-1))<HDTMAB loaded clinoptilolite (125.00 mg g(-1))). The adsorption data fitted well with the Langmuir and Freundlich isotherms. The slow nutrient release studies have been performed by thin layers-funnel analytical test and soil column percolating system. The obtained results indicate that SMSs are very good adsorbent for NO(3)(-) and a slow release of nitrogen is achievable as it releases NO(3)(-) still after 15-20 days of leaching study.

Sorption behaviour of nanocrystalline MOR type zeolite for Th(IV) and Eu(III) removal from aqueous waste by batch treatment.

The nanocrystalline mordenite (MOR) type zeolite materials with initial chemical composition Na(2)O:Al(2)O(3):10SiO(2):48H(2)O have been synthesized under hydrothermal conditions. MOR1 and MOR2 are spherically shaped nanocrystals, whereas MOR3 and MOR4 have rod-like morphology. This paper reports the sorption characteristics of MOR analogues for Th(IV) and Eu(III) removal from aqueous nuclear waste. Sorption of Th(IV) and Eu(III) on MOR1, MOR2, MOR3 and MOR4 in a single component system with varying initial metal ion concentration, solution pH, contact times, sorbent dose and temperatures has also been investigated. Further, the Langmuir and Freundlich sorption models have been applied to describe equilibrium isotherms at different temperatures. The adsorption capacity increases largely with increasing solution pH and temperature of the system. Specific surface area and pore volume have been investigated by Brunauer-Emmett-Teller (BET) method. The N(2) adsorption isotherm presents a type IV isotherm with narrow hysteresis loop which indicates the presence of mesopores related to inter-particle voids. Thermodynamic results indicate that the sorption follows an endothermic physisorption process. It has been found that these exchangers have good sorption capacity and out of which MOR4 has highest sorption capacity. Thus, nanocrystalline MOR4 is proved to be good sorbent for both Th(IV) and Eu(III).

Sorption of 137Cs, 133Ba and 154Eu by synthesized sodium aluminosilicate (Na-AS)

Sodium aluminosilicate has been synthesized by solution route for use as a sorbent for various radionuclides. It was characterized by XRD, zeta potential, BET surface area, FTIR spectroscopy and site density measurement. Sorption studies of (137)Cs, (133)Ba and (154)Eu on synthesized sodium aluminosilicate have been carried out at varying pH (3-10). Sorption of all the metal ions was found to increase with pH of suspension with the saturation value increasing with the oxidation state of metal ion. Effect of Aldrich humic acid (2mg/l) on sorption was also investigated. In case of (137)Cs, the sorption was not affected by the presence of humic acid, while in case of (133)Ba and (154)Eu, sorption was enhanced at lower pH and decreased at higher pH in presence of HA. A series of experiments were carried out for (154)Eu sorption on sodium aluminosilicate at various conditions. Sorption of europium was analyzed by different sorption isotherms, viz., Freundlich and D-R isotherm. Thermodynamic data reveal sorption phenomena as endothermic and spontaneous. Studies were further extended to find out effect of diverse ions (Ca(2+) and CO(3)(2-)) on sorption of europium.

Role of magnetite and humic acid in radionuclide migration in the environment.

Sorption of (137)Cs, (90)Sr, (154)Eu and (141)Ce by magnetite has been studied at varying pH (4 to 11) in the presence and absence of humic acid. The sorption studies have also been carried out at varying ionic strength (0.01 to 0.2 M NaClO(4)) and humic acid concentration (2 to 20 mg/L). Percentage sorption of (137)Cs and (90)Sr was found to be pH dependent, with the sorption increasing with increasing pH of the suspension. At any pH, the percentage sorption of (90)Sr was higher than that of (137)Cs. The results have been explained in terms of the electrostatic interaction between the positively charged metal ions and the surface charge of the magnetite which becomes increasingly negative with increasing pH. On the other hand, (154)Eu and (141)Ce were found to be strongly sorbed by the magnetite at all pH values, with the sorption being independent of pH. The strong sorption of trivalent and tetravalent metal ions suggests the role of complexation reactions during sorption, apart from the electrostatic interactions. However, in the case of (141)Ce surface precipitation of Ce(III) formed by reduction of Ce(IV) in the presence of magnetite cannot be ruled out. Presence of humic acid (2 mg/L) was found to have negligible effect on sorption of all metal ions.

Use of Surfactant-Modified Zeolites for Arsenate Removal from Pollutant Water

Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. HDTMA-modified erionite (SME), HDTMA-modified cowlesite (SMW), and HDTMA-modified willhendersonite (SMW) have been proposed for the sorption of As(V) from aqueous solution (HDTMA = hexadecyletrimethyl ammonium bromide). Experiments have been conducted to examine the extent of arsenic removal as a function of pH. The effect of initial arsenic concentration and liquid to solid ratio in the batch reactions has also been studied. Influence of time on arsenate efficiency of different sorbents reveal that SME, SMC, and SMW require about 7 hours, to reach the state of equilibrium. Modified zeolites were investigated by x-ray diffraction, Fourier transform infrared analysis, energy dispersive spectroscopy, and scanning electron microscopy. Sorption data for each anion was well described by Freundlich isotherm equation. Thermodynamic parameters (ΔH°, ΔG°, and ΔS°) for As(V) sorption on the modified zeolites were also determined from the temperature dependence.

Sorption of Chromate and Arsenate by Surfactant Modified Erionite (E-SMZ)

In recent years, growth of various industry has led to the introduction of pollutants in nature, especially heavy metal ions such as Cr(III) and As(V), which are usually present in wastewater. Heavy metals containing waste are generated from metallurgical, mining, chemical, leather, distilleries, sugar, battery, electroplating, and pigment industries, to name a few. Chromium is found in natural water in oxidation states, Cr(III) and Cr(VI). The former is an essential element for mammals whereas the latter is reported to be toxic. Similarly, arsenic is an ubiquitous contaminant that can be found in high concentrations in natural waters and wastewaters. Arsenic containing waste streams are generated mainly by the microelectronic industry and by pesticide and pharmaceutical facilities. It occurs in two oxidation states that form oxyanions, arsenate As(V), and arsenite As(III); arsenite is more mobile and toxic than . As arsenic is a major hazardous contaminant for human health, its removal is an issue of increasing concern. Zeolites are crystalline, hydrated aluminosilicates containing exchangeable alkaline and alkaline earth cations in their structural frameworks. Since zeolites have a permanent negative charge on their surfaces, they have no affinity for anions. However, recent studies have shown that modification of zeolite with certain surfactants or metal cations yield sorbents with a strong affinity for many anions. Zeolite has high internal and external surface areas and high internal and external cation exchange capacities suitable for the surface modification by cationic surfactant (HDTMA). When the initial surfactant concentration is less than the critical micellar concentration (CMC), the sorted surfactant molecules primarily form a monolayer; limited chromate and arsenate sorption indicates that the patchy bilayer may also be formed. When the surfactant concentration is greater than the CMC and enough surfactant exists in the system, the sorbed surfactant molecules form a bilayer, producing maximum chromate and arsenate sorption. Quantitative sorption of chromate and arsenate and desorption of bromide ions indicate that the sorption of oxoanions is primarily due to surface anion exchange.