Continuous Fixed-Bed Column Studies on Congo Red Dye Adsorption-Desorption Using Free and Immobilized Nelumbo nucifera Leaf Adsorbent

The adsorption of Congo red (CR), an azo dye, from aqueous solution using free and immobilized agricultural waste biomass of Nelumbo nucifera (lotus) has been studied separately in a continuous fixed-bed column operation. The N. nucifera leaf powder adsorbent was immobilized in various polymeric matrices and the maximum decolorization efficiency (83.64%) of CR occurred using the polymeric matrix sodium silicate. The maximum efficacy (72.87%) of CR dye desorption was obtained using the solvent methanol. Reusability studies of free and immobilized adsorbents for the decolorization of CR dye were carried out separately in three runs in continuous mode. The % color removal and equilibrium dye uptake of the regenerated free and immobilized adsorbents decreased significantly after the first cycle. The decolorization efficiencies of CR dye adsorption were 53.66% and 43.33%; equilibrium dye uptakes were 1.179 mg g–1 and 0.783 mg g–1 in the third run of operation with free and immobilized adsorbent, respectively. The column experimental data fit very well to the Thomas and Yoon–Nelson models for the free and immobilized adsorbent with coefficients of correlation R2 ≥ 0.976 in various runs. The study concludes that free and immobilized N. nucifera can be efficiently used for the removal of CR from synthetic and industrial wastewater in a continuous flow mode. It makes a substantial contribution to the development of new biomass materials for monitoring and remediation of toxic dye-contaminated water resources.

Species diversity of macrophytes in Jagadishpur Reservoir, Kapilvastu District, Nepal

The present research was conducted for quantitative study and diversity analyses of aquatic macrophytes dwelling littoral zone of Jagadishpur reservoir, Kapilvastu district in three seasons, as winter (December), summer (April), and rainy (August). Altogether 58 species of macrophytes were recorded in study site, of which highest number of species (54) was occupied by angiosperms followed by three species of pteridophytes and one species of alga. These macrophytes varied in different morphological groups, viz., emergent, submerged, and rooted-floating leaf type. Maximum number of species were represented by emergents (39) followed by rooted-floating leaf type (12) and submerged (7) macrophytes. There was distinct seasonal variation in the distribution of macrophytes: based on importance value index, Nelumbo nucifera (IVI = 22.87), Scripus sp. (IVI = 28.01), Ipomoea carnea (IVI = 24.67) and Typha angustifolia (IVI = 29.01) were dominant in the winter; Nelumbo nucifera (IVI = 20.05), Cynodon dactylon (IVI = 20.07) and Ipomoea carnea (IVI = 21.17) were dominant in the summer and Nelumbo nucifera (IVI = 23.8) and Scripus sp. (IVI =25.56) were dominant in the rainy season. The highest species diversity (H’) of macrophytes was observed during summer (3.451), followed by rainy season (3.135) and winter (3.008). The luxuriant growth of aquatic macrophytes evidenced the highly productive nature of the lake, while the dominance of emergents among the growth forms indicates the encroachment of littoral vegetation, indicating a successional trend toward marsh meadow.

Chemical and Microbial Characteristics of Blackening Disease in Lotus (Nelumbo nucifera Gaertn.) Caused by Hirschmanniella diversa Sher

The lotus (Nelumbo nucifera Gaertn.) is widely cultivated in Asia, but a blackening disease in the lotus tuber, called “kurokawa-senchu-byo”, is a serious problem caused by the Hirschmanniella diversa Sher plant-parasitic nematode. To effectively control the disease, we must elucidate the blackening mechanisms; therefore, in this study, we performed a soil chemical analysis and an evaluation of the disease level in the lotus cultivation fields, identified the chemical components of the black spots on the lotus surface, and performed a 16S rRNA gene-based microbial community analysis of the black spots. Using linear regression analysis, a positive linear relationship with a strong correlation between the damage index values and fertilizer components such as P2O5 was observed. As a result of scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis, phosphorus (P) and iron (Fe) were found to be concentrated in the black spots of the lotus tubers. Furthermore, we found that the concentrations of P and Fe in the black spots were 1.5- and 2.7-fold higher, respectively, than those found in the healthy parts of the lotus tubers. A 16S rRNA gene analysis revealed that dissimilatory Fe(III)-reducing bacteria (DIRB) were predominant in the black spots, suggesting that these bacteria are important to the formation of P and Fe compounds in the black spots.

A review on Extraction of alkaloid from Nelumbo nucifera Embryos and Leaves for Production of Dietary Supplement

Lotus (Nelumbo nucifera Gaertn.) commonly distributed in low-lying and flooded areas like Southern Vietnam provides flowers, leaves, seeds, embryos, and edible rhizomes. All parts of the plant show good pharmacokinetic properties, especially lotus embryos and leaves. Studies have shown that lotus plums and leaves have many bioactive compounds such as alkaloids, flavonoids, triterpenoids, and polyphenols, in which alkaloids are one of mainly bioactive compound kinds. So that, there are many studies investigating extraction methods that increase the amount of alkaloid from lotus leaves, embryos. There are some conventional extract methods such as soak, heat reflux, Soxhlet, etc… and some modern extract methods as microwave, ultrasounds, enzyme assisted, supercritical fluids (S-CO2). At present, lotus leaves, embryos and their bioactivities can have application potential in the supplementary food such as protect-liver, anti-neurotic, etc.. The aim of this paper is to review a variety of develop methods used in the alkaloid extraction from lotus embryos, leaves. Besides, this study also introduces some pharmacokinetic properties of alkaloid which can use in functional foods.