Biosorbents for heavy metals removal and their future

Silver nanoparticles (NPs) have been the subjects of researchers because of their unique properties (e.g., size and shape depending optical, antimicrobial, and electrical properties). A variety of preparation techniques have been reported for the synthesis of silver NPs; notable examples include, laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods. This review presents an overview of silver nanoparticle preparation by physical, chemical, and biological synthesis. The aim of this review article is, therefore, to reflect on the current state and future prospects, especially the potentials and limitations of the above mentioned techniques for industries.

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Synthesis of silver nanoparticles: chemical, physical and biological methods.

http://fac.ksu.edu.sa/sites/default/files/Abdel-Raouf%20et%20al%2C2012.pdf

Microalgae and wastewater treatment.

Biogenic synthesis of nanoparticles: A review

Using aqueous cyanobacterial extracts in the synthesis of silver nanoparticle is looked as green, ecofriendly, low priced biotechnology that gives advancement over both chemical and physical methods. In the current study, an aqueous extract of Oscillatoria limnetica fresh biomass was used for the green synthesis of Ag-NPs, since O. limnetica extract plays a dual part in both reducing and stabilizing Oscillatoria-silver nanoparticles (O-AgNPs). The UV-Visible absorption spectrum, Fourier transforms infrared (FT-IR), transmission electron microscopy (TEM) and scanning electron microscope (SEM) were achieved for confirming and characterizing the biosynthesized O-AgNPs. TEM images detected the quasi-spherical Ag-NPs shape with diverse size ranged within 3.30–17.97 nm. FT-IR analysis demonstrated the presence of free amino groups in addition to sulfur containing amino acid derivatives acting as stabilizing agents as well as the presence of either sulfur or phosphorus functional groups which possibly attaches silver. In this study, synthesized Ag-NPs exhibited strong antibacterial activity against multidrug-resistant bacteria (Escherichia coli and Bacillus cereus) as well as cytotoxic effects against both human breast (MCF-7) cell line giving IC50 (6.147 µg/ml) and human colon cancer (HCT-116) cell line giving IC50 (5.369 µg/ml). Hemolytic activity of Ag-NPs was investigated and confirmed as being non- toxic to human RBCs in low concentrations.

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Synthesis and biological characterization of silver nanoparticles derived from the cyanobacterium Oscillatoria limnetica.

Near shore surface water (0.5 m) of an estuarine station along eastern Indian coast was studied for the first time to understand the seasonal composition, distribution and assemblage patterns of micro phytoplankton in relation to different environmental variables. Regular samplings at bi weekly intervals for micro phytoplankton and water samples were carried out for a period of 2 years (July 2007–June 2009). Implementation of multivariate procedures like principal component analysis and multi dimensional scaling allowed us to enumerate the regulatory role of environmental variables in seasonal micro phytoplankton succession. The habitat water was slightly alkaline with variations in salinity from 4 to 17 psu. 25 micro phytoplankton taxa were recorded during the study period, with green algal dominance in summer and diatom dominance in winter. Seasonal changes in abundance and the diversity of micro phytoplankton population differed significantly, showing maximum diversity in autumn and minimum in winter. Species richness ranged from 7 to 16 with low inter annual variations. The study area represented a habitat where nutrients were optimally present with low micro phytoplankton cell counts. Distinct seasonal succession pattern was prevalent in the study area where nutrient concentrations, temperature and salinity played deterministic roles in regulating seasonal micro phytoplankton assemblages.

Seasonal Dynamics of Surface Micro Phytoplankton Assemblages in an Understudied Tropical Estuarine Station Along the Bhagirathi–Hooghly Estuary, India

Trentepohlia sundarbanensis is proposed new to science and is characterized by its cell dimensions, sporangial structure and branching pattern. The species was collected from the brackish water zone of Cheramatla Island (N 22°00.117’, E 088°42.608’), located in the Indian Sundarbans. The species grows on the bark of a halophytic mangrove plant, Avicennia alba. In this study the new species’ morphology and relationship with morphologically close species are discussed.

Trentepohlia sundarbanensis sp. nov. (Trentepohliaceae, Ulvophyceae, Chlorophyta), a new chlorophyte species from Indian Sundarbans

Floristic survey of microplanktonic cyanobacteria and chlorophyta from different ecological niches of West Bengal, India

In first inter-governmental conservation convention at Ramsar, it was decided to designate the important ecosystem throughout the world as ‘Ramsar Site’. Presently in India 26 such sites have been identified. One of which is East Calcutta Wetland (88°27’ E and 22°27’ N), principally used for sewage stabilization and fish production. This wetland had been found to harbor planktonic chlorophytes as the dominating flora controlling the productivity of the ecosystem (more than 90% of total population). Floristic pattern is an important indicator of an ecosystem as any change in plankton flora indicates the altered environmental condition. In the present investigation a thorough survey was carried out for 2 years (January 2012 to January 2014) for documentation and taxonomic identification of cholorophyte population of this important site. A total number of 61 taxa belonging to 17 different genera had been recorded. Among these 13 taxa belonging to 7 different genera such as, Scenedesmus (2 spp.), Desmodesmus (3 spp.) Tetraedron (3 spp.), Pediastrum (1 sp.), Stauridium (2 spp.), Chlorococcum and Kirchneriella, (1 spp. each) were designated as major taxa showing maximum variation in species diversity. Detail morphological studies of dominant taxa were also done with the help of Scanning Electron Microscopy (SEM).

An investigation on Morphotaxonomy and Diversity of Planktonic Chlorophytes from fresh water Eutrophic Wetland of Indian Ramsar Site

Influence of physical and chemical environment of a water body together with the growth pattern of individuals plays important roles in phytoplankton dynamics.

Ruma Pal

Papers

Seasonal Dynamics of Surface Micro Phytoplankton Assemblages in an Understudied Tropical Estuarine Station Along the Bhagirathi–Hooghly Estuary, India

Trentepohlia sundarbanensis sp. nov. (Trentepohliaceae, Ulvophyceae, Chlorophyta), a new chlorophyte species from Indian Sundarbans

Floristic survey of microplanktonic cyanobacteria and chlorophyta from different ecological niches of West Bengal, India

An investigation on Morphotaxonomy and Diversity of Planktonic Chlorophytes from fresh water Eutrophic Wetland of Indian Ramsar Site

Physicochemical Environment of Aquatic Ecosystem