Changes in growth and phycocolloid content of Gelidiella acerosa and Gracilaria edulis

Results obtained on seasonal growth, yield and physical properties of agar in Gelidiella acerosa and Gracilaria edulis for a period of one year are presented. Vegetation of these two species occurred throughout the year with two peak growth periods

Seasonal changes in growth & alginic acid & mannitol contents in Sargassum ilicifolium (Turner) J. agardh & S. myriocystum J. agardh

Young plants of S. ilicifolium and S. myricosystum appear in April and May and reach the maximum size in September or October. Alginic acid yield varies with the seasonal growth behaviour of these alginophytes. with maximum yield in July or August. Alginic acid content varies from 22.3 to 30.8% in S. ilieifolium and from 15.9 to 34.5% in S. myriocyslum. Mannitol content ranges from 2 to 5 and 1.3 to 5% in S. jlicifolium and S. myriocysmm respectively. The suitable harv.esting period for getting the maximum yidd of algin ic acid appears to be between July and September

Seaweed culture - its feasibility and industrial utilization

Culture of seaweeds is practiced since ages in countries such as Japan, China and Korea. Seaweed cultivation is an industry in Japan as a part-time avocation for land farmers and fishermen. The seaweeds cultured mainly in these countries are Porphyra, Undaria, Laminaria, Enteromorpha and Monostroma. In India seaweed culture is yet to develop on commercial lines. While the demand for these seaweeds is for food purposes in foreign countries, their demand in India is for the extraction of two phytochemicals namely agar-agar and algin. In recent years many factories manufacturing these chemicals have come up in India as a consequence of which the demand for the agarophytes and alginophytes has gone up. In order to maintain a continuous supply of this raw material to the industry, methods to augment the supplies through culture practices have to be developed

Seaweeds

Research works oti various aspects of seaweeds have been caried out since last five decades. They inchide resources survey, studies on distribution, Uixonomy, ecology, biology, phycocolioids, biochemicals, culture and utilisation of marine algae growing in Tamil Nadu, Kercda, Lakshadwe^p and Andaman-Nicobar Islands. Information was also gathered since 1978 on the quantity of seaweeds commercially exploited from the natural seaweed beds occurring in Tamil Nadu coast. The results obtained on these aspects are reviewed in this paper. The prospects of seaweed research, industry and utilisation in India are also briefly described

Removal and degradation of mixed dye pollutants by integrated adsorption-photocatalysis technique using 2-D MoS2/TiO2 nanocomposite

Two-dimensional (2D) Molybdenum disulfide (MoS2) has become one of the most exciting areas of research for adsorbents due to its high surface area and abundant active sites. Mainly, 2D MoS2 show promising removal of textile dye pollutants by adsorption process, but it show high affinity for anionic type of dyes, that limits its performance in mixed dye pollutants treatment. Herein, we demonstrate an integrated approach to remove mixed dye pollutants (anionic and cationic) concurrently by combining adsorption and photocatalysis process. We synthesize MoS2/TiO2 nanocomposites for different weight percentages 2.5, 5, 10, 20, 30 and 50 wt% of pre-synthesized flower-like MoS2 nanoparticle by a two-step hydrothermal method. We demonstrate a new process of two-stage adsorption/photocatalysis using high wt% of MoS2 (Stage-I) and low wt% of MoS2 (Stage-II) nanocomposites. The proposed two-stage integrated adsorption and photocatalysis process using 50% and 2.5% of MoS2 coated TiO2, respectively showed complete removal of methylene blue dye ∼5 times faster than conventional single-stage (adsorption or photocatalysis) water treatment process. Furthermore, the feasibility of the proposed two-stage method in mixed dye pollutants removal (anionic and cationic) testified, which showed excellent performance even in doubling the dye pollutant concentration. This work brings a deeper insight into understanding the morphology and concentration of 2-D MoS2 in MoS2/TiO2 nanocomposite in tackling mixed dye pollutants and the possibilities of applying in textile dyeing industries wastewater treatment plants

Alginic acid and mannitol contents in relation to Growth in Stoechospermum marginatum (C. Agardh) Kuetzing

Results obtaiined on the yield of alginic acid and mannitol contents of Stoechospermum marginatum carried out for one ye:ir during 1976 are presented. Young plants of S. marginatum appeared from May and June and reached harvestable size in September. The yield of alginx acid and ni'tnnitol was found to be lower than Sargassum and Turbinaria spp. The alginic add content was found to be high during the months September to Decemiber. Alginic acid content varied from 14.5 to 23.8% and the mannitol content Vc^ied from 1.2 to 2.7%

Ultrafast epitaxial growth of CuO nanowires using atmospheric pressure plasma with enhanced electrocatalytic and photocatalytic activities

This work reports an environment friendly alternative to epitaxially grow copper oxide nanowires (NWs) on copper substrates using single step atmospheric pressure plasma jet assisted oxidation. NWs of average length 300 nm are grown rapidly in 5 minutes along with transforming the surface to superhydrophilic. This method introduces defects in the nanowire structure which is otherwise difficult to achieve due to the highly isotropic nature of nanowire growth. High resolution transmission electron microscopy reveals vacancies and structural defects such as lattice twinning and kinks. Theoretical investigations using density functional theory calculations indicated that oxygen vacancies reduces the adsorption energy of methanol molecules onto the CuO (111) surface and shifts the Fermi level towards conduction band. During electrocatalysis, these defect-rich nanowires exhibit twice the catalytic activity toward oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) in comparison to the traditionally thermally grown nanowires. Moreover, retreating the electrodes after each stability test drops the contact resistance similar to the prisitine sample. Additionally, these NW photocathodes demonstrate an exceptional photocurrent of 2.2 mAcm–2 and have an excellent degradation activity towards organic pollutants namely phenol and paracetamol. This facile growth method can be used to engineer nanowires of other transition metals with enhanced activities

Chemical composition of seaweeds

Considerable work has been done on the chemical aspects of Indian seaweeds during the last three decades, of which those up to 1970 have been reviewed by Umamaheswara Rao (1970). In this chapter the information so far collected on the mineral constituents, carbohydrates and other chemicals is presented

Seaweed culture

Seaweed culture has perforce to be adopted should the supply of raw material to Industries be uninterrupted ,like in the case of the Japanese and Korean Porphyra industries, the Chinese Laminaria industry and the Philippines Eucfieuma Industry, which are now in the main based on cultured raw material. The culture is at present almost entirely confined to the Orient, reaching its peak of sophistication in Japan and China. The necessity of marine algal cultivation in India and the principles and problems involved therein are discussed by Thivy (1964), Krishnamurthy( 1967) and Chennubhotia (1976)

Doped MXenes—A new paradigm in 2D systems: Synthesis, properties and applications

Since 2011, 2D transition metal carbides, carbonitrides and nitrides known as MXenes have gained huge attention due to their attractive chemical and electronic properties. The diverse functionalities of MXenes make them a promising candidate for multitude of applications. Recently, doping MXene with metallic and non-metallic elements has emerged as an exciting new approach to endow new properties to this 2D systems, opening a new paradigm of theoretical and experimental studies. In this review, we present a comprehensive overview on the recent progress in this emerging field of doped MXenes. We compare the different doping strategies; techniques used for their characterization and discuss the enhanced properties. The distinct advantages of doping in applications such as electrocatalysis, energy storage, photovoltaics, electronics, photonics, environmental remediation, sensors, and biomedical applications is elaborated. Additionally, theoretical developments in the field of electrocatalysis, energy storage, photovoltaics, and electronics are explored to provide key specific advantages of doping along with the underlying mechanisms. Lastly, we present the advantages and challenges of doped MXenes to take this thriving field forward