Removal of EDTA from Aqueous Solutions Using Activated Carbon Prepared from Rubber Wood Sawdust: Kinetic and Equilibrium Modeling

Adsorptive removal of EDTA (ethylenediaminetetraacetic acid) from aqueous solution was studied using steam pyrolyzed activated carbon. Rubber wood sawdust, obtained from a local timber facility at Kodangavila, Trivandrum, Kerala, India was used as the precursor for the production of the activated carbon. Batch adsorption experiments were employed to monitor and optimize the removal process. The experimental parameters, i. e., solution pH, agitation time, initial EDTA concentration and adsorbent dosage, affecting the adsorption of EDTA onto sawdust activated carbon (SDAC) were optimized. The inner core mechanism for the interaction between EDTA and SDAC, which resulted in the adsorption process, was also discussed. The change in amount of EDTA adsorbed onto SDAC and CAC (commercial activated carbon) was compared over a wide range of pH (2.0–8.0). The maximum removal of EDTA took place in the pH range of 4.0–6.0 for SDAC and 5.0–5.5 for CAC, which demonstrates the effectiveness of the former adsorbent. Kinetic as well as equilibrium studies were performed to determine the rate constant and adsorption capacity, respectively. The adsorption kinetic data was fitted with pseudo‐first‐order kinetics and the equilibrium data was shown to follow the Langmuir isotherm model. These observations explain the formation of a monolayer of EDTA on the surface of SDAC as confirmed by the slow approach to equilibrium after 4 h of contact time. The adsorption capacity of SDAC for the removal of EDTA was 0.526 mmol/g and is seen to be greater than that of CAC and other reported adsorbents (0.193–0.439 mmol/g). Finally, it is clear that the production of steam pyrolyzed activated carbon in the presence of K₂CO₃ greatly enhanced EDTA removal and resulted in a product with possible commercial value for wastewater treatment strategies.     

Rapid visual screening of different housing typologies in Himachal Pradesh,India

Natural Hazards - Methods capable of assessing the vulnerability of houses for future earthquakes are of fundamental importance for the safety and development of an area. As the detailed assessment...     

A study on reflection pattern of swells from the shoreline of peninsular India

Information on reflected surface gravity waves from the shoreline is required for understanding the coastal hydrodynamics. We have quantified the reflected swells (frequency band 0.045–0.12 Hz) from the west and east coast of India based on the spectral wave data derived from the directional waverider buoys. Reflection coefficient, ratio of the reflected and incident spectral energy, was used to quantify the reflected waves. Influence of the seasons, cyclone, relative depth, land/sea breeze, tides and tidal current on the reflected waves were examined. For the locations off the west coast of India, seasons have large impact on the reflection coefficient and were relatively less during the monsoon season due to the increase in incident wave energy. Locations off the east coast of India show almost the same reflection coefficient throughout the year and have no significant seasonal variations. The reflection coefficient off Puducherry was higher than that for other locations due to the low incident wave energy. The reflection coefficient was low during the cyclone period, but the reflected energy during cyclone was higher than that during the normal condition due to the high incident wave energy. High-energy reflected waves show large variation with tide due to the trapping and dissipation of reflected wave by bottom friction and this effect cause low reflection in deep water location than shallow water location. The reflection coefficient decreases with increase in relative depth off west coast of India.     

Heavy metal accumulation in the surficial sediments along southwest coast of India

Concentration and distribution of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) in surface sediments collected from five stations located along the southwest coast of India were investigated seasonally to assess whether there is insidious buildup of heavy metals. Spatial variation was in accordance with textural characteristics and organic matter content. The concentration of the metals in sediments of the study area followed the order: Zn > Cr > Ni > Cu > Pb > Cd > Hg. The use of geochemical tools and sediment quality guidelines to account for the magnitude of heavy metal contamination revealed high contamination in monsoon and impoverishment during post-monsoon. Estimated total metal concentrations in the present investigation were comparable with other studies; however, concentrations of Ni and Zn were higher than that of other coastal regions. Concentrations of metals in sediment largely exceed NOAA effects range:low (e.g., Cu, Cr, Hg) or effects range:median (e.g., Ni) values. This means that adverse effects for benthic organisms are highly probable.