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The removal of Congo red dye from an aqueous solution using perlite, a volcanic siliceous rock, as a low cost adsorbent was studied. Adsorption experiments were carried out as batch studies at different adsorbent dose, pH, temperature and initial dye concentration. The dye adsorption equilibrium was rapidly attained after 40 min of contact time. The adsorbent was characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Langmuir and Freundlich isotherms were studied for the adsorption data over a concentration range of 20 to 100 mg/L. The thermodynamic parameters such as entropy of adsorption (DS 0 ), enthalpy of adsorption (DH 0 ) and Gibbs free energy of adsorption (DG 0 ) were obtained and analyzed. Kinetic studies showed that the adsorption process obeyed the pseudo first order kinetic model. The dimensionless separation factors (R L ) showed that perlite could be used to remove Congo red from an aqueous solution.

Nymphaea rubra stem was used as a low cost and easily available biosorbent for the removal of Reactive Red 2 dye from an aqueous solution. Initially, the effects of biosorbent dosage (0.2 -1.0 g L -1 ), pH (1 -6), and dye concentration (30 -110 mg L -1 ) on dye removal were studied. Batch experiments were carried out for biosorption kinetics and isotherm studies. The results showed that dye uptake capacity was found to increase with a decrease in biosorbent dosage. Equilibrium uptake capacity was found to be greatest at a pH value of 2.0, when compared to all other pH values studied. The equilibrium biosorption isotherms were analyzed by the Freundlich and Langmuir models. The equilibrium data was found to fit very well with the Freundlich isotherm model when compared to the Langmuir isotherm model. The kinetic data was analyzed using pseudo-first order and pseudo-second order kinetic models. From the results, it was observed that the kinetic data was found to fit the pseudosecond order kinetic model very well. The surface morphology of the stem of the N. rubra biosorbent was exemplified by scanning electron microscopy. Fourier transform infrared analysis was employed to confirm the existence of an amine group in the stem of N. rubra.

Equilibrium Uptake and Bioaccumulation of Basic Violet 14 Using Submerged Macrophyte Hydrilla verticillataThe percentage removal and uptake capacity of Basic Violet 14 using Hydrilla verticillata with living biomass was studied under batch conditions. The survival of H. verticillata was studied using the chlorophyll content in the living biomass. Bioaccumulation of Basic Violet 14 using H. verticillata was tested by varying the wet sorbent dosage (0.5-2.5 g), initial pH (3-8), and initial dye concentrations (5-25 mg L À1 ). The results show that the plant was effectively accumulating the Basic Violet 14 dye. The uptake capacity of Basic Violet 14 dye was observed as 5.9 and 21.3 mg g À1 at the initial dye concentration of 5 and 25 mg L À1 , respectively, for a biomass of 5 g L À1 (wet weight) at pH 7.0 for 144 h. In general, the plant growth was found to be normal at lower concentrations and showed higher removal efficiency. It was also observed that removal efficiency of H. verticillata was found to decrease with increase in initial dye concentration. The biomass sample surface was analyzed using SEM imaging and functional groups present in the biomass were analyzed using FTIR. The equilibrium uptake capacity was analyzed by Langmuir and Freundlich isotherms. The equilibrium data was found to be fit well to both Langmuir and Freundlich isotherm models with higher coefficient of determination. In the last decades, the use of phyto-technologies has become an effective alternative method for the remediation of contaminated water systems [5]. Phytoremediation is defined as the use of plants, both terrestrial and aquatic; to absorb, concentrate, and precipitate contaminants from polluted aqueous sources with low contaminant concentration in their roots [6]. The U.S. Environmental Protection Agency (EPA) seeks to protect human health, environment associated with hazardous waste sites, and encourages the development of innovative technologies such as phytoremediation to clean up hazardous sites [7].Most of the work has been already established on the accumulation of heavy metal using plant such as Hydrilla verticillata for cadmium accumulation [8], Pistia stratiotes for arsenate uptake [9], Wolffia globosa for an indicator of metal pollution in the water bodies [10], P. stratiotes for lead uptake [11]. Only limited work has been established for the removal of textile dyes using living aquatic plant. In this present study, H. verticillata was used as living biomass for the accumulation of basic dye from synthetic dye solution.Basic dyes are salts of the colored organic bases containing amino and imino groups and also combined with a colorless acid, such as hydrochloric or sulfuric acid. They are brilliant and most fluorescent among all synthetic dyes. Basic Violet 14 was selected as a model compound to estimate the accumulation capacity of H. verticillata. It is a submerged plant, and it has been observed to grow luxuriantly in various contaminated water bodies of India [12]. H. verticillata has attracted the attention ...

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Groundwater quality in Chennai city along the Cooum river, during the premonsoon (June–July) and postmonsoon (Dec–Jan) for three years, from 2009 to 2011, was analyzed. Groundwater samples were collected from 20 bore wells on either side of the river. The analysis focused on the determination of seven specific water quality parameters, namely, pH, EC, TDS, BOD, COD, Na and Pb, using standard procedures. The statistical analysis, like the mean and standard deviation, coefficient of variance, and correlation, and multilinear regression analysis of the obtained data were carried out. The analysis of the collected samples reveals that the stated water quality parameters have not complied with the WHO standards, and the water is not fit for drinking and domestic purposes. The correlation and multilinear regression analyses suggest that the conductivity has a significant correlation with the other six considered water quality parameters.

The present work reports the dispersion of multiwalled carbon nanotubes (MWCNTs) in water using a short chain carboxyl-tailed ionic liquid (IL), 1-carboxymethyl-3-methyl imidazolium tetrafluoroborate ([cmmim][BF4]), as an IL-based hydrophilic surfactant, instead of long-chain hydrophobic ILs. MWCNTs can be dispersed effectively in the aqueous solution of [cmmim][BF4] due to their molecular structure, including one imidazolium ring head group and one carboxyl group with fewer hydrophobic chains. The resulting MWCNT suspensions are stable for more than a month, and no precipitation is observed. The transmission electron microscopy results showed that the structural integrity of MWCNTs did not deteriorate because of their dispersal in water. Ultraviolet–visible–near infrared spectral studies confirm the presence of IL molecules onto the surface of the MWCNTs. X-Ray photoelectron spectroscopy and Fourier transform Raman studies confirmed the cation–π or π–π interactions between the MWCNTs and IL molecules, which makes the suspension of MWCNTs more stable.