Removal of Tannic Acid From Aqueous Solution by Cloud Point Extraction and Investigation of Surfactant Regeneration by Microemulsion Extraction

The aim of this work is the extraction of tannic acid (TA) with two commercial nonionic surfactants, separately: Lutensol ON 30 and Triton X-114 (TX-114).The experimental cloud point extraction results are expressed by four responses to surfactant concentration and temperature variations: extent of TA extraction (E), remaining solute (X s,w) and surfactant (X t,w) concentrations in dilute phase and volume fraction of coacervate (Φc) at equilibrium. An empirical smoothing method was used and the results are represented on three dimensional plots. In optimal conditions, the extraction extent of TA reaches 95 and 87 % using TX-114 and Lutensol ON 30, respectively. Sodium sulfate, cetyltrimethylammonium bromide (CTAB) addition and pH effect are also studied. Finally, the possibility of recycling of the surfactant is proved

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage

Adsorption Characteristics of Hg(II) on Humus-Kaolin Complex: Kinetics and Equilibrium

807-814The kinetics and equilibrium of the adsorption of Hg(II) by humic acid coated kaolin (HA-kaolin), a synthetic soil , are studied. The parameters studied are: pH, initial metal ion concentration, particle size of the HA-kaolin and temperature. The uptake of Hg(II) increases as the pH is increased and reaches a maximum of 82.8% for the initial concentration of 10 mg/L at pH 9.0. The applicability of external mass transfer and intraparticle mass transfer diffusion models has been investigated. The kinetic parameters such as mass transfer coefficient, diffusion coefficient and intraparticle rate constant as a function of initial metal concentration, particle size of the solid and temperature have been calculated for predicting the nature of adsorption. The intraparticle diffusion of metal ions through pores in the HA-kaolin is found to be the main rate limiting step. Temperature dependence indicates the endothermic nature of the process. The significance of the two linear relationships obtained by plotting the data according to the conventional Langmuir equation is discussed in terms of the binding energies of the two population sites involved which have a widely differing affinity for Hg(II) ions

<span style="font-size:12.0pt;font-family:"Times New Roman","serif"; mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-ansi-language: EN-IN;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">Influence of organic ligands on kinetics of adsorption of lead(II) by kaolin under various <i style="mso-bidi-font-style:normal">p</i>H conditions</span>

1029-1034Adsorption of lead(II) from aqueous solution in presence of nitrilotriacetic acid(NTA) and ethylenediaminetetraacetic acid(EDTA) by kaolin has been studied using the batch equilibrium method. The study shows that Pb(II) adsorption by kaolin at different concentrations of NTA and EDTA obeys multiple first-order kinetics. The rate constants of Pb(II) adsorption for both fast and slow processes in presence and absence of organic ligands at different <i style="mso-bidi-font-style: normal">pH values have also been determined. With increase in pH the adsorption of NTA and EDTA decreases. In the absence of organic ligands the rate constants of initial fast process were 18-27 times higher than the slow process in the pH range of 2.0 to 9.0. Maximum adsorption of organic ligands takes place at pH 2.0. NTA and EDTA have a significant promoting effect on the adsorption of Pb on to kaolin at pH 2.0 whereas the ligands have a significant retarding effect on the adsorption at pH 4.0 and 9.0. The kaolin surface carries a net positive charge at pH 2.0, thus negatively charged Pb-NT A or Pb-EDTA complexes can be readily adsorbed. Adsorbed NTA and EDTA at kaolin surface provide new adsorption sites for Pb(II) ions.</span

Sorption recovery of metal ions from aqueous solution using humus-boehmite complex

286-292Humic acid (HA) was immobilized on boehmite (AlOOH) by batch equilibration. Removal of Pb(II), Hg(II) and Cd(II) from aqueous solution was studied using the batch equilibrium method. Experiments were earned out as a function of pH and concentration of metal ions. It was shown that the maximum adsorption of 96.7 % for Pb(II) occurred at an optimum pH of 5.5 whereas the maximum adsorption of 91.7% for Hg(II) and 80.8% for Cd(II) was observed at pH 6.0. The adsorption of metal ion proceeds predominently by the cation-exchange mechanism. Adsorption isothermal data could be interpreted by the Langmuir and Freundlich isotherm equations. Langmuir and Freundlich constants have been determined . Adsorption experiments were carried out to investigate the competitive effect on the uptake of metal ions from binary mixtures. Sheindorf -Rebhun - Sheintuch (SRS) model was used to study the competitive interactions for the adsorption of Pb-Hg, Pb-Cd and Cd-Hg mixtures by the adsorbent

Phosphorus distribution in sediments of Edava-Nadayara and Paravur lake systems along the south west coast of India

186-191Total P in the sediments increase with increasing percentage of organic carbon and high correlation was seen in the retting zone. Total P concentration in the sediments ranges from 46:8 to 82 mu g-at.g(-1) in retting zone and from 28.4 to 49.8 mu g-at.g(-1) in non-retting zone of Edava-Nadayara and Paravur lake systems. Neither clay content nor calcium content appear to be significantly correlated with variation in total inorganic phosphorus content in the sediments of these lakes. CDB-P was found to be a major constituent of the sediment inorganic phosphorus reservoir in these lakes. Iron content was found to be significantly correlated with variation in NaOH-P in the lake sediments of non-retting zone

Tannin adsorption characteristics of bed sediments of Edava-Nadayara and Paravur backwater systems, southwest coast of India

37-42The adsorption behaviour of tannin was investigated under varying factors like, time of contact, pH, salinity and the presence of anions such as chloride, chlorate, nitrate, acetate, sulphate and phosphate. The removal of tannin by sediments was found to be pH and salinity dependent. Adsorption of tannin by sediments increases with clay content associated with the samples. Maximum adsorption of tannin was observed at pH 5.0. The percentage removal of tannin increases with increase in salinity. The data indicated that the presence of phosphate ions play an important role in retarding the adsorption of tannin by sediments and phosphate effectively competes with tannin for adsorption sites on sediments. The applicability of Langmuir and Freundlich isotherm models has been tested. Sediments from non-retting zone possessed higher adsorption capacity based on the Langmuir maxima