Milovan Purenovic

Synthesis of composite by application of mixed Fe, Mg (hydr)oxides coatings onto bentonite--a use for the removal of Pb(II) from water.

The procedure for obtaining a bentonite based composite involves the application of mixed Fe and Mg hydroxides coatings onto bentonite particles in aqueous suspension and subsequent thermal treatment of the solid phase at 498 K. Structural and textural modifications of montmorillonite which occurred during the synthesis of composite were confirmed by XRD technique and N(2) adsorption at 77K. The composite structure was found to be less ordered, while its specific surface area was about two times higher than the specific surface area of the starting/native bentonite. The effectiveness of the composite in Pb(II) removal from aqueous solutions at different initial concentrations, pH and ionic strengths of the solutions was examined. The equilibrium adsorption data were analyzed using three widely applied isotherms: Langmuir, Freundlich and Dubinin-Radushkevich. The composite effectively removes both ionic and colloidal forms of Pb(II) from water and the maximum adsorption capacity obtained from the Langmuir equation was 95.88 mg/g. The main mechanisms of Pb(II) removal at low pH values were ion-exchange and outer-sphere surface complexation.

A direct potentiometric titration study of the dissociation of humic acid with selectively blocked functional groups

A direct potentiometric titration method was applied to commercial and soil humic acids in order to determine their carboxyl and phenol group concentrations and apparent and intrinsic pK. In that context, acid-base properties of humic acids are interpreted by selective blocking of carboxylic and phenolic groups by esterification and acetylation. Differences in underivatized and derivatized HAs acid-base properties are ascribed to carboxyl and phenol groups influence on total humic acidity. Potentiometric data were treated with the modified Henderson-Hasselbalch equation. Infra red results, the acidic group contents and the average values of apparent and intrinsic pK for underivatized and derivatized HAs confirmed the selectivity of esterification derivatization method. After blocking of the functional groups, the values of acidic group contents decreased, while the value of apparent pK increased after derivatization. Phenol groups cannot be specifically identified by the acetylation method, due to low selectivity of the acetylation method.

Comparison of new biosorbents based on chemically modified Lagenaria vulgaris shell

AbstractSorption characteristics of three Lagenaria vulgaris-based biosorbents: raw biomass (rLVB), acid–base-activated biomass (aLVB) and sulfuric acid-treated biomass (ccLVB), were compared as a function of contact time, initial methylene blue concentration, and initial pH, in order to evaluate the effect of chemical modifications. The adsorption studies of raw and chemically modified L. vulgaris biomass were compared in batch mode. The Fourier transform Infrared spectroscopy (FTIR) results of biosorbents’ characterization showed presence of different functional groups which can be responsible for sorption of MB from aqueous solutions. Moreover, FTIR analysis reveals that acid–base activation of raw biomaterial resulted in hydrolysis of esters providing more reactive sites (–COO−), while sulfuric acid-treatment method introduced new functional groups such as –SO3−. Surface functional groups containing oxygen, such as carboxylic, lactonic, and phenolic, are quantified using the Boehm’s method. The kineti...

INFLUENCE OF THE FLUORESCENT BRIGHTENER PERIBLANC BA ON THE DEGREE OF WHITENESS OF THE KNITTED COTTON FABRIC

In this study the influence of the different fluorescent brightener Periblanc BA concentrations on the degree of knitted cotton fabric whiteness was investigated. Two consecutive experimental runs were performed. The first was the bleaching of the knitted cotton fabric with hydrogen peroxide using the methods of two and single bath exhaustion while the second was the optical bleaching with fluorescent brightener Periblanc BA using the exhaustion method. CIE Whiteness Index and Tint value were measured on the Color-Eye 3000 spectrophotometer at the standard illuminant D65 (Ice-Texicon, d/8, D65/10°) while K/S values were determined using the Kubelka Munk equation. The results show that cotton fabric bleached with fluorescent brightener Periblanc BA after bleaching with hydrogen peroxide using two bath exhaustion method has higher degree of whiteness (118.8) with a reddish tint in comparison to the one bleached with hydrogen peroxide using single bath method (106.1).

MICROSTRUCTURE CHARACTERIZATION OF POROUS MICROALLOYED ALUMINIUM-SILICATE CERAMICS

Kaolinite and bentonite clay powders mixed with active additives, based on Mg(NO 3 ) 2 and Al(NO 3 ) 2 , sintered at high temperatures produce very porous ceramics with microcrystalline and amorphous regions and highly developed metalized surfaces (mainly with magnesium surplus). Microstructure investigations have revealed non-uniform and highly porous structure with broad distribution of grain size, specifically shaped grains and high degree of agglomeration. The ceramics samples were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction analysis (XRD) and IR spectroscopy analysis, prior and after treatment in “synthetic water”, i.e. in aqueous solution of arsenic-salt. Grain size distribution for untreated and treated samples was done with software SemAfore 4. It has shown great variety in size distribution of grains from clay powders to sintered samples.

Synthesis and characterization of resorcinol formaldehyde carbon cryogel as efficient sorbent for imidacloprid removal

AbstractCarbon cryogel (CC) has been prepared through sol gel polycondensation of resorcinol with formaldehyde in basic aqueous solution followed by freeze-drying and carbonization. Porous properties of CC analyzed by gravimetric McBain method confirmed the expected surface area and degree of mesoporosity. Obtained powdered material was used for the removal of pesticide imidacloprid from aqueous solutions under regular batch adsorption procedure. A set of several isotherm models including Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Brouers–Sotolongo, Redlich–Peterson, Sips, Toth, Jovanovic, Hurkins–Jura, Halsey and Radke–Prausnitz model was used for nonlinear fitting of equilibrium data. Several models fitted with quite high correlation coefficients. Bangham and Elovich model fitted suitably for kinetic study indicating that pesticide diffusion into carbons pores is important step which dictates the process rate. Suitability of kinetic models decreased with the increase in adsorbent dosage. Imidac...

The acid–base, morphological and structural properties of new biosorbent obtained by oxidative hydrothermal treatment of peat

Samples of natural peat (NP) were hydrothermally treated at different temperatures in oxidative and acidic aqueous medium to tailor their acid–base, adsorption, morphological and other properties. The obtained materials were thoroughly characterized by SEM, XRD and FTIR techniques, followed by determination of pHpzc, examination of adsorption characteristics and the extent of organic matter leaching in water. Acid–base characteristics of these materials were examined by potentiometric and conductometric titration of corresponding aqueous suspensions. Experimental potentiometric data were interpreted using ProtoFit software (NEM, non-electrostatic model) which provided pKa values and concentrations of surface sites which are compared with corresponding values obtained by conductometric titration method. There are two main types of surface groups (carboxylic and phenolic) that are dominant in the materials and determine their acid–base behavior in the aqueous medium. Temperature during oxidative hydrothermal treatment has no significant effect on the total number of surface groups, but influences the ratio of carboxylic and phenol-type groups. Hence, acid–base properties of peat can be tailored, which is useful in designing and improving adsorptive characteristics of peat for the preferential removal of certain pollutants from water.

New Composite Materials in the Technology for Drinking Water Purification from Ionic and Colloidal Pollutants

© 2012 Ranđelovic et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. New Composite Materials in the Technology for Drinking Water Purification from Ionic and Colloidal Pollutants