No abstract

Locally available apricot (Prunus armeniaca L.) shells classified as a waste product from fruit processing, were alkali activated in order to develop an efficient heavy metal ions sorbent for water purification. To examine the changes occurred after alkali treatment, raw (SH) and modified apricot shells (SHM) were thoroughly characterized in terms of their chemical composition and surface properties. Chemical analysis revealed that alkaline treatment causes the disintegration of hemicellulose (its content decreased from 19.2 to 3.5 %), which was in accordance with FTIR results. SEM micrographs and the mercury intrusion porosimetry revealed a larger surface area and porosity of SHM. Bohem's acid-base titration method indicated that the most of the SHM surface carboxylic groups were in sodium salt form and together with the pH of points of zero charge showed increase of surface alkalinity after modification. Treatment with NaOH enhanced the adsorption capacity by 154, 61 and 90 % for Cu 2+ , Zn 2+ and Pb 2+ , respectively. The amount of cations released from SHM was almost equal to the amount of adsorbed metal ions, suggesting ion exchange mechanism. The pseudo-second order kinetic indicated that the heavy metals cations were bound predominantly by complexation. In order to establish the effectiveness of the biosorbent in real wastewater sample, SHM was employed for cleaning-up of drain water emanating from atomic adsorption spectrophotometer. The SHM showed high removal efficiency towards multiple metal ions. The amounts of Fe, Pb, Cu and Cr ions were reduced by 97, 87, 81 and 80 %, respectively, while Ni and Zn amounts were reduced for 33 and 14 %. Used biosorbent SHM can be successfully regenerated with HCl (desorption > 95 %) and after regeneration biosorbent can be reused or it can be safely disposed.

No abstract

No abstract

BACKGROUND: Lead is one of the frequent contaminants of industrial wastewater. Since it has been shown that aquatic plants can be used for the removal of heavy metals, herein Pb(II) biosorption by Myriophyllum spicatum and its compost were investigated. Effects of pH, ionic strength and contact time were analyzed using a batch experiment. Biomasses were characterized chemically and by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques.

This work was undertaken to study the influence of soil type and its physical and chemical properties on uranium sorption and bioavailability, in order to reduce the uncertainty associated with this parameter in risk assessment models and safe food production. The tests were conducted on three types of Serbian soils: alluvium, chernozem, and gajnjaca, from which 67 samples were taken. Dominant factors of uranium mobilisation: the specific content of total/ available form of uranium and phosphorus, the degree of acidity (pH KCl ), and humus content and their correlation, were analysed. Content of available uranium form, according to the type of soil decreases in the following order: gajnjaca>alluvium>chernozem. It was found the medium correlation between pH values and available content of uranium in chernozem and gajnjaca, statistically significant at the level of significance of 99% and the alluvium at the level of significance of 95%. Correlation coefficients in all cases were negative, indicating that the reduction in pH increases the mobility of uranium and thus its availability for the adoption of the plants. Soil pH was the only dominant factor that significantly controlled the uranium value with no further significant contribution of other soil parameters.

-Introduction. Apricots (Prunus armeniaca L.) have an important role in Serbia's fruit production. Average annual production of 25,035 t generates approximately 1,577 t apricot stone (AS) waste and most of it ends up in landfill sites. In order to minimize the environmental impact, an investigation of the possible use of AS was done by developing a biosorbent for wastewater treatment. Materials and methods. AS waste from the fruit processing industry was used to remove Cu(II) ions from water solution by batch adsorption techniques. This solid waste residue was characterized by FTIR, SEM and EDX. The effects of pH, contact time, metal concentration and biosorbent dosage on the process of biosorption were studied. Results and discussion. Obtained FTIR results confirm that the uptake of Cu(II) ions from aqueous solution involves carboxylate moieties from lignin and fatty acids. Also, the presence of seeds in the AS blend significantly increased biosorption performance providing active sites important for the sorption process. The ion exchange mechanism was also confirmed. The best fitting adsorption model is the Langmuir model and the maximum biosorption capacity (q max ) is 4.45 mg L −1 at pH 5.0. Biosorption of the Cu(II) ions follows a pseudo secondorder kinetic model. According to thermodynamic parameters the biosorption process is endothermic and spontaneous. Conclusion. Numerous biosorbents were investigated for biosorption of Cu(II) ions from aqueous solution, but no report on application of untreated AS waste has been found in literature. This preliminary study confirmed that this material can successfully and rapidly remove dissolved copper ions from dilute solutions.Keywords: Serbia / apricot / Prunus armeniaca / waste management / biosorption / copper ions Résumé -Application des déchets de noyaux d'abricot issus de l'industrie agro-alimentaire à la dépollution : étude de la biosorption du cuivre. Introduction. L'abricot (Prunus armeniaca L.) tient une place importante dans l'économie de la Serbie. La production annuelle moyenne de 25 035 t génère environ 1 577 t de déchets de noyaux d'abricots (AS) dont la plus grande partie se retrouve dans des sites d'enfouissement. Afin de minimiser l'impact environnemental de ces déchets, une l'utilisation possible des AS a été envisagée, visant à développer un biosorbant pour le traitement des eaux usées. Matériel et méthodes. Les déchets AS provenant de l'industrie agro-alimentaire ont été utilisés pour éliminer les ions Cu (II) de solutions aqueuses par des techniques d'adsorption par lots. Le résidu des déchets solides a été caractérisé par spectroscopie infrarouge à transformation de Fourier (FTIR), microscopie électro-nique (SEM) et radioscopie à dispersion d'énergie (EDX). Les effets du pH, du temps de contact, de la concentration et du dosage du métal sur le biosorbant ont été étudiés au cours du processus de biosorption. Résultats et discussion. Les résultats obtenus par FTIR confirment que l'absorption des ions Cu (II) de la solution aqueuse met e...

In this study, raw corn silk was considered for the removal of cadmium ions from aqueous solutions. In order to improve adsorption characteristics, the KOH treatment was applied as a route to obtain modified materials. Both materials before and after metal adsorption were characterized by pHPZC, SEM-EDX and FTIR analysis. SEM images and FTIR spectra revealed that alkali modification caused some structural changes that could improve the adsorption properties of the investigated material. The experimental results and the ion-exchange study revealed that the biosorption process of cadmium ions on to raw and modified corn silk was caused predominantly by the ion-exchange mechanism, followed by chemisorption. The kinetic parameters implied that there are three stages in the biosorption process. In addition, the cadmium adsorption on both materials is very fast and is followed by the pseudo-second-order kinetic model. The experimental results were fitted by two and three parameter isotherm models, while the Sips isotherm model best describes the biosorption process on both materials. According to the Sips isotherm model, the maximum adsorption capacity of cadmium adsorbed on modified materials was 49.06 mg g−1, which is 2.23 times greater in comparison to the raw material (21.96 mg g−1). Furthermore, the mechanisms of cadmium adsorption onto the investigated materials are summarized in order to better understand the modification influence on the adsorption properties of corn silk. In order to examine reusability of the investigated material, diluted nitric acid was used for regeneration. A desorption study was performed in three adsorption-desorption cycles. A high desorption efficiency (˃85%) indicated that MCS after Cd adsorption can be efficiently recovered and reused for a new adsorption cycle.