Tomasz Bajda and Zenon Kłapyta
Sorption of Chromate by Clinoptilolite Modified With Alkylammonium Surfactants
Clinoptilolite from Dylągówka (Poland) with an external cation exchange capacity (ECEC) of 16 meq/100 g determined by adsorption of alkylammonium ions was treated with hexadecyltrimethylammonium (C16) and dioctadecyldimethylammonium (2C18) bromides in amounts equivalent to 1.0 and 1.5 ECEC. The products were characterized using IR spectroscopy and C and N determinations. The sorption of chromate on the modified mineral was measured spectrophotometrically as a function of pH, concentration of Cr(VI) or the proportion of the sorbent to solution. The amount of chromate removed from the solution continuously decreased with increasing pH in the range 1.3-10. At pH 2.6-3.1, the maximum adsorption of Cr(VI) by the organo-zeolites (103 and 124 mmol/kg) was observed for the samples modified using a 1.5 ECEC surfactant concentration. Considerably lower adsorption values (37 and 46 mmol/kg) were obtained with sorbents prepared using a 1.0 ECEC concentration of the alkylammonium ions.
Tomasz Bajda, Tomasz Marchlewski and Maciej Manecki
Pyromorphite formation from montmorillonite adsorbed lead
The reaction of Pb-adsorbed montmorillonite with aqueous solutions of PO4 and Cl ions results in the decrease in phosphate concentration associated with the formation of a new phase - pyromorphite Pb5(PO4)3Cl. Pyromorphite crystals range in size from hundreds of nm to several tens of μm, depending on the PO4, K, and Ca concentrations in the reacting system. A strong ion-exchange effect of K+ and Ca2+ cations on desorption of Pb2+ from Pb-adsorbed montmorillonite was observed. Also, a high concentration of cations leads to a rapid desorption of Pb and the formation of fine pyromorphite crystals. In contrast, low PO4, K and Ca concentrations result in the formation of relatively large euhedral crystals. Final Pb concentrations are much lower in experimental sets than in control experiments with no phosphate present.
Piotr Turek, Tomasz Bajda and Maciej Manecki
Mimetite Pb5(AsO4)3Cl is the most insoluble lead arsenate mineral and could be used in remediation techniques to reduce As(V) mobility in soils. However, low-molecular-weight organic acids such as malic acid increase its solubility. The effect of malic acid on the dissolution of mimetite strongly depends on the pH of the equilibrium solution. At low pH, mimetite is decomposed mostly by the mechanism of protonation. With increasing pH, the solubility of mimetite decreases and a greater influence in its dissolution is ascribed to complexation of Pb(II) by organic ligands. During dissolution experiments, the amount of arsenic released to solution was > 26% higher in organic solutions than in inorganic solutions, and the amount of lead was > 8% greater. The solubility product of mimetite (KSP) was calculated in order to quantify the thermodynamic stability of the investigated mineral. The value obtained, i.e., -24.52 ± 0.49 fluctuates between the values of -21.69 ± 1.05 and -27.87 ± 0.42 reported in the literature.
Magdalena Wołowiec and Tomasz Bajda
In water treatment plants, a large amount of wastewater and sludge is generated during the processing of drinking water. The composition of the sludge is determined by the type and raw water chemistry, as well as the methods and materials used for purification. The major components of the sludge are iron and manganese oxyhydroxides. In the past, the sludge was landfilled, but for environmental reasons it became necessary to find uses for the sludge. The aim of this study was to identify examples of using this sludge. Nowadays, the sludge is applied in the treatment of municipal wastewater, agriculture, and the production of cement and bricks, among others. Attention was also paid to the possibility of using the water processing sludge in different sorption applications.
Urszula Janicka, Tomasz Bajda and Maciej Manecki
The bromide analogue of pyromorphite Pb5(PO4)3Br was synthesized and characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The solubility of the brompyromorphite was measured at 25°C and pH values of 2.0, 2.6 and 3.2. For the 3 pH measurements, the average solubility product, log KSP, for the reaction Pb5(PO4)3Br ⇔ 5Pb2+ + 3PO- 3- + Br- at 25ºC is -77.38 ± 0.70. The free energy of formation, ΔG°f,298, calculated from this measured solubility product is -3724.7 ± 4.3 kJ mol−1. These results confirm that brompyromorphite is more soluble than pyromorphite.
Agnieszka Grela, Michał Łach, Tomasz Bajda and Janusz Mikuła
In Poland, by 2020 430,000 Mg of hazardous waste will be formed annually by the combustion of waste. This waste must be properly managed so as not to endanger the environment. One promising way to manage selected waste is to process it in the synthesis of materials characterised by sorption properties. The results presented in this paper concern the possibility of producing sorbents from waste materials marked with codes 190112 and 190114, which came from two waste incineration plants in Poland. Alkaline activation was performed using two methods: a) hydrothermal, in a solution of 8 M NaOH at 75°C for 24 h; and b) in an autoclave, using a solution of 2 M NaOH at 140°C for 6 h. XRD analyses led to the identification of materials after synthesis of the following zeolite phases: analcime, chabazite and thomsonite. chabazite and analcime can be valuable absorbent materials.
Barbara Muir, Magdalena Wołowiec, Tomasz Bajda, Paulina Nowak and Piotr Czupryński
The use of zeolites as sorbents has been investigated as a replacement for existing costly methods of removing organic contaminants from water solutions. Zeolites can be modified by inorganic salts, organic surfactants, metals or metal oxides in order to increase their adsorption capacity. The unique ion exchange and adsorption properties of zeolites make them very suitable for application in the removal of organic compounds such as volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), phenols and other complex petrochemicals. Many different studies have demonstrated their effectiveness in reducing the concentrations of organic contaminants as well as petroleum derivatives in water, which has been summarized in this paper.
Krzysztof Gondek, Monika Mierzwa-Hersztek, Bożena Smreczak, Agnieszka Baran, Michał Kopeć, Tomasz Mróz, Paweł Janowski, Tomasz Bajda and Anna Tomczyk
The aim of this research was to determine the effect of thermal conversion temperature and plant material addition to sewage sludge on the PAHs content and the activity of selected γ-radionuclides in biochars, and to conduct an ecotoxicological assessment. The pyrolysis of the mixtures of sewage sludge and plant materials at 300°C and such temperature caused an increase in the contents of 2- and 3-ring hydrocarbons. During the pyrolysis of organic materials at 600°C, the amount of the following compounds was reduced in biochars: benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3c,d]pyrene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene. Among γ-radioisotopes of the elements, natural radiogenic isotopes were dominant. 137Cs was the only artificial radioactive isotope. The pyrolysis of the mixtures of municipal sewage sludge and plant materials revealed that isotope 40K had the highest radioactive activity. In the case of other analysed nuclides, activities of 212Pb, 214Pb, 214Bi, and 137Cs were determined after the sample pyrolysis. The extracts from the mixtures of sewage sludge and plant materials were non-toxic to Vibrio fischeri.