Linda Ansone

Use of peat-based sorbents for removal of arsenic compounds

AbstractIt is important to apply sorbent materials for purification of water from arsenic contamination due to serious arsenic pollution worldwide. We have developed new sorbents based on natural materials that provide a cheap and environmentally friendly alternative. For the first time, peat modified with iron compounds and iron humates were tested for sorption of arsenic compounds. The highest sorption capacity was found in peat modified with iron compounds. We have found that sorption of different arsenic speciation forms was strongly dependent on solution pH, reaction time and temperature. Calculations of the sorption process using thermodynamic parameters indicate the spontaneity of sorption process and its endothermic nature. Sorption kinetics showed that most arsenates are removed within 2 hours, and the kinetics of arsenate sorption on modified peat can be described by the pseudo-second order mechanism.

Reconstruction of past anthropogenic impact intensity in Lake Engure using sedimentary record analysis

Reconstruction of past anthropogenic impact intensity in Lake Engure using sedimentary record analysis Environmental pollution with trace elements is considered as one of the most important environmental problems. Analysis of trace element accumulation in sedimentary phases of lakes may reflect the overall regional pollution level, and analysis of trace element accumulation patterns in sediment profiles can help to reconstruct the history of anthropogenic impact. The aim of this study was to analyse trace element concentrations in sediments of Lake Engure in Latvia and to determine factors influencing their availability. The metal concentrations in sediments of Lake Engure are at background levels, especially compared with metal concentrations in West European countries. However, the change in element concentration in sedimentary profiles provides information about trends of recent accumulation (within the last 100 years) and on the balance between natural and human-induced accumulation processes. Antropogēnās ietekmes intensitātes rekonstrukcija Engures ezerā, izmantojot nogulumu sastāva analīzi Vides piesārņojums ar toksiskiem mikroelementiem ir viena no nozīmīgām vides problēmām. Mikroelementu uzkrāšanās ezeru nogulumos ļauj novērtēt vispārējos piesārņojuma līmeņus ezera sateces baseinā, bet metālu sadalījums nogulumu vertikālajā profilā atspoguļo cilvēka ietekmes mainības raksturu. Pētījuma mērķis ir analizēt mikroelementu koncentrāciju Engures ezera nogulumos un izvērtēt to saturu ietekmējošos faktorus. Salīdzinot ar mikroelementu koncentrāciju Rietumeiropas valstu ūdenstilpju nogulumos, metālisko elementu koncentrācijas Engures ezerā ir tuvu fona līmenim. Tomēr pētīto elementu koncentrāciju izmaiņas nogulumu profilā ļauj izvērtēt antropogēnās slodzes mainības raksturu pēdējo 100 gadu laikā un raksturot antropogēno un dabiski noritošo procesu mainības raksturu.

Behaviour of Nanomaterials in the Environment: A Study of Interaction between Humic Acids and Fullerene C60

Behaviour of Nanomaterials in the Environment: A Study of Interaction between Humic Acids and Fullerene C60 Interaction between buckminsterfullerene and humic substances of different origin was investigated using fluorescence spectrometry as function of concentration of humic substances, pH and ionic strength. Binding constants of humic substances and buckminsterfullerene were calculated. It can be suggested that the complexation was driven by hydrophobic interaction depending on properties of the interacting compounds. Hydrophobic interaction model was indicated by linear Stern-Volmer plot, and high Kd values characterized interaction between buckminsterfullerene and humic acids. The results of this study support the development of understanding of fate of nanomaterials in environment as well as development of analytical techniques for nanomaterials in water and wastewater treatment approaches. Nanomateriāli Vidē: Mijiedarbības Izpēte Starp Humusvielām un Fullerēnu C60 Mijiedarbība starp bukminsterfullerēnu un dažādas izcelsmes humusvielām pētīta, izmantojot fluorescences spektrometriju, atkarībā no humusvielu koncentrācijas, šķīduma pH un jonu spēka. Aprēķinātas fullerēna - humusvielu kompleksveidošanās konstantes. Domājams, ka reakcijas pamatā ir hidrofoba mijiedarbība, ko nosaka reagējošo vielu īpašības. Šterna-Volmera grafika line-aritāte norāda uz hidrofobo mijiedarbību, un augstās Kd vērtības raksturo mijiedarbību starp bukminsterfullerēnu C60 un humīnskābēm. Šī pētījuma rezultāti var tikt izmantoti, lai izprastu nanomateriālu izturēšanos vidē, kā arī nano-materiālu pētījumu analītisko metožu attīstībai ūdens un notekūdeņu attīrīšanas procesiem.

Removal of arsenic compounds with peat, peat-based and synthetic sorbents / Usuwania związków arsenu za pomocą torfu, sorbentów na bazie torfu i sorbentów syntetycznych

Abstract Arsenic contamination of waters is a global problem; therefore, new approaches for its removal are needed. Peat, peat modified with iron compounds, iron humates and polymeric cation exchangers modified with iron were prepared and tested for sorption of arsenic compounds in comparison with weakly basic anionites. The highest sorption capacity was observed when peat sorbents modified with iron compounds were used. Sorption of different arsenic speciation forms onto iron-modified peat sorbents was investigated as a function of pH and temperature. It was established that sorption capacity increases with a rise in temperature, and the calculation of sorption process thermodynamic parameters indicates the spontaneity of sorption process and its endothermic nature. Abstrakt Skażenie wód arsenem jest problemem globalnym, dlatego potrzebne są nowe sposoby jego usuwania. Zbadano sorpcję związków arsenu przez torf, torf modyfikowany związkami żelaza, sole żelaza i kwasów humusowych oraz polimerowe kationity modyfikowane żelazem. Wyniki porównano z sorpcją związków arsenu przez anionity słabo zasadowe. Najwyższą wydajność sorpcji zaobserwowano dla torfowych sorbentów modyfikowanych związkami żelaza. Badano sorpcję różnych form specjacyjnych arsenu na sorbentach na bazie torfu modyfikowanych żelazem, w zależności od pH i temperatury. Stwierdzono wzrost pojemności sorpcyjnych tego materiału wraz ze wzrostem temperatury. Obliczone parametry termodynamiczne procesu sorpcji wskazują na samorzutność tego procesu i jego endotermiczność.

Arsenic Sorption onto Peat and Iron Humates

Environmental pollution with arsenic is a global problem; therefore, new remediation methods are needed. Peat modified with iron compounds and iron humates were prepared and tested for sorption of arsenic compounds. The highest sorption capacity was observed when iron-modified peat was used. Sorption of different arsenic speciation forms onto iron-modified peat sorbents was investigated as a function of pH, reaction time and temperature. Sorption capacity increases with temperature and was spontaneous and endothermic.