Linda Eglite

Comparative study for separation of aquatic humic-type organic constituents by DAX-8, PVP and DEAE sorbing solids and tangential ultrafiltration: elemental composition, size-exclusion chromatography, UV-vis and FT-IR.

Aquatic humic-type solutes were separated in parallel from the same fresh water source by four different procedures: non-ionic polymethyl methacrylate (DAX-8) and functional cross-linked polyvinylpyrrolidone (PVP) resins, functional diethylaminoethyl cellulose (DEAE) and tangential ultrafiltration completed with a weakly basic anion exchange resin (IRA-67). The similarity-dissimilarity between the quantities and qualities of the different humic samples is discussed, especially in the light of the original dissolved organic matter (DOM). During the past two decades, a significant progress has occurred in the aquatic humic research due to the so-called hydrophobic-hydrophilic properties possessed by certain non-ionic sorbing solids. As a result of many coincidences, it may be justifiable to examine critically the prevailing isolation techniques of aquatic humic solutes and to try to update their complicated definitions. For that reason, it is reasonable to summarize the leading principles of different isolation techniques in Section 1 of this article. The results of the present study strongly support the applicability of the PVP resin, alone or completed in sequence with a suitable non-ionic sorbing solid, for isolation of aquatic humic-type solutes from both quantitative and qualitative points of view. In certain cases, the DEAE cellulose gives a useful alternative for conventional sorbing solids in the isolation of the bulk of aquatic humic solutes. The base-catalyzed ester hydrolysis of the HM during the chromatographic isolation of the DOM seems to be relative minor.

Sorption of humic substances on aquifer material at artificial recharge of groundwater

Experiments in batch equilibrium system were carried out to evaluate the importance of physical and chemical factors determining the sorption efficiency of humic substances (HS) on aquifer material, which has been used for artificial recharge of groundwater (ARG) in drinking water production. Results showed that an increase of the amount of clay in the aquifer material and a decrease of pH in water increased the sorption efficiency. The sorption of higher molecular weight, more hydrophobic and aromatic HS (Aldrich and forest soil humic acids) were greater than the sorption of acidic HS (river fulvic acids), either on the aquifer material or to its representative sorbing phases, clay and organic matter. The sorption on the aquifer material was largely due to physical sorption (hydrophobic attractions). This study showed the importance of HS composition on their removal during ARG and contributed to an understanding of the HS sorption mechanisms in this process.

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.

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.