Paavo Perämäki

Micellar-enhanced ultrafiltration for the removal of cadmium and zinc: use of response surface methodology to improve understanding of process performance and optimisation.

In this study, removal of cadmium and zinc from their respective water samples was conducted by micellar-enhanced ultrafiltration (MEUF), using sodium dodecyl sulfate (SDS) as the surfactant. Response surface methodology (RSM) was used for modelling and optimising the process, and to gain a better understanding of the process performance. Face Centred Composite (CCF) Design was used as the experimental design. The factors studied were pressure (P), nominal molecular weight limit (NMWL), heavy metal feed concentration (C(Zn), C(Cd)) and SDS feed concentration (C(SDS)). Using RSM the retention of heavy metals was maximized while optimising the surfactant to metal ratio (S/M). Response surface plots improved the understanding the effect of the factors on permeate flux. Concentration polarisation was negligible and therefore, high NMWL membranes with high pressure provided high flux with negligible effect on the retention of heavy metals. The optimal conditions of zinc removal were C(SDS)=13.9 mM, C(Zn)=0.5 mM, NMWL=10 kDa and P=3.0 bar, and for cadmium removal C(SDS)=14.2 mM, C(Cd)=0.5 mM, NMWL=10 kDa and P=3.0 bar. The retentions achieved were 98.0+/-0.4% for zinc and 99.0+/-0.4% for cadmium. To improve resource efficiency, the surfactant was reclaimed after use; 84% of the initial SDS was recovered by precipitation.

Chemical and physical properties of cyclone fly ash from the grate-fired boiler incinerating forest residues at a small municipal district heating plant (6 MW)

In Finland, the new limit values for maximal allowable heavy metal concentrations for materials used as an earth construction agent came into force in July 2006. These limit values are applied if ash is utilized, e.g. in roads, cycling paths, pavements, car parks, sport fields, etc. In this study we have determined the most important chemical and physical properties of the cyclone fly ash originating from the grate-fired boiler incinerating forest residues (i.e. wood chips, sawdust and bark) at a small municipal district heating plant (6 MW), Northern Finland. This study clearly shows that elements are enriched in cyclone fly ash, since the total element concentrations in the cyclone fly ash were within 0.2-10 times higher than those in the bottom ash. The total concentrations of Cd (25 mg kg(-1); d.w.), Zn (3630 mg kg(-1); d.w.), Ba (4260 mg kg(-1); d.w.) and Hg (1.7 mg kg(-1); d.w.) exceeded the limit values, and therefore the cyclone fly ash cannot be used as an earth construction agent. According to the leached amounts of Cr (38 mg kg(-1); d.w.), Zn (51 mg kg(-1); d.w.) and sulphate (50,000 mg kg(-1); d.w.), the cyclone fly ash is classified as a hazardous waste, and it has to be deposited in a hazardous waste landfill.

Thermal and infrared spectroscopic characterization of historical mortars

Abstract The characterization of historical mortars was performed by thermal analysis (TG-DTG), simultaneous infrared spectroscopy (TG-FTIR) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The samples were taken from St. John Church (Tartu, Estonia), built in the 13th–14th centuries. The analyses are important for the restoration of the church. In reality, mortar is a very difficult system, the lime is accompanied with different hydraulic components. TG-DTG analysis and FTIR methods can be used to identify various components of mortar and to observe the reactions associated with the controlled heating at 25–900°C in dynamic air and nitrogen atmosphere. The elemental composition of the acid-soluble components (ASC) was determined by using the ICP-AES techniques.

The 800 year long ion record from the Lomonosovfonna (Svalbard) ice core

We present a high-resolution record of water-soluble ion chemistry from a 121 m ice core spanning about 800 years. The core is well dated to 2/3 depth using cycle counting and reference horizons and a simple but close fitting model for the lower 1/3 of the core. This core suffers from modest seasonal melt, and so we present concentration data in decadal running means to minimize percolation effects. Sea-salt ions (Na+, Cl−, Mg2+, and K+) account for more than 70% of all ions. In general, sea-salt ion concentrations are rather variable and have no clear association with climatic variations. Sulfate, with 74% being from non-sea-salt sources, has higher concentrations than seen on Vestfonna ice cap but lower than in Ny-Alesund aerosols, suggesting central Spitsbergen receives more marine (westerly) air masses than Ny-Alesund but more sulfate enriched (easterly) air masses than Nordaustlandet. Clear anthropogenic impacts are found for sulfate, nitrate, and ammonium (and probably excess chloride) after the mid twentieth century, with sulfate showing a significant rise by the end of the nineteenth century. Sulfate and methanesulfonate concentrations correlate well during the twentieth century, and it is clear that most of the preindustrial sulfate is of biogenic origin. Terrestrial component (Ca2+) has the highest concentrations in the coldest part of the Little Ice Age, suggesting more windy conditions, transporting local terrestrial dust to the ice cap. All ion concentrations decrease at the end of the twentieth century, which reflects loss of ions by runoff, with non-sea-salt magnesium being particularly sensitive to melting.

Simple procedure for ion chromatographic determination of anions and cations at trace levels in ice core samples

Several suppressed and non-suppressed ion chromatography (IC) elution systems were compared for the determination of ng ml ˇ1 levels of major cations and anions, including formate and methyl sulphonate, in ice core samples using a small (0.2‐ 0.8 ml) sample volume. The use of a suppression unit considerably enhanced the sensitivity of the anion determinations, but had no remarkable effect on the sensitivity of the cation determinations. Optimized analytical conditions were further validated in terms of accuracy, precision and total uncertainty and the results showed the reliability of the IC methods. In addition, contamination problems associated with handling the ice core were investigated, and a simple and almost contamination free ice handling procedure is presented. # 1999 Elsevier Science B.V. All rights reserved.

The Icelandic Laki volcanic tephra layer in the Lomonosovfonna ice core, Svalbard

The largest sulphuric acid event revealed in an ice core from the Lomonosovfonna ice cap, Svalbard, is associated with the densest concentration of microparticles in the ice core at 66.99 m depth. Electron microscope analysis of a volcanic ash particle shows it has the same chemical composition as reported for debris from the eruption of Iceland’s Laki fissure in 1783 and confirms the identification of the tephra. Most of the particles in the deposit are not ash, but are common sand particles carried aloft during the eruption event and deposited relatively nearby and downwind of the long-lasting eruption. The tephra layer was found 10 - 20 cm deeper than high sulphate concentrations, so it can be inferred that tephra arrived to Lomonosovfonna about 6 - 12 months earlier than gaseous sulphuric acid precipitation. The sulphuric acid spike has a significant cooling impact recorded in the oxygen isotope profile from the core, which corresponds to a sudden drop in temperature of about 2 °C which took several years to recover to previous levels. These data are the first particle analyses of Laki tephra from Svalbard and confirm the identification of the large acidic signal seen in other ice cores from the region. They also confirm the very large impact that this Icelandic eruption, specifically the sulphuric acid rather than ash, had on regional temperatures.

Leachability of metals in fly ash from a pulp and paper mill complex and environmental risk characterisation for eco-efficient utilization of the fly ash as a fertilizer

Abstract A five-stage, sequential leaching procedure was used to determine the distribution of metals (Cd, Cu, Pb, Cr, Zn, Ni, Co, As, V, Ba, Ti and K) in fly ash from a pulp and paper mill complex between the water-soluble fraction (H2O), exchangeable fraction (CH3COOH), easily reduced fraction (HONH3Cl), oxidizable fraction (H2O2.CH3COONH4), and the residual fraction (HF+HNO3+HCl). The possible environmental risk associated with the eco-efficient utilization of fly ash as a fertilizer, especially the Cd load, was estimated. In addition, the mobility (i.e. bioavailability) of Cd, Cu, Pb, Zn, Ni and Cr was evaluated. The fly ash was derived from an electrostatic precipitator of a fluidized bed boiler in the co-combustion (55% bark and wood residues,45% peat) process at pulp and paper mill in Northern Finland. The accuracy of the leaching procedure was tested using a certified reference material SRM 1633b (Coal Fly Ash). The metals were determined by graphite furnace atomic absorption spectrometry (GFAAS) or by inductively coupled plasma atomic emission spectrometry (ICP-AES). The mobility factors (i.e. bioavailability) of the metals followed the order: Cd, Cu, Zn, Ni, Pb and Cr. The fly ash from the pulp and paper mill was enriched in Ca, Mg, P and K, and could therefore be used as a soil amendment for liming purposes.

Analysis of archaeological samples and local clays using ICP-AES, TG–DTG and FTIR techniques

The spectrochemical and thermal analysis of different archaeological samples as bricks, terra-cotta and local clays were carried out. The concentration of major and minor elements of samples was determined by sequential inductively coupled plasma atomic emission spectrometry. The method was tested by determining Si, Al, Fe, Ca, Mg, Mn, Pb, Cu, Zn, Ti, Na and K in the standard solutions and reference material GXR-4. The precision of the determination (relative standard deviation) ranged from 0.4 to 1.54%. The clay minerals are the main materials for the production of bricks and terra-cotta figures. Thermogravimetric (TG) and differential (TG-DTG) analysis and Fourier transform infrared spectrometry (FTIR) methods can be used for the study of characteristic reactions, associated with the course of the heating. The TG-DTG curves were obtained in the temperature range 25-900 degrees C, and the dynamic experiment was carried out in the air and nitrogen atmosphere. The infrared evolved gas analysis was performed using FTIR in the dynamic nitrogen atmosphere.

Determination of low methylmercury concentrations in peat soil samples by isotope dilution GC-ICP-MS using distillation and solvent extraction methods

Most often, only total mercury concentrations in soil samples are determined in environmental studies. However, the determination of extremely toxic methylmercury (MeHg) in addition to the total mercury is critical to understand the biogeochemistry of mercury in the environment. In this study, N2-assisted distillation and acidic KBr/CuSO4 solvent extraction methods were applied to isolate MeHg from wet peat soil samples collected from boreal forest catchments. Determination of MeHg was performed using a purge and trap GC-ICP-MS technique with a species-specific isotope dilution quantification. Distillation is known to be more prone to artificial MeHg formation compared to solvent extraction which may result in the erroneous MeHg results, especially with samples containing high amounts of inorganic mercury. However, methylation of inorganic mercury during the distillation step had no effect on the reliability of the final MeHg results when natural peat soil samples were distilled. MeHg concentrations determined in peat soil samples after distillation were compared to those determined after the solvent extraction method. MeHg concentrations in peat soil samples varied from 0.8 to 18 μg kg(-1) (dry weight) and the results obtained with the two different methods did not differ significantly (p=0.05). The distillation method with an isotope dilution GC-ICP-MS was shown to be a reliable method for the determination of low MeHg concentrations in unpolluted soil samples. Furthermore, the distillation method is solvent-free and less time-consuming and labor-intensive when compared to the solvent extraction method.

Warm summers and ion concentrations in snow : comparison of present day with Medieval Warm Epoch from snow pits and an ice core from Lomonosovfonna, Svalbard

Snow pits sampled during two consecutive years (2001, 2002) at the summit of Lomonosov- fonna ice cap in central Spitsbergen, Svalbard, showed that ion concentrations were spatially homogeneous. The snowpack on Lomonosovfonna shows no evidence of aerosol deposition from Arctic haze, in contrast to Holtedahlfonna (a glacier at a similar altitude in northern Spitsbergen) where there is a clear signature. In common with many other ice caps in the Arctic, Lomonosovfonna experiences periodic melting, and the deepest of the snow pits contained a record of one exceptionally warm (2001) and one long summer (2000). The most easily eluted species are nitrate and the divalent ions. Very low ion concentrations and high values of a melt indicator log ((Na + )/(Mg 2+ )) were a result of either deep percolation or runoff of ions during melting. Comparing the snow-pit record with the ion record of more than 800 years from an ice core drilled on Lomonosovfonna in 1997 reveals some layers with similar composition to those that suffered significant melting in the snowpack: a few years in the 20th century and around AD 1750, and all of the core from before AD 1200 show unusually heavy melting.