Search results for "kemikaalit"

Study of Ni, Pt, and Ru Catalysts on Wood-based Activated Carbon Supports and their Activity in Furfural Conversion to 2-Methylfuran

2018

Bio‐based chemicals can be produced from furfural through hydrotreatment. In this study, 2‐methylfuran (MF), a potential biofuel component, was produced with Pt, Ru, and Ni catalysts supported on wood‐based activated carbons. The catalytic hydrotreatment experiments were conducted in a batch reactor at 210–240 °C with 2‐propanol as solvent and 40 bar H2 pressure. Two types of activated carbon supports were prepared by carbonization and activation of lignocellulosic biomass (forest‐residue‐based birch and spruce from Finland). Both types of activated carbons were suitable as catalyst supports, giving up to 100 % furfural conversions. The most important factors affecting the MF yield were the…

A fugacity model assessment of ibuprofen, diclofenac, carbamazepine, and their transformation product concentrations in an aquatic environment

2018

An updated version of FATEMOD, a multimedia fugacity model for environmental fate of organic chemicals, was set up to assess environmental behaviour of three pharmaceuticals in northern Lake Päijänne, Finland. Concentrations of ibuprofen, diclofenac, and carbamazepine were estimated at various depths at two sites: near a wastewater treatment plant and 3.5 km downstream the plant. When compared with environmental sampling data from corresponding depths and sites, the predicted concentrations, ranging from nanograms to hundreds of nanograms per litre, were found to be in good agreement. Weather data were utilised with the model to rationalise the effects of various environmental parameters on…

Emerging technologies for enhanced removal of residual antibiotics from source-separated urine and wastewaters: A review.

2022

Antibiotic residues are of significant concern in the ecosystem because of their capacity to mediate antibiotic resistance development among environmental microbes. This paper reviews recent technologies for the abatement of antibiotics from human urine and wastewaters. Antibiotics are widely distributed in the aquatic environment as a result of the discharge of municipal sewage. Their existence is a cause for worry due to the potential ecological impact (for instance, antibiotic resistance) on bacteria in the background. Numerous contaminants that enter wastewater treatment facilities and the aquatic environment, as a result, go undetected. Sludge can act as a medium for some chemicals to …

Yritystoimijoiden asenteet valmisteilla olevaan Euroopan unionin kemikaalilainsäädäntöön (REACH)

2006

Advancing the ecotoxicological relevancy of zebrafish : application of early-juvenile 20dpfZF to assess xenoestrogenicity of environmental chemicals …

2014

Conversion of Xylose to Furfural over Lignin-Based Activated Carbon-Supported Iron Catalysts

2020

In this study, conversion of xylose to furfural was studied using lignin-based activated carbon-supported iron catalysts. First, three activated carbon supports were prepared from hydrolysis lignin with different activation methods. The supports were modified with different metal precursors and metal concentrations into five iron catalysts. The prepared catalysts were studied in furfural production from xylose using different reaction temperatures and times. The best results were achieved with a 4 wt% iron-containing catalyst, 5Fe-ACs, which produced a 57% furfural yield, 92% xylose conversion and 65% reaction selectivity at 170 &deg

Chemical Pretreatments of Wood Chips Prior to Alkaline Pulping - A Review of Pretreatment Alternatives, Chemical Aspects of the Resulting Liquors, an…

2015

The chemical industry is being forced to evaluate new strategies for more effective utilization of renewable feedstocks to diminish the use of fossil resources. In this literature review, the integration of both acidic and alkaline pretreatment phases of hardwood and softwood chips with chemical pulping is discussed. Depending on the pretreatment conditions, high-volume sulfur-free fractions with varying chemical compositions can be produced. In case of acidic pretreatments, the major products include carbohydrates (mono-, oligo-, and polysaccharides), whereas under alkaline (i.e., aqueous NaOH) pretreatment conditions, the sulfur-free fractions of aliphatic carboxylic acids, lignin, and ex…

New applications of zoobenthos measurements for risk assessment of chemicals in aquatic ecosystems

2015

Artikkeliväitöskirja. Yhteenveto-osa ja viisi artikkelia. (Artikkelit eivät avoimesti saatavilla.) Article dissertation. An introduction and five articles (not available in this version). Benthic animals in aquatic ecosystems suffer from various anthropogenic pollutants. A challenge in risk assessment of chemicals in aquatic ecosystems (i.e. ecological risk assessment) has been to balance cost-efficiency and effectiveness in detecting early warning signals of chemicals. In this study, hyperspectral imaging and behavioural measurements were evaluated as novel applications for detecting chemical effects on benthic animals, and the reliability of the incidence of chironomid morphological defor…

Environmental context determines pollution impacts on ecosystem functioning

2023

Global change assessments have typically ignored synthetic chemical pollution, despite the rapid increase of pharmaceuticals, pesticides and industrial chemicals in the environment. Part of the problem reflects the multifarious origins of these micropollutants, which can derive from urban and agricultural sources. Understanding how micropollutants harm ecosystems is a major scientific challenge due to asymmetries of stress across trophic levels and ecological surprises generated by multiple drivers interacting in human-impacted landscapes. We used field assays above and below municipal wastewater treatment plants (WWTPs) in 60 sampling locations across 20 Swiss streams to test how micropoll…

Potential of municipal sewage treatment plants to remove bis(2-ethylhexyl) phthalate

2004

Sanna Marttinen tutki väitöskirjatyössään muovin pehmentimenä käytettävän DEHP-kemikaalin pitoisuuksia ja käyttäytymistä yhdyskuntajätevedenpuhdistamolla. Täyden mittakaavan puhdistamoilla tehtyjen tutkimusten sekä laboratorio- ja pilot-kokeiden avulla Marttinen selvitti puhdistamojen kykyä poistaa DEHP:a jätevesistä ja siten vähentää DEHP:n ympäristökuormitusta. The removal of bis(2-ethylhexyl) phthalate (DEHP) at municipal sewage treatment plants (STPs) was studied at full-scale plants and in experiments carried out with sewage, reject water and sludge containing native DEHP. DEHP concentration in Finnish sewages was typically at a level of 100 µg/l. Most of the DEHP was sorbed to colloid…