Water treatment using cryogel-based adsorbents - Targeting environmental pollutants at low concentrations

The lack of safe, clean water is strongly linked to poverty, underdevelopment and poor health. Water is needed not only to sustain life, but to produce food and in industrial processes. Anthropogenic pollution and natural events can jeopardize access to safe water. Inorganic pollutants or toxic metal ions such as arsenic and cadmium are of special concern since these are persistent and accumulate in nature. Contaminated water used for direct consumption or for irrigation of crops can thus lead to direct and indirect exposure to humans to these metals. To improve access to safe water, treatment must be developed to remove even low concentrations of toxic metal ions. Adsorption is a suitable technique. In this work, adsorbents were developed for various kinds of water sources; dinking water, wastewater, industrial water and leachate from a biogas process, all of which contained metal ions, such as As or Cd, at low concentrations. The adsorbents developed were based on a polymer cryogels, produced via cryoconcentration. Cryogels have a highly interconnected and porous structure, making them suitable for water treatment. The cryogels evaluated in this thesis were all based on the polymer polyacrylamide (pAAm). In the first study, a pAAm cryogel was chemically modified with chelating functionalities suitable for the removal of heavy metals (i.e. Cu2+, Zn2+, Pb2+ and Ni2). A rational design was suggested, involving preparation of the polymer inside plastic carriers to increase the mechanical stability of the material. Another strategy using particles was explored by embedding either nanoparticles (NPs) or molecularly imprinted polymers (MIPs) in pAAm-cryogels. The ability of Al2O3 NPs or MIPs in cryogels (called Alu-cryo and MIP-cryo, respectively), to remove As(V) was investigated. Both Alu-cryo and MIP-cryo exhibited adsorption capacities similar to those when the respective particles were applied in suspension. MIP-cryo showed higher selectivity but lower adsorption capacity than Alu-cryo. To improve the removal of As(III) without any pretreatment, co-precipitated Fe-Al hydrous oxides were prepared and embedded in cryogels. As(III) could be removed from smelting wastewater in flow-through mode, reducing the concentration to European industrial emission standards. The removal of Cd2+ from leachate resulting from the anaerobic digestion of seaweed was studied using hydrothermally modified TiO2 embedded in cryogels. This cryogel was shown to be successful in removing Cd2+ when tested in flow-through mode, and high adsorption capacities were obtained. Toxicity and particle leakage were studied in NP-embedded cryogels. Although no evidence of particle leaking was found, toxicity resulted from the leakage of the monomer acrylamide from the cryogel. The findings of this work show that cryogel-based adsorbents have potential in water treatment, due to their broad range of applications and the flexibility of the material. New and improved methods of particle immobilization in cryogels should be investigated, and pAAm should be replaced by non-toxic alternatives. Making cryogel materials with high adsorption capacities, which can be regenerated, can reduce the cost of water treatment. It is also important that novel technology meets environmental safety requirements to ensure the supply of safe water

Costs and quality of life associated with osteoporosis related fractures - Results from a Swedish survey

There are few studies investigating the consequences of osteoporotic (low bone density) fractures in terms of costs and health outcomes. The purpose of this Swedish pilot study is to assess the costs and quality of life related to fractures of the hip, spine, wrist and shoulder and further to identify important cost items that should be included in future studies in this area. Data were collected using a questionnaire administered by a nurse at Malmö University Hospital. The costs are collected based on a societal perspective and include both direct and indirect costs. Health effects were measured by the EuroQol questionnaire, rating scale method and the SF-36. The total costs varied between SEK 23 000 for a wrist fracture and SEK 63 000 for a hip fracture. Although that the response rate is low the cost and quality of life related to hip fracture are close to the results presented in other studies. The major new finding is that spine fractures are associated with higher costs and lower quality of life than previously assumed. Future studies must include a sufficient number of patients in order to obtain reliable cost and health effect estimates after osteoporotic fractures in general and after spine fractures in particular. Such studies will provide important inputs for health economic evaluations assessing the cost-effectiveness of the treatment and prevention of osteoporosis.costs; fracture; osteoporosis; quality of life

Polymer functionalized nanocomposites for metals removal from water and wastewater: An overview

Pollution by metal and metalloid ions is one of the most widespread environmental concerns. They are non-biodegradable, and, generally, present high water solubility facilitating their environmental mobilisation interacting with abiotic and biotic components such as adsorption onto natural colloids or even accumulation by living organisms, thus, threatening human health and ecosystems. Therefore, there is a high demand for effective removal treatments of heavy metals, making the application of adsorption materials such as polymer-functionalized nanocomposites (PFNCs), increasingly attractive. PFNCs retain the inherent remarkable surface properties of nanoparticles, while the polymeric support materials provide high stability and processability. These nanoparticle-matrix materials are of great interest for metals and metalloids removal thanks to the functional groups of the polymeric matrixes that provide specific bindings to target pollutants. This review discusses PFNCs synthesis, characterization and performance in adsorption processes as well as the potential environmental risks and perspectives. (C) 2016 Elsevier Ltd. All rights reserved

Klassrummet - En tillgänglig lärmiljö

Syftet med denna empiriska studie är att bidra med kunskap om lärares möjligheter till att anpassa lärmiljön för alla elever i klassrummet. Studien avser därtill att kartlägga vilka olika möjligheter respektive hinder elever och lärare ser och möter. Vidare har syftet varit att få med elevernas egna perspektiv på vilka möjligheter och hinder de möter i sitt lärande. Slutligen är syftet med studien att bidra till en fördjupad kunskap om hur de olika hindren i elevernas lärmiljö kan undanröjas för att förse dem med en optimal utbildning.Motivet till att jag valt detta specifika ämnesområde, tillgänglig lärmiljö, är att jag i min kommande yrkesroll såsom speciallärare betraktar förebyggandet av hinder för inlärning som en viktig del av mitt uppdrag. I de vägledande styrdokumenten står att alla elever ska ges en likvärdig utbildning. Utbildningen skall dessutom anpassas utifrån var och ens förutsättningar och behov. Då min inriktning är svenska fokuserar studien i första hand på elevers kommunikativa förmågor och på hur utvecklingen av dessa möjliggörs, samt på vilka sätt eventuella hinder för inlärandet kan undanröjas.Metoden är kvalitativ då jag genomfört semistrukturerade intervjuer med ett antal lärare och elever. Tidigare forskning som studien refererar till är genomförd i Sverige, Danmark, övriga Europa och USA. Deras syften och resultat diskuteras i förhållande till de vilka framkommit i min studie. Slutligen tas förekommande skillnader i definitionen av begreppet inkludering upp.Denna studie bygger på det sociokulturella lärandet, på Vygoskijs teorier och på KASAM. I resultaten kan tendenser till samsyn mellan lärare och elever ses vad det gäller lärmiljö och delaktighet. Vissa aspekter betonades under intervjuerna i varierad grad, en del var viktigare ur ett elevperspektiv medan andra mer togs upp ur ett pedagogperspektiv. Studien bidrar till en utvidgad kunskap kring hur elever ser på sitt lärande och sin lärmiljö. Vidare ger den en bild av lärares tankar kring deras uppdrag med fokus på lärmiljön i klassrummet och deras möjligheter till anpassningar utifrån alla elevers individuella behov

Applications of Cryogels in Water and Wastewater Treatment

Cryogels have potential for applications in water and wastewater treatment. However, maximum levels of exposure to both incorporated materials in cryogels (i.e., nanoparticles [NPs]) and monomers, as a result of leakage, must be established before cryogel composites can be implemented in the large-scale treatment of water. Other factors, such as cost and reuse, must also be studied for each specific adsorbent. One of the greater advantages of cryogels is the flexibility of their preparation. The material can be prepared as monoliths, discs, beads or particles, to suit specific requirements. Results on a laboratory scale may be different from those obtained when treating real water and wastewater due to differences in scale and water chemistry. The social acceptance of the technology and its overall environmental impact must also be assessed. This chapter starts with describing how cryogel materials have been developed from their initial applications in water treatment to more recent developments. This is followed by current published results obtained from the treatment of water from different sources, including both lab-scale evaluations as well as real water samples. As the main application of cryogels within water treatment today is as adsorbent materials, these will be given the main focus for this chapter but still include more recent research results from applications regarding disinfection and oil absorption. The main pollutants of interest for this chapter are inorganic pollutants such as metals and metalloids (e.g. cadmium and arsenic), but organic contaminants are also mentioned. Future challenges in this area today, regarding cryogel applications, cover the need for system regeneration, the deposition of the pollutant and, finally, the total cost of the treatment

Klassrummet - En tillgänglig lärmiljö

Syftet med denna empiriska studie är att bidra med kunskap om lärares möjligheter till att anpassa lärmiljön för alla elever i klassrummet. Studien avser därtill att kartlägga vilka olika möjligheter respektive hinder elever och lärare ser och möter. Vidare har syftet varit att få med elevernas egna perspektiv på vilka möjligheter och hinder de möter i sitt lärande. Slutligen är syftet med studien att bidra till en fördjupad kunskap om hur de olika hindren i elevernas lärmiljö kan undanröjas för att förse dem med en optimal utbildning.Motivet till att jag valt detta specifika ämnesområde, tillgänglig lärmiljö, är att jag i min kommande yrkesroll såsom speciallärare betraktar förebyggandet av hinder för inlärning som en viktig del av mitt uppdrag. I de vägledande styrdokumenten står att alla elever ska ges en likvärdig utbildning. Utbildningen skall dessutom anpassas utifrån var och ens förutsättningar och behov. Då min inriktning är svenska fokuserar studien i första hand på elevers kommunikativa förmågor och på hur utvecklingen av dessa möjliggörs, samt på vilka sätt eventuella hinder för inlärandet kan undanröjas.Metoden är kvalitativ då jag genomfört semistrukturerade intervjuer med ett antal lärare och elever. Tidigare forskning som studien refererar till är genomförd i Sverige, Danmark, övriga Europa och USA. Deras syften och resultat diskuteras i förhållande till de vilka framkommit i min studie. Slutligen tas förekommande skillnader i definitionen av begreppet inkludering upp.Denna studie bygger på det sociokulturella lärandet, på Vygoskijs teorier och på KASAM. I resultaten kan tendenser till samsyn mellan lärare och elever ses vad det gäller lärmiljö och delaktighet. Vissa aspekter betonades under intervjuerna i varierad grad, en del var viktigare ur ett elevperspektiv medan andra mer togs upp ur ett pedagogperspektiv. Studien bidrar till en utvidgad kunskap kring hur elever ser på sitt lärande och sin lärmiljö. Vidare ger den en bild av lärares tankar kring deras uppdrag med fokus på lärmiljön i klassrummet och deras möjligheter till anpassningar utifrån alla elevers individuella behov

Läsinlärning i teori och praktik - vad säger forskningen och vilka metoder förespråkas i praktiken?

Syftet med examensarbetet är att göra en jämförande undersökning mellan vad forskning och yrkesverksamma lärare anser om läsinlärning och de metoder som förespråkas. I litteraturdelen beskrivs olika teorier kring läsinlärning samt olika metoder för att arbeta med detta. Vi använder oss av en kvalitativ undersökningsmetod, intervjuer, för att få reda på hur lärare arbetar och vilka metoder de förespråkar. De lärare vi intervjuat använder sig av de båda grundmetoderna, helordsmetoden och ljudningsmetoden vid läsinlärningen för att tillgodose alla elever. Den vanligaste metoden som de intervjuade lärarna använder är helordsmetoden, dock påpekar samtliga vikten av att eleverna har ljuden med sig för att bli goda läsare. Lärarna menar att genom att använda sig av texter som utgår från eleverna eller som anknyter till deras vardag blir läsningen mer meningsfull och lustfylld

Reversible in situ precipitation: a flow-through approach for coating macroporous supports with metal hydroxides

In this study we report on the production of metal-hydroxide-coated macroporous polymers (MHCMPs), which mainly involves a polyacrylamide backbone coated with iron-aluminium double hydroxides. The coating process is fast, occurs using relatively mild reagents at room temperature, and can be repeated multiple times, thus making it a very simple and flexible process. Electron microscopy and energy dispersive X-ray spectroscopy studies showed that metal hydroxide coating occurred throughout the polymer backbone. It was shown that the mass of metal hydroxides incorporated in the MHCMPs could be adjusted by varying the initial salt solution concentration or the number of cycles in the process. Under the studied conditions, on a polymer backbone of mass 25 mg, we observed a maximum metal hydroxide mass incorporation of 18 mg for the MHCMPs produced at 6 cycles by using 0.4 M iron and aluminium salt solution. Nitrogen adsorption isotherms indicated that the surface area of the MHCMPs increased linearly with the increase in the mass of metal hydroxides incorporated. The polymer backbone with no mass incorporated showed a BET surface area of 18 m(2) g(-1) and the MHCMPs with maximum mass incorporation under the studied conditions showed a BET surface area of 63 m(2) g(-1). MHCMPs with varying mass incorporations were applied for arsenic (As(III)) adsorption and showed a high As(III) removal, indicating that they can serve as potential adsorbents. In addition, MHCMPs incorporated with other metal hydroxides were also produced and characterized to show that this method is applicable for coating these as well

Arsenite adsorption on cryogels embedded with iron-aluminium double hydrous oxides: Possible polishing step for smelting wastewater?

Arsenic is among the most toxic elements and it commonly exists in water as arsenite (As(III)) and arsenate (As(V)) ions. As(III) removal often requires a pre-oxidation or pH adjustment step and it is a challenge to adsorb As(III) at circumneutral pH. In this study, iron-aluminium double hydrous oxides were synthesized and incorporated into cryogels. The resulting composite cryogels were evaluated for As(III) adsorption. Initial experiments indicated that the adsorbent showed similar adsorption kinetics for both As(V) and As(III) ions. The adsorption of As(III) best fit the Langmuir isotherm and the maximum adsorption capacity was 24.6mg/g. Kinetic modeling indicated that the mechanism of adsorption was chemisorption, making the adsorbent-adsorbate interactions independent of charge and hence allowing the adsorbent to function equally efficient across pH 4-11. A Swedish smelting wastewater was used to evaluate the adsorption performance in continuous mode. The studies showed that the adsorbent was successful in reducing the arsenic concentrations below the European Union emission limit (0.15mg/l) in a smelting wastewater collected after two precipitation processes. The arsenic removal was obtained without requiring a pH adjustment or a pre-oxidation step, making it a potential choice as an adsorbent for As(III) removal from industrial wastewaters