This article gives an overview of the application of nanomaterials in environmental remediation. In the area of environmental remediation, nanomaterials offer the potential for the efficient removal of pollutants and biological contaminants. Nanomaterials in various shapes/morphologies, such as nanoparticles, tubes, wires, fibres etc., function as adsorbents and catalysts and their composites with polymers are used for the detection and removal of gases (SO2, CO, NOx, etc.), contaminated chemicals (arsenic, iron, manganese, nitrate, heavy metals, etc.), organic pollutants (aliphatic and aromatic hydrocarbons) and biological substances, such as viruses, bacteria, parasites and antibiotics. Nanomaterials show a better performance in environmental remediation than other conventional techniques because of their high surface area (surface-to-volume ratio) and their associated high reactivity. Recent advances in the fabrication of novel nanoscale materials and processes for the treatment of drinking water and industrial waste water contaminated by toxic metal ions, radionuclides, organic and inorganic solutes, bacteria and viruses and the treatment of air are highlighted. In addition, recent advances in the application of polymer nanocomposite materials for the treatment of contaminants and the monitoring of pollutants are also discussed. Furthermore, the research trends and future prospects are briefly discussed.

A review on nanomaterials for environmental remediation

Using pre-established trial sites on allophanic soils, we investigated the impacts of long to medium-term pastoral management practices, such as fertilisation and grazing intensity, on a range of soil biological and biochemical properties; hot water-extractable C (HWC), water-soluble C (WSC), hot-water extractable total carbohydrates, microbial biomass-C and N and mineralisable N These properties were examined for their usefulness as soil quality indicators responding to changes in the rhizosphere caused by management practices Adjacent cropping, market garden and native bush sites located on similar soil types were included to determine the changes in soil biological and biochemical properties resulting from changes in land use The seasonal variability of HWC and its relationship with other labile fractions of soil organic matter was also examined

Microbial biomass-C, mineralisable N and extractable total carbohydrates showed promise in differentiating treatment and land use effects However, HWC was one of the most sensitive and consistent indicators examined at 52 different sites The impact of different land uses on the amounts of HWC in the same soil type was far greater than that was observed for the soil organic carbon The average values of HWC for soil under different land use were: native (4000 μg C g−1 soil), sheep/beef pastures (3400), dairy pastures (3000), cropping (1000) and market gardening soils (850) HWC was also sensitive to differences within an ecosystem, eg effects of grazing intensities and effects of N or P fertilisers on pastures The sheep and beef/cattle grazed pastures always had higher amounts of HWC than the intensively grazed dairy pastures Nitrogen fertiliser application (200 and 400 kg N ha−1 yr−1) over the previous 5 yr had significant (P<0001) negative impacts on HWC and other soil microbial properties In contrast, long-term application of P fertilisers had a significant (P<0001) positive effect on the HWC levels in pastoral soils In the case of long-term P trials, HWC increased even though no increase in the total soil carbon pool was detected

HWC was positively correlated with soil microbial biomass-C (R2=084), microbial nitrogen (R2=072), mineralisable N (R2=086), and total carbohydrates (R2=088) All these correlations were significant at P<0001 level of significance The HWC was also positively correlated with WSC and total organic C However, these correlations were poorer than those found for other soil parameters Most of these measurements have been actively promoted as key indicators of soil quality Given the strong correlations between HWC and other biochemical measurements, HWC could be used as an integrated measure of soil quality When HWC is extracted, other pools of labile nutrients are also extracted along with C Therefore it is suggested that decline in HWC would also indicate a decline in other labile organic pools of nutrients such as nitrogen, sulphur and phosphorus About 40–50% of the C in the HWC extract was present as carbohydrates

Hot-water extractable carbon in soils: a sensitive measurement for determining impacts of fertilisation, grazing and cultivation

A novel magnetic biochar efficiently sorbs organic pollutants and phosphate

Water purification using magnetic assistance: a review.

Use of magnetic techniques for the isolation of cells

The ability of orange peel and sawdust waste, a waste material derived from the commercial processing of orange and wood production, to remove Pb(II), Ni(II) and Cd(II) ions from aqueous solution was determined. Biosorption by raw waste materials could be a cost effective technique for removing metals ions from aqueous solutions. The performance of a new biosorbents system, consisting of biological matrix which was magnetically modified by iron oxide nanoparticles, was studied. The use of low-cost and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods. The sorption of metal ions was investigated by determination of adsorption isotherms. The binding of metal ions was found to be dependent on pH. Magnetic orange peel and magnetic sawdust were found to be an effective sorbent for metal ions in the range of low concentrations.

Modified biological sorbents from waste for the removal of metal ions from the water system

Lead ions sorption using magnetically modified sorbent based on titanium dioxide powder

New insoluble chromolytic substrates for the determination of proteolytic activity were prepared by incorporation of dyed proteins into the structure of calcium sulphate dihydrate. The prepared substrates could detect approximately 0.25–1.0 μg of trypsin per ml. The spontaneous leakage of dyed substances in water solutions was negligible.

Insoluble chromolytic substrates for the determination of proteolytic activity

The FPLC system was used for the microdetermination of enzyme activities via the micromeasurement of absorbance of the reaction mixture. The sample loop was directly connected with the monitor. The solution to be measured was injected into the flow of water and the monitor response was measured as a peak height with the built-in integrator. Only 40 μl of the solution are needed for one absorbance measurement.

Ivo Šafařík

Papers

Modified biological sorbents from waste for the removal of metal ions from the water system

Lead ions sorption using magnetically modified sorbent based on titanium dioxide powder

Insoluble chromolytic substrates for the determination of proteolytic activity

The use of FPLC for microdetermination of enzyme activity

A modified fibrin plate for rapid detection of proteinases and proteinase inhibitors in fractions after liquid chromatography.