[en] Perfluorooctane sulfonate (PFOS) has been classified as a persistent organic pollutant that contributes to water pollution due to its slow environmental degradation properties. Due to the need for effective removal of PFOS from polluted water bodies, a supramolecular hydrogel incorporating sodium alginate and β-cyclodextrin (SA-β-CD hydrogel) was developed to facilitate the entrapment of PFOS. The adsorption study has been utilised to remove PFOS via batch experiment procedure on several adsorptive parameters such as pH, contact time and initial concentration. The optimum conditions with a dose of 1280 mg of SA-β-CD hydrogels beads were applied at 70°C, contact time of 30 minutes, pH of 5.5, 10 mL of 10.0 ppm of PFOS solution, and 250 rpm of stirring rate were reported. The adsorption capacity and efficiency removal of PFOS by SA-β-CD hydrogel beads has achieved up to 0.0764 mg/g and 84.72%, respectively. Based on the data obtained, the adsorption kinetic study, which follows a pseudo-second-order model, was fitted to illustrate the adsorption of PFOS by SA-β-CD hydrogel beads, with an R² value of 0.990. The adsorption isotherm study showed that the adsorption of PFOS by SA-β-CD hydrogel beads fits the Langmuir isotherm model, with an R² value of 0.987. The adsorption of PFOS occurs as a monolayer/single layer and involves chemisorption to the hydrogel beads. Therefore, this work demonstrates that SA-β-CD hydrogel beads may be useful in controlling environmental water pollution. (author)

[en] Noxious heavy metal ions contamination has become a serious environmental problem nowadays. Among all the toxic heavy metal ions, lead(II) ion, is the most commonly encountered in industrial and agricultural wastewater and in acidic wash-away from landfills site. Hence, the removal of lead traces from the environment has gained a special concern due to their persistence. In this study, batch experiments were conducted to study the capability of hybrid graphite nanoflakes/mesoporous silica nanoparticles (GNP-MSN), amine functionalized mesoporous silica (NH₂-MSN) and pristine graphite nanoflakes (GNP) as adsorbents for removal of lead from aqueous. The influence of several parameters such as pH of the aqueous sample, amount of adsorbent, initial concentration of the lead(II) ions and contact time were examined to optimize the adsorption efficiency of the adsorbents under study. Lead(II) ion can be extracted at pH 4 from sample volume of 10 mL with concentration of 10 ppm by utilizing 10 mg of each respective adsorbent. The analysis of the sample was done by using Flame Atomic Absorption Spectroscopy (FAAS). Furthermore, GNP-MSN also has greatly reduced the aggregation of pristine graphite in water in which GNP-MSN is more easily to be removed from tested sample by centrifugation process compared to pristine graphite. In term of consistency and selectivity of the lead(II) ions removal, GNP-MSN show the highest efficiency since it is able to remove lead(II) ions with higher adsorption capacity (23.940 mg/g) compared to NH₂-MSN (9.230 mg/g) and GNP (1.113 mg/g). Based on kinetic study, both GNP and NH₂-MSN were best-fitted with pseudo-second order while GNP-MSN fitted well with pseudo-first order. (author)

[en] Agarose-chitosan-integrated multiwalled carbon nanotubes (Agr-Ch-MWCNTs) film solid phase microextraction (SPME) was developed and applied for the determination of tricyclic antidepressant drugs (TCAs) in aqueous samples using high performance liquid chromatography-ultraviolet detection (HPLC-UV). Integration of highly interconnected pores of MWCNTs in the agarose-chitosan matrix increases the hydrophobic sites, surface area and porosity of the materials and thus enhancing the extraction efficiency. The film of blended agarose and chitosan allows good dispersion of MWCNTs, prevents the leaching of MWCNTs during application and enhances the film mechanical stability. Optimized parameters for SPME parameters were obtained which no addition of salt included, sample pH = 11, 30 minutes extraction time, iso-propanol as desorption solvent and 0.4 % w/v MWCNTs loading in agarose-chitosan matrix. The matrix match calibration curves demonstrated good linearity in the range of 10-500 ppb with excellent coefficients determination (r² = 0.9944-0.9961), good limits of detection (LODs) in the range of 3.13-3.60 ppb, high analyte recoveries (92.04-110.00 %) and low relative standard deviations (RSD < 6.85). (author)

[en] Sample preparation is important to produce a clean extract to enhance detection sensitivity and minimize instrument maintenance. A micro-solid phase extraction (µ-SPE) technique using magnetic molecularly imprinted polymers (magnetic-MIPs) as the adsorbents combined with micro-high performance liquid chromatography and ultraviolet detection (µ-HPLC-UV) has been developed for the determination of selected polycyclic aromatic hydrocarbons (PAHs), namely benzo[a]pyrene, phenanthrene, fluoranthene and pyrene in environmental water samples. The magnetic-MIPs were characterized using scanning electron microscopy, Brunauer–Emmett–Teller, thermogravimetric analysis and vibrating sample magnetometer to finalize the physical properties of the magnetic-MIPs. The µ-SPE was then optimized using one variable at a time approach to enhance the extraction efficiency. Under the optimal extraction conditions, the feasibility of using magnetic-MIPs as the adsorbents for the extraction of the selected PAHs was proven with a wide linearity range (5-250 µg L-1), good repeatability (relative standard deviation <10%), ultra-trace detection limits (0.01-0.02 µg L-1) and good relative recovery (80.2-119.3%) for the application in the environmental water. The doubt of using the µ-SPE was investigated by calculating the measurement uncertainty. The estimated combined standard uncertainties for the determination of the selected PAHs were in the range of 0.0678-0.0890. It was concluded that the uncertainty of the µ-SPE-µ-HPLC-UV is mainly attributed to its accuracy. Nevertheless, the results showed that the measurement uncertainty of the proposed magnetic-MIPs-based µ-SPE-µ-HPLC-UV was at an acceptable level. The method is beneficial to the routine analysis, especially in providing simple and sensitive determination of the selected PAHs in environmental water. The µ SPE technique consumes minimal amounts of solvent and traces of adsorbents, which then greatly minimizes the waste and analysis costs in routine analysis. (author)

[en] Field-amplified sample injection-capillary zone electrophoresis (FASI-CZE) method was developed to enhance the detection sensitivity of anticancer drug 5-fluorouracil (5-FU). The analyte was introduced electrokinetically for 5 s into a capillary loaded with highly conductive background electrolyte (BGE). The injected analyte migrated in negative polarity, reducing separation time to 5 minutes as compared to positive polarity in hydrodynamic injection-CZE (18 minutes). FASI-CZE was optimized based on three parameters: Sample injection time (5 s, 10 s, and 40 s), BGE concentration in sample (3 mM, 5 mM, and 10 mM) and BGE concentration (15 mM and 25 mM). Optimization of FASI-CZE was conducted to achieve optimal conditions as followed: 15 mM borate BGE containing 0.1% w/v hexadimethrine bromide (HDMB), 5-FU and 5-BrU (IS) prepared in 5 mM diluted BGE, 20% v/v organic modifier in mixture sample was injected at -5 kV for 5 s. The separation was conducted using -25 kV and detected at the wavelength of 234 nm in diode array detection (DAD). The precision was reasonable; %RSD 4.43% at low concentration levels (5 mg/L). The LOD value was 0.24 mg/L when applied with FASI as compared to 0.58 mg/L using HDI-CZE. The sensitivity enhancement factor (SEF) was almost 3 times higher than HDI-CZE at positive polarity, showing that the proposed of FASI-CZE approach is appropriate for the study of 5-FU at trace level. (author)