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Diapers are reusable waste. This research presents physicochemical properties of sodium polyacrylate in new (ND) and used (UD) diapers, via wavelength-dispersive X-ray fluorescence (WDXRF), Fourier transform infrared (FTIR), X-ray diffraction (XRD), pH, turbidity and colour. Additional constituents detected in ND, while others were slightly higher in UD. Slight decrease (2000–2500 cm−1, UD) and bulk peaks (3287–3333 cm−1, UD) were observed and functional group at 2897 cm−1 (ND) disappeared showing their role as absorption sites. The pH (6.83–8.50), turbidity (16.3–36.6 NTU) and colour (153–432 Pt.Co) values were obtained. Thus, this provides a baseline reference for diapers application in concrete technology.

A promising method of Carbon dioxide (CO2) valorization is to use green microalgae photosynthesis to process biofuel. Two Phase Partitioning Bioreactors (TPPBR) offer the possibility to use non-aqueous phase liquids (NAPL) to enhance CO2 solubility; thus making CO2 available to maximize algae growth. This requires relatively less toxic hydrophobic Ionic Liquids (ILs) that comprise a new class of ionic compounds with remarkable physicochemical properties and thus qualifies them as NAPL candidates. This paper concerns the synthesis of ILs with octyl and butyl chains as well as different cations containing aromatic (imidazolium, pyridinium) and non-aromatic (piperidinum, pyrrolidinium) rings for CO2 absorption studies. The authors measured their respective toxicity levels on microalgae species, specifically, Scenedesmus quadricauda, Chlorella vulgaris and Botryococcus braunii. Results revealed that octyl-based ILs were more toxic than butyl-based analogues. Such was the case for bmim-PF6 at double saturation with an absorbance of 0.11, compared to Omim-PF6 at 0.17, bmim-NTf2 at 0.02, and Omim-NTf2 at 0.14, respectively. CO2 uptake results for ILs bearing octyl-based chains compared to the butyl analog were 54% (nCO2/nIL) (i.e., moles of CO2 moles of IL) and 38% (nCO2/nIL), respectively. Conclusively, 1-butyl-1-methylpiperidinium absorbed 13% (nCO2/nIL) and appeared the least toxic, having an absorbance of 0.25 at 688 nm (double saturation at 7 d) compared to 1-butyl-3-methylimidazolium, which showed the highest toxicity with zero absorbance. Accordingly, these findings suggest that 1-butyl-1-methylpiperidinium is capable of transporting CO2 to a system containing green microalgae without causing significant harm; thus allowing its use in TPPBR technology.

Butylpyridinium thiocyanate [BuPyr]SCN ionic liquid was synthesized by metathesis and characterized. NMR spectrum has shown the [BuPyr] cation while FTIR has shown the SCN anion peak which confirms the structure of the synthesized ionic liquid. The ionic liquid was impregnated on activated carbon in order to enhance performance of sulfur dioxide adsorption compared to the non-impregnated raw activated carbon. Two types of activated carbons were used; activated carbon cylindrical granules and cloth. Different percentages of ionic liquid loading (1%, 10% and 20%) were applied. The capacity of the adsorbent for treatment of 10 ppm and 50 ppm SO2 was determined by breakthrough curve analysis whereby optimum breakthrough time was obtained. [BuPyr]SCN impregnated on activated carbon cloth have shown higher adsorption performance.