In the last few decades, water pollution by different organic and inorganic species has become one of the most critical issues in many regions of the world. The consumption of the contaminated water ...is of major human health concern. The presence of antibiotics and EDCs in the aquatic environment causes critical problems to human health and aquatic organisms. The efficacy for removing antibiotics and EDCs in traditional wastewater treatment plants is not satisfactory by considering technology, cost and overall performance. On the other hand, adsorptive materials are cost effective and highly suitable for removal of antibiotics and EDCs. In this study, different adsorptive materials such as biorchar, functionlaized biochar and a biochar composite sorbent were prepared by the utilization of woody biomasses (bamboo and eucalyptus) and scrap iron material. Biochar was prepared at 380-400 0C via pyrolysis process and then modified using oH3PO4 to produce functionalized biochar (fBC) at 600 0C. The functionalized biochars were named as fBC-1(prepared from bamboo) and fBC-2 (prepared from eucalyptus globules). Finally, fBC-2 was used to prepare a biochar composite with zerovalent-iron (synthesized from scrap iron). These materials were used to remove antiobiotics and EDCs in single and competitive mode.Single and competitive sorption properties and mechanism of functionalized biochar for removing sulfonamide antibiotics from water:Single and competitive sorption of ionisable sulphonamides sulfamethazine, sulfamethoxazole and sulfathiazole on functionalized biochar was highly pH dependent. The equilibrium data were well represented by both Langmuir and Freundlich models for single solutes, and by the Langmuir model for competitive solutes. Sorption capacity and distribution coefficient values decreased as sulfathiazole > sulfamethoxazole > sulfamethazine. The sorption capacity of each antibiotic in competitive mode is about three times lower than in single solute sorption. The kinetics data were best described by the pseudo second-order model for single solutes, and by PSO and intra-particle diffusion models for competitive solutes. Adsorption mechanism was governed by pore filling through diffusion process. The findings from pH shift, FTIR spectra and Raman band shift showed that sorption of neutral sulfonamide species occurred mainly due to strong H-bonds followed by π+ -π electron-donor-acceptor (EDA), and by Lewis acid-base interaction. Moreover, EDA was the main mechanism for the sorption of positive sulfonamides species. The sorption of negative species was mainly regulated by proton exchange with water forming negative charge assisted H-bond (CAHB), followed by the neutralization of –OH groups by H+ released from functionalized biochar surface; in addition, π-π electron-acceptor-acceptor (EAA) interaction played an important role.Competitive sorption affinity of sulfonamides and chloramphenicol antibiotics toward functionalized biochar for water and wastewater treatment:Competitive sorption of sulfamethazine (SMT), sulfamethoxazole (SMX), sulfathiazole (STZ) and chloramphenicol toward functionalized biochar (fBC) was highly pH dependent with maximum sorption at pH ∼4.0–4.25. The Langmuir and Freundlich models well represented equilibrium data in the order STZ > SMX > CP > SMT. Kinetics data were slightly better fitted by the pseudo-second-order model than pseudo first-order and intra-particle-diffusion models. Maximum sorptive interactions occurred at pH 4.0–4.25 through H-bonds formations for neutral sulfonamides species and negative charge assisted H-bond (CAHB) formation for CP, in addition to π-π electron-donor-acceptor (EDA) interactions. EDA was the main mechanism for the sorption of positive sulfonamides species and CP at pH < 2.0. Sorption of negative sulfonamides species and CP at pH > 7.0 was regulated by H-bond formation and proton exchange with water by forming CAHB, respectively. The results suggested fBC to be highly efficient in removing antibiotics mixture.
Gold-modified TiO
(Au-TiO
) photocatalysts were utilised for the degradation of estrone (E1), a major endocrine disrupting chemical in water and wastewater. Au-TiO
catalysts were synthesised by a ...deposition-precipitation method with gold loadings of 0-8% (wt%). The Au-TiO
nanocomposite exhibited superior activity compared to P25 TiO
under UVA (λ=365nm), cool white (λ>420nm) and green (λ=523nm) light emitting diodes (LEDs), for treating 1mgl
of E1. The 4wt% Au loading was found to produce the best photocatalytic activity with a rate constant of 2.44±0.36h
, compared to 0.06±0.01h
for P25 TiO
, under visible light. In total 4 by-products were identified, one from negative ionization mode (m/z=269) and three from positive ionization mode (m/z=287) during photocatalysis, which were also degraded with time by Au-TiO
. For different water matrices, the photodegradation rate of E1 decreased in the order: ultrapure water>synthetic wastewater≈wastewater effluent from membrane bio-reactor. Overall, 4wt% Au-TiO
demonstrated superior performance compared to P25 TiO
in water and wastewater.
In this work, new partially substituted derivatives of octa(3-thiopropyl)silsesquioxane (SSQ-8SH) were synthesized. The article compares the thiol-ene reaction using two methods: radical mechanism, ...thermally initiated (AIBN), and in the presence of a photoinitiator (DMPA). Both the crystalline and the oil forms of SSQ-8SH were functionalized. Olefins with nonpolar alkyl groups (hexene, octene, and octadecene) and vinyltrimethoxysilane, allyl glycidyl ether, allyl 2,2,3,3,4,4,5,5-octafluoropentylether, allyl methacrylate, and styrene were used in the reactions, allowing to obtain seven new derivatives. All compounds were characterized using spectroscopic (1H NMR and 29Si NMR) and spectrometric (MALDI-TOF-MS) methods. The influence of functional groups on the water contact angle value was determined. The functionalization of the compound led to a contact angle value above 95° (SSQ-4SH-4OD). Density measurements and thermogravimetric analysis (TGA) were carried out for all compounds. The highest onset temperature (357.4 °C) and temperature at the maximum mass loss rate (377.3 °C) were observed for SSQ-SH-4OD. The addition of alkyl groups significantly decreased the density of compounds with increasing chain length (1.198 g/cm3; 1.162 g/cm3; 1.095 g/cm3 for hexene, octene, and octadecene, respectively). Silsesquioxanes have potential applications in various materials, such as UV-curable resins, allowing to modify, for example, their surface properties. Modification of a commercial photocurable resin with selected derivatives was carried out to determine the impact on physicochemical properties (TGA, WCA).
Insight into biochar properties and its cost analysis Ahmed, Mohammad Boshir; John L. Zhouauthor; Huu Hao NgoauthorSchool of Civil and Environmental Engineering, University of Technology Sydney, Broadway, NSW 2007, Australia ...
2015
Journal Article
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