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The application of a char derived from fruit peel waste and other municipal wastes as solid fuel depends on its physico-chemical properties. In this work, fruit peel waste (FW) along their mixture with facial tissue waste (FT) and wrapping paper waste (WP) as well as their respective hydrochars (FWHC, FTHC, and WPHC) produced via hydrothermal carbonization (HTC) was characterized in detail to ascertain their applicability as solid fuel. Moreover, the elemental O contents for FTHC and WPHC were about 12.8 and 5.1% respectively higher than FWHC. Heating value analysis indicated that WPHC had the highest HHV of 5164 kcal/kg. Combustion kinetic studies, carried out by thermogravimetric technique, revealed that about 33.78 kJ/mol of energy was required to generate a combustion reaction for WP, higher than the energy required to ignite WPHC (28.2 kJ/mol). The regression coefficient (R2) values were higher than 0.94, indicating that the Arrhenius equation could be used to model the sample combustion process. Overall, the study showed that Co-HTC of FW with paper-based municipal waste such FT and WP is an effective method of converting FW to a cleaner hydrochar (HC) with high calorific value and less sulphur content. [ABSTRACT FROM AUTHOR]

Water pollution by synthetic anionic dyes is one of the most critical ecological concerns and challenges. Therefore, there is an urgent need to find an efficient adsorbent and photocatalyst for dye removal. In the present study, we aimed to fabricate a hybrid mesoporous composite of spongy sphere-like SnO2 and three-dimensional (3D) cubic-like MgO (SnO2/MgO) as a promising adsorbent/photocatalyst to remove the anionic sunset yellow (SSY) dye from real wastewater at neutral pH conditions. The as-synthesized SnO2 and MgO composite was investigated using XRD, SEM, EDX, TEM, XPS, BET, and zeta potential. The experimental study of the SSY removal using SnO2/MgO composite was performed at different conditions, such as pH, stirring time, dose, and temperature. More than 99% of 10 mg/L SSY was effectively adsorbed from aqueous solution using 40 mg of SnO2/MgO composite at pH 7 and a stirring time of 60 min. The SSY adsorption behavior was well fitted by pseudo-second order and the Langmuir model, indicating that the SSY was chemisorbed to the composite-active sites as a monolayer. On the other hand, photocatalytic degradation process exhibited better results in terms of speed of removal and used quantity of photocatalyst, where 20 mg of SnO2/MgO composite can be used to remove > 99% of SSY dye within 30 min. Mechanism of SSY adsorption and photocatalytic degradation was discussed. In addition, elution experiments demonstrated that the SnO2/MgO composite as an SSY adsorbent could be reused for nine cycles without considerable reduction in the SSY adsorption efficiency. Therefore, this work exhibited that the mesoporous SnO2/MgO composite can be considered an effective adsorbent/photocatalyst to remove SSY dye from real industrial effluent water at neutral pH conditions. [ABSTRACT FROM AUTHOR]

The potency of the prepared glassy polyvinyl alcohol/silica gel hybrid composite to remove safranin from aqueous solutions has been explored. The obtained hybrid composite was firstly characterized by FTIR, XRD, SEM, EDX and TGA. Factors affecting the safranin removal process like pH, adsorption time, initial concentration of dye, adsorbent amount and temperature, were fully investigated. The obtained data were treated using four kinetically models and two adsorption isotherm models. Results of kinetic study revealed that the pseudo first order was good in agreement with experimental results rather than pseudo second order, Weber and Morris Intraparticle model and Elovich model. The equilibrium adsorption isotherms revealed that Langmuir model was suitable and well compatible with experimental results than Freundlich one. The maximum adsorption capacities at 293, 303 and 318 K were 9.5, 11 and 12.5 mg g−1, respectively. Thermodynamic studies surmised that the removal process was spontaneous, endothermic and physisorption controlled (ΔHo = 17.48 kJ mol−1). [ABSTRACT FROM AUTHOR]

A simple ionic liquid-assisted approach for the fabrication of graphene-based nanocomposite is reported. Pd–CuO/rGO and Au–CuO/rGO nanocomposites are successfully fabricated with the assistance of the ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate. The physicochemical features of nanocomposite are systematically characterized by XRD, FT-IR, Raman spectroscopy, XPS, TGA, FESEM, AFM, and HRTEM. Carbon monoxide has been used as a probe molecule to emphasize the performance of the fabricated materials. The results indicate that the incorporation of a little quantity of ionic liquid results in the creation of uniformly dispersed NPs simultaneously with the reduction of graphene oxide (GO) into rGO, which leads to a low-temperature CO oxidation process. Besides, the Au–CuO/rGO catalyst achieved excellent durability in CO oxidation for 14 h, without detectable deactivation. The low-temperature CO oxidation was mainly induced by the synergistic effects between the components of catalysts. The Au or Pd and CuO combination not only generates more interfaces, which is more favorable for the activation of oxygen but also enhances the catalyst reduction behavior. Consequently, a graphene composite catalyst can be considered a potential CO oxidation candidate. [ABSTRACT FROM AUTHOR]

Most research studies regarding the contamination of urban road dust (RD) focused on mega cities, but little consideration is given for small cities in border areas. The present work investigated the trace elements content in 16 RD samples of particle size < 63 μm at six areas with different anthropogenic activities in Sakaka city, KSA. The trace elements were analyzed using XRF and ICP-MS. Significantly high trace elements concentrations were recorded at small-scale industrial area. Concentrations of trace elements are ranked as Fe > Mn > Pb > Zn > Cr > Cu > Co > As > Se. The contamination evaluation through enrichment factor calculation refers to the existence of an anthropogenic source for certain trace elements, such as Fe, Zn, Mn, Cu, and Pb. The values of contamination factor indicate the contamination of RD samples collected from small-scale industrial area with these trace elements. The highest pollution load index value recorded at this industrial area suggests that it is a highly polluted area. This was confirmed by applying the one-way ANOVA test for the difference analysis between the investigated areas. The correlation between most of the detected trace elements at the small scale-industrial area was lost due to the variation in their industrial sources. The health risk of some detected trace elements was estimated for two groups of populations, namely workers at the small scale-industrial area and residents (adults and children) at residential areas at this city under study. Workers and resident children were more likely affected by arsenic through the ingestion pathway to cancer because of its higher cancer risk values that were more than the acceptable value 1 × 10−6. Workers and residents (adults and children) are susceptible to noncarcinogenic risks through the ingestion pathway of Fe because of its higher hazard quotient values that are more than one. [ABSTRACT FROM AUTHOR]