Efforts to reduce air pollution in developing countries may require increased use of biomass fuels. Even biomass fuels are a sustainable alternative to fossil fuels there is limited quantitative information concerning heavy metal content in their ashes. Therefore, this study focuses on the determination of the heavy metal concentrations in wood pellet ash obtained from the combustion of 10 pellet brans from Bosnia and Herzegovina and Italy, the effects of adding the ashes to soils, and the assessment of health risk assessment. Ash content was determined by gravimetric method. The amount and composition of ash remaining after combustion of wood pellets varies considerably according to the type of biomass and wood from which the pellet is made. Samples were prepared by wet digestion using HNO3, and heavy metals are determined by atomic absorption spectroscopy-flame and graphite furnace. The results showed that the lowest concentration in ashes was obtained for Co 0.01 mg kg−1 and the highest for Fe 571.63 mg kg−1. The Hazard Index (HI), calculated for non-cancerous substances for children was 2.23E−01, and the total Risk index was 4.54E−05. As for adults, HI was 1.51E−02, while the Risk index value was 3.21E−06. Human health risk calculated through HI and Risk index for children and adults associated with analyzed pellets is not of significant concern. The calculated enrichment factor and metal pollution index for wood pellet ashes indicate the risk of soil contamination with heavy metals. From this point of view, analyzed samples of ashes could be a serious contaminant of soil, so further monitoring is required.

Abstract This study reveals novel data on adsorptive removal of Pb(II) from single metal solution, as well as from multi-metal solution containing Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II) and Zn(II) ions along with Pb(II) using inorganic SiO2–MoO3 sorbent in a batch system. The results of multi-metal solution system were strongly pH-depended and due to occurred precipitation of Fe(III) in the form of hydroxide. The parameters affecting the sorption efficiency (contact time, sorbent dosage and initial analyte concentration) were evaluated for single solution system. The optimal conditions for SiO2–MoO3 sorbent indicated high affinity toward Pb(II) ions within following process parameters; pH value 3, sorbent dosage 50 ​mg and contact time 60 ​min for maximum Pb2+ concentration of 100 ​mg/L. The adsorption data for Pb(II) utilizing SiO2–MoO3 best fit to pseudo-second-order kinetic model (R2 ​= ​0.9998) and Langmuir isotherm model (R2 ​= ​0.9320) with an adsorption capacity of 222.20 ​mg/g and Reff >95%. According to thermodynamic study, the adsorption process is feasible, spontaneous and exothermic (ΔG ​= ​−18.6 ​kJ/mol, ΔH ​= ​−7.5 ​kJ/mol and ΔS ​= ​37.32 ​J/mol K). The results of present study demonstrated that SiO2–MoO3 material as a renewable sorbent for Pb(II) removal.

In this research an electrochemical technique in combination with powdered activated carbon (PAC) for the removal of micropollutants by adsorption as an advanced stage purification step from effluents of pilot plant wastewater treatment plants (WWTP). The effluents of sedimentation tank comprised of wastewater plus PAC (WWPAC). The pilot plant mainly consists of two parts; the first one consists of electrocoagulation (EC) reactor and the second consists of electrophoretic deposition (EPD) discs and electroflotation (EF) setup. The electrocoagulation (EC) reactor is a fiber box consisting of two chambers and thirty four plates of one material (either Fe or Al) on the whole in one EC reactor while one cell has seventeen plates. Both types of electrodes have been tested with the outflow of sedimentation tank. The outflow from the sedimentation tank has been entered into the EC reactor for the determination of EC reactor efficacy for the successful accomplishment of EC process at the designed pilot plant for WW treatment. The effect of different operational parameters; PAC dosage (20 mg), electrode nature (Fe and Al), current density (0.34–2.02 A/m2) has been studied to find out the optimum conditions. Sludge volume index (SVI) of the sludge, thermogravimetric (TG), differential thermal analyses (DTA) and particle size distribution (PSD) of the flocs generated after the EC process has also been studied. The turbidity, pH and conductivity of effluents before and after EC treatment has also been carried out. This pilot plant research gave promising results for future work in advance wastewater treatment direction.

Hexavalent chromium (Cr(VI)) is an environmental pollutant with vast mutagenic and carcinogenic potential. Various past and recent studies confirm the deleterious effects of Cr(VI) in different models, from invertebrates to mammalians. However, there is a lack of studies that comprehensively assess and correlate Cr(VI) accumulation patterns and the resulting physiological responses. Here we used an attractive toxicological model, male Japanese quail (Coturnix japonica), as an alternative probing system to evaluate Cr(VI) accumulation in the vital organs, including the brain, heart, kidneys, liver, and testes after 20 days of exposure to 1.2 μg/mL and 2.4 μg/mL potassium dichromate-K2Cr2O7 ingested in the form of drinking water. The observed effects were correlated with the shift in immune system readiness, hematological indices, serum biochemistry and enzyme activity. Regardless of the exposure dose, the Cr(VI) distribution and accumulation pattern in terms of relative Cr(VI) concentration in tissues was: testes > kidneys > liver > heart > brain. Moreover, Cr(VI) triggered the development of microcytic and hypochromic anemia and reduced the immune system's readiness to cope with challenges. Besides, serum biochemistry presented significant shifts, including reduction of serum electrolytes and proteins and an increase in creatine kinase (CK) and lactate dehydrogenase (LDH) activity. Our study provides novel toxicological data that can be translated to higher animal models to help in the extrapolation of Cr(VI) toxicity in humans.

Abstract Rectangular shaped GO-CuO nanocomposites have gained special attention because of spectacular applications in wastewater treatment. However, due to a lack of research, the fuel additive properties of GO-CuO are still unreported. A proper synthesis and characterisation methods are necessary to investigate the fuel additive properties of GO-CuO. The present research demonstrates the synthesis of graphene oxide (GO) sheets via modified Hummers' method. Further, GO-CuO nanohybrid was prepared by fast, cost-effective, and easy to handle solvothermal approach. The crystal data such as crystal structure, unit cell parameters, space groups, crystal system, and coordinates were explained via XRD analysis. Physical and combustion properties of fuel were analysed at different concentrations (0, 20, 40, 60, and 80 ppm) of diesel-GO-CuO blend for fuel quality parameters. The flash point and fire point of pure diesel oil were observed as 78 and 80 °C which were decreased to 50 and 58 °C, respectively, at 80 ppm concentration. With GO-CuO nanocomposites, the cloud point and pour point decrease until a temperature of −8 °C and − 19 °C, respectively, with a pronounced decrease in the viscosity up to 1.83 mm2/s. Further, the photocatalytic degradation of Methylene Red (MR) dye is studied with the effect of changing H2O2, photocatalyst, and dye concentrations with time. Remarkably, the reaction kinetics and MR degradation of about 94% with sixth-time recyclability were observed. The results of this study showed improved MR degradation when using GO-CuO with H2O2. GO-CuO applications can be utilised to remove other dyes in future and to improve fuel quality parameters.

Abstract Simultaneous adsorption of heavy metals in complex multi metal system is insufficiently explored. This research gives results of key process parameters optimization for simultaneous removal of Cd(II), Co(II), Cr(III), Cu(II), Mn(II), Ni(II) and Pb(II) from aqueous solution (batch system). New lemon peel-based biomaterial was prepared and characterized by infrared spectroscopy with Fourier transformation (FTIR), scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), while the quantification of metals was made by atomic absorption spectrometry (AAS). Simultaneous removal of seven metals ions was favorable at pH 5 with 300 mg/50 mL solid-liquid phase ratio, within 60 min at room temperature with total obtained adsorption capacity of 46.77 mg g−1. Kinetic modeling showed that pseudo-second order kinetic and Weber-Morris diffusion models best describe the adsorption mechanism of all seven heavy metals onto lemon peel.

Abstract Simultaneous adsorption of heavy metals in complex multi metal system is insufficiently explored. This research gives results of key process parameters optimization for simultaneous removal of Cd(II), Co(II), Cr(III), Cu(II), Mn(II), Ni(II) and Pb(II) from aqueous solution (batch system). New lemon peel-based biomaterial was prepared and characterized by infrared spectroscopy with Fourier transformation (FTIR), scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), while the quantification of metals was made by atomic absorption spectrometry (AAS). Simultaneous removal of seven metals ions was favorable at pH 5 with 300 mg/50 mL solid-liquid phase ratio, within 60 min at room temperature with total obtained adsorption capacity of 46.77 mg g−1. Kinetic modeling showed that pseudo-second order kinetic and Weber-Morris diffusion models best describe the adsorption mechanism of all seven heavy metals onto lemon peel.

This article reports on an investigation into the ability of SiO2–Ta2O5 as a new sorbent for simultaneous preconcentration of Cd(ii), Co(ii), Cr(iii), Cu(ii), Fe(iii), Mn(ii), Ni(ii) and Pb(ii) ions from water by the column method and the parameters involved in this process.

This article reports on an investigation into the ability of SiO2–Ta2O5 as a new sorbent for simultaneous preconcentration of Cd(ii), Co(ii), Cr(iii), Cu(ii), Fe(iii), Mn(ii), Ni(ii) and Pb(ii) ions from water by the column method and the parameters involved in this process.