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This study demonstrates the use of an ecofriendly activated carbon (AC) prepared from pea peels by chemical activation with zinc chloride for the biosorption of Cr (VI) from aqueous solutions. The prepared AC was characterized by Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller analyzer (BET). Characterization of AC confirmed the presence of majorly carbonyl and hydroxyl groups, which constitute important adsorption centers. The results declared that prepared AC is designed to be a very good adsorbent for efficient removal of Cr (VI). The maximum adsorption capacity was 480.05 mg/g at an initial Cr (VI) concentration of 400 mg/L. [ABSTRACT FROM AUTHOR]

Textile and dye industries have discharged various kinds of toxic residual dyes particularly azo dyes into the environment. In addition to its resistance to biological degradation, Direct Red 23 (DR-23) azo dye is considered toxic, carcinogenic, teratogenic, and mutagenic to the ecosystem. The aim of this study was to investigate the efficiency of different advanced oxidation processes (AOPs) for DR-23 dye detoxification. Single and combined patterns of AOPs, namely ozonation (O3), O3/ultraviolet (UV), O3/UV/hydrogen peroxide (H2O2), and O3/ultrasonic (US), were applied. The effect of pH (3–11) and initial dye concentration (100-500 mg/L), with implication of UV, H2O2, and US, on dye removal efficiency were studied. Decolorization efficiency was found considerably depends on the initial dye concentration and the pH of the solution. The maximum decolorization was obtained at pH 9. The color removal efficiency reached 100% for 100 mg/L DR-23 dye at 15 min using both O3 and O3/UV processes. The half-life of O3, O3/UV, O3/UV/H2O2, and O3/US were found to be 12.4, 9.0, 15.8, and 10.5 min, respectively. The kinetic of AOPs for DR-23 dye removal followed the pseudo-first-order. For example, the rate constant (kobs) of 400 mg/L dye increased to about 38% using O3/UV as compared to O3 alone. Furthermore, LC-(ESI)-MS/MS analysis of the treated DR-23 dye solution was performed to study the final degradation products. It was shown that a DR-23 dye radical underwent partial and complete decomposition of the dye ring to form final products, namely oxalic acid and formic acid. [ABSTRACT FROM AUTHOR]

The hexavalent chromium (Cr(VI)) reported severe threat to the environment and public health as it is considered potentially mutagenic and carcinogenic. This communication demonstrates a chemical modification process of sugarcane bagasse cellulose for the removal of Cr(VI) from aqueous solutions. Cellulose was extracted from sugarcane bagasse followed by succination to form cellulose succinate (CS), which was then reacted with acetic anhydride to form cellulose succinic anhydrides (CSA). The latter was then reacted with triethylenetetramine (TETA) to form CS-TETA (CST). The prepared CST was characterized by Fourier transform infrared spectrometry (FTIR), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and Brunauer–Emmett–Teller (BET) analyzer. The maximum removal efficiency of Cr(VI) by CST reached nearly 100% after 180 min, which was obtained at pH 1.0. The adsorption process fit well with the pseudo-second-order kinetic model, while the rate constant was 9.13 × 10−3 g/mg min. The isothermal study showed that the results closely aligned with the Langmuir isotherm model and the maximum adsorption capacity was 12.4 mg/g. [ABSTRACT FROM AUTHOR]

Acid Yellow 11 (AY-11) is a toxicant azo dye discharged into the aquatic environment from textile, leather, food, and paper industries. This manuscript demonstrates the oxidation processes of AY-11 by ozone (O3) and ultraviolet (UV) assisted ozonation for decolorization and detoxification. Parameters affecting the performance of AY-11 decolorization process were optimized. The results revealed that the initial dye concentration and pH were effective parameters controlling the decolorization performance. More than 99% of decolorization was obtained within the first 20 min of the ozonation process at 100 µg/mL AY-11 dye and pH 9. The decolorization of AY-11 by O3/UV was slightly less efficient than the individual use of O3 in terms of chemical oxygen demand and color removal. Kinetics analysis indicated that AY-11 dye decolorization followed the pseudo-second order. The final degradation products of AY-11 dye in wastewater were identified using GC-MS. The AY-11 dye degradation intermediates were identified using LC-ESI-MS/MS. The toxicity test on the zooplankton of the treated aqueous solution indicated that the O3 and O3/UV treatments reduced the toxicity effect. [ABSTRACT FROM AUTHOR]

The residue levels of 16 polycyclic aromatic hydrocarbons (PAHs) were quantified and assessed in five seafood species from Al-Jubail, Arabian Gulf, Saudi Arabia during spring 2017. Samples were subjected to extraction by ultrasonic and cleanup by column chromatography followed by separation and quantification by HPLC. For quality control of analytical results, the range of recovery of PAHs obtained from spiking was 62.54-108.91%, with exceptions in three PAHs. The two pelagic fish recorded the highest residue levels of ∑PAHs (541.31 and 545.52 ng/g), followed by bottom-dwelling fish (341.01 and 403.14 ng/g) and Crustaceans (312.10 ng/g). The samples recorded moderate contamination by ∑PAHs based on an international scale. The diagnostic ratios and principal component analysis identified the petrogenic (dominant) and pyrolytic sources of PAHs in samples, besides other unknown sources. The cluster analysis shows similar composition of PAHs in both examined bottom-dwelling fish species. The highest concentration of ∑PAHCARC was recorded in Scomberomorous commerson (0.051 ng/g) with the highest ∑PAHCARC% (10.87). This indicates a slight adverse effect of these species on human health. The human health risk assessment also revealed possible non-carcinogenic adverse effect in the long term of consumption. [ABSTRACT FROM AUTHOR]

The levels of some potentially toxic metals (Cr, Mn, Fe, Co, Cu, Zn, Cd, and Pb) were quantified in 60 street dust samples from Khamees-Mushait city, Saudi Arabia. Samples were taken from three locations at each functional area (total 18 including traffic, industrial, residential, and workshops) and at each control area (total two including a park and a new domestic planner). Heavy metals concentrations were quantified in less than 106 mm particle-size using inductively-coupled plasma-optical emission spectrometer after microwave wet digestion. The total concentrations (μg/g) were in the ranges of Cr 128.48-277.53, Mn 589.43-1091.45, Fe 43478.26-99151.63, Co 23.04-55.22, Cu 10.46-176.13, Cd 0.30-1.99, and Pb 9.36-340.56. The accuracy of results was examined using standard quality control samples, spiking, and a certified reference material. The overall recovery was in the range of 86.2-113.3%. The enrichment factors and the geoaccumulation indices, besides principal component analysis, reveal various levels of enrichment by Fe, Cu, Zn, and Pb from functional areas of congested traffic, commercial activities, and metallic workshops activities. In contrast, no significant enrichment by Cr, Mn, and Co was recorded. The cluster analysis revealed that the metallic workshops and the vehicle scrap workshops are the hottest functional areas. [ABSTRACT FROM AUTHOR]

Urbanization and population are increasing significantly across the world resulting in increase in vegetarian food demand and hence exposure to pesticides and pollutants. This study aimed at monitoring and assessing the levels of three groups of toxicants including organophosphate pesticides (OPPs), other selective pesticides used in Saudi Arabia (SPs) and polychlorinated biphenyl (PCBs). The study included 69 samples of 23 different species of fruit and vegetables consumed in Asir region, Saudi Arabia. After extraction, clean-up and pre-concentration, the analytes were separated and quantified by ultra-performance liquid chromatography equipped with photodiode detector. The ranges of limits of detection (LOD, gg/ml) were as follows: OPPs 0.008-0.147, SAPs 0.006-0.619 and PCBs 0.002-0.007. Many toxicants were found < LOD. For OPPs, butachlor, metachlor and prometon were detected in few species. Simazine and atrazine were detected in the majority of samples (45-6000 gg/kg). For SPs, abamectin was also detected in the majority of samples (12.18-441.0 gg/kg). Emamectin, profenofos and cypermethrin were detected in few samples. For PCBs, PCB 110, PCB 138 and PCB 180 were detected in few samples. The potential exposure to cancerous and non-cancerous diseases for adults and children from consumption of fruit and vegetables were estimated in terms of estimated daily intake (EDI), hazard quotient (HQ), hazard index (HI) and lifetime cancer risk (LCR). HQ and HI values of detected OPPs, SAPs and PCBs were < 1 indicating no significant risk, with the exception of the cancer and non-cancer HQ for adults and children from emamectin in some samples, besides HI non-cancer and cancer of SAPs for adults from some samples. Additionally, atrazine, PCB 101, PCB 180, and PCB 153 recorded safe LCR levels (1x10-4 - 1x10-6), with the exception of PCB 138 in arugula. [ABSTRACT FROM AUTHOR]

This manuscript reports the contents of selected metals in street dust from functional areas in Khamees-Mushait city, Saudi Arabia. The metals were quantified using inductively-coupled plasmamass spectrometry. Acceptable recovery (87.2- 109.3%) was obtained using spiking and certified reference material approaches. The metal contents (μg/g) recorded the following ranges: As 3.42- 44.76, Se 2.64-38.25, Sr 4 14.56-3692.93, Ce 0.04- 0.42 and U 1.25-19.70. The principal component analysis extracted one significant component. Significant correlations (r > 0.9) were obtained for AsSe, As-U, Se-U and Sr-Ce. The cluster analysis classified sampling sites into two main clusters; one of them was represented by one site. The GIS mapping revealed heterogeneous spatial distribution with hot spots in the centers of the east side of the study area. The geo-accumulation index classified the study area at low hazardous level while the enrichment factor classified the study area at levels from minimal to moderate pollution. As reported possible adverse health effect on children while no adverse health effects were observed from As on adult and from Sr and U on both children and adult. On the other hand, As reported a non-carcinogenic risk for both children and adult. [ABSTRACT FROM AUTHOR]