Mohammad W. Kadi

Soil Pollution Hazardous to Environment: a case study on the chemical composition and correlation to automobile traffic of the roadside soil of Jeddah city, Saudi Arabia.

Soil samples from different roads in Jeddah city were collected and analyzed for their elemental composition. The effects of traffic conditions were critically investigated to reflect the effect of the heavy and light traffic on the soil composition. Samples were analyzed for K, As, Co, Cr, Ni, Pb, Sb, V, and Zn. The results revealed great dependence of lead and zinc contents on traffic conditions. The lead content lies in the range 0.3-104.8+/-0.003 mg/kg for the samples of high traffic conditions and 0.3+/-0.0mg/kg being for the sample with no traffic activity, whereas 104.8+/-0.003 mg/kg was for the one of the most used highways area in Jeddah city. Zinc level lies in the range 56.59+/-0.003-456.93+/-0.06 mg/kg which is quite close to lead pattern. The high zinc concentration was found along the main turn roads. The high zinc content in tested soil samples may come from traffic sources, especially vehicle tires. Concentrations of other elements showed little dependence on traffic conditions.

Brominated and organophosphate flame retardants in indoor dust of Jeddah, Kingdom of Saudi Arabia: Implications for human exposure.

Different flame retardants (FRs) namely polybrominated diphenyl ethers (PBDEs), emerging brominated/chlorinated flame retardants (Br/Cl FRs), and organophosphate FRs (OPFRs) were analyzed in cars, air conditioner (AC) filters and floor dust of different households from Jeddah, Kingdom of Saudi Arabia (KSA). To the best of our knowledge, this is first study in literature reporting emerging Br/Cl FRs and OPFRs in AC filter dust and also first to report on their occurrence in dust from KSA. Chlorinated alkyl phosphate, penta-BDEs, BDE-209, and decabromodiphenylethane (DBDPE) were the major chemicals in dust samples from all microenvironments. ΣOPFRs occurred at median concentrations (ng/g dust) of 15,400, 10,500, and 3750 in AC filter, car and house floor dust, respectively. For all analyzed chemicals, relatively lower levels were observed in floor dust than car and AC filter dust. The profiles of FRs in car dust were different from AC filter and floor dust, which reflected their wider application as FR and plasticizer in variety of household and commercial products. For toddlers, assuming high dust intake and 95th percentile concentrations, the computed exposure estimation for BDE-99 was higher than RfD values.

Enhanced photocatalytic hydrogen generation of mesoporous rutile TiO2 single crystal with wholly exposed {111} facets

Abstract The development of semiconductor photocatalysts with highly reactive facets exposed has great potential to improve their photocatalytic reactivity. We report the synthesis of mesoporous rutile TiO 2 single crystals with tunable ratios of {110} and {111} facets through the seeded-template hydrothermal method. With increasing the amount of morphology controlling agent NaF, the facet ratio of {111} to {110} increases, and eventually the mesoporous rutile TiO 2 single crystals with wholly exposed {111} reactive facets are obtained. The resultant faceted mesoporous single crystals exhibit a superior photocatalytic performance of hydrogen evolution to mesoporous single crystals with a large percentage of thermodynamically stable {110} facets, as well as the solid rutile single crystals.

Design and construction of a film of mesoporous single-crystal rutile TiO2 rod arrays for photoelectrochemical water oxidation

A film of mesoporous single-crystal rutile TiO2 rod arrays supported on a transparent conductive glass substrate was synthesized with the assistance of a template layer of closely packed silica nanospheres. This film was used as a photoanode and showed significant improvement for photoelectrochemical water oxidation compared with a reference film of nonporous single-crystal rutile TiO2 rod arrays.

Organohalogenated contaminants in sediments and bivalves from the Northern Arabian Gulf

Several classes of Organohalogenated contaminants (OHCs) were determined in sediments and bivalves collected from Kuwait coast. The levels and profile of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) were compared in both sediments and bivalves. PCB-153 and -138 were the major contributors towards total OHCs followed by DDT and its metabolites (DDTs). The higher contribution of DDTs (~40%) and BDE-47 (~15%) in bivalves as compared to that in associated sediments indicated high biota-sediment accumulation factors (BSAF). Higher BSAF (values for heavier PCBs, DDTs and PBDEs) also indicated their high accumulation potential from sediment into associated biota at most of the studied locations. Overall, OHCs in sediments and bivalves measured in current study were lower than those reported in the literature worldwide. Most of the sediment concentrations of OHCs (ng/g, dry weight) were in the range of permissible guideline values proposed by Canadian Sediment Quality Guidelines (CSQGs), with few exceptions for DDTs (5 ng/g) and PCBs (22.7 ng/g). Similarly, 10% of bivalve samples contained high levels (ng/g, lipid weight) of PCBs (300) and DDTs (150) and were above the set safety benchmarks. This study establishes baseline for future monitoring programs.

Enhanced Photocatalytic Activity of ZrO2-SiO2 Nanoparticles by Platinum Doping

ZrO2-SiO2 mixed oxides were prepared via the sol-gel method. Photo-assisted deposition was utilized for doping the prepared mixed oxide with 0.1, 0.2, 0.3, and 0.4 wt% of Pt. XRD spectra showed that doping did not result in the incorporation of Pt within the crystal structure of the material. UV-reflectance spectrometry showed that the band gap of ZrO2-SiO2 decreased from 3.04 eV to 2.48 eV with 0.4 wt% Pt doping. The results show a specific surface area increase of 20%. Enhanced photocatalysis of Pt/ZrO2-SiO2 was successfully tested on photo degradation of cyanide under illumination of visible light. 100% conversion was achieved within 20 min with 0.3 wt% of Pt doped ZrO2-SiO2.

Phthalates and polycyclic aromatic hydrocarbons (PAHs) in the indoor settled carpet dust of mosques, health risk assessment for public

A number of studies have reported the occurrence of phthalates and polycyclic aromatic hydrocarbons (PAHs) in indoor settled dust from different occupational and residential settings around the world but limited studies are available from public and religious places. In recent decades Kingdom of Saudi Arabia (KSA) has experienced tremendous industrial growth especially in the petroleum industries, and as result environmental issues related with such industries have also increased but scientific data is still scarce to understand the impact on public health. Therefore, the main objective of this study was to report the phthalates and PAHs profile in the settled dust collected from various mosques of Jeddah, an important part of people living in the region, and to evaluate the health risk associated with these chemicals via dust ingestion, inhalation and dermal contact for the general public who attend mosques for prayers. Phenanthrene (500-3000 ng/g), pyrene (40-1220 ng/g), and chrysene (95-4590 ng/g) were the major PAHs and ∑12PAHs concentrations ranged from 2550 to 9150 ng/g. Whereas, DEHP (<LOQ-292900 ng/g) and BzBP (<LOQ-292900 ng/g) were the major phthalates in the mosque dust. Health risk assessment for the public was calculated by incremental lifetime cancer risk (ILCR), and daily exposure to via dust ingestion, inhalation, and dermal contact for both PAHs and phthalates. At the same time, benzo[a]pyrene equivalent carcinogenic power (BaPE) (median 145 ng/g) was calculated for PAHs. The ILCR for PAHs was in line with the reference values of USEPA. At the same time, exposure via dust ingestion on daily basis reached up to 82 ng/kg bw/day for DEHP for young children. The study showed general public is exposed to these chemicals in the studied area and major exposure routes are dermal and ingestion.

Decoration of mesoporous graphite-like C3N4 nanosheets by NiS nanoparticle-driven visible light for hydrogen evolution

Separation of photogenerated electrons from holes is an important factor that increases hydrogen evolution rate in the water splitting reaction. This recombination prevention can be achieved by co-catalyst’s deposition onto the semiconductor material’s surfaces. In this contribution, synthesis of mesoporous C3N4 of graphite-like structure by a combustion technique employing high mesoporous silica as a template has been achieved. Subsequently, NiS nanoparticles were decorated as g-C3N4 nanosheets at various NiS contents (5–20%). the photocatalytic efficiency of the prepared NiS/g-C3N4 nanocomposites was investigated and compared with those of pure NiS and g-C3N4 for evolution of hydrogen using glycerol as a scavenger upon visible light illumination. The findings indicated that the content of deposited NiS nanoparticles onto g-C3N4 is significant in the enhancement of the photocatalytic response of g-C3N4. 15% NiS/g-C3N4 nanocomposite is the optimized photocatalyst and its photocatalytic activity is larger than both NiS and g-C3N4 by about 48 and 114 times, respectively. 15% NiS/g-C3N4 nanocomposite has photocatalytic stability up to five times. The enrichment of the photocatalytic efficiency of NiS/g-C3N4 photocatalyst could be attributed to the presence of NiS nanoparticles as co-catalyst, which enables efficient charge carrier separation of g-C3N4, mesostructure, large surface area and narrow band gap.

{111}晶面暴露对介孔金红石TiO 2 单晶光催化产氢的促进作用

Abstract The development of semiconductor photocatalysts with highly reactive facets exposed has great potential to improve their photocatalytic reactivity. We report the synthesis of mesoporous rutile TiO 2 single crystals with tunable ratios of {110} and {111} facets through the seeded-template hydrothermal method. With increasing the amount of morphology controlling agent NaF, the facet ratio of {111} to {110} increases, and eventually the mesoporous rutile TiO 2 single crystals with wholly exposed {111} reactive facets are obtained. The resultant faceted mesoporous single crystals exhibit a superior photocatalytic performance of hydrogen evolution to mesoporous single crystals with a large percentage of thermodynamically stable {110} facets, as well as the solid rutile single crystals.

Article (Special Issue on Photocatalysis)Enhanced photocatalytic hydrogen generation of mesoporous rutile TiO2 single crystal with wholly exposed {111} facets

Abstract The development of semiconductor photocatalysts with highly reactive facets exposed has great potential to improve their photocatalytic reactivity. We report the synthesis of mesoporous rutile TiO 2 single crystals with tunable ratios of {110} and {111} facets through the seeded-template hydrothermal method. With increasing the amount of morphology controlling agent NaF, the facet ratio of {111} to {110} increases, and eventually the mesoporous rutile TiO 2 single crystals with wholly exposed {111} reactive facets are obtained. The resultant faceted mesoporous single crystals exhibit a superior photocatalytic performance of hydrogen evolution to mesoporous single crystals with a large percentage of thermodynamically stable {110} facets, as well as the solid rutile single crystals.