Md. Hasan Zahir

Preparation and characterization of mesoporous ceria–zirconia–alumina nanocomposite with high hydrothermal stability

CeO 2 –ZrO 2 –γ-Al 2 O 3 mixed oxides with different molar compositions have been synthesized by the sol-gel method using nitrate–alkoxide precursors. Some relationships between the molar composition of the ternary systems and their textural and structural properties are presented. CeO 2 –ZrO 2 –γ-Al 2 O 3 mixed oxides have been studied and characterized using x-ray diffraction, transmission electron microscopy, and Raman spectroscopic analyses. By complete porosity analyses of all samples before and after hydrothermal (up to 75% steam) treatment at 500 °C, we have been able to optimize a highly hydrothermally stable CeO 2 –ZrO 2 –γ-Al 2 O 3 system with a molar ratio of 10:10:80 mol%. γ-Al 2 O 3 alone and CeO 2 -doped as well as ZrO 2 -doped γ-Al 2 O 3 were also investigated by the hydrothermal treatment, and their steam-sensitive properties have been compared with those of the ternary CeO 2 –ZrO 2 –γ-Al 2 O 3 system.

Synthesis and Properties of Waterborne Polyurethane (WBPU)/Modified Lignin Amine (MLA) Adhesive: A Promising Adhesive Material

A series of waterborne polyurethane (WBPU)/modified lignin amine (MLA) adhesives was prepared using MLA as a chain extender by a prepolymer mixing process. A successful Mannich reaction was achieved during the synthesis of MLA by reacting lignin with bis(3-aminopropyl)amine. Higher tensile strength, Young’s modulus, and thermal stability were recorded for WBPU/MLA adhesives with higher MLA contents. The WBPU/MLA adhesive materials were used to coat polyvinyl chloride (PVC) substrates. The adhesive strength increased with increasing MLA content. More importantly, the MLA also enhanced the WBPU/MLA coating in terms of adhesive strength at moderately high temperatures as well as under natural weather exposed conditions. The adhesive strength was essentially unaffected with 6.48 mol % MLA in the WBPU/MLA coating after exposure to natural weather conditions for 180 days.

Synthesis and Characterization of Trivalent Cerium Complexes of p-tert-Butylcalix[4,6,8]Arenes: Effect of Organic Solvents

Reaction of Ce with p-tert-butylcalix[n]arene (n = 4, 6, 8) yields purple crystalline complexes structurally as [Ce(p-tertbutylcalix[4]arene-3H) 2 (NO 3 )(DMF) x ](2 − x)DMF (1), [Ce(p-tert-butylcalix[6]arene-4H) 2 (NO 3 )(DMF) x ](3 − x)DMF (2), and [Ce(p-tert-butylcalix[8]arene-7H) 2 (NO 3 )(DMF) 6 ] (3), where DMF = N,N-dimethylformamide. The properties and coordination characteristics of the three calixarene complexes were determined by elemental analyses, electronic absorption, X-ray absorption spectroscopy (EXAFS), TG-DTA, FT-IR, SEM, and H-NMR spectroscopy.The effect of various organic solvents on complexes 1, 2, and 3 has been discussed based on results from electronic absorption spectra.The polar protic solvents showed the most significant molar extinction coefficients in comparison with those of nonpolar and polar aprotic solvents. The Ce ions in the complexes are proved to combine with the ligand phenolic groups, oxygen atoms of DMF molecules, and/or OH ions.

Trihalomethanes in desalinated water: Human exposure and risk analysis

ABSTRACT Desalinated seawater is used to satisfy domestic water demands in many countries. The treated freshwater is blended with desalinated water to increase the water supply. The desalinated and blended water contains disinfection byproducts (DBPs), some of which may induce cancer risk to human. In this study, concentrations of trihalomethanes (THMs) in desalinated and blended water in Saudi Arabia were investigated, and human exposure and risk were predicted. The intakes of THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) were predicted to be 8.38 × 10−5, 7.57 × 10−5, 2.54 × 10−5, and 4.32 × 10−4 mg/kg-d, respectively. The overall cancer risk and hazard index were estimated to be 1.78 × 10−5 (range: 7.40 × 10−7–9.26 × 10−5) and 3.49 × 10−2 (range: 1.20 × 10−3–2.34 × 10−1), respectively. The probabilities of cancer risk exceeding the risk levels of 1 × 10−6, 1 × 10−5, and 5.0 × 10−5 were 1.0, 0.775, and 0.012, respectively. The loss of disability adjusted life years (DALYs) was predicted to be 25.1 per year while the cancer risk represented 8.48 × 10−7 DALY per person per year. The financial burden from such risk was estimated to be US

Multi-component catalysts with spinel structure for the selective reduction of nitrogen oxide by ethylene in lean-exhaust gas streams

2.72 (range: US

Modeling lead concentration in drinking water of residential plumbing pipes and hot water tanks

2.52–2.91) million per year. The findings may assist in better understanding and reducing cancer risk from DBPs in desalinated and blended water.

Host–Guest Extraction of Heavy Metal Ions with p-t-Butylcalix[8]arene from Ammonia or Amine Solutions

The Ga2O3-Al2O3-ZnO (GAZ) multi-component spinel powders with incorporated Cu2+, Co2+, Fe2+, Ni2+, Mn2+ and In2+ metal cations were synthesized by co-precipitation method from a mixed solution of nitrate salts. Spinel crystal structure of each composition was confirmed by XRD measurements. The multi-component oxide powders were tested in the reduction of nitrogen oxide (NO) under lean conditions. Among the catalysts tested, In2O3-containing GAZ with a pure spinel phase structure showed promising catalytic activity in the NO reduction in the presence of 10% H2O vapor. In addition, the effect of H2O vapor and SO2 on the selective reduction of NO over In2O3-GAZ/cordierite and In2O3-GAZ/metal honeycombs catalysts has been investigated.

GDC Electrolytes With Patchwork Type Morphology and Their Microtubular SOFC Applications

Drinking water is a potential source of exposure to lead (Pb), which can pose risk to humans. The regulatory agencies often monitor Pb in water treatment plants (WTP) and/or water distribution systems (WDS). However, people are exposed to tap water inside the house while water may stay in the plumbing premise for several hours prior to reaching the tap. Depending on stagnation period and plumbing premise, concentrations of Pb in tap water can be significantly higher than the WDS leading to higher intake of Pb than the values from WDS or WTP. In this study, concentrations of Pb and water quality parameters were investigated in WDS, plumbing pipe (PP) and hot water tanks (HWT) for 7months. The samples were collected and analyzed on bi-weekly basis for 7 times a day. Several linear, non-linear and neural network models were developed for predicting Pb in PP and HWT. The models were validated using the additional data, which were not used for model development. The concentrations of Pb in PP and HWT were 1-1.17 and 1-1.21 times the Pb in WDS respectively. Concentrations of Pb were higher in summer than winter. The models showed moderate to excellent performance (R2=0.85-0.99) in predicting Pb in PP and HWT. The correlation coefficients (r) with the validation data were in the ranges of 0.76-0.90 and 0.97-0.99 for PP and HWT respectively. The models can be used for predicting Pb in tap water, which can assist to better protect the humans.

Nanostructural Characterization of Hydrothermally Stable γ-Alumina-Based Composite Materials by Transmission Electron Microscopy

The capacities of the p-t-butylcalix[8]arene (abbreviated as H8L) host to extract toxic divalent heavy metal ions and silver from aqueous solution phases containing ammonia or ethylene diamine to an organic phase (nitrobenzene, dichloromethane, or chloroform) were carried out. When the metal ions were extracted from an aqueous ammonia solution, the metal ion selectivity for extraction was found to decrease in the order Cd2+> Ni2+> Cu2+> Ag+> Co2+> Zn2+. When the aqueous phase contained ethylene diamine, excellent extraction efficiencies of 97% and 90% were observed for the heavy metal ions Cu2+ and Cd2+, respectively. Under the same conditions the extraction of octahedral type metal ions, namely, Co2+ and Ni2+, was suppressed. The extraction of transition metal cations by H8L in ammonia and/or amine was found to be pH dependent. Detailed analysis of extraction behavior was investigated by slope analysis, the continuous variation method, and by loading tests.

A review on current status and challenges of inorganic phase change materials for thermal energy storage systems

A patchwork type morphology was formed due to an accidental addition of excess polyvinyl butyral (PVB) polymer powder into the Gadolinia doped Ceria (GDC) slurries during the preparation of homogeneous slurries by a wet atomization process. GDC thin layer has been fabricated on the top of porous tubular anode (GDC-NiO) support at 1400 °C. The results of this study show that polymer can be used not only to fabricate a dense electrolyte but also to generate a nanoporous grain boundary. The fabricated electrolytes have been tested for SOFC (Solid Oxide Fuel Cell) applications in the intermediate-temperature region. The single-cell with dense electrolytes performance test showed a high power density at 550 °C with wet H2 fuel. The effect of different polymers, such as polyvinyl pyrrolidinone (PVP) and polytetrafluoroethylene (PTFE), into the electrolyte slurry was also tested. The polymer binder used in preparing GDC slurry is preferably neither PVP nor PTFE, and/or contains no amounts of these polymers.Copyright