BACKGROUND Plating and pickling processes are the most effective ways for increasing the strength of metal structures, and workers in these units are exposed to various contaminants, including acid mists. The aim of this study was to investigate the effect of protective masks in decreasing the respiratory symptoms and the aerobic capacity of workers that are exposed sulfuric acid mist. METHOD...

A LTHOUGH MANY METHODS have been published for the determination of pregnanediol in urine, we found none of them fully satisfactory. The first gravimetric method (1), and colorimetric methods derived from this one (2, 3), are rather unspecific, because, especially under pathologic conditions, fairly large amounts of similar compounds are found in the so-called pregnanediol fraction. Determinati...

in this study, different contents of nano-silica, 2 wt.%, 4 wt.% and 6 wt.%, have been added to bitumen tomodify the physical, mechanical and rheological properties of warm mix asphalt (wma). wma iscontaining 2 wt.% of sasobit (mixture of long-chain hydrocarbons). various quality control tests have beencarried out to characterize the modified bitumen and wma. the rheological investigations show...

New modified acidic catalysts were prepared from the treatment of silica, titania and silica prepared from hydrolyzed tetraethyl orthosilicate (TEOS) with sulfuric and phosphoric acid. The sulfated and phosphated silica synthesized from TEOS were calcined at 450 and 650 ◦C. These catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmissio...

two simple protocols for the synthesis of three-component condensation reaction of an aldehyde, β-ketoester and urea or thiourea to obtain the 3, 4-dihydropyrimidin-2(1h)-ones (thiones) using nano silica phosphoric acid are reported. short reaction times, high yields, reusability of catalyst and easy workup are some advantages of these protocols.

Technologies to collect and reuse sulfuric acid waste is attracting attention to reduce industrial waste in semiconductor manufacturing plants. Reusing sulfuric acid has a high economic value. By using sulfuric acid recycling equipment based on an atmospheric distillation method, we evaluated the recovery percentage of sulfuric acid, the concentration and quality of recycled sulfuric acid, and ...

This paper studies the recent investigations and development of combined application of Pozzolanic additions Nano-Silica (NS) and Fly Ash (FA) on the strength properties of concrete for sub sequential growth of concrete industry. This investigation not only saves the natural resources but also controls the environmental pollution by usage of wastes. The limited work is done on partial replaceme...

Sulfuric acid is a common chemical that is widely used in industry and is found in consumer products (e.g., car batteries, cleaning products). In the United States sulfuric acid is ranked number one in terms of production volume. Sulfur trioxide is a precursor to the production of sulfuric acid. Oleum (fuming sulfuric acid) is sulfur trioxide absorbed in concentrated sulfuric acid. Sulfur triox...

Concrete is the most widely used material for the construction of the wastewater collection, storage, and treatment infrastructure. The chemical and physical characteristics of hydrated Portland cement may make it susceptible to degradation under highly acidic conditions. As a result, some concrete wastewater infrastructure may be susceptible to a multistage degradation process known as microbi...