Physiochemical Properties and Removal Methods of Phenolic Compounds from Waste Waters

In this chapter, phenol and chlorophenols are investigated in terms of their production histories, physiochemical properties, pollution resources, and removal methods. It is seen that both phenol and chlorophenols are highly toxic compounds, produced from natural and anthropogenic sources, which are hazardous to both humans and the environment even at very low concentrations. The typical industries which produce phenol and chlorophenol pollution are petrochemical, textile, plastics, resin, dye, pharmaceutical, iron and steel, pulp and paper industries as well as the petroleum refineries, and coal gasification operations. Phenol is a highly corrosive and nerve poisoning agent. It causes harmful health effects, such as sour mouth, diarrhea, and impaired vision. It is also toxic for the ecosystem with toxicity levels ranging between 10-24 mg/L for humans, 9-25 mg/l for fish, and lethal blood concentration around 150-mg/100 ml. Chlorophenols found in natural waters or drinking water also cause serious health problems such as histopathological alterations, genotoxicity, mutagenicity, and carcinogenicity among others. Due to the aforementioned reasons, the phenolic compounds in wastewaters or drinking water must be removed using a suitable wastewater treatment method such as adsorption, extraction, electrochemical oxidation, biodegradation, catalytic wet air oxidation, or enzyme treatment among others

Leaders and followers in hot IPO markets

We model the dynamics of going public within an IPO wave. The model predicts that firms with better growth opportunities can find it optimal to go public early and accept underpricing of their issues to signal quality. Data supports this prediction as, on average, early movers underprice their issues significantly more and we show that leaders (early movers with high underpricing) obtain much higher valuations when going public than other IPO firms. Furthermore, after going public, leaders invest significantly more, their sales grow faster, and their profitability remains higher compared to other IPO firms

IPO Waves in China and Hong Kong

We analyze the anatomy of IPO waves in China and Hong Kong and draw comparisons with the US IPO cycles. The lead–lag relationship between IPO initial returns and IPO volume observed in the US is absent in these two Asian markets. Similar to the US, IPO volume in Hong Kong is sensitive to changes in market conditions and exhibits seasonal variations. In sharp contrast, however, Chinese IPO activity is much less responsive to past market returns and volatility. Surprisingly, hot markets still emerge in China, not because of market forces as in the US and Hong Kong, but due to regulatory choices

A Comparative Characterization of the HPA-MCM-48 Type Catalysts Produced by the Direct Hydrothermal and Room Temperature Synthesis Methods

MCM-48 type support materials synthesized by the direct hydrothermal synthesis (HTS) and room temperature synthesis (RTS) methods were incorporated with tungstophosphoric acid (TPA) in the range of 10–40 wt% by using a wet impregnation technique in methanol solutions. Resulting HPA-MCM-48 catalysts were characterized by the XRD, Nitrogen Physisorption, SEM, TEM, EDS, and FT-IR methods in order to determine the effects of different initial synthesis conditions on the catalyst properties. RTS samples were found to have better crystalline structures, higher BET surface areas, and higher BJH pore volumes than HTS samples. They also had slightly higher TPA incorporation, except for the 40 wt% samples, as evidenced by the EDS results. Keggin ion structure was preserved, for both methods, even at the highest acid loading of 40 wt%. It was concluded that the simpler and more economical RTS method was more successful than the HTS method for heteropoly acid incorporation into MCM-48 type materials

Fortification of edible zein films with thyme, laurel and orange essential oils and determination of their antifungal and radical scavenging properties

The purposes of this research were: (a) to produce zein films by adding certain essential oils (EOs), (b) to identify their antifungal activity on some yeasts and molds, and (c) to develop an edible zein film that can inhibit the growth of Aspergillus fumigatus which was identified in a previous study as the most heat resistant mold isolated from marga-rines. Zein films fortified with thyme (Thymus vulgaris), laurel (Laurus nobilis) and orange (Citrus sinensis) EO were tested for their antifungal activities against 3 molds and 5 yeasts by measuring inhibition zone diameters. Considering the single effect, thyme EO was determined as the most effective one. Furthermore, the antifungal activities of thyme EO combined with the other EOs were also studied. From the obtained data, films containing thyme EO in combination with laurel EO were found as the most effective against Aspergillus fumigatus. Then, minimally inhibitory concentration against Aspergillus fumigatus was determined for the zein film obtained from film solutions including only thyme EO as 1.7 % (v/w), combinations of thyme-laurel EO as 1.6 % (v/w). Also, thyme oil was found as EO having the highest radical scavenging activity and total phenolic compounds among the three EOs. © M. & H. Schaper GmbH & Co.NKUBAP.00.24This study was financially supported by Namik Kemal University Scientific Research Projects Coordination Department, project number NKUBAP.00.24.DR.10.06. This article is produced from Ph.D. thesis of Cigdem Mecitoglu Gucbilmez

Ethylene and acetaldehyde production by selective oxidation of ethanol using mesoporous V-MCM-41 catalysts

Vanadium-incorporated MCM-41 type catalytic materials, which were synthesized by a direct hydrothermal synthesis procedure, showed very high activity and high selectivity in the production of ethylene from ethanol in an oxidative process. Ethylene selectivity showed a significant increase with an increase in temperature over 300 degrees C, while relatively high acetaldehyde selectivities were observed at lower temperatures. An ethylene yield value of 0.66 obtained at 400 degrees C with an O-2/ethanol feed ratio of 0.5 was beneficial from the point of view that these results might open a new pathway for the production of ethylene from a nonpetroleum environmentally friendly feedstock, namely, bioethanol. The optimum V/Si ratio of the catalyst, which gave the maximum ethylene yield, was found to be around 0.04. Experimental results showing the formation of acetaldehyde and not showing the formation of ethylene in the absence of gas-phase oxygen and the catalyst deactivation observed in such conditions suggested a redox mechanism involving the surface lattice oxygen of the catalyst in acetaldehyde production, while the involvement of adsorbed oxygen was concluded to take place in the formation of ethylene

Vanadium incorporated high surface area MCM-41 catalysts

High surface area MCM-41 (1452 m(2)/g) and V-MCM-41 materials were synthesized by a direct hydrothermal synthesis method. Characteristic XRD patterns, SEM and AFM photographs indicated no significant change in the morphology of MCM-41 by incorporation of vanadium. XPS and EDS results proved that incorporation of vanadium into the MCM-41 structure was successfully achieved when vanadyl sulfate hydrate was used as the vanadium source. However, use of ammonium vanadate as the vanadium source was not equally successful

Optimization of the locations of side streams in a filter cake washing process

A macroscopic model was developed to perform optimization studies for countercurrent, nonequilibrium, displacement filter cake washing on a belt filter with incoming side streams. Each washing stage was assumed to contain a number of perfect mixing cells connected in series. The optimum locations of the side streams, which yielded the minimum exit solute concentration for the washed cake, were evaluated. Three cases were considered: Incoming side stream added to the wash liquor flow, incoming side stream added to the cake flow and incoming side streams added to both flows simultaneously. A parameter study was performed systematically to determine the effect of washing parameters on the optimum side stream locations