Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) - Volume 8, Issue 2, 2015

Carbon materials of either the nano-sizes or nano-structures are referred to nanocarbons, which from buckminsterfullerene (C60) discovered in 1985 to recent graphenes have attracted great attention of scientists and engineers in the wide fields of science and technology. Here we briefly describe nanocarbons such as graphene and carbon nanotubes (CNTs) including carbon nanofibers (CNFs) and carbon nanohorns (CNHs) with highlights on the emergence of their applications in bio-medical devices.

A comprehensive analysis of the growth of research activity has been conducted in the field of “Renewable Energy” originating from Arab countries. A bibliometric analysis based on databases Scopus was carried out to follow research activities in this field during the period from 1966-2014. Both quantitative and qualitative perceptions were taken into consideration. This study will improve the understanding of research trends in disciplines related to Renewable Energy. A total of 1,620 documents were published from Arab world. The highest number of articles associated with “Renewable Energy” was from Egypt (20.6%), followed by Saudi Arabia (16.7%). The maximum number of citations was 244 for a paper from Oman. The most productive journal was Renewable Energy. The study identified 723 (44.6%) papers with Arab-foreign country collaborations. The most productive institution was Centre de Developpement des Energies Renouvelables, Algeria. The authors declare that these results are up to the date of 2014, may be some researchers have more publications but it did not appear in the search because not all journals are included in Scopus and some others, and even included in the database, some of its volumes are not included yet.

Successfully studies were developed to produce reduced graphene oxide by green reduction of graphene oxide using environmentally-friendly reducing agents. Here for the first time, we report the green reduction of oxidized graphite (OG) to reduced graphene oxide (RGO) using the green plant called Zygophyllum album L.f. (Z. album) which revealed strong reducing activity. Techniques of TEM, Raman, FTIR and BET were carried out for characterization of both samples. Comparative adsorption studies for the removal of p-nitrophenol (PNP) using OG and RGO from aqueous solution in batch mode were studied. Impacting parameters such as pH of solution, adsorbent dose, agitation time, initial concentration of PNP and temperature were estimated. Kinetic studies confirmed that pseudo-second-order kinetic model successfully represented the adsorption process. Batch adsorption isotherms were examined by Langmuir, Freundlich and Florry-Hugins adsorption isotherms. It was found that the experimental data fitted well with the Langmuir model. At different pHs, the isotherms and thermodynamics of adsorption process were also measured, showing that PNP adsorption capacity was significantly pH dependent and endothermic. Maximum adsorption capacities occurred at pH 4 (i.e., 333.3 and 500 mg PNP per gram of OG and RGO, respectively). Therefore, the prepared adsorbents of OG and RGO could be used as potential adsorbents for removing the p-nitrophenol from wastewater.

Esterified modified corn starch has been prepared with corn starch as raw material, acetic acid as activator, acetic anhydride as esterifying agent, and concentrated sulfuric acid as catalyst. Certain substitution degree (DS=0~0.5) of starch acetate (SA) was prepared. Esterified starches reaction conditions were optimized by single factor and orthogonal experiment. Esterified starch was characterized using Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM) and differential scanning calorimetry (DSC) analysis method. The experimental results show that under the conditions where temperature is 75oC, time is 1.5h, concentrated sulfuric acid is 0.13mL, acetic acid is 0.7 (volume ratio of acetic acid and acetic anhydride), substitution degree of SA can reach 0.45. The esterified starch FTIR analysis proves that acetyl groups are introduced successfully. Starch microstructures of SEM show that the esterified starch has a loose and porous structure. DSC analysis shows that the melting temperature of starch decreases with the increase of substitution degree, which made film formation possible.

New reaction scheme is suggested for the initiated nonbranched-chain addition of free radicals to the multiple bond of the molecular oxygen. The scheme includes the addition reaction of the peroxyl free radical to the oxygen molecule to form the tetraoxyl free radical. This reaction competes with chain propagation reactions through a reactive free radical. The chain evolution stage in this scheme involves a few of free radicals, one of which (tetraoxyl) is relatively low-reactive and inhibits the chain process by shortening of the kinetic chain length. Based on the proposed scheme rate equations (containing one to three parameters to be determined directly) are deduced using quasi-steady-state treatment. The kinetic description with use the obtained rate equations is applied to the γ-induced nonbranched-chain processes of the free-radical oxidation of liquid oxylene at 373 K and hydrogen dissolved in water containing different amounts of oxygen at 296 K. The ratios of rate constants of competing reactions and rate constants of addition reactions to the molecular oxygen are defined. In these processes the oxygen with the increase of its concentration begins to act as an oxidation autoingibitor (or an antioxidant), and the rate of peroxide formation as a function of the dissolved oxygen concentration has a maximum. From the energetic standpoint possible nonchain pathways of the free-radical oxidation of hydrogen and the routes of ozone decay via the reaction with the hydroxyl free radical in the upper atmosphere (including the addition yielding the hydrotetraoxyl free radical, which can be an intermediate in the sequence of conversions of biologically hazardous UV radiation energy) were examined. The energetics of the key radical-molecule gas-phase reactions is considered.