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American Society for Testing and Materials

Superoxide ion (O2•–) is of great significance as a radical species implicated in diverse chemical and biological systems. However, the chemistry knowledge of O2•– is rather scarce. In addition, numerous studies on O2•– were conducted within the latter half of the 20th century. Therefore, the current advancement in technology and instrumentation will certainly provide better insights into mechanisms and products of O2•– reactions and thus will result in new findings. This review emphasizes the state-of-the-art research on O2•– so as to enable researchers to venture into future research. It comprises the main characteristics of O2•– followed by generation methods. The reaction types of O2•– are reviewed, and its potential applications including the destruction of hazardous chemicals, synthesis of organic compounds, and many other applications are highlighted. The O2•– environmental chemistry is also discussed. The detection methods of O2•– are categorized and elaborated. Special attention is given to the f...

Superoxide Ion: Generation and Chemical Implications

Biodiesel occupies a prominent position among the alternatives to conventional petrodiesel fuel owing to various technical and economic factors. It is obtained by reacting the parent vegetable oil or fat with an alcohol )transesterification) in the presence of a catalyst to give the corresponding monoalkyl esters, which are defined as biodiesel. Because of the nature of the starting material, the production process, and subsequent handling, various factors can influence biodiesel fuel quality. Fuel quality issues are commonly reflected in the contaminants or other minor components of biodiesel. This work categorizes both the restricted species in biodiesel and the physical properties prescribed by the standards, and details the standard reference methods to determine them as well as other procedures. Other aspects of biodiesel analysis, including production monitoring and assessing biodiesel/petrodiesel blends, are also addressed. The types of analyses include chromatographic, spectroscopic, physical properties-based, and wet chemical methods. The justifications for specifications in standards are also addressed.

Analyzing biodiesel: standards and other methods

Dyes are an important class of organic pollutants and are well known for their hazardous effects on aquatic life in general and human beings in particular. In order to reduce the negative effects of dye contaminated wastewater on humans and the environment, the wastewater must be treated carefully before discharge into main streams. Advances in science and technology have led to the evolution of several techniques for the removal of dyes from industrial and domestic effluents. In this review, the more recent methods for the removal of dyes from water and wastewater have been discussed. Wastewater treatment techniques such as adsorption, oxidation, flocculation–coagulation, membrane filtration and biological treatment have been highlighted. In addition, efforts were made to review all the available techniques and recently published studies from 2010–2014. Furthermore, the performance and special features of these technologies have been summarised. Advantages and limitations of each technique are also presented. A thorough literature survey revealed that chemical oxidation, adsorption, and biological treatments have been the most frequently investigated techniques for dye removal over the past few years.

https://pubs.rsc.org/en/content/articlepdf/2015/ra/c4ra16959j

Recent advances in new generation dye removal technologies: novel search for approaches to reprocess wastewater

Ash-related issues during biomass combustion: Alkali-induced slagging, silicate melt-induced slagging (ash fusion), agglomeration, corrosion, ash utilization, and related countermeasures

During the last two decades, and particularly during the last few years, the environmental sector has shown a largely growing interest in the treatment of different types of water and wastewater by electrocoagulation (EC). The aim of this work was to review studies, conducted mainly during 2008-2011, on the wide and versatile range of feasible EC applications employed in the purification of different types of water and wastewater. The EC applications discussed here were divided into 7 following categories: tannery, textile and colored wastewater; pulp and paper industry wastewater; oily wastewater; food industry wastewater; other types of industrial wastewater; surface water as well as model water and wastewater containing heavy metals, nutrients, cyanide and other elements and ions. In addition, this paper presents an overview of the optimum process conditions (treatment times, current densities, and initial pH) and removal efficiencies (mostly high) achieved for the EC applications discussed. In the vast majority of the studies discussed in this review, the aforementioned values were found to be in the range of 5 - 60 min (typically less than 30 min), 10 - 150 A/m 2 and near neutral pH, respectively. Both operating costs and electrical energy consumption values were found to vary greatly depending on the type of solution being treated, being between 0.0047 - 6.74 €/m 3 and 0.002 - 58.0 kWh/m 3 , but in general they were rather low (typically around 0.1 - 1.0 €/m 3 and 0.4 - 4.0 kWh/m 3

/pdf/recent-applications-of-electrocoagulation-in-treatment-of-4athqfc3jc.pdf

Recent Applications of Electrocoagulation in Treatment of Water and Wastewater—A Review

Physical activation of carbon residue from biomass gasification: Novel sorbent for the removal of phosphates and nitrates from aqueous solution

The main goal of this research was to investigate the possibility of the utilization of carbon residue from biomass gasification process with and without chemical activation as a low cost sorbent for iron(II), copper(II) and nickel(II) ions from an aqueous solution. Commercial activated carbon was used as a reference sample. Batch experiments were done to evaluate the influence of pH, initial metal concentration and contact time. The optimum pH required for maximum adsorption was found to be 4, 5 and 8, for iron, copper and nickel, respectively. According to the results, the removal of metals by carbon residue with and without chemical activation was higher than commercial activated carbon. The highest maximum experimental sorption capacities ( q m ,exp ) for iron, copper and nickel by activated carbon residue were 21, 23 and 18 mg g −1 , respectively. The experimental equilibrium sorption data were tested for the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) equations. Depending on the system the Langmuir or Freundlich isotherms have been found to provide the best correlation. The kinetics of iron, copper and nickel sorption by different adsorbent materials followed the pseudo-second-order model. Other tested kinetic models were the pseudo-first-order and the Elovich models. Weber Morris's intraparticle diffusion model showed that there are two or three different stages for the removal of metals.

Chemically activated carbon residue from biomass gasification as a sorbent for iron(II), copper(II) and nickel(II) ions

Removal of aqueous As(III) and As(V) by hydrous titanium dioxide.

The electrocoagulation (EC) process employed in the removal of phosphate from synthetic wastewater (SWW, 30 mg/l) was optimized, followed by successful scale-up experiments. The optimum process conditions (96% phosphate removal) for laboratory-scale SSW were found to be: anode/cathode = Al/Fe (although Fe/Al performed similarly), initial pH = 5, current density = 100 A/m 2 , treatment time = 15 min, supporting electrolyte = 1.0 g/l NaCl and electrode gap = 7 mm. Real industrial phosphate-containing mining wastewater (MWW) and dairy wastewater (DWW) were also treated with EC, with high pollutant removal efficiencies (optimal phosphate removal of 79% and 93% in 30 min and 60 min, respectively) achieved over the wide initial pH range studied. Electricity consumption and operating costs values in optimum conditions were low for all wastewaters: 0.75 kWh/m 3 and 0.17 €/m 3 for SSW (laboratory scale), 2.11 kWh/m 3 and 0.28 €/m 3 for MWW, and 1.46 kWh/m 3 and 0.31 €/m 3 for DWW. To summarize, the feasibility of using EC in removing phosphate from the wastewater types studied was proven. Utilization of the resulting EC sludge – a potentially valuable phosphorus source in the future (especially in granulated bio ash-based fertilizer products) – was also studied and is discussed.

Toivo Kuokkanen

Papers

Recent Applications of Electrocoagulation in Treatment of Water and Wastewater—A Review

Physical activation of carbon residue from biomass gasification: Novel sorbent for the removal of phosphates and nitrates from aqueous solution

Chemically activated carbon residue from biomass gasification as a sorbent for iron(II), copper(II) and nickel(II) ions

Removal of aqueous As(III) and As(V) by hydrous titanium dioxide.

Removal of phosphate from wastewaters for further utilization using electrocoagulation with hybrid electrodes – Techno-economic studies