Elisama Vieira dos Santos

Combined soil washing and CDEO for the removal of atrazine from soils

In this work, it is studied the removal of atrazine from spiked soils by soil washing using surfactant fluids, followed by the treatment of the resulting washing waste by electrolysis with boron doped diamond (BDD) anode. Results confirm that combination of both technologies is efficient for the removal and total mineralization of atrazine. Ratio surfactant/soil is a key parameter for the removal of atrazine from soil and influences significantly in the characteristic of the wastewater produced, affecting not only to the total organic load but also to the mean size of micelles. The higher the ratio surfactant soil, the lower is the size of the particles. Electrolyses of this type of waste attain the complete mineralization. TOC and COD are removed from the start of the treatment but the key of the treatment is the reduction in size of the micelles, which lead to a higher negative charge in the surface and to the faster depletion of the surfactant as compared with the pesticide.

Decontamination of produced water containing petroleum hydrocarbons by electrochemical methods: a minireview

Produced water (PW) is the largest waste stream generated in oil and gas industries. The drilling and extraction operations that are aimed to maximize the production of oil may be counterbalanced by the huge production of contaminated water (called PW) with pollutants, such as heavy metals, dissolved/suspended solids, and organic compounds. PW is conventionally treated through different physical, chemical, and biological methods. In offshore platforms, because of space constraints, compact physical and chemical systems are used. However, major research efforts are being developed with innovative technologies for treating PW in order to comply with reuse and discharge limits. Among them, electrochemical technologies have been proposed as a promising alternative for the treatment of this kind of wastewaters. Then, this paper presents a minireview of efficient electrochemical technologies used until now for treating PW generated by petrochemical industry.

Removal of oxyfluorfen from ex-situ soil washing fluids using electrolysis with diamond anodes.

In this research, firstly, the treatment of soil spiked with oxyfluorfen was studied using a surfactant-aided soil-washing (SASW) process. After that, the electrochemical treatment of the washing liquid using boron doped diamond (BDD) anodes was performed. Results clearly demonstrate that SASW is a very efficient approach in the treatment of soil, removing the pesticide completely by using dosages below 5 g of sodium dodecyl sulfate (SDS) per Kg of soil. After that, complete mineralization of organic matter (oxyflourfen, SDS and by-products) was attained (100% of total organic carbon and chemical oxygen demand removals) when the washing liquids were electrolyzed using BDD anodes, but the removal rate depends on the size of the particles in solution. Electrolysis of soil washing fluids occurs via the reduction in size of micelles until their complete depletion. Lower concentrations of intermediates are produced (sulfate, chlorine, 4-(trifluoromethyl)-phenol and ortho-nitrophenol) during BDD-electrolyzes. Finally, it is important to indicate that, sulfate (coming from SDS) and chlorine (coming from oxyfluorfen) ions play an important role during the electrochemical organic matter removal.

Determinação do teor de cálcio em comprimido à base de lactato de cálcio utilizado no tratamento da osteoporose

The present study utilized thermogravimetry (TG) and optical emission spectrometry with inductively coupled plasma (ICP/OES) to determine the amount of calcium in calcium lactate tablets used in the treatment of osteoporosis. Thermogravimetry results indicated that the decomposition temperature of CaCO3 occurred at 603.9 and 609.4 oC in the samples of calcium lactate and tablets, respectively. The calcium content obtained by TG for the tablets sample showed a similar result to that disclosed by ICP-OES, indicating a value of 8.93% for both techniques.

Photo-Electrochemical Technologies for Removing Organic Compounds in Wastewater

Abstract In recent years, electrochemical technologies for the prevention and remediation of environmental pollution have been strongly developed. A review of photoelelectrocatalysis (PEC) for the treatment of wastewater is presented in this chapter. Different types of photo-anodes and cathodes have been developed and studied to increase the efficiency of PEC for the removal of organic compounds. An interesting parameter that was investigated in the last work is the generation of an active species by the utilization of proper cathodes. Moreover, this chapter deals with the keys factors affecting the PEC, including electrolyte oxidation.

Electrochemical advanced oxidation processes (EAOPs) as alternative treatment techniques for carwash wastewater reclamation

Electrochemical advanced oxidation processes such as electrooxidation (EO), electrooxidation with hydrogen peroxide generation (EO-H2O2) and electro-Fenton process (EF) have been investigated as alternative treatment techniques for complete removal of anionic surfactants and organic matters from real carwash wastewater. The electrochemical processes were performed with acidified real carwash wastewater using boron doped anode and carbon felt cathode. In all cases, the chemical oxygen demand (COD) removal efficiency was always increased with rise in applied current and complete organic matter decay was achieved at applied current of 500 mA or above after 6 h of electrolysis. Faster and higher COD decay was observed with EF compared to either EO or EO-H2O2 treatment, at all currents and electrolysis time. Besides, complete degradation of anionic surfactants - the major organic content of the wastewater could be achieved at all applied currents studied irrespective of the process used, indicating the efficacy of processes for total remediation of real carwash wastewater. The short-chain carboxylic acids formed as the final organic byproducts were identified and quantified by ion-exclusion chromatography. More so, lower energy consumption and higher current efficiency were achieved with EF compared to EO-H2O2. Electrochemical treatment was found to be a powerful technology for the complete abatement of organic matter in carwash wastewater for possible reuse.

Modified Diamond Electrodes for Electrochemical Systems for Energy Conversion and Storage

The aim of this chapter was to summarize the techniques used for surface modification of BDD materials, improving their catalytic efficiency as supported catalysts for PEM fuel cells (methanol and ethanol oxidation) as well as the studies concerning to the production of electrochemical capacitors using BDD materials. Also, the recent advances on the use of modified BDD materials for fuel cells will be discussed.

Electrochemical Oxidation of Oxalic Acid at Different Anode Materials: Applicability of Electroanalysis for Monitoring OA Degradation

The electrochemical oxidation (EO) of oxalic acid (OA) has been studied, in acidic media at Ti/PbO2, highly boron-doped diamond (BDD), Pt and graphite electrodes by applying 60 mAcm−2 of current density. Generally, EO is monitored by chromatography techniques; but the aim of this work is to show the applicability of electroanalysis for detection of OA concentration during its oxidation; by differential pulse voltammetry (DPV) using two different analytical procedures (by analytical curve and by successive addition standard). The results obtained by DPV analysis showed that OA was oxidized at several substrates to CO2 with different results, showing that the performances of the process dramatically depend on the anodic material. Higher removal efficiencies were obtained at Ti/PbO2, graphite and BDD anodes. Finally, DPV analyses were compared with classic titration method achieving a good fit, confidence intervals and limits. The results are described and discussed in the light of the existing literature.