boron and 1-4-dioxane

Ring cleavage of cyclic ether substituents attached to a boron cage via an oxonium oxygen atom are amongst the most versatile methods for conjoining boron

Topics: Boranes; Boron; Dioxanes; Halogens; Nitrogen; Temperature

The treatment of 1,4-dioxane solution by electrochemical oxidation on boron-doped diamond was studied using a central composite design and the response surface methodology to investigate the use of SO4 (2-) and HCO3 (-) as supporting electrolytes considering the applied electric current, initial chemical oxygen demand (COD) value, and treatment time. Two industrial effluents containing bicarbonate alkalinity, one just carrying 1,4-dioxane (S1), and another one including 1,4-dioxane and 2-methyl-1,3-dioxolane (S2), were treated under optimized conditions and subsequently subjected to biodegradability assays with a Pseudomonas putida culture. Electrooxidation was compared with ozone oxidation (O3) and its combination with hydrogen peroxide (O3/H2O2). Regarding the experimental design, the optimal compromise for maximum COD removal at minimum energy consumption was shown at the maximum tested concentrations of SO4 (2-) and HCO3 (-) (41.6 and 32.8 mEq L(-1), respectively) and the maximum selected initial COD (750 mg L(-1)), applying a current density of 11.9 mA cm(-2) for 3.8 h. Up to 98 % of the COD was removed in the electrooxidation treatment of S1 effluent using 114 kWh per kg of removed COD and about 91 % of the COD from S2 wastewater applying 49 kWh per kg of removed COD. The optimal biodegradability enhancement was achieved after 1 h of electrooxidation treatment. In comparison with O3 and O3/H2O2 alternatives, electrochemical oxidation achieved the fastest degradation rate per oxidant consumption unit, and it also resulted to be the most economical treatment in terms of energy consumption and price per unit of removed COD.

Topics: Biodegradation, Environmental; Boron; Diamond; Dioxanes; Electrochemical Techniques; Hydrogen Peroxide; Industrial Waste; Oxidation-Reduction; Ozone; Salts; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical

A study of the anodic oxidation of 1,4-dioxane, a refractory water pollutant, by boron-doped diamond (BDD) electrodes was carried out under a range of major system variables: initial concentration, current density, temperature, pH, and electrolyte concentration. The 1,4-dioxane removal behavior was monitored by chemical oxygen demand (COD), and the results were compared with theoretical models for the electrochemical incineration of organic compounds. The removal efficiency of COD was shown to be greater than 95% in most cases, and no electrode fouling was observed during the reaction. Experimental degradation behavior agreed well with the theoretical models, implying that system variables can be predicted, even when the process is applied at pilot scale. Processes conducted at lower initial concentrations and higher temperatures yielded better energy consumption efficiency. Conditions of higher current density yielded faster degradation but need greater quantities of charge loading into the system. Therefore, a compromise between treatment time and energy consumption is required to achieve the desired efficiency. Meanwhile, pH and electrolyte concentrations did not affect reaction efficiency, suggesting that pH adjustment prior to wastewater treatment is not necessary. Thus, anodic oxidation of 1,4-dioxane by BDD electrodes promises to be both an economical and an efficient in wastewater treatment process.

Topics: Algorithms; Boron; Diamond; Dioxanes; Electrochemistry; Electrodes; Electrolytes; Hydrogen-Ion Concentration; Incineration; Models, Chemical; Oxidation-Reduction; Oxygen; Pilot Projects; Temperature; Waste Disposal, Fluid; Water Pollutants, Chemical