Molecular laser-induced breakdown spectroscopy technique for the detection of nitrogen in waters

Nitrogen (N) content is a significant indicator for use in evaluating eutrophication. However, the conventional method, such as alkaline potassium persulfate digestion ultraviolet (UV) spectrophotometric or Kjeldahl method, always require...

Photochemical treatment of an actual municipal wastewater by means of UV, potassium persulfate and iron

The photochemical treatment of an actual municipal wastewater (MWW) from wastewater treatment plant (WWTP) in Kazakhstan has been studied in the present work. The MWW has been taken after mechanical treatment stage and characterized. The photochemical treatment included the use of the photo-Fenton-like process in the batch photoreactor with a UV irradiation at 254 nm for 120 min. Experiments have been done without adjusting the initial pH of wastewater, which was around 7.7. Potassium persulfate (K2S2O8) was activated by means of UV and ferric ions, which led to generation of highly oxidative sulfate and peroxymonosulfate radicals. The concentration of Fe2+ ions ranged from 20 to 100 ppm, while the concentration of K2S2O8 was in between 5 and 25 mmol/L. 83% removal of total organic carbon (TOC) was achieved after 120 min of treatment using 15 mmol/L K2S2O8 and 20 ppm Fe2+, while 75% removal of total carbon (TC) was observed at 15 mmol/L K2S2O8 and 100 ppm Fe2+. As the carboxylic acids are common organic intermediates after photochemical treatment, the presence of formate and acetate anions in effluents were further detected on the ion chromatography.

Corrosion inhibitor system for blocking polymer well by potassium persulfate injection

Purpose This paper aims to clarify the corrosion inhibition effect of different corrosion inhibitor systems on the corrosion of metal pipe string by potassium persulfate plugging agent, so as to improve the injection capacity of polymer plugging well and reduce the corrosion of steel by oxidant plugging agent. Design/methodology/approach The effect of different corrosion inhibitors on the corrosion inhibition of N80 carbon steel in 1% potassium persulfate solution was studied by electrochemical experiment and weight loss experiment. The corrosion inhibition mechanism of potassium persulfate inhibitor and the synergistic mechanism among different inhibitors were analyzed. Findings The results indicated that when the temperature was 50°C, the inhibition effect of 0.2% sodium molybdate with a single inhibitor was the best at pH 8.5, and the inhibition rate was 70.17%. The inhibition efficiency of 0.2% sodium molybdate + 0.3% sodium silicate in the composite inhibition system can reach 94.38%. In the temperature range of 20°C–60°C, with the increase of system temperature, the inhibition effect of corrosion inhibitor will gradually weaken. Originality/value The corrosion inhibition system of N80 steel in potassium persulfate oxidant was mainly studied, and it clarified the influence of temperature and pH value on the corrosion inhibition effect, which provided guidance and suggestions for the corrosion inhibition of tubular string in the oilfield.

Effects of Functionalization in Different Conditions and Ball Milling on the Dispersion and Thermal and Electrical Conductivity of MWCNTs in Aqueous Solution

In this work, the effects of a functionalization method involving different conditions and milling processes on the dispersion and thermal and electrical conductivity of multiwalled carbon nanotubes were studied. The surfaces of MWCNTs were modified using a mixture of sulfuric and nitric acid as an acid treatment and potassium persulfate and sodium hydroxide as an alkaline treatment to achieve more hydrophilic MWCNTs. The morphological and structural investigations were carried out using transmission electron microscopy and Fourier transform infrared spectroscopy. Furthermore, the dispersion characteristics and thermal and electrical conductivity of the as-prepared water-based nanofluids were measured. As a result, the dispersion characteristics revealed that the best dispersion and stability results were obtained for alkaline-treated MWCNTs using potassium persulfate and sodium hydroxide. The thermophysical study using a thermal conductivity analyzer exhibited that the thermal conductivity of the pristine MWCNT nanofluid (0.1 wt%) was enhanced from 603.5 to 610.4 mW/m·K and the electrical conductivity of the raw MWCNT nanofluid was increased from 16.2 to 125.8 μS/cm at 25 °C after alkaline treatment and milling processes, which were performed using planetary ball milling. Regarding the overall results, the milling process and mild alkaline oxidation process are more environmentally friendly, effective, and convenient for the functionalization of CNTs, without requiring any organic solvents or strong acids.

Diiiodine/Potassium Persulfate Mediated Synthesis of 1,2,3-Thiadiazoles from N-Tosylhydrazones and a Thiocyanate Salt as a Sulfur Source under Transition-Metal-Free Conditions

A highly efficient method for the synthesis of 1,2,3-thiadiazoles has been developed by utilizing readily available tosylhydrazones and ammonium thiocyanate with ecofriendly EtOH as the solvent at room temperature. The reaction shows a wide scope of substrates and good functional-group tolerance. This protocol can be scaled up to a gram level and can be applied to coupling reactions with 4-(4-bromophenyl)-1,2,3-thiadiazole as the substrate.