Treatment of simulated wastewater containing Reactive Red 195 by zero-valent iron/activated carbon combined with microwave discharge electrodeless lamp/sodium hypochlorite

A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon （ZVI/AC）, microwave discharge electrodeless lamp/sodium hypochlorite （MDEL/NaCIO） and the combination of ZVI/AC- MDEL/NaCIO was conducted. The preliminary results showed the two steps method of ZVI/AC-MDEL/NaCIO had much higher degradation efficiency than both single steps. The final color removal percentage was nearly up to 100% and the chemical oxygen demand reduction percentage was up to approximately 82%. The effects of operational parameters, including initial pH value of simulated wastewater, ZVI/AC ratio and particle size of ZVI were also investigated. In addition, from the discussion of synergistic effect between ZVI/AC and MEDL/NaCIO, we found that in the ZVI/AC-MEDL/NaCIO process, ZVI/AC could break the azo bond firstly and then MEDLfNaCIO degraded the aromatic amine products effectively. Reversing the order would reduce the degradation efficiency.

Study on Influencing Factors and Kinetics of Removal of Ammonia Nitrogen from High Salinity Wastewater by Sodium Hypochlorite Oxidation

The influencing factors and kinetics of oxidative degradation of ammonia nitrogen in high salinity wastewater by sodium hypochlorite oxidation( Na Cl O) were studied. The results showed that the degradation process of ammonia nitrogen by sodium hypochlorite accorded with a pseudo first-order kinetics model,and the influencing factors included Na Cl O dosage,initial concentration of ammonia nitrogen,salinity,temperature,and so on. When Na Cl O dosage was 0. 6%( MCl∶ MN= 13. 76),the reaction rate constant was up to 0. 015 75 min^(-1). The higher the initial concentration of ammonia nitrogen was,the worse the effect of oxidation reaction was. When the initial concentration did not exceed 45 mg/L,the effect on oxidation reaction rate constant increased with the increase of the initial concentration. Low salinity had no effect on ammonia nitrogen oxidation.When salinity was higher than 2. 0%,the inhibition effect on ammonia nitrogen oxidation would increase,and the reaction rate constant decreased obviously with the increase of salinity. The improvement of reaction temperature was beneficial to ammonia oxidation degradation. As temperature increased from 10 to 35 ℃,the reaction rate constant rose from 0. 00188 to 0. 01043 min^(-1).

Generation of sodium hypochlorite (NaOCl) from sodium chloride solution using C/PbO_2 and Pb/PbO_2 electrodes

Two modified electrodes （Pb/PbO2 and C/PbO2） were prepared by electrodepositing a lead oxide layer on lead and carbon sub- strates. These modified electrodes were used as anodes for the generation of sodium hypochlorite （NaOC1） from sodium chloride solution. Different operating conditions and factors affecting the treatment process of NaOC1 generation, including current density, pH values, con- ductive electrolytes, and electrolysis time, were studied and optimized. By comparison the C/PbO2 electrode shows a higher efficiency than the Pb/PbO2 electrode for the generation of NaOC1.

Molybdenum removal from copper ore concentrate by sodium hypochlorite leaching

The removal of molybdenum from a copper ore concentrate by sodium hypochlorite leaching was investigated. The results show that leaching time,liquid to solid ratio,leaching temperature,agitation speed,and sodium hypochlorite and sodium hydroxide concentrations all have a significant effect on the removal of molybdenum.The optimum process operating parameters were found to be：time,4 h;sodium hydroxide concentration,10%;sodium hypochlorite concentration,8%;liquid to solid ratio,10：1;temperature,50℃;and, agitation speed,500 r/min.Under these conditions the extraction of molybdenum is greater than 99,9%and the extraction of copper is less than 0.01%.A shrinking particle model could be used to describe the leaching process.The apparent activation energy of the dissolution reaction was found to be approximately 8.8 kJ/mol.

Comparison of Decontamination Efficacy between the Rapid Hygrothermal Pasteurization and Sodium Hypochlorite Treatments

We developed a novel rapid hygrothermal pasteurization (RHP) method using saturated water vapor with a dew point of 100℃. The aim of this paper is to compare the effect of RHP treatment versus conventional sodium hypochlorite (NaClO) treatments on inactivation of natural mesophilic bacteria and quality attributes on fruits and vegetables. The RHP treatment was performed within a second by free-falling samples (cabbage, cucumber, carrot, bell pepper, pineapple and melon) through cylindrical processing chamber filled with steam. NaClO treatment was performed by washing samples with NaClO solution (100 mg/mL of free chlorine (pH 7), for 1 min). The RHP treatment showed a significantly higher inactivation effect than NaClO treatment on all tested samples. The RHP treatment had a slightly larger influence on color and vitamin C content than NaClO treatment in cabbage. Furthermore, the effects of treatment time and operated temperature were also determined using microbial model system. Elongation of treatment time did not significantly increase the microbial inactivation effect. Lowering of operated temperature by mixing air into steam tended to decrease the inactivation effect. From these results, RHP treatment could be used as an alternative method for decontaminating microorganisms on fruits and vegetables, except on leafy vegetable. In addition, it is suggested that microbial inactivation by RHP treatment was achieved through the initial condensation stage of water vapor on sample surface. By contrast, interfusion of air disturbed the effective condensation of water vapor.

Effects of Different Concentrations and Exposure Time of Sodium Hypochlorite on the Structural,Compositional and Mechanical Properties of Human Dentin

This study evaluated the effects of sodium hypochlorite（NaOCl） with different concentrations and exposure time on the structural, compositional and mechanical properties of human dentin in vitro. Sixty dentin slabs were obtained from freshly extracted premolars, randomly distributed into four groups（n=15）, and treated with 1%, 5%, 10% NaOCl and distilled water（control group）, respectively, for a total of 60 min. Attenuated total reflection infrared（ATR-IR） spectroscopy, Raman spectroscopy and X-ray diffraction（XRD） were carried out before, 10 min and 60 min after the treatment. Scanning electron microscopy（SEM） and flexural strength test were conducted as well. The results showed that dentins experienced morphological alterations in the NaOCl groups, but not in the control group. Two-way repeated-measures analysis of variance revealed that the carbonate：mineral ratio（C：M）, Raman relative intensity（RRI）, a-axis, c-axis length and full width at half maximum（FWHM） with the increase of time and concentration in the NaOCl groups were not significantly different from those in the control group（P〉0.05）. Nevertheless, the mineral：matrix ratio（M：M） increased and the flexural strength declined with the increase of concentration and the extension of time in the NaOCl groups（P〈0.05）. Additionally, it was found that the M：M and the flexural strength remained unchanged after 1% NaOCl treatment（P〉0.05）, and the morphology changes were unnoticeable within 10 min in 1% NaOCl group. These results indicated that NaOCl has no significant effects on the inorganic mineral of human dentin; but it undermines and eliminates the organic content concentration-and time-dependently, which in turn influences the flexural strength and toughness of dentins. In addition, an irrigation of 1% NaOCl within 10 min can minimize the effects of NaOCl on the structural and mechanical properties of dentin during root canal treatment.

Multiple rapid-responsive probes for hypochlorite detection based on dioxetane luminophore derivatives

In recent years,various methods for detecting exogenous and endogenous hypochlorite have been studied,considering its essential role as a biomolecule.However,the existing technologies still pose obstacles such as their invasiveness,high costs,and complicated operation.In the current study,we developed a glow-type chemiluminescent probe,hypochlorite chemiluminescence probe(HCCL)-1,based on the scaffold of Schaap's 1,2-dioxetane luminophores.To better explore the physiological and pathological functions of hypochlorite,we modified the luminophore scaffold of HCCL-1 to develop several probes,including HCCL-2,HCCL-3,and HCCL-4,which amplify the response signal of hypochlorite.By comparing the luminescent intensities of the four probes using the IVIS®system,we determined that HCCL-2 with a limit of detection of 0.166 mM has enhanced sensitivity and selectivity for tracking hypochlorite both in vitro and in vivo.

New insights into enhancement of sodium hypochlorite on formation and properties of anodic films on Ti6Al4V alloy

Anodic films were successfully fabricated on Ti6A14V alloy by anodic oxidation method in an environmental friendly electrolyte with and without sodium hypochlorite. The anodic films were characterized by means of the scanning electron microscope （SEM） and energy dispersive spectrometer （EDS）. Results revealed that the addition of sodium hypochlorite leads to the ultrafast growth of oxide films, and results in the significant changes of morphology and thickness. The influence of sodium hypochlorite on formation and crystallization of oxide films as a function of anodizing time was discussed. Meanwhile, potentiodynamic electrochemical tests and dry sliding wear tests were performed to evaluate the corrosion resistance and tribological properties of oxide films. It was found that the oxide film fabricated with the existence of sodium hypochlorite had improved corrosion resistance and tribological properties than the one formed without sodium hypochlorite. Moreover, the effect mechanism of sodium hypochlorite on the growth rate and surface morphologies of oxide films during the anodizing process was discussed. It was found that hypochlorite ions participated in the reaction on anode which causes the rapid growth of oxide films and then affect the whole anodizing process.

Oxidation of Lingwu Coal Extraction Residue in Aqueous Sodium Hypochlorite under Mild Conditions

To investigate the structural features and provide an alternative method for high value-added utilization of coal, Lingwu coal was first extracted with organic solvent at room temperature. Then its extraction residue was oxidized in aqueous sodium hypochlorite(ASHC) under mild conditions. The effects of oxidation conditions, such as temperature, reaction time, the ratio of Lingwu coal extraction residue(LCER, g) to ASHC(m L) and p H value, on the product distributions and compositions were investigated. The results of gas chromatography/mass spectrometry(GC/MS) suggested that 53 kinds of methyl esterified products were detected in total, and benzene carboxylic acids were the main oxidation products, while chloro-substituted benzene carboxylic acids were the main by-products. Higher yield and fewer kinds of organic acids could be obtained at lower p H value, especially for the main objective product, benzene carboxylic acids.

Detection of <i>Para</i>-Chloroaniline Resulting from the Interaction between Sodium Hypochlorite and Chlorhexidine Analyzed by Mass Spectrometry

5.1% of sodium hypochlorite (NaOCl) mixed with 2% of chlorhexidine (CHX) forms a brown precipitate that corresponds to para-chloroaniline (PCA), whether PCA is formed after the combination of NaOCl, CHX, and ethylenediaminetetraacetic acid (EDTA) by means of electron impact (high resolution and interlaced scanning) and ionization by fast atom bombardment (FAB), was analyzed. The brown precipitate, showed signals 127 and 153 Da, corresponding to p-chloroaniline and p-chlorophenyl isocyanate, respectively. These results were analyzed and compared with signals from the interlaced scanning program and confirmed with high resolution mass spectrometry analysis and compared with the NIST database. The mass spectra of this precipitated after different days confirmed the evolution of byproducts with the presence of a peak m/z = 127, due to the decrease of the fragment m/z = 153, which disappeared after 180 days. A blue and a white precipitate were observed by the addition of CHX (2%) with or without polyethylene glycol, respectively, EDTA (17%) and NaOCl (5.1%) precipitates contain chlorhexidine (m/z = 505), but no PCA was detected. We confirmed that PCA is not formed directly as a byproduct of CHX oxidation, but through the formation of the para-chlorophenyl isocyanate intermediate, which degrades slowly to PCA.

Subcutaneous Emphysema Caused by Sodium Hypochlorite plus RC-Prep

Introduction: “RC-Prep”, a chemo-mechanical preparation for root canals, includes EDTA and urea peroxide as ingredients. For lubrication and its chelating effect, RC-Prep is useful as an adjunct in root canal enlargement. Furthermore, its cleaning action, due to its foaming properties in combi-nation with sodium hypochlorite, can be useful in root canal treatment in many situations. Methods: In a case of upper gingiva swelling, we used sodium hypochlorite with RC-Prep in the treatment of an infected root canal of the left maxillary premolar at the first visit. Within 2 min after use, the patient’s face became swollen. We kept the root canal open, and conducted a CT scan to investigate. Results: We diagnosed subcutaneous emphysema and prescribed 1 week of pain killers and antibiotics. The pain and swelling in the face finally resolved at 11 days after the incident. Conclusions: The cause of the emphysema was considered to have been the use of a sodium hypo-chlorite solution after using RC-Prep for an opened root apex.

Development of the Sea Urchin Arbacia Punctulata in the Presence of the Environmental Toxin Sodium Hypochlorite

Sodium hypochlorite (NaOCl) or bleach, found in effluent from wastewater treatment plants, can act as an environmental toxin. The sea urchin Arbacia punctulata is a common subject of embryological toxicity tests due to its sensitivity to environmental pollutants. Using concentrations of NaOCl that mimic those found in treated wastewater (0.11 ppm, 0.06 ppm, and 0.03 ppm) we observed minimal affects on early larval development, though most larvae took longer to develop at higher NaOCl concentration. There was a significant difference in the percentage of non-normal plutei based on concentration (P = 0.038) and significant interaction between the percent of each morphology and NaOCl concentration (P = 0.0027). The most significant change in non-normal plutei was in the retarded (shortened skeletal rods) malformation which increased in frequency with NaOCl concentration (P = 0.001). There was a significant reduction in skeletal length in both normal and retarded plutei (P < 0.05) as NaOCl increased.

Effect of Pretreatment of Sulfide Refractory Concentrate with Sodium Hypochlorite, Followed by Extraction of Gold by Pressure Cyanidation, on Gold Removal

The majority of the refractory gold and silver occurs in occlusion in sulphides, then precious metal dissolution is possible by first oxidizing auriferous sulfide concentrate using sodium hypochlorite-sodium-hydroxide solution followed of pressure cyanidation of the oxidized concentrate, for the extraction of precious metals. This process was conducted and evaluated under cyanide and oxygen pressure. This versatile approach offers many advantages, including low temperatures, low pressure and less costly materials of construction than conventional pressure oxidation. In this study, the effect of oxygen pressure, concentration of sodium hypochlorite, temperature, and initial pH, in precious metals recovery and As removal were evaluated using a 24 factorial design. Characterization of the ores showed that pyrite and arsenopyrite were the main minerals present on the concentrate. The best results for gold extraction were obtained with oxygen pressure of 80 psi, 10% (w/w) sodium hypochlorite, temperature of 80℃, at pH = 13, and a constant stirring speed of 600 rpm. These conditions allowed an approximated 60% of gold and 90% of silver extractions in 1 hr.

Fluorine-doped carbon quantum dots with deep-red emission for hypochlorite determination and cancer cell imaging

As a type of new carbon-based nanomaterials,carbon dots(CDs)possess exceptional optical properties,making them highly desirable for use in fluorescent sensors.However,the CDs with deep-red(DR)or near-infrared(NIR)emission have rarely been reported.In this work,we prepared deep-red emissive fluorine-doped carbon quantum dots(F-CDs)by introducing a precursor simultaneously containing fluorine and amidogen.The synergistic effect of nitrogen doping and D-π-A pattern production contributed to the maximum emission of F-CDs at 636 nm with an absolute quantum yield of 36.00%±0.68%.Moreover,we designed an F-CDs-based fluorescence assay to determine the content of hypochlorite(ClO^(-)),with a limit of detection(LOD)as low as 15.4 nmol/L,indicating the high sensitivity of F-CDs to ClO^(-).In real samples,the F-CDs-based fluorescent sensor exhibited excellent sensitivity and selectivity in the detection of ClO^(-),with an error below 2%,suggesting their great potential in daily life.In cancer cell imaging,the F-CDs not only demonstrated high sensitivity to ClO^(-)but also exhibited excellent mitochondria targeting,as evidenced by the high Pearson's correlation coefficient(PCC)of 0.93 in colocalization analysis.The work presented here suggests the great potential of replacing commercial dyes with F-CDs for highly specific mitochondria labeling and cell imaging.

Aging of PVDF and PES ultrafiltration membranes by sodium hypochlorite:Effect of solution pH

Sodium hypochlorite(NaClO)is a commonly applied cleaning agent for ultrafiltration membranes in water and wastewater treatment.Long-term exposure to NaClO might change the properties and performance of polymeric membranes,and ultimately shorten membrane lifespan.Active species in NaClO solution vary with solution pH,and the aging effects can change depending on the membrane material.In this study,the aging of polyvinylidene fluoride(PVDF)and polyethersulfone(PES)membranes by NaClO at pH 3–11 was investigated by examining variations in chemical composition,surface charge,surface morphology,mechanical strength,permeability,and retention ability.Polyvinyl pyrrolidone(PVP),which was blended in both membranes,was oxidized and dislodged due to NaClO aging at all investigated pH values,but the oxidation products and dislodgement ratio of PVP varied with solution pH.For the PVDF membrane,NaClO aging at pH 3–11 caused a moderate increase in permeability and decreased retention due to the oxidation and release of PVP.The tensile strength decreased only at pH 11 because of the defluorination of PVDF molecules.For the PES membrane,NaClO aging at all investigated pH resulted in chain scission of PES molecules,which was favored at pH 7 and 9,potentially due to the formation of free radicals.Therefore,a decrease in tensile strength and retention ability,as well as an increase in permeability,occurred in the PES membrane for NaClO aging at pH 3–11.Overall,the results can provide a basis for selecting chemical cleaning conditions for PVDF and PES membranes.

High efficient probes with Schiff base functional receptors for hypochlorite sensing under physiological conditions

A series of novel and convenient fluorescent probes with Schiff base functionality were presented for direct detection of OCI via the irreversible OCl-promoted oxidation and hydrolyzation reaction in formation of the ring-opened product, fluorescein. Prominent high sensitivity, selectivity and antiinterference OCl-induced fluorescence and color change over a wide range of tested metal ions performance were observed for each probe under physiological conditions, thus making the probes well suitable for sensing of OCl in living cells.

A fluorometric and mitochondrion-targetable probe for rapid,naked-eye test of hypochlorite in real samples

Hypochlorite anion is a ubiquitous reactive molecule in the terminal disinfection systems, inflammatory stress and immune systems. Thus, rapid and visual monitoring ClO^- in water and biological samples is very meaningful for water quality safety and toxicity assessment of contaminants. Herein, a colorimetric and fluorometric probe（Rh-ClO） based on rhodamine B fluorophore and thiophene-2-carbohydrazide has been unveiled and successfully utilized for ClO^- detection in water samples and HeLa cells. Upon addition of ClO^-, color changes of solution from colorless to pink were immediately visible to the nakedeyes, meanwhile, brilliant red fluorescence was observed under excited at UV light（365 nm）. Rh-ClO displayed high selectivity and sensitivity for ClO^- , and the detection limit was 7 mmol/L calculated from the fluorescence titration. With the aid of its merits including rapid response to ClO^- within 10 s, Rh-ClO and its test paper could successfully detect ClO^- in water. Additionally, HeLa cells image co-stained with Rh-ClO and Rh123 demonstrated that Rh-ClO possessed excellent and fast cell-membrane permeability and mitochondrion-targetability. It was clearly confirmed that Rh-ClO would be a promising probe for rapid tracking of ClO^- in water samples and in mitochondria of living cells.

Effect of pyrolysis on Zhaotong lignite oxidation with aqueous sodium hypochlorite

The pyrolysis treatment of lignites could remove thermal-unstable aliphatic structures but enrich aromatic structures in resulting pyrolysis residues,which would facilitate producing benzene polycarboxylic acids(BPCAs).Herein,the demineralized Zhaotong lignite(DZL)was pyrolyzed at 250-550℃ to afford the corresponding pyrolysis residues.Subsequently,DZL and its pyrolysis residues were subjected to oxidation with aqueous sodium hypochlorite.By XRD,FTIR,and element analyses,it was found that the content and polycondensation degree of aromatic structures simultaneously increased with increasing pyrolysis temperature.Furthermore,the yield and selectivity of BPCAs both increased along with raising pyrolysis temperature in resulting products from fully oxidation of DZL and its pyrolysis residues.Based on the distribution of BPCAs,peri-condensed aromatic structures were dominant in DZL and its DPRs,and obviously increased with increasing pyrolysis temperature.More interestingly,good correlation was found between the yield of BPCAs and aromaticity parameters.Meanwhile,the yield of benzenepentacrboxylic acid was well associated with polycondensation degree parameters.

Hantzsch Ester Modified Asymmetric BODIPY Probe with Ultra-high Sensitivity for Ultra-fast Detection of Endogenous Hypochlorite in Living Cells

Hypochlorite(ClO^(-))is an important reactive oxygen species produced by the immune system to fight off invading pathogens,but its over-expression can interfere with normal physiological process and induce serious diseases.Although a variety of molecular probes have been reported for detecting ClO^(-),the development of advanced fluorescent tools with faster response and higher sensitivity to precisely monitor ClO^(-)remains a challenge.In this work,two Hantzsch ester(a derivative of 1,4-dihydropyridine)derived fluorescent probes MeDHP-BCl and MeDHP-PhBCl were constructed based on asymmetric BODIPY-matrix.These probes exhibit significant fluorescence turn-on in the ultra-sensitive(detection limit<1 nmol/L)and ultra-fast response(≤5 s)to ClO^(-).The reaction has been determined to be a highly selective N-chlorination of Hantzsch ester which cannot be activated by various common bioactive species,including nitric oxide(NO)that could oxidize Hantzsch ester under aerobic physiological conditions in most reports.MeDHP-PhBCl possessed a relatively longer fluorescence emission wavelength and higher quantum yield after activation,while more notably,MeDHP-BCl displayed lower cytotoxicity and more remarkable fluorescence increment in the response to ClO^(-),enabling selective and precise visualization of endogenous ClO^(-)over-expression in living RAW264.7 cells.