Acid Red Research Articles

Improving Azo Dye Decolorization Performance and Halotolerance of Pichia occidentalis A2 by Static Magnetic Field and Possible Mechanisms Through Comparative Transcriptome Analysis.

A halotolerant yeast, Pichia occidentalis A2, was recently isolated that can decolorize various azo dyes. The azo dye decolorization performance of this strain was characterized, including the degradation pathway and detoxification effects of this yeast. Additionally, the effect of static magnetic field (SMF) on this decolorization process was investigated. Activities of key enzymes were analyzed to estimate the change of metabolic activity. Furthermore, possible mechanisms were analyzed through detecting differentially expressed genes between yeast A2 in the absence and presence of SMF. The results indicated that yeast A2 displayed the optimal decolorization performance when the concentrations (in g/L) of glucose, (NH4)2SO4, yeast extract, and NaCl were 4.0, 1.0, 0.1, and ≤30.0, respectively. Meanwhile, the optimal rotation speed, temperature, and pH were 160 rpm, 30°C, and 5.0, respectively. Acid Red B was decolorized and detoxified by yeast A2 through successive steps, including cleavage of the naphthalene–amidine bond, reductive deamination, oxidative deamination/desulfurization, open-loop of hydroxy-substituted naphthalene, and tricarboxylic acid cycle. The dye decolorization efficiency and halotolerance of yeast A2 were enhanced by 206.3 mT SMF. The activities of manganese peroxidase, and laccase were elevated 1.37- and 1.16-fold by 206.3 mT SMF, but lignin peroxidase activity showed little change. It was suggested from the transcriptome sequence that the enhanced halotolerance might be related to the upregulated genes encoding the enzymes or functional proteins related to intracellular synthesis and accumulation of glycerol.

Linear attenuation current input mode: A novel power supply mode for electrochemical oxidation process

At present, the most considerable defects of electro-catalytic process lie in low current efficiency and high specific energy consumption. Besides electrodes, current parameters and reaction system, the power supply mode is also of great significance for optimization of electrochemical oxidation. Traditional power supply modes include constant voltage mode, constant current mode and pulse mode. Based on the concept of limiting current density, this paper proposed a linear attenuation power supply mode and set up three different application modes. This novel power supply mode is to make the current input into the electro-catalytic system continuously decay over reaction time, which were simulated adopting a computer-controlled programmable DC power. Acid Red G, phenol, guaiacol, salicylic acid and actual water samples from sewage treatment plant were taken as the target organic substance, furthermore, the advantages and disadvantages of three linear attenuation modes and traditional constant current mode were compared through electrochemical oxidation experiments in terms of varying evaluation parameters. The experimental results indicated that Mode I (same initial current density, different attenuation rates) obtained higher average current efficiency and lower specific energy consumption than constant current mode in order to achieve the equivalent degradation performance. However, the decolorization rate and COD removal rate of Mode I were lower than those of traditional constant current mode. Mode II (direct linear attenuation) and Mode III (constant current before linear attenuation) were superior to the traditional constant current mode with the same input total power in the aspects of decolorization rate, COD removal rate, average current efficiency, specific energy consumption and etc. Those results were further verified in different organic matters wastewater samples and actual wastewater samples. For actual wastewater samples treatment, the experimental average current efficiency and specific energy consumption of Mode II (6.96 %, 0.237 kWh·gCOD-1), Mode III (8.89 %, 0.209 kWh·gCOD-1) and traditional constant current mode (5.18 %, 0.343 kWh·gCOD-1) indicated that, in practical engineering, more preferable current efficiency and lower energy consumption can be achieved by Mode II and Mode III over traditional constant current mode. Those demonstrated that the newly proposed linear attenuation mode (especially Mode III) can effectively improve the current efficiency of electrochemical oxidation process and reduce the specific energy consumption.

PENETAPAN KADAR VITAMIN C PADA BEBERAPA JENIS CABE (CAPSICUM ANNUM L.) DAN PAPRIKA (CAPSICUM ANNUM L. VAR. GROSUM) DENGAN METODE TITRASI IODIMETRI

Ascorbic acid is one of the nutrients that acts as an antioxidant to effectively overcome free radicals that can damage cells or tissues, including protecting the lens from oxidative damage caused by radiation. Ascorbic acid is abundant in fruits and vegetables, one of which is chili and pappers.The purpose of this study was to determine the content of the content and differences in levels of ascorbic acid content in several types of chillies and peppers. The method used in this study is the Iodimetry method, because ascorbic acid is a reducing agent which is strong enough, easily oxidized and iodine is easily reduced. This is one of the requirements of the compound can be done by the Iodimetry method. This research included descriptive research, with samples of red chili, cayenne pepper, curly green chili, red peppers, yellow peppers and green peppers obtained in the market of the old deli and its surroundings. This research begins with making samples, then performs qualitative tests, making standard solutions and determining ascorbic acid levels. During the titration process replication is done 6 times to compare the results of each titration. The results showed levels of ascorbic acid Red Chilli = 0.1856%, Cayenne pepper = 0.0739%, Curly green Chili = 0.0882%, Red peppers = 0.1945%, Yellow paprika = 0.1886%, and Green peppers = 0.1631%. Conclusions showed that the highest ascorbic acid levels were found in red pappers samples which were 0.1945% and the lowest ascorbic acid levels were in the cayenne sample which was 0.0739%. Suggestions for future researchers should be continued with other parameters and samples.

Degradation of azo dye Acid Red 14 (AR14) from aqueous solution using H2 O2 /nZVI and S2 O8 2- /nZVI processes in the presence of UV irradiation.

Azo dyes are mostly toxic and carcinogenic and cause harm to humans and the environment. This study was conducted to investigate the degradation of azo dye acid red 14 (AR14) from aqueous solution using hydrogen peroxide (H2 O2) /nano zerovalent iron (nZVI) and persulfate (S2 O8 2- )/nZVI processes in the presence of ultraviolet (UV) irradiation. This experimental study was carried out in a laboratory-scale batch photoreactor with a useful volume of 1 L. The nZVI was synthesized by the sodium borohydride (NaBH4 ) reduction method. In these processes, the effects of parameters including initial pH, H2 O2 concentration, S2 O8 2- concentration, nZVI dose, concentration of AR14 dye, and reaction time were studied. The results showed that decolorization increased by increasing the nZVI dosage, H2 O2 and S2 O4 2- concentrations, and reaction time, or decreasing dye concentration and pH. However, a too high oxidant concentration (H2 O2 and S2 O4 2- ) could inhibit the degradation. The experimental conditions for degradation of AR14 by UV/S2 O8 2- /nZVI and UV/H2 O2 /nZVI processes were as follows: [H2 O2 ]=10mM, [S2 O8 2- ]=8mM, AB14 dye=100mg/L, pH=3, and nZVI dose=0.05g. Under these conditions, the highest removal efficiencies of AR14, chemical oxygen demand (COD), and total organic carbon (TOC) for the UV/S2 O8 2- /nZVI process were 93.94%, 86.5%, and 81.6%, respectively, while these values were 89.3%, 79.57%, and 72.9% for the UV/H2 O2 /nZVI, respectively. Also, the average oxidation state (AOS) was decreased from 2.93 to 2.14 in the effluent of the UV/S2 O8 2- /nZVI process and from 2.93 to 2.2 for the UV/H2 O2 /nZVI process. The results showed that the ratio of biochemical oxygen demand (BOD5 ) to COD in the effluents of the UV/S2 O8 2 /nZVI and UV/H2 O2 /nZVI processes after 90min was 0.63 and 0.74, respectively. These findings suggest biodegradability improvement. PRACTITIONER POINTS: Photocatalytic degradation of azo dye Acid Red 14 (AR14) was achieved using H2 O2 /nZVI and S2 O8 2- /nZVI processes in the presence of UV irradiation. Effects of operating parameters on photocatalytic degradation AR14 dye were evaluated in the UV/H2 O2 /nZVI and UV/S2 O8 2- /nZVI processes. Biodegradability and mineralization studies of AR14 dye photocatalytic degradation were performed for the UV/H2 O2 /nZVI and UV/S2 O8 2- /nZVI processes.

Hybrid polyvinyl alcohol/polyvinyl chloride nanocomposites reinforced with graphene-carbon nanotube for acid red environmental treatments

ABSTRACT Hybrid polyvinyl alcohol and polyvinyl chloride/graphene and carbon nanotube nanocomposites PVA–PVC/Gr–CNTsa-e were successfully synthesized by a solution-casting method. Mixed Gr–CNTs ratio (50%:50%) was prepared in 2, 5, 10, 15, and 20 wt% and added to the host polymers (PVA/PVC). The characterization tools for the fabricated nanocomposites show homogenous interaction between the fillers and PVA/PVC polymer matrix. A significant improvement in the thermal properties of the (PVA/PVC) matrix was observed by adding mixed fillers, even at low loadings of mixed Gr–CNTs on to the matrix. Scanning electron microscopy and transmission electron microscopy images of the prepared composites show a good dispersion of PVA–PVC and mixed Gr–CNTs and present core-shell morphology. Impressive improvement in the percentage of acid red removal using PVA–PVC/Gr–CNTsa–e was achieved and improved with time, solution temperature, and composites mass. The process of removing acid red was described kinetically and thermodynamically. The pseudo-second-order kinetic model is the most appropriate kinetic model to describe the adsorption of acid red by PVA–PVC and PVA–PVC/Gr–CNTsd nanocomposites from an aqueous solution. Our results offer a facile method for the removal of acid red from three types of water: red sea, tap water, and distilled water.

Adsorptive removal of bulky dye molecules from water with mesoporous polyaniline-derived carbon.

Polyaniline-derived carbon (PDC) was obtained via pyrolysis of polyaniline under different temperatures and applied for the purification of water contaminated with dye molecules of different sizes and charge by adsorption. With increasing pyrolysis temperature, it was found that the hydrophobicity, pore size and mesopore volume increased. A mesoporous PDC sample obtained via pyrolysis at 900 °C showed remarkable performance in the adsorption of dye molecules, irrespective of dye charge, especially in the removal of bulky dye molecules, such as acid red 1 (AR1) and Janus green B (JGB). For example, the most competitive PDC material showed a Q0 value (maximum adsorption capacity) 8.1 times that of commercial, activated carbon for AR1. The remarkable adsorption of AR1 and JGB over KOH-900 could be explained by the combined mechanisms of hydrophobic, π–π, electrostatic and van der Waals interactions.

Retraction Note to: Ni/Co/Ti layered double hydroxide for highly efficient photocatalytic degradation of Rhodamine B and Acid Red G: a comparative study

Retraction of ‘Ni/Co/Ti layered double hydroxide for highly efficient photocatalytic degradation of Rhodamine B and Acid Red G: a comparative study’ by Priyadarshi Roy Chowdhury and Krishna G. Bhattacharyya, Photochem. Photobiol. Sci., 2017, 16, 835–839.

Photocatalytic Performance of PVP-Doped TiO<sub>2</sub> Nanorod Arrays Prepared by Hydrothermal Method

Here we synthesized a high-density single crystal anatase phase TiO2/ITO nanorods array composite by one-step hydrothermal method. TiCl4, H2O, and HCl were used as the titanium precu-rsor, oxygen source, and inhibitors, respectively. The TiO2 nanorods array were analyzed using X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDX), scanning electron microscopy (SEM), optical contact angle tester and ultraviolet-fluorescence spectrophotometer, separately. The nanorods in the composite grew along the [101] crystal plane, with a diameter of about 500 nm and a length of about 3 μm. The effect of PVP addition on the crystal phase and morphology of TiO2 na-norod arrays was investigated. When the amount of PVP added was 0.5g, the diameter of nanorods was about 77-120nm, and a neat array structure appeared. In the photocatalytic experiment, methyl orange and acid red were used as degraded materials, the photocatalytic degradation rate was up to about 100%. When the hydrophilicity was the best, the optical contact angle of the sample after ultr-aviolet light irradiation was 7.2°. These results indicated that TiO2 after doping experiments got better photocatalytic properties.

Synthesis and characterization of ZnO nanoparticles via zeolitic imidazolate framework-8 and its application for removal of dyes

Zinc oxide (ZnO) nanoparticles were obtained via calcination of zeolitic imidazolate framework-8 (ZIF-8). The activities of prepared ZnO nanoparticles at different temperature 450, 550, and 650 °C were investigated for the adsorption of acid red 57 (AR57) and remazole red (RR) dye. The synthesized ZnO nanoparticles were characterized by different spectroscopic studies such as FTIR, X-ray diffraction, energy-dispersive X-ray spectroscopy, N2 adsorption–desorption and pH titration for determination of Zero-point charge (pHZPC). The mechanism of adsorption behavior of AR57 and RR are studied with respect to temperature, pH and concentration. Experimental data indicated that the adsorption capacity of ZnO for AR57 and RR was higher in acidic rather than in basic solutions. The activation energy of adsorption was also evaluated for the adsorption of AR57 and RR onto ZnO nanoparticles. Langmuir and Freundlich adsorption models were also applied to describe the equilibrium isotherms and the isotherm constants. The pseudo-first-order and pseudo-second-order model equations were used to analyze the kinetics of the adsorption process. The adsorption efficiency of ZnO nanoparticles was found in the order: 450 > 550 > 650 °C. The activation energy, enthalpy, change of free energy and entropy of adsorption were also evaluated for the adsorption of AR57 and RR onto ZnO nanoparticles. The thermodynamics of the adsorption indicated spontaneous and exothermic nature of the process.

Probe sonication synthesis of ZnFe2O4 NPs for the photocatalytic degradation of dyes and effect of treated wastewater on growth of plants

Today world is facing water pollution resulting from various sectors and presenting serious ecological concerns. The reusability of polluted water could be a promising study for the sustainable wastewater management strategy. In this, prepared ZnFe2O4nano-photocatalyst was employed for photocatalytic degradation of organic dye pollutants namely Acid Red 88 (AR-88), Acid Orange 8 (AO 8) and Malachite Green (MG) under Sun light and UV irradiation. The UV-induced dye degraded wastewater samples were used to examine the green assessment towards the growth of Eleusine coracana (Finger millet) and Vigna unguiculata (Black eyed beans) plant. The results showed excellent plant growth in dye degraded wastewater sample noticed in the period of 3–5 days compared to pure water as control and with retard growth observed in dye solution. Thus, present research reported that the sustainability issues related to photodegradation of contaminated dye solution using prepared nano material was tested and efficiently using treated waste water in growing plants.

Constructed wetland–microbial fuel cell for azo dyes degradation and energy recovery: Influence of molecular structure, kinetics, mechanisms and degradation pathways

Complete degradation of azo dye has always been a challenge due to the refractory nature of azo dye. An innovative hybrid system, constructed wetland-microbial fuel cell (CW-MFC) was developed for simultaneous azo dye remediation and energy recovery. This study investigated the effect of circuit connection and the influence of azo dye molecular structures on the degradation rate of azo dye and bioelectricity generation. The closed circuit system exhibited higher chemical oxygen demand (COD) removal and decolourisation efficiencies compared to the open circuit system. The wastewater treatment performances of different operating systems were ranked in the decreasing order of CW-MFC (R1 planted-closed circuit) > MFC (R2 plant-free-closed circuit) > CW (R1 planted-open circuit) > bioreactor (R2 plant-free-open circuit). The highest decolourisation rate was achieved by Acid Red 18 (AR18), 96%, followed by Acid Orange 7 (AO7), 67% and Congo Red (CR), 60%. The voltage outputs of the three azo dyes were ranked in the decreasing order of AR18 > AO7 > CR. The results disclosed that the decolourisation performance was significantly influenced by the azo dye structure and the moieties at the proximity of azo bond; the naphthol type azo dye with a lower number of azo bond and more electron-withdrawing groups could cause azo bond to be more electrophilic and more reductive for decolourisation. Moreover, the degradation pathway of AR18, AO7 and CR were elucidated based on the respective dye intermediate products identified through UV–Vis spectrophotometry, high-performance liquid chromatography (HPLC), and gas chromatograph-mass spectrometer (GC–MS) analyses. The CW-MFC system demonstrated high capability of decolouring azo dyes at the anaerobic anodic region and further mineralising dye intermediates at the aerobic cathodic region to less harmful or non-toxic products.

The use of aminated cotton fibers as an unconventional sorbent to remove anionic dyes from aqueous solutions

This study aimed to investigate the sorption of anionic dyes (Reactive Black 5, Reactive Yellow 84, Acid Red 18, and Acid Yellow 23) by cotton fibers aminated with epichlorohydrin and ammonia water (ACFs) as well by unmodified cotton fibers (CFs). CFs and ACFs were characterized based on FTIR, elemental analysis (C/N content) and pHPZC. The effect of solution pH (pH 2–11) and contact time on the removal of dye was studied as well. The kinetic experimental data were fitted to pseudo-first order, pseudo-second order, and intraparticle diffusion model. Equilibrium isotherms were analyzed based on Langmuir and Freundlich isotherms. The efficiency of dye sorption on CFs was the most effective at pH 2, whereas on ACFs—at pH 3–4. ACFs and CFs changed the pH value of the sorption solution. The system tended to obtain a pH value close to the pHPZC value of the sorbent (pHPZC = 7.85 for CFs/pHPZC = 8.15 for ACFs). ACFs had a shorter dye sorption equilibrium time compared to the CFs. The sorption of dyes on cotton sorbents proceeded in 2 main phases. The best match to the experimental data was shown by the pseudo-secondary model. Having amine functional groups, the ACFs ensured far better sorption of anionic dyes than CFs did. The maximum Reactive Black 5 sorption capacity of ACFs was Qmax = 36.77 mg/g, which was 1240% higher than that of CFs (Qmax = 2.74 mg/g).

Pulsed electrochemical oxidation of acid Red G and crystal violet by PbO2 anode

Present work investigates the application of pulsed electrochemical oxidation technique using DSA anode, titanium coated with PbO2layer, for degradation of Acid Red G (anionic dye) and Crystal Violet (cationic dye). Decolorization efficiency, COD and TOC removal efficiency were measured and contrasted by varying process parameters such as current density, initial organic concentration, pulse frequency, pulse duty cycle and NaCl dosage. Furthermore, decay kinetics for color and COD removal process, average current efficiency and energy consumption were evaluated under diverse arguments. The results indicated that current density, pulse duty cycle and NaCl dosage exerted a positive influence on the performance of pulse electrochemical degradation for ARG and CV, namely, with the growth of relevant influencing factors, the corresponding removal efficiency, kinetic constant of decolorization and COD removal reaction, and specific energy consumption increased accordingly, whereas the average current efficiency gradually decreased. However, the initial concentration of ARG and CV had a negative influence on the pulse electrochemical degradation process, that is, with the increase of initial dye concentration could lead to the reduction of the corresponding removal efficiency, kinetic constant of decolorization and COD removal reaction and energy consumption, on the contrary, the average current efficiency went up. Being different from ARG degradation process, there were some substances adhering to the cathode during CV electrochemical degradation process due to its positive charge. Under same conditions, the degradation indexes of pulse constant current power supply mode were better than those of direct constant current mode, which was coincident for both ARG and CV.

Modeling and optimization of Photocatalytic Decolorization of binary dye solution using graphite electrode modified with Graphene oxide and TiO2.

In this paper, the experimental design methodology was employed for modeling and optimizing the operational parameters of the photocatalytic degradation of a binary dye solution using a fixed photocatalytic compound. The compound used was modified graphite electrode (GE) with graphene oxide (GO) on which TiO2 nanoparticles were immobilized. GO nanoparticle was deposited on graphite electrode (GO-GE) using electrochemical approach. TiO2 nanoparticles were immobilized on GO-GE by solvent evaporation method. A binary solution containing mixture of methylene blue (MB) and acid red 14 (AR14) was chosen as dye model. The degradation intermediates were detected and analyzed using gas chromatography. Effect of different factors on the photocatalytic decolorization efficiency was investigated and optimized using response surface methodology (RSM). The obtained results indicated that the prepared TiO2-GO-CE can decolorize MB with high efficiency (93.43%) at pH11, dye concentration of 10mg/L and 0.04g of immobilized TiO2 on the GO fabricated plates after 120min of photocatalytic process. It was demonstrated that by modifying GE with GO the stability of the electrode was remarkably enhanced. The ANOVA results (R2 = 0.97 and P value <0.0001 for MB, R2 = 0.96 and P value <0.0001 for AR14) and numerical optimization showed that it is possible to make good prediction on decoloration behavior and save time and energy with less number of experiments using design of experiments (DoE) like the RSM. Graphical abstract Wastewater treatment processWastewater treatment process.

Preparation of a novel nitrogen-containing graphitic mesoporous carbon for the removal of acid red 88

A novel nitrogen-containing graphitic mesoporous carbon was prepared through MnO-templated method using polyacrylonitrile (PAN) as both carbon and nitrogen sources, and MnCO3 as both template and catalyst precursors. The effects of preparation conditions on the physicochemical properties of obtained samples were systematically investigated. The results showed that as the decrease of the weight ratios of PAN and MnO (2:1–1:4), the increase of carbonization temperature (700–900 °C) and pre-oxidation temperature (180–200 °C), the samples had higher specific surface area, mesopores volume and ratios, up to 507 m2/g, 0.824 cm3/g and 96.83%, respectively. Moreover, the prepared samples presented relatively high graphitic degree and nitrogen contents (~2.21%). The adsorption capacity for acid red 88 (AR88) was as high as 309 mg/g, which were dramatically affected by the mesoporous properties and C- and N-containing groups on the surface of prepared carbon. The rich graphic carbon and pyridine-N in mesoporous carbon generated π-π dispersion and electrostatic interaction with AR88, respectively, which jointly were responsible for the adsorption process. The results of the isotherm and kinetic studies indicated that the AR88 adsorption on mesoporous carbon could be well depicted using Langmuir model and pseudo-2nd-order model.

A modular functionalized anode for efficient electrochemical oxidation of wastewater: Inseparable synergy between OER anode and its magnetic auxiliary electrodes

Oxygen evolution reaction (OER) anodes, (e.g., IrO2) are well-known inefficient catalysts for electrochemical oxidation (EO) of refractory organics in wastewater due to the high energy consumption via OER. However, in this study this kind of anode participated in a very effective EO process via a specific modular anode architecture. Traces of magnetic Fe3O4/Sb-SnO2 particles as auxiliary electrodes (AEs) were attracted on the surface of the two-dimensional (2D) Ti/IrO2-Ta2O5 by a NdFeB magnet, and thereby constituted a new magnetically assembled electrode (MAE). MAE could be renewed by recycling its AEs. The electrochemical properties as well as the EO performances of the MAE could be regulated by adjusting the loading amount of AEs. Results showed that even a small amount of AEs could increase surface roughness and offer massive effective active sites. When removing color of azo dye Acid Red G, the optimal MAE exhibited ∼1100 % and ∼500 % higher efficiencies than 2D Ti/IrO2-Ta2O5 and 2D Ti/Sb-SnO2, respectively. The superiority of the MAE was also applicable in degrading phenol. The synergy between Ti/IrO2-Ta2O5 and magnetic Sb-SnO2 particles was therefore discussed.

Titanium dioxide/magnetic metal-organic framework preparation for organic pollutants removal from water under visible light

Developing high-efficient supporter is important for enhancing pollutants removal efficiency of a catalyst. Materials Institute Lavoisier-101(Cr) (MIL-101(Cr)) is one of metal-organic frameworks (MOFs). In this study, a novel visible-light-driven absorptive photocatalyst, TiO2-loaded magnetic MOFs composite (TiO2/mag-MIL-101(Cr)), was synthesized to improve the reusability, the adsorption and photocatalytic efficiency under visible-light. The as-synthesized TiO2/mag-MIL-101(Cr) was systematically characterized and used for adsorbing and photodegrading refractory organics, bisphenol-F (BPF) and acid red 1 (AR1), from water. Mag-MIL-101(Cr) remarkably enhances the light-absorption of TiO2, and the band-gap value of TiO2/mag-MIL-101(Cr) is 1.61 eV. TiO2/mag-MIL-101(Cr) exhibited outstanding removal efficiency to bisphenol-F and AR1, which was attribute to the large adsorption capacity of mag-MIL-101(Cr) and the enhanced separation properties of photogenerated electrons and holes. In the photocatalytic process, h+ is proved to be a predominant active species, while ·OH and ·O2− play an auxiliary role. The proposed strategy is an attempt to design new semiconductor-MOF photocatalytic materials for degrading organic contaminants in water under visible light.

Analysis of Hydroxyl Radical and Hydrogen Peroxide Generated in Helium-Based Atmospheric-Pressure Plasma Jet and in Different Solutions Treated by Plasma for Bioapplications

This study systematically analyzed reactive species generated with self-built helium-based low-temperature atmospheric-pressure plasma jet (He-APPJ); we measured the hydroxyl radical (·OH) and hydrogen peroxide (H2O2) above surfaces of plasma–treating solutions and in plasma-treated medium (PTM) of different solutions, including deionized water, phosphate buffered saline, and Dulbecco’s modified Eagle medium. The effects of adding O2 into He working gas on ·OH and H2O2 generation were discussed. The MCF7 cell responses to plasma treatment were also observed. The ·OH emission (309 nm) in He-APPJ and above surfaces of plasma–treating solutions were analyzed through optical emission spectroscopy, and concentrations of ·OH and H2O2 in different solutions were measured using terephthalic acid and Amplex Red, respectively. In our plasma system, it was observed that higher conductivity of solutions may cause stronger ·OH emission above solution. The ingredients of the solution may affect the concentrations of ·OH and H2O2. Addition of 0.1% O2 generates strongest ·OH emission above surfaces of plasma–treating solution with our He-APPJ, and thus, the highest H2O2 concentration in PTM. The MCF7 cell viability is influenced by the H2O2 concentration in PTM. The results of this study can facilitate further study of plasma effects on PTM and cell culture.

Promotion effect of PANI on Fe-PANI/Zeolite as an active and recyclable Fenton-like catalyst under near-neutral condition

A Fenton-like catalyst, Fe doped PANI loaded on zeolite (Fe-PANI/Zeolite) was synthesized by polymerizing aniline (PANI) and loading iron via a one-pot in-situ hydrothermal process. The XPS and UV–Vis spectra indicated that the Fe2+ and Fe3+ were doped into PANI and formed a complex via Fe-N interaction, and the TEM image showed that no Fe oxides particles were formed. The Fe-PANI/Zeolite showed significant Fenton-like catalytic activity in a wide pH range (3.0–8.0), and its catalytic activity was studied in detail at pH 6. With the optimized FeCl3-to-aniline molar ratio of 3:1, the Fe-PANI/Zeolite synthesized at 130 °C for 12 h showed the highest efficiency for Fenton-like catalytic degradation of Acid Red G (ARG). The active species of the Fe-PANI/Zeolite were Fe and PANI, and especially under near-neutral condition the PANI played the key role by promoting the reduction of Fe3+ to Fe2+, resulting in enhancing the Fenton-like reaction activity. Fe-PANI/Zeolite catalyst shows high potential in organic pollutants removal in wastewater treatment without any additional assistant measure to enhance its activity.

Batch Equilibrium and Kinetic Studies of Anionic and Cationic Dyes Adsorption onto Al−Pillared Clay from a Local Cameroonian Clay Materials in Aqueous Medium

The present work report removal of acid red 14 (AR14) and basic violet 3 (BV3) as anionic and cationic dyes, respectively, by adsorption process in batch mode from aqueous solution onto natural and modified forms of a local Cameroonian clay. The efficiency of these adsorbents materials (purified natural clay, P−Clay, sodium−clay, Na−Clay, and aluminium−pillared, Al−PILC) to remove dyes from aqueous medium was examined at different initial concentrations, pH, and ionic strengths. At the optimal contact time of 20 minutes, the maximum adsorbed dye amount on various adsorbents was obtained at pH 9 and pH 3 for AR14 and BV3 dyes, respectively. Adsorption process of both dyes on purified or modified clay was pH depend and the dyes molecules sorption over the clay surface occurs by electrostatic interactions. Ionic strength influenced significantly AR14 and BV3 dyes adsorption. Homo-ionization and pillaring clay increased its adsorption capacity. Kinetic studies showed that adsorption follows a pseudo−second−order model, and rate constants were evaluated. Non-linear fit of adsorption isotherm, qe vs Ce, were S−class for adsorption of both dye onto AL−PILC, indicating the heterogeneity of the adsorbent surface which leaded to a multilayer adsorption with interactions between dye molecules. Langmuir and Freundlich models were the best fits to the experimental data with the maximum adsorption capacities of AL−PILC for AR14 and BV3 dyes of 1.4 mg g-1 and 3.0 mg g-1, respectively. Lower adsorption capacities calculated from Langmuir isotherm model than the experimental values indicated adsorption mechanism occurs by multilayer formation on the adsorbent surface.