scholarly journals Adsorption-Oxidation Mechanism of δ-MnO2 to Remove Methylene Blue

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ge Yan ◽  
Pu Wang ◽  
Yuqian Li ◽  
Zhangjie Qin ◽  
Shuai Lan ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Adsorption Mechanism ◽  
Ph Value ◽  
Oxidation Mechanism ◽  
Superior Performance ◽  
Adsorption Ability ◽  
Initial Ph ◽  
Effects Of Ph ◽  
Ph Conditions ◽  
Positively Charged

The material, δ-MnO2, has exhibited superior performance on the removal of methylene blue (MB), but the process is significantly impacted by pH, and the impacting mechanism is still unclear. In this study, the effects of pH on the removal mechanism of MB using synthesized δ-MnO2 were investigated by distinguishing the adsorption and oxidation of MB by δ-MnO2 during the removal process in the dark. The results show that the total removal efficiency of MB by δ-MnO2 decreased significantly with an increase in the pH. MB could be removed by δ-MnO2 via an adsorption mechanism and oxidation mechanism, and the proportion of adsorptive removal and oxidative removal was different under different pH conditions. With an increase in the initial pH from 2.00 to 8.05, the redox potential of δ-MnO2 decreased, and its oxidation ability for the removal of MB also gradually decreased. In contrast, the surface negative charges of δ-MnO2 increased with an increase in the pH, and the adsorption ability towards positively charged MB also gradually increased. This indicates that the effects of pH on the removal of MB by δ-MnO2 are primarily dominated by its influence on the oxidation ability of δ-MnO2. In addition, it is further proved that the pH value has a significant effect on the oxidation and adsorption of MB on δ-MnO2. Moreover, the significant effects of pH on the oxidation of MB by δ-MnO2 are further demonstrated by observing the changes in Mn2+ and the UV-Vis spectra of intermediate products during the reaction, as well as the changes in the FTIR and XPS characterizations of δ-MnO2 after the reaction.

scholarly journals The Removal of Methylene Blue Dye from Aqueous Solutions Using Activated and Non-Activated Bentonites

2003 ◽  
Vol 21 (5) ◽  
pp. 451-462 ◽  
Author(s):  
Sameer Al-Asheh ◽  
Fawzi Banat ◽  
Leena Abu-Aitah
Keyword(s):  
Methylene Blue ◽  
Ph Value ◽  
Sodium Dodecyl ◽  
Freundlich Isotherm ◽  
Blue Dye ◽  
Batch Adsorption ◽  
Ionic Surfactant ◽  
Methylene Blue Dye ◽  
X Ray Diffraction ◽  
Initial Ph

An improvement in the adsorption capacity of naturally available bentonite towards water pollutants such as Methylene Blue dye (MBD) is certainly needed. For this purpose, sodium bentonite was activated by two methods: (1) treatment with sodium dodecyl sulphate (SDS) as an ionic surfactant and (2) thermal treatment in an oven operated at 850°C. Batch adsorption tests were carried out on removing MBD from aqueous solution using the above-mentioned bentonites. It was found that the effectiveness of bentonites towards MBD removal was in the following order: thermal-bentonite > SDS-bentonite > natural bentonite. X-Ray diffraction analysis showed that an increase in the microscopic bentonite platelets on treatment with SDS was the reason behind the higher uptake of MBD. An increase in sorbent concentration or initial pH value of the solutions resulted in a greater removal of MBD from the solution. An increase in temperature led to an increase in MBD uptake by the bentonites studied in this work. The Freundlich isotherm model was employed and found to represent the experimental data well.

Preparation of Persimmon Tannins Immobilized on Collagen Adsorbent and Research on its Adsorption to Cr(VI)

2013 ◽  
Vol 743-744 ◽  
pp. 523-530 ◽  
Author(s):  
Jian Cui ◽  
Zhong Min Wang ◽  
Feng Lei Liu ◽  
Pei Bang Dai ◽  
Ran Chen ◽  
...  
Keyword(s):  
Adsorption Mechanism ◽  
Ph Value ◽  
Effect Of Temperature ◽  
Major Influence ◽  
Initial Concentration ◽  
Adsorbent Dosage ◽  
Adsorption Data ◽  
Initial Ph ◽  
Pseudo Second Order ◽  
Ph Range

Persimmon tannins (PT) were immobilized on a matrix of collagen fiber by cross-linking of glutaraldehyde. The adsorption behaviours to Cr (VI) on PT were investigated including the effects of initial pH, initial concentration of Cr (VI), temperature, adsorbent dosage, adsorption kinetics and the recycling performance of PT adsorbents. The results showed that pH value had a major influence in adsorption. PT showed a strong adsorbability to Cr (VI) in the pH range of 1.0 to 3.0, whereas the effect of temperature on the adsorption was comparatively weaker. The adsorption equilibrium could be well described by Freundlich equation. PT adsorption efficiency of Cr (VI) reached 98.04% and the maximum equilibrium adsorption capacity of Cr (VI) was up to 49.01 mg/g at 303 K with a pH value of 2.0, 100 mg/L of initial concentration of Cr (VI) and 0.1g of adsorbent dosage. The adsorption data could be well fitted by pseudo-second-order rate model. PT adsorbents were characterized by FTIR and EDS. The analysis indicated that the adsorption mechanism was mainly contributed by redox adsorption.

scholarly journals Effects of pH value on the surface morphology of BiVO4microspheres and removal of methylene blue under visible light

2012 ◽  
Vol 9 (6) ◽  
pp. 616-624 ◽  
Author(s):  
Jun-Qi Li ◽  
Zhan-Yun Guo ◽  
De-Fang Wang ◽  
Hui Lui ◽  
Juan Du ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Surface Morphology ◽  
Visible Light ◽  
Ph Value ◽  
Effects Of Ph

Oxidative Decolorization of Azo Dyes with Copper Phthalocyanine Supported Mg-Al Hydrotalcites

2016 ◽  
Vol 703 ◽  
pp. 306-310
Author(s):  
Min Hong Xu ◽  
Jian Li Ma ◽  
Meng Xia Qian ◽  
Hui Na Qin
Keyword(s):  
Molecular Structure ◽  
Methylene Blue ◽  
Methyl Orange ◽  
Azo Dyes ◽  
Acidic Solution ◽  
Copper Phthalocyanine ◽  
Ph Value ◽  
Influence Factors ◽  
Amido Black ◽  
Initial Ph

Oxidative decolorization of azo dyes with a heterogeneous catalyst copper phthalocyanine supported Mg-Al hydrotalcites was studied and the influence factors such as initial pH value, temperature, H2O2 and CuPc-LDHs/H2O2 system were discussed. The results indicated that acidic solution and high temperature were conducive to oxidative decoloration of methyl orange. CuPc-LDHs/H2O2 system showed excellent oxidative decoloration capacity to remove azo dyes. The effects of oxidative decolorization of azo dyes were related to the molecular structure and weight of azo dyes. Oxidative decoloration effects followed the order as congo red > amido black > methyl blue> methyl orange> methylene blue.

scholarly journals Neem Leaves as Adsorbent for Dye Waste water Treatment

2019 ◽  
Vol 8 (9) ◽  
pp. 3071-3073
Keyword(s):  
Methylene Blue ◽  
Adsorption Capacity ◽  
Ph Value ◽  
Low Cost ◽  
Waste Water Treatment ◽  
Blue Dye ◽  
Aqueous Streams ◽  
Neem Leaves ◽  
Initial Ph ◽  
Adsorbent System

In the present investigation , neem leaves are obtained from the agricultural fields and its potential for the removal of dye is tested with the model system of methylene blue in water . The MB has health hazards, its been reported that exposures to the dyes cause allergic reactions, and hence its reflected as toxic. The results obtained from batch experiments are quite useful in giving information about the efficacy of dye-adsorbent system. The influence of factors such as the initial pH value, adsorbent dose, and time of contact was investigated. The results indicate that the percentage removal also increased with the rise in the adsorption capacity (qe). 82% of colour elimination can be obtained at the dose of 100g/l NLP for methylene blue of 10mg/l concentration. The optimal parameters for this experiment were 10mg/l for initial dye concentration, 5gm/50ml adsorbent dosage and pH 8. In the batch system, the adsorption capacity was increased when the parameters were increased until it achieved the equilibrium. Langmuir adsorption isotherm graphics plotted with l/qevis 1/Ce. Trend lines for the adsorption data of different concentration of methylene blue with neem leave as adsorbent is plotted. The linear regression was piloted using plot l/qevis 1/Ce; it was found that R2 value are quite closer to 1 signifying Langmuir isotherm as a good fit for this experimental data. Results indicated that neem leaves has potential to remove Methylene Blue Dye from aqueous streams and can be successfully used as a low cost adsorbent.

Adsorption of lead using a novel xanthated carboxymethyl chitosan

2013 ◽  
Vol 69 (2) ◽  
pp. 298-304 ◽  
Author(s):  
Qingping Song ◽  
Chongxia Wang ◽  
Ze Zhang ◽  
Jiangang Gao
Keyword(s):  
Adsorption Capacity ◽  
Photoelectron Spectroscopy ◽  
Adsorption Mechanism ◽  
Ph Value ◽  
Carboxymethyl Chitosan ◽  
Langmuir Model ◽  
Maximum Adsorption Capacity ◽  
Visible Spectra ◽  
Initial Ph ◽  
Uv Visible

Adsorption of Pb(II) was studied using a novel xanthated carboxymethyl chitosan (XCC). The XCC was synthesized using the xanthation reaction of N-carboxymethyl chitosan (NCMC). The chemical structure of XCC was characterized by UV–visible spectra. The effects of initial pH value of the solutions, contact time and adsorption isotherms on adsorption of Pb(II) were investigated. Moreover, the possible adsorption mechanism was identified using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The experimental results showed XCC experienced a high adsorption capacity. The adsorption isotherm followed the Langmuir model. The maximum adsorption capacity obtained from the Langmuir model was 520.8 mg/g. Thermodynamic studies revealed a spontaneous and exothermic adsorption process. FTIR and XPS studies showed that the carboxyl groups, nitrogen atoms and sulfur atoms participated in the adsorption of Pb(II).

scholarly journals The Proliferation Rule of Microcystis Aeruginosa Under Different Initial pH Conditions and its Influence on the pH Value of the Environment

2021 ◽  
Author(s):  
Sijie Wei ◽  
Guanjie Zhuang ◽  
Lirijian Cheng ◽  
Shoubing Wang
Keyword(s):  
Microcystis Aeruginosa ◽  
Ph Value ◽  
Control Strategies ◽  
Scientific Basis ◽  
Cyanobacterial Blooms ◽  
Ph Values ◽  
Inoculation Density ◽  
Initial Ph ◽  
Ph Conditions ◽  
Optimal Ph

Abstract This study investigated the characteristics of the proliferation process of Microcystis aeruginosa and its changes to environmental pH values under different initial pH values and different initial inoculation densities. The results showed that although the initial pH value or the initial inoculation density was different, the pH values of the culture systems fluctuated up and down throughout the proliferation of M. aeruginosa, both on a daily and hourly time scale, and then tended to stabilize around the same value of 10.0 at the end of proliferation. The optimal pH value for the proliferation of M. aeruginosa was 9.56. This study creatively proposes that the period when the environmental pH value starts to rise rapidly toward 9.0 could be selected as an early warning period for a cyanobacterial outbreak, and the environmental pH value could be adjusted to below 8.0 to delay the outbreak. These results provide a scientific basis for further understanding the mechanism of cyanobacterial blooms and formulating pH-based control strategies.

scholarly journals Taguchi Optimization of Catalytic Ozonation Process Using Modified Bone Char Ash for Removal of Methylene Blue from Aqueous Solution

2020 ◽  
Vol 7 (2) ◽  
pp. 66-71
Author(s):  
Ghorban Asgari ◽  
Somaye Akbari
Keyword(s):  
Methylene Blue ◽  
Reaction Time ◽  
Textile Industry ◽  
Ph Value ◽  
Catalytic Ozonation ◽  
Bone Char ◽  
Operational Parameters ◽  
Taguchi Optimization ◽  
Initial Ph ◽  
Ozonation Process

Methylene blue (MB) dye is an environmental contaminant that has been mostly used in textile industry. Taguchi orthogonal array design was employed as an optimization method to reduce the number of experiments. In this research, bone char ash modified by MgO-Fe catalyst was applied for degradation of MB in catalytic ozonation process (COP) system and operational parameters including initial MB dosages, initial pH, catalyst dose, and contact time were optimized with Taguchi method. Accordingly, the best condition for the removal of MB obtained at initial MB concentration of 20 mg/L, reaction time of 15 minutes, initial pH value of 10, and catalyst concentration of 0.1 g/L. Additionally, optimization of experimental set-up showed that the MB concentration had a notable effect on MB degradation in COP process (55.6%), and reaction time had a negligible effect (1.98%). At this condition, total organic carbon (TOC) removal was determined to be 31% but in longer time, its removal increased to 65%.

Effects of pH Value and Water Content of Sol on TiO2 Photocatalytic Activity Prepared by SAS

2013 ◽  
Vol 774-776 ◽  
pp. 864-867
Author(s):  
Zai Feng Shi ◽  
Su Min Zhang ◽  
Su Guo
Keyword(s):  
Methylene Blue ◽  
Particle Size ◽  
Photocatalytic Activity ◽  
Citric Acid ◽  
Water Content ◽  
Mass Fraction ◽  
Ph Value ◽  
Sol Gel ◽  
Raw Material ◽  
Effects Of Ph

To investigate the effects of sol pH value and water content on photocatalytic activity of TiO2 prepared with sol-gel auto-igniting synthesis (SAS) method, TiO(NO3)2 was prepared with TiCl4 as raw material and used as precursor of TiO2. By changing sol pH value and water content, different TiO2 powders were prepared and characterized with XRD, SEM and photodegradation of methylene blue (MB). Results indicated that TiO2 presented the highest photocatalytic activity while sol pH value and mass fraction of water were adjusted to 7 and 50% respectively while the mole ratio of n (TiCl4): n (citric acid): n (ammonium nitrate) was fixed as 1: 1: 3. The TiO2 powders were confirmed as loose and porous anatase type with particle size of 15 nm by SEM and XRD.

Sign in / Sign up

Export Citation Format

Share Document