scholarly journals Degradation of methylene blue by natural manganese oxides: kinetics and transformation products

2019 ◽  
Vol 6 (7) ◽  
pp. 190351 ◽  
Author(s):  
Shuangxi Zhou ◽  
Zhiling Du ◽  
Xiuwen Li ◽  
Yunhai Zhang ◽  
Yide He ◽  
...  

In this study, natural manganese oxides (MnO x ), an environmental material with high redox potential, were used as a promising low-cost oxidant to degrade the widely used dyestuff methylene blue (MB) in aqueous solution. Although the surface area of MnO x was only 7.17 m 2 g −1 , it performed well in the degradation of MB with a removal percentage of 85.6% at pH 4. It was found that MB was chemically degraded in a low-pH reaction system and the degradation efficiency correlated negatively with the pH value (4–8) and initial concentration of MB (10–50 mg l −1 ), but positively with the dosage of MnO x (1–5 g l −1 ). The degradation of MB fitted well with the second-order kinetics. Mathematical models were also built for the correlation of the kinetic constants with the pH value, the initial concentration of MB and the dosage of MnO x . Furthermore, several transformation products of MB were identified with HPLC-MS, which was linked with the bond energy theory to reveal that the degradation was initiated with demethylation.

2019 ◽  
Vol 79 (8) ◽  
pp. 1561-1570
Author(s):  
Wei Chen ◽  
Fengting Chen ◽  
Bin Ji ◽  
Lin Zhu ◽  
Hongjiao Song

Abstract The adsorption behavior and the underlying mechanism of methylene blue (MB) sorption on biochars prepared from different feedstocks at 500 °C were evaluated. The biochar feedstocks included Magnolia grandiflora Linn. leaves biochar (MBC), pomelo (Citrus grandis) peel biochar (PBC) and badam shell biochar (BBC). The results of characterizing and analyzing the samples showed that different biochars had different effects on the adsorption of MB. It could be found that MBC had the best adsorption effect on MB due to its largest average pore diameter of 5.55 nm determined by Brunauer-Emmett-Teller analysis. Under the optimal conditions, the maximum adsorption capacities of BBC, PBC and MBC were 29.7, 85.15 and 99.3 mg/g, respectively. The results showed that the amount of adsorption was affected by the pH value. The maximum adsorption capacity of MBC was 46.99 mg/g when it was at pH of 3, whereas for the same experimental conditions the maximum adsorption capacity of BBC and PBC was 25.29 mg/g at pH of 11 and 36.08 mg/g at pH of 7, respectively. Therefore, MBC was found to be a most efficient low-cost adsorbentl for dye wastewater treatment compared with BBC and PBC, and it had the best removal effect under acidic conditions.


2011 ◽  
Vol 197-198 ◽  
pp. 996-999 ◽  
Author(s):  
Kun Hong Hu ◽  
Yong Kui Cai ◽  
Sai Li

A MoS2/TiO2 composite was synthesized and its photocatalytic activity for the degradation of methylene blue was evaluated. The results showed that the nano-MoS2/TiO2 composite presented excellent photocatalytic properties in the degradation reaction of methylene blue, which was ascribed to the good absorption of nano-MoS2/TiO2 in the visible light region. The decoloration rate of methylene blue solution was influenced by the dosage of nano-MoS2/TiO2 and the initial concentration of methylene blue. However, both the pH value and the degradation temperature had negligible effects on the decoloration rate of methylene blue. Moreover, the nano-MoS2/TiO2 composite as the degradation catalyst of methylene blue was of good regeneration properties.


2017 ◽  
Vol 19 (4) ◽  
pp. 697-705 ◽  

This study was conducted to remove Methylene Blue (MB) from aqueous solution using activated carbon prepared from N. microphyllum (AC-NM) as a new, cheap, and non-toxic. Design of experiments based on Response Surface Methodology (RSM) conducted to investigate the effect of variables namely; initial dye concentration, pH, contact time and absorbent dosage. An empirical model was developed applying ANOVA analysis. The interaction effects of all factors and their optimization have been carried out using RSM. Dye removal efficiency increased to more than 90% with increasing pH and initial concentration of dye from 3 to 11 and 10 to 210 mg/L, respectively under 1.1 to 1.4 g/L of absorbent dosage. Among factors, initial concentration of MB known as an important factor with P- value <0.0001. The experimental data are fitted with Freundlich model based on multi layer adsorption states (R2=0.99). The adsorption kinetics well described by second order model with R2 = 0.98. This novel absorbent has different advantages such as low cost, high ability to absorb pollutants and easily available that can be suggested for water and wastewater treatment.


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.


2013 ◽  
Vol 864-867 ◽  
pp. 679-683 ◽  
Author(s):  
Hong Tao Zhu ◽  
Hong Yu Ge ◽  
Shou Chang Jiao

In this paper, we discuss experimental method of synthetic HTLcs by coprecipitation method,and factors of this HTLcs catalytic decomposition of methylene blue. Experimental results show that the Optimal catalytic conditions is: Catalyst is 0.75g/L, H2O2concentration is 0.75% and Reaction time was2.5h when the initial concentration of methylene blue is 20mg/L and the PH value of solution is 2.The decolorization rate of Methylene blue can reach 96.56%.


2012 ◽  
Vol 512-515 ◽  
pp. 195-198
Author(s):  
Jin Ye Niu ◽  
Zhi Wei Chen ◽  
Cheng Gong Sun ◽  
Liu Feng ◽  
Zheng Min Li ◽  
...  

Lithium dizirconium phosphate (LiZr2(PO4)3) possesses good ionic conductivity owing to its unique framework structure and can be used as favorable anode material in Li-ion battery. LiZr2(PO4)3 is commonly prepared by solid phase reaction in which higher temperature is needed and pure LiZr2(PO4)3 without other phases is difficult to obtain in the final products. In this paper, low cost hydrothermal synthesis of pure (LiZr2(PO4)3) was studied. Effects of the hydrothermal conditions (molar ratios of Li+ to ZrOCl2, addition of HF, pH values of reaction system and hydrothermal temperatures) on the phase composition of the products were investigated. The results showed that pure LiZr2(PO4)3 was successfully prepared at lower temperature of 80°C for 24h with the addition of HF when the pH value was adjusted to 5.0 and the molar ratio of Li+ to ZrOCl2 was 0.5 with the concentration of ZrOCl2 as 0.6mol/L. The phases and purity of the final products were characterized by XRD analysis.


2012 ◽  
Vol 610-613 ◽  
pp. 194-197
Author(s):  
Li Ping Chen ◽  
Si Qin Dalai

With sunflower straw as low-cost biosorbent, the biosorption of methylene blue (MB) from aqueous solution was studied by batch biosorption technique. The biosorption experiments were carried out under different conditions of solution pH, sunflower straw dose, and temperature. The results showed that biosorption of MB on to sunflower straw affected remarkably by the pH value, and the maximum biosorption amount was achieved at an optimum pH of 12.0; the equilibrium biosorption amount decreased as temperature was increasing, and the biosorption process might be depicted primly by Langmuir function; It was shown that the biosorption of methylene blue could be described by the pseudo-second-order equation.


Author(s):  
Yigezu Mekonnen Bayisa ◽  
Tafere Aga Bullo ◽  
Mohammed Seid Bultum

In recent decades, research concerning and knowledge about the external benefits of renewable raw materials have intensified the efforts for investigating the major sources, causes, and effects of wastewater from solid waste and industries or households. In this study bio-matter and low-cost photocatalyst was prepared for photodegradation on the removal of methylene blue from wastewater treatment, and characterized by Fourier-transform infrared (FTIR) spectroscopy, UV-spectrometer, and X-ray diffractometer (XRD). The effects of initial concentration of methylene blue, amount of dopant, and degradation time were investigated on the percentage degradation of methylene blue using the calcinated eggshell doped titanium dioxide nanoparticle catalysts. At sufficient contact time and low initial concentration, the increment in dopant dose from 0.5 to 2.5 g/l results in an increment of methylene blue degradation efficiency, from 52.5 % to 95.8%. It was shown that a calcinating eggshell doped titanium dioxide photocatalyst method for wastewater treatment is a promising option for the degradation of methylene blue from industrial wastewater under the stated condition.


2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Fatima Zohra Boubekri ◽  
Amal Benkhaled ◽  
Zineb Elbahri

Abstract Novel bio-composite films based on Algerian earth chestnut i.e. Bunium incrassatum roots (Talghouda, TG) and cellulose derivatives (ethylcellulose; EC and cellulose acetate; AC) are prepared and tested for methylene blue (MB) adsorption from aqueous solutions. The biomaterial films are elaborated by dissolution solvent evaporation technique and are characterized by infrared spectroscopy, X-ray diffraction, SEM and optical microscopy. The pHpzc is also determined. For the adsorption tests, design of experiments based on 23 factorial design is built and followed. So, the effects of TG:EC:AC ratio, pH and MB initial concentration are discussed on the basis of mathematical modelling using Minitab software. Mathematical relations between equilibrium adsorption percentages and capacities versus selected variables were obtained and illustrated by surface plots. The interactive effects between variables have been also identified. The results showed that the MB adsorption percentage exceeded 83% and is mostly affected by pH value. Nevertheless the adsorption capacity is affected by MB initial concentration.


2017 ◽  
Vol 11 (12) ◽  
pp. 102 ◽  
Author(s):  
Muhammad Saleem ◽  
Mehmood Ali ◽  
Zia Siddiqi ◽  
Abdulrahman Saud Al Qahtani

Saudi Arabian desert tree Acacia (Vachellia Seyal) used to produce Activated Carbon (AC) by phosphoric acid mediated chemical activation at low temperature. Characterization of AC done based on proximate and detailed analysis including Moisture content, Total Ash content, pH value, Iodine number, Methylene blue number, pore volume and BET surface area. Results revealed that properties of produced activated carbon (PAC) are comparable to commercial activated carbon (CAC). Low ash content and hardness making it suitable for water and wastewater treatment. Cost of production found to be less than $0.5/kg. Both AC used to treat wastewater containing Methylene Blue (MB) dye. Initially the removal efficiency of CAC is higher than the PAC however, both AC reached to similar removal (95.3% for PAC and 98.2% for CAC) within one hour. Growing demand of AC in the country can be meet by producing low cost locally available waste materials Acacia seyal tree branches.


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