scholarly journals Mechanisms of chromium(VI) removal from solution by zeolite and vermiculite modified with iron(II)

Author(s):  
Maria Isabel Garcia Rosa ◽  
Gabriella Andrade Boga ◽  
Suellen Silva Vieira Cruz ◽  
Fabio Ramos Dias Andrade ◽  
Sheila Aparecida Correia Furquim ◽  
...  

Abstract Mechanisms of Cr(VI) reduction by Fe(II) modified zeolite and vermiculite were evaluated. Adsorbents were treated with Fe(SO4).7H2O to saturate their exchange sites with Fe(II). Vermiculite (V-Fe) adsorbed more Fe(II) (21.8 mg g−1) than zeolite (Z-Fe) (15.1 mg g−1). Z-Fe and V-Fe were used to remove Cr(VI) from the solution by batch test to evaluate the effect of contact time and Cr(VI) initial concentration. Cr(VI) was 100% reduced to Cr(III) by Z-Fe and V-Fe from solution with 18 mg L−1 Cr(VI) in 1 minute. Considering that 3 moles Fe(II) are required to reduce 1 mole Cr(VI) (3Fe+2 + Cr+6 → 3Fe3+ + Cr+3), the iron content released from Z-Fe and V-Fe were sufficient to reduce 100% of Cr(VI) in solution by up to 46.8 mg L−1 Cr(VI), and about 90% (V-Fe) and 95% (Z-Fe) in solution with 95.3 mg L−1 Cr(VI). The assess of the Fe(II), Cr(III), Cr(VI), and K+ contents of the adsorbents and solutions after batch tests indicated that K+ ions from K₂Cr₂O₇ solution were the main cation adsorbed by Z-Fe, while vermiculite did not absorb any of these cations. The H+ of the acidic solution (pH around 5) may have been adsorbed by V-Fe. Therefore, the release of Fe(II) from Z-Fe and V-Fe involved cation exchange between, respectively, K+ and H+ ions from solution. The reduction of Cr(VI) by Fe(II) caused the precipitation of Cr(III) and Fe(III), and the decrease of pH of the solution to < 5. As acidity limits the precipitation of Cr(III) ions, they remained in solution and were not adsorbed by both adsorbents (since they prefer to adsorb K+ and H+). To avoid oxidation, Cr(III) can be removed by precipitation or adsorption by untreated minerals.

2011 ◽  
Vol 197-198 ◽  
pp. 131-135
Author(s):  
Li Fang Zhang ◽  
Ying Ying Chen ◽  
Wen Jie Zhang

Biosorption of chromium (VI) ions from aqueous solution with fungal biomass Penicillium sp. was investigated in the batch system. The influence of contact time, solution pH, biosorbent concentration, initial concentration of Cr (VI) ions and temperature on biosorption capacity of Cr (VI) ions was studied. The uptake of Cr (VI) was highly pH dependent and the optimum pH for biosorption of Cr (VI) ions was found to be 2.0. Biosorption capacity of Cr (VI) ions decreased with increased biosorbent concentration and increased with increase in initial concentration of Cr (VI) ions. The experiment results also showed that high temperatures increased the biosorption capacity of Cr (VI) by fungal biomass. It was found that the biosorption equilibrium data were fitted very well to the kangmuir as well as to the Freundlich adsorption model. The maximum sorptive capacities obtained from the Langmuir equation at temperature of 20, 30 and 40°C were 25.91, 32.68 and 35.97 mg/g for Cr (VI) ions, respectively. The results of this study indicated that the fungal biomass of Penicillium sp. is a promising biosorbent for removal of chromium (VI) ions from the water.


2018 ◽  
Vol 382 ◽  
pp. 307-311 ◽  
Author(s):  
Jumaeri ◽  
Sri Juari Santosa ◽  
Sutarno

Adsorption of anionic dyes Congo Red (CR) on HDTMA surfactant-modified zeolite A has been studied. The zeolite A, which is synthesized from coal fly ash, was modified with surfactant hexdeciltrimethylammonium bromide (HDTMA-Br) as much as 200% cation exchange capacity (CEC) of the zeolite. The effect of pH, contact time and initial concentration on the CR adsorption has been evaluated.The adsorption was carried out in a batch reactor at various pH, contact time and initial concentration on the given temperature. The amount CR adsorption varies as a function of pH, contact time and initial concentration of solution. Adsorption model of Langmuir and Freundlich from empirical data is used for this experiment. The Langmuir isotherm is more suitable for this adsorption. The experimental data fulfilled pseudo second-order kinetic models. The surfactant-modified zeolite A is more effective than zeolite A without modified on the adsorption of CR in aqueous solution.


2016 ◽  
Vol 721 ◽  
pp. 143-148 ◽  
Author(s):  
Nora Noureddine ◽  
Samia Benhammadi ◽  
Fouad Kara ◽  
Hakim Aguedal ◽  
Abdelkader Iddou ◽  
...  

A bacterial strain Pseudomonas aeruginosa isolated from an uncontaminated soil has been used for the removal of hexavalent chromium (Cr (VI)). The experiments were carried out in batch system in a culture broth. The results obtained have shown that 100% of Cr (VI) are removed. Contact time, initial concentration of the hexavalent chromium, temperature, as well as the nature of the culture broth have influenced this elimination. To the initial concentration of 20g/L of Cr (VI) the elimination rates are lower, while the reverse occurs for an initial concentration of 8g/L. This study allows considering the use of Pseudomonas aeruginosa in the treatment of water polluted by toxic heavy metals such as Cr (VI).


Author(s):  
Ketyla K. R. do Nascimento ◽  
Fernando F. Vieira ◽  
Marcello M. de Almeida ◽  
Josué da S. Buriti ◽  
Aldre J. M. Barros ◽  
...  

ABSTRACT The disposal of industrial wastewater into aquatic bodies without proper treatment can cause severe damage to the environment and human health. The objective of this study was to perform the drying of the sweet orange (Citrus sinensis L. Osbeck) peel cultivar Pêra and evaluate the viability of its use as biosorbent in the removal of a direct dye. Drying was carried out in an oven with air circulation at temperatures of 60 and 80 ºC. The mathematical models of Page, Henderson and Pabis, Logarithmic, Midilli and Two-term exponential were fitted to the moisture data as a function of time. The material was characterized by scanning electron microscopy, point of zero charge, and infrared spectroscopy. In the adsorption study, a complete 24 factorial design was used to analyze the influence of mass, initial concentration, solution pH and contact time on adsorbed quantity (qt) and removal percentage of the dye (R%). In the drying, the two-term exponential model fitted best to the experimental data. The characterization of the material indicated that the adsorbent has zero charge point of 3.5 and porous structure, and the infrared analysis indicated the presence of carboxylic and hydroxyl groups. In the adsorption, the adsorbed quantity of the dye increased under conditions of lower pH and biosorbent mass and higher initial concentration and contact time. The removal percentage of dye increases with higher biosorbent mass. The biosorbent used is a promising waste for the adsorption of the burgundy-16 dye.


2014 ◽  
Vol 661 ◽  
pp. 51-57
Author(s):  
Mohd Zawawi Mohamad Zulhelmi ◽  
Alrozi Rasyidah ◽  
Senusi Faraziehan ◽  
Mohamad Anuar Kamaruddin

Biosorption process is considered as economical treatment to remove metal from the aqueous solution compared to other established methods. In this study, Saccharomyces cerevisiae was used as biosorbent and subject to immobilization process which consists of ethanol treatment for the removal of binary metals, lead (II) and nickel (II) from aqueous solution. Response surface methodology (RSM) was used to optimize effective parameters condition and the interaction of two or more parameters in order to obtain high removal of the binary metals. The parameters that have been studied were initial concentration of binary metals solution (10 - 60 mg/L), biosorbent dosage (0.2 - 1.0 g), pH (pH 2 - pH 6) and contact time (30 - 360 minutes) towards lead (II) and nickel (II) ions removal. Based on analysis of variance (ANOVA), biosorbent dosage, solution pH and contact time factor were found significant for both responses. Through optimization procedure, the optimum condition for lead (II) and nickel (II) ions removal were obtained at initial concentration of 10.0 mg/L, biosorbent dosage of 1.0 g, solution pH of pH 6, and contact time of 360.00 minutes, which resulted in 95.08 % and 21.09 % removal of lead (II) and nickel (II) ions respectively.


2017 ◽  
Vol 57 (2) ◽  
Author(s):  
Guillermina Burillo ◽  
Juan Serrano-Gómez ◽  
Juan Bonifacio-Martínez

Polypropylene (PP) grafted with dimethylaminoethylmethacrylate (DMAEMA), was prepared by irradiation with a <sup>60</sup>Co γ source. The obtained PP-<em>g</em>-DMAEMA was used to study the Cr(VI) ion adsorption as a function of contact time, initial pH, initial concentration of metal ion and temperature. Chromium adsorption data on PP-<em>g</em>-DMAEMA at various initial concentration fit well the Freundlich and Langmuir isotherms. The maximum adsorption capacity (a<sub>max</sub>) was found to be 0.3103 × 0<sup>-4</sup> mol g<sup>-1</sup>. The thermodynamic parameters ΔH<sup>0</sup>, ΔG<sup>0</sup> and ΔS<sup>0</sup> were estimated showing the adsorption process to be exothermic and spontaneous.


2012 ◽  
Vol 518-523 ◽  
pp. 797-800 ◽  
Author(s):  
Xuan Lin Tang ◽  
Huan Zhen Zhang ◽  
Shuang Zhao ◽  
Shu Fen Gong

CAL beads were made by dropping wise mixture of chitosan and alumina into NaOH solution. Effects of contact time, adsorbent dosage, initial concentration and pH on fluoride removal were carried out by batch experiments. Results show that adsorption rate was relatively rapid in the first 6 h, thereafter distinctly decreased until adsorption reached the equilibrium within 48 h, at this time, adsorption capacity was up to 0.67 mg/g, which was much higher than raw chitosan (0.052 mg/g). Fluoride removal increased significantly with an increase of adsorbent dosage, however, it rose slowly when the adsorbent dosage was above 16 g/L. Adsorption capacity reduced from 0.75 mg/g to 0.64mg/g when solution pH rose from 4 to 7, nevertheless, adsorption was relatively independent on solution pH between 7 and 10.


2011 ◽  
Vol 17 (4) ◽  
pp. 385-395 ◽  
Author(s):  
Maurice Onyango ◽  
Jacob Kittinya ◽  
Nomcebo Hadebe ◽  
Vincent Ojijo ◽  
Aoyi Ochieng

Melanoidin is responsible for the dark brown colour of distillery wastewater. Discharge of coloured wastewater has a major environmental impact on the biota of the receiving water body. Consequently, this study explores the removal of melanodin from aqueous solution. The equilibrium, kinetics and thermodynamics of melanoidin sorption are studied by varying initial solution pH, initial concentration, adsorbent dose and temperature. Kinetically, the melanoidin removal from solution by a surfactant modified zeolite is rapid and the amount adsorbed is dependent on pH, initial concentration, adsorbent dose and temperature. The equilibrium sorption data are fitted to the Freundlich and Langmuir models while the sorption, kinetics is described by the Ho pseudo-second order and Elovich models. The thermodynamic analysis indicates that the sorption is spontaneous and endothermic in nature. The FTIR spectra analyses show no new peaks or shift in peaks after sorption indicating that the melanoidin sorption may have occurred by a physical process. The results from desorption studies showed that melanoidin eluted back easily to the solution using distilled water which corroborates the physical sorption mechanism.


Author(s):  
Bahman Hassan-Zadeh ◽  
Reza Rahmanian ◽  
Mohammad Hossein Salmani ◽  
Mohammad Javad Salmani

Introduction: Nanoporous silica has received growing interest for its unique application potential in pollutant removal. Therefore, the development of a simple technique is required to synthesize and functionalize the nanoporous materials for industrial application. Materials and Methods: The synthesis of nanoporous silica was investigated by the template sol-gel method, and it functionalized as an adsorbent for adsorption of malachite green. The morphology and structure of the prepared and functionalized nanoporous silica were studied using X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), and nitrogen adsorption-desorption technique. Subsequently, the effective parameters such as solution pH, contact time, and initial concentration on the adsorption process were optimized by adsorption tests. Results: The results showed that high-order nanoporous silica had been produced with an average diameter of 20.12 nm and average pore volume of 1.04 cm3.g−1. It was found that the optimum parameters of pH, initial concentration and contact time for malachite green adsorption on nanoporous silica were 6.5, 10 mg.l-1, and 60 min, respectively. The experimental data confirmed the Freundlich model (R2 = 0.995) and the obtained kinetic data followed the pseudo-first-order equation. The maximum adsorption capacity calculated by Langmuir isotherm was found to be 116.3 mg.g-1. Conclusion: The high adsorption capacity showed that the acid-functionalized nanoporous silica adsorbent can be used as an adequate adsorbent to remove malachite green from aquatic environments. The large surface area can be suggested that the silica nanoporous will have potential application prospects as the adsorbent.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1313 ◽  
Author(s):  
Leili Mohammadi ◽  
Abbas Rahdar ◽  
Razieh Khaksefidi ◽  
Aliyeh Ghamkhari ◽  
Georgios Fytianos ◽  
...  

There are different ways for antibiotics to enter the aquatic environment, with wastewater treatment plants (WWTP) considered to be one of the main points of entrance. Even treated wastewater effluent can contain antibiotics, since WWTP cannot eliminate the presence of antibiotics. Therefore, adsorption can be a sustainable option, compared to other tertiary treatments. In this direction, a versatile synthesis of poly(styrene-block-acrylic acid) diblock copolymer/Fe3O4 magnetic nanocomposite (abbreviated as P(St-b-AAc)/Fe3O4)) was achieved for environmental applications, and particularly for the removal of antibiotic compounds. For this reason, the synthesis of the P(St-b-AAc) diblock copolymer was conducted with a reversible addition fragmentation transfer (RAFT) method. Monodisperse superparamagnetic nanocomposite with carboxylic acid groups of acrylic acid was adsorbed on the surface of Fe3O4 nanoparticles. The nanocomposites were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) analysis. Then, the nanoparticles were applied to remove ciprofloxacin (antibiotic drug compound) from aqueous solutions. The effects of various parameters, such as initial drug concentration, solution pH, adsorbent dosage, and contact time on the process were extensively studied. Operational parameters and their efficacy in the removal of Ciprofloxacin were studied. Kinetic and adsorption isothermal studies were also carried out. The maximum removal efficiency of ciprofloxacin (97.5%) was found at an initial concentration of 5 mg/L, pH 7, adsorbent’s dosage 2 mg/L, contact time equal to 37.5 min. The initial concentration of antibiotic and the dose of the adsorbent presented the highest impact on efficiency. The adsorption of ciprofloxacin was better fitted to Langmuir isotherm (R2 = 0.9995), while the kinetics were better fitted to second-order kinetic equation (R2 = 0.9973).


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