Fluoride removal using calcined Mg/Al layered double hydroxides at high fluoride concentrations

The aim of this study was to investigate the removal of high fluoride concentrations by Mg/Al layered double hydroxide (LDH). Batch experiments were conducted using calcined Mg/Al LDH at 105 °C (LDH-105), 300 °C (LDH-300), and 700 °C (LDH-700). The Brunauer-Emmett-Teller (BET) analysis showed that the specific surface area of LDH-700 was 1.7−1.8 times larger than those of LDH-105 and LDH-300. The X-ray diffractometry (XRD) analysis indicated that LDH-105 had a layered structure (Mg4Al2(OH)12CO3 · 3H2O) while LDH-300 and LDH-700 were composed of mixed metal oxides (Al8O3N6 + Mg0.44Al0.56) and magnesium oxide (MgO), respectively. Batch tests showed that the fluoride sorption capacity of LDH-700 was 1.7−2.9 times greater than those of LDH-105 and LDH-300 at initial fluoride concentrations of 100 and 200 mg/L. The kinetic data showed that fluoride sorption to LDH-700 arrived at equilibrium after 12 h. The equilibrium test demonstrated that the maximum sorption capacity of LDH-700 was 91.401 mg/g. Additional batch experiments indicated that the sorption capacity of LDH-700 decreased slightly when the solution pH was increased from 4.0 to 9.0. Moreover, fluoride sorption to LDH-700 decreased considerably in the presence of anions such as phosphate, sulfate, and carbonate in the following order: HPO42− > SO42− > CO32− > Cl− > NO3−.

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Removal of Fluoride on Chitosan Coated Alumina (CAL) from Aqueous Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.797 ◽

2012 ◽

Vol 518-523 ◽

pp. 797-800 ◽

Cited By ~ 2

Author(s):

Xuan Lin Tang ◽

Huan Zhen Zhang ◽

Shuang Zhao ◽

Shu Fen Gong

Keyword(s):

Aqueous Solution ◽

Adsorption Capacity ◽

Contact Time ◽

Adsorption Rate ◽

Fluoride Removal ◽

Batch Experiments ◽

Solution Ph ◽

Initial Concentration ◽

Adsorbent Dosage ◽

Naoh Solution

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.

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Adsorption of Toxic Zinc by Functionalized Lignocellulose Derived from Waste Biomass: Kinetics, Isotherms and Thermodynamics

Sustainability ◽

10.3390/su131910673 ◽

2021 ◽

Vol 13 (19) ◽

pp. 10673

Author(s):

Jiatao Dang ◽

Hui Wang ◽

Chongqing Wang

Keyword(s):

Heavy Metals ◽

Aqueous Solution ◽

Sorption Capacity ◽

Photoelectron Spectroscopy ◽

Removal Rate ◽

Waste Biomass ◽

Sorption Mechanism ◽

Solution Ph ◽

Maximum Sorption Capacity ◽

Isotherms And Thermodynamics

Heavy metals pollution receives worldwide attention due to great toxicity, significant bio-accumulation and non-biodegradability. Adsorption is a promising technique for removing heavy metals from wastewater. Adsorption of zinc (Zn(II)) from aqueous solution was investigated by functionalized lignocellulose derived from fallen leaves. Alkalized lignocellulose (AC), xanthated lignocellulose (XC) and carboxylated lignocellulose (CC) were characterized by Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effect of sorbent dosage, solution pH, sorption time and initial Zn(II) concentration on Zn(II) sorption was investigated by single-factor experiment. Sorption kinetics, isotherms and thermodynamics were examined to reveal sorption mechanism. The sorption capacity and removal rate remarkably depend on experimental variables. Zn(II) sorption onto AC, XC and CC is well described by the pseudo second order kinetics and Langmuir isotherm. The sorption process is fast, reaching sorption equilibrium at 30 min. The maximum sorption capacity of Zn(II) onto CC is 46.49 mg/g, higher than that onto AC, XC and other reported sorbents. Thermodynamic parameters indicate that Zn(II) sorption is a spontaneous process. Sorption mechanism is majorly attributed to surface complexation. This work shows the feasibility of removing toxic Zn(II) from aqueous solution by locally available biomass, providing a sustainable approach for wastewater treatment.

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Природные материалы для сорбционной очистки хром- и кадмийсодержащих инфильтратов полигонов ТБО

Vodosnabzhenie i sanitarnaia tehnika ◽

10.35776/mnp.2019.12.02 ◽

2019 ◽

pp. 13-19

Author(s):

A. Safonov ◽

N. Andriushchenko ◽

N. Popova ◽

K. Boldyrev

Keyword(s):

Sorption Capacity ◽

Electron Acceptors ◽

Bacterial Cells ◽

Maximum Sorption Capacity ◽

Sorption Material ◽

Maximum Sorption ◽

Properties Of Materials ◽

Solid Waste Landfills ◽

Sorption Characteristics

Проведен анализ сорбционных характеристик природных материалов (вермикулит, керамзит, перлит, цеолит Трейд ) при очистке кадмий- и хромсодержащих сточных вод с высокой нагрузкой по ХПК. Установлено, что цеолит обладает максимальными сорбционными характеристиками для Cd и Cr и наименьшим биологическим обрастанием. При использовании вермикулита и керамзита или смесей на их основе можно ожидать увеличения сорбционной емкости для Cd и Сr при микробном обрастании, неизбежно происходящем в условиях контакта с водами, загрязненными органическими соединениями и биогенами. При этом биообрастание может повысить иммобилизационную способность материалов для редоксзависимых металлов за счет ферментативных ресурсов бактериальных клеток, использующих их в качестве акцепторов электронов. Эффект микробного обрастания разнонаправленно изменял параметры материалов: для Cr в большинстве случаев уменьшение и для Cd значительное увеличение. При этом дополнительным эффектом иммобилизации Cr является его биологическое восстановление биопленками. Варьируя состав сорбционного материала, можно подбирать смеси, оптимально подходящие для очистки вод инфильтратов с полигонов твердых бытовых отходов с высокой нагрузкой по ХПК и биогенным элементам как при использовании in situ, так и в системах на поверхности.The analysis of the sorption characteristics of natural materials (vermiculite, expanded clay, perlite, Trade zeolite) during the purification of cadmium and chromium-containing leachate with a high COD load was carried out. It was determined that zeolite had the maximum sorption capacity for Cd and Cr and the lowest biological fouling. When using vermiculite and expanded clay or mixtures on their basis, one can expect an increase in the sorption capacity for Cd and Cr during microbial fouling that inevitably occurs during contacting with water polluted with organic compounds and nutrients. In this case biofouling can increase the immobilization properties of materials for redox-dependent metals due to the enzymatic resources of bacterial cells that use them as electron acceptors. The effect of microbial fouling changed the parameters of materials in different directions: for Cr, in most cases, downward, and for Cd, significantly upward. Moreover, chromium biological recovery by biofilms is an additional effect of immobilization. Varying the composition of the sorption material provides for selecting mixtures that are optimally suitable for the purification of leachates from solid waste landfills with high COD and nutrients load, both when used in situ and in surface systems.

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Verification of anoxic phosphate uptake as the main biochemical mechanism of the “dephanox” process

Water Science & Technology ◽

10.2166/wst.1997.0365 ◽

1997 ◽

Vol 35 (10) ◽

pp. 87-94 ◽

Cited By ~ 7

Author(s):

R. Sorm ◽

J. Wanner ◽

R. Saltarelli ◽

G. Bortone ◽

A. Tilche

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Uptake Rate ◽

Phosphate Uptake ◽

Biochemical Mechanism ◽

Batch Experiments ◽

Batch Tests ◽

Genetic Probes ◽

Activated Sludge Systems ◽

Removal System

The phenomenon of anoxic phosphate uptake with simultaneous denitrification was studied. For this purpose kinetic batch tests have been carried out by using the activated sludge samples from three modifications of nutrient removal activated sludge systems: two based on an anaerobic-anoxic-oxic (A2/O) system and a third on an anaerobic-oxic (A/O) system. The results showed significant differences in anoxic phosphate uptake rate between activated sludge which was alternatively exposed to anoxic conditions and activated sludge from the A/O arrangement. These differences were also accompanied by different denitrification rates. Simultaneously with batch experiments the microscopic observation of activated sludge samples was carried out. Neisser and Gram stained samples showed clear differences in shape, size and distribution of polyphosphate accumulating bacteria between A2/O and A/O Processes. Moreover, experiments performed using genetic probes confirmed the differences in microbiological composition of activated sludge samples from different nutrient removal system arrangements.

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Phosphate Removal Using Polyethylenimine Functionalized Silica-Based Materials

Sustainability ◽

10.3390/su13031502 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1502

Author(s):

Maria Xanthopoulou ◽

Dimitrios Giliopoulos ◽

Nikolaos Tzollas ◽

Konstantinos S. Triantafyllidis ◽

Margaritis Kostoglou ◽

...

Keyword(s):

Sorption Capacity ◽

Removal Rate ◽

Phosphate Concentration ◽

Phosphate Removal ◽

Equilibrium Studies ◽

Maximum Sorption Capacity ◽

Algae Blooms ◽

Maximum Sorption ◽

Phosphate Anions ◽

Adsorbent Dose

In water and wastewater, phosphate anions are considered critical contaminants because they cause algae blooms and eutrophication. The present work aims at studying the removal of phosphate anions from aqueous solutions using silica particles functionalized with polyethylenimine. The parameters affecting the adsorption process such as pH, initial concentration, adsorbent dose, and the presence of competitive anions, such as carbonate, nitrate, sulfate and chromate ions, were studied. Equilibrium studies were carried out to determine their sorption capacity and the rate of phosphate ions uptake. The adsorption isotherm data fitted well with the Langmuir and Sips model. The maximum sorption capacity was 41.1 mg/g at pH 5, which decreased slightly at pH 7. The efficiency of phosphate removal adsorption increased at lower pH values and by increasing the adsorbent dose. The maximum phosphate removal was 80% for pH 5 and decreased to 75% for pH 6, to 73% for pH 7 and to 70% for pH 8, for initial phosphate concentration at about 1 mg/L and for a dose of adsorbent 100 mg/L. The removal rate was increased with the increase of the adsorbent dose. For example, for initial phosphate concentration of 4 mg/L the removal rate increased from 40% to 80% by increasing the dose from 0.1 to 2.0 g/L at pH 7. The competitive anions adversely affected phosphate removal. Though they were also found to be removed to a certain extent. Their co-removal provided an adsorbent which might be very useful for treating waters with low-level multiple contaminant occurrence in natural or engineered aquatic systems.

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Synthesis of Magnesia Powder from East Java Dolomite through Leaching, Precipitation and Calcination

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1112.550 ◽

2015 ◽

Vol 1112 ◽

pp. 550-554

Author(s):

M. Zaki Mubarok ◽

Christian Adi Kurniawan

Keyword(s):

Particle Diameter ◽

Acid Leaching ◽

Xrd Analysis ◽

Sem Analysis ◽

Leach Solution ◽

Water Removal ◽

Solution Ph ◽

Crystal Water ◽

Lower Temperature ◽

Co Precipitation

At the present paper, a process of magnesia (MgO) synthesis from East Java dolomite through hydrochloride acid leaching, precipitation and calcination as well as characteristic of the product is discussed. Results of the experimental works show that the dissolution rate of magnesium and calcium from dolomite in hydrochloride acid solution was very rapid. Complete magnesium extraction was obtained by the leaching test with acid concentration of 1.5 molar, particle size distribution of -325#, solid-liquid ratio 1:20 (g/mL), stirring speed 200 rpm at room temperature after only 10 seconds. Precipitation of Mg(OH)2 by the addition of 20% (v/v) CaO slurry into pregnant leach solution resulted in 97.5% Mg precipitation after 1 minute. Solution pH must be maintained at a level of 10-10.5 by adjusting CaO addition in order to minimize calcium co-precipitation and to obtain high purity of Mg(OH)2 precipitate. Calcinations of Mg(OH)2 were performed at temperature range of 550-800°C in which 99% of crystal water removal took place after 5 minute at temperature of 800°C. Lower temperature requires longer time of crystalline water removal from Mg(OH)2. XRF analysis showed MgO purity of 88% with the main impurities of calcium and chloride. XRD analysis detected the presences of calcium as calcite (CaCO3) and portlandite (Ca(OH)2) as impurities in the MgO product. SEM analysis of the MgO powder revealed a nano size of MgO with particle diameter of about 50 nm.

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Use of bentonite to control the release of copper from contaminated soils

Soil Research ◽

10.1071/sr07079 ◽

2007 ◽

Vol 45 (8) ◽

pp. 618 ◽

Cited By ~ 45

Author(s):

Wanting Ling ◽

Qing Shen ◽

Yanzheng Gao ◽

Xiaohong Gu ◽

Zhipeng Yang

Keyword(s):

Heavy Metals ◽

Sorption Capacity ◽

Contaminated Soils ◽

Montmorillonite Clay ◽

Maximum Sorption Capacity ◽

Maximum Sorption ◽

Wide Ph Range ◽

Ph Dependent ◽

Ph Range ◽

Soil Ageing

A decrease in release and availability of heavy metals in soil has been of worldwide interest in recent years. Bentonite is a type of expandable montmorillonite clay, and has strong sorption for heavy metals. In this work, the control of amended bentonite on the release of copper (Cu2+) from spiked soils was investigated using a batch equilibrium technique. Sorption of Cu by bentonite was pH-dependent, and could be well described using the Langmiur model. Maximum sorption capacity of the bentonite used in this study was 5.4 mg/g, which was much greater than soils reported in the literature. The extent of Cu2+ release from spiked soils was correlated with slurry concentrations, pH, and soil ageing process. In all cases, the amendment of bentonite was observed to effectively decrease the release of Cu2+ from soils. The apparent aqueous concentrations of Cu2+ released from soils devoid of bentonite treatment were 113–1160% higher than those from the soils amended with bentonite. Moreover, the magnitude of Cu2+ release decreased with increasing amount of bentonite added to soils. The bentonite added was more effective in retaining Cu2+ in sorbents for aged contaminated soils. Such enhanced retention resulting from the presence of bentonite was observed within a wide pH range from 2.5 to 7.0. Bentonite, as one of the most abundant minerals in soils, is regarded to improve the soil overall quality. The results obtained from this work provide useful information on utilisation of bentonite to control the release of heavy metals from contaminated soils.

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Heavy Metal Removal by the Waste Biomass of Penicillium chrysogenum

Water Quality Research Journal ◽

10.2166/wqrj.2001.042 ◽

2001 ◽

Vol 36 (4) ◽

pp. 793-803 ◽

Cited By ~ 15

Author(s):

Tadeusz Skowroński ◽

Jacek Pirszel ◽

Barbara Pawlik Skowrońska

Keyword(s):

Heavy Metal ◽

Sorption Capacity ◽

Penicillium Chrysogenum ◽

Metal Removal ◽

Binding Capacity ◽

Heavy Metal Removal ◽

Dry Weight ◽

Waste Biomass ◽

Metal Sorption ◽

Maximum Sorption Capacity

Abstract Metal sorption capacity of the granulated biosorbent derived from the waste biomass of Penicillium chrysogenum was examined. The potential metal sorption abilities of the biosorbent were estimated as the cation-exchange capacity, using a potentiometric titration. The total binding capacity, calculated for the pH range 3 to 8 was about 511 µeq/g dry weight. The granular biosorbent was capable of Cd, Zn, Cu and Pb binding. The kinetics of the heavy metal sorption were typical of the microbial dead biomass; metals were bound in the first few minutes. Sorption was a saturable process and the maximum sorption capacity, calculated from the Langmuir equation for the particular heavy metals was: 96 mg Pb; 21.5 mg Cd; 13 mg Zn and 11.7 mg Cu (per g dry weight). Optimum pH values for Cd, Zn and Cu sorption were about 7, while for Pb about 6. Heavy metal removal from different solutions was examined using the biosorption columns packed with P. chrysogenum, which efficiently removed Cd from 1 mM Cd solution, or Cd and Zn from the industrial wastewater. The studied biosorbent was capable of accumulating Cd and Zn even at the high Ca concentration.

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Application of spheroidal agglomerates of γ-Al2O3 in the fluoride removal from aqueous medium

Acta Universitaria ◽

10.15174/au.2019.2036 ◽

2019 ◽

Vol 29 ◽

pp. 1-16

Author(s):

Rafael Romero Toledo ◽

Víctor Ruiz Santoyo ◽

Ulises Zurita Luna ◽

Gustavo Rangel Porras ◽

Merced Martínez Rosales

Keyword(s):

Aqueous Medium ◽

Fluoride Removal ◽

Batch Experiments ◽

Activated Alumina ◽

27Al Nmr ◽

First Order ◽

First Order Kinetics ◽

Effective Removal ◽

Adsorption Processes ◽

Ft Ir

A spheroidal agglomerate γ-Al2O3 adsorbent obtained from pseudoboehmite for effective removal of fluoride from aqueous medium was investigated in the present study. The surface properties were characterized by several techniques: XRD, physisorption of N2, FE-SEM/EDS, 27Al NMR, FT-IR Pyridine adsorption, PZ and particle size. Batch experiments were conducted and they were compared with a commercial activated alumina (AA). The process was carried out at pH 5, 7, and 9, then at 25 and 35 ºC. Batch experimental results indicated that the spheroidal agglomerates of γ-Al2O3 remove up to 15 mg/g with a higher adsorption capacity than AA of 13 mg/g, at pH 5, studied at 25 and 35 °C. The F− adsorption processes in γ-Al2O3 and AA followed the pseudo-first-order kinetics and the Langmuir isotherm. The results showed an adsorbent effective for removal of F−.

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