scholarly journals Magnetic Fe3O4-Ag0 Nanocomposites for Effective Mercury Removal from Water

2020 ◽  
Vol 12 (13) ◽  
pp. 5489
Author(s):  
Vassilis J. Inglezakis ◽  
Aliya Kurbanova ◽  
Anara Molkenova ◽  
Antonis A. Zorpas ◽  
Timur Sh. Atabaev
Keyword(s):  
Solid Phase ◽  
Removal Rate ◽  
Average Diameter ◽  
Synthesis Process ◽  
Metallic Silver ◽  
Green Method ◽  
Slow Increase ◽  
Fast Kinetics ◽  
Removal Capacity ◽  
Magnetic Fe3o4

In this study, magnetic Fe3O4 particles and Fe3O4-Ag0 nanocomposites were prepared by a facile and green method, fully characterized and used for the removal of Hg2+ from water. Characterizations showed that the Fe3O4 particles are quasi-spherical with an average diameter of 217 nm and metallic silver nanoparticles formed on the surface with a size of 23–41 nm. The initial Hg2+ removal rate was very fast followed by a slow increase and the maximum solid phase loading was 71.3 mg/g for the Fe3O4-Ag0 and 28 mg/g for the bare Fe3O4. The removal mechanism is complex, involving Hg2+ adsorption and reduction, Fe2+ and Ag0 oxidation accompanied with reactions of Cl− with Hg+ and Ag+. The facile and green synthesis process, the fast kinetics and high removal capacity and the possibility of magnetic separation make Fe3O4-Ag0 nanocomposites attractive materials for the removal of Hg2+ from water.

Biological Filters for Post-Denitrification

1993 ◽  
Vol 27 (5-6) ◽  
pp. 369-379 ◽  
Author(s):  
Svend-Erik Jepsen ◽  
Jes la Cour Jansen
Keyword(s):  
Carbon Source ◽  
Wastewater Treatment Plants ◽  
Removal Rate ◽  
Head Loss ◽  
Slow Increase ◽  
Loading Rates ◽  
Carrier Material ◽  
External Carbon Source ◽  
Removal Capacity ◽  
Biological Filters

Nitrifying wastewater treatment plants exist in many European countries. These plants can be extended for Total-Nitrogen removal by a post-denitrification stage using an external carbon source. A compact solution for this process is submerged biological filters. Two pilot plants have been used as post-denitrification reactors, a down-flow filter with expanded slate as carrier material (Biocarbone) and an up-flow filter with polystyrene pellets as carrier material (Biostyr). Nitrified wastewater was treated to a stable effluent quality from both pilot plants to below the Danish effluent standard which is 8 mg Tot-N/l. The pilot plants have been operated at different loading rates with acetate as external carbon source. Stable removal with effluent nitrate less than 5 mg NO3-N/l was obtained for loading rates up to more than 4 kg NO3-N/m3 d at 10-17°C. The removal capacity of the pilot plants has been shown to be independent of time from last backwash. The removal rate over different sections of the filters does not change within one operation cycle. The backwash removes the excess biomass and particles which cause the head loss, but the removal capacity remains in the filter. The head loss development in the two systems is quite different. In the Biostyr system, the head loss raises close to linear with time (load), while the Biocarbone shows slow increase in head loss with time until the surface is clogged by incoming particles and biomass growth. When this occurs, the nitrogen bubbles, which are produced in the lower part of the filter, are trapped just below the top layer. The void volume of the filter is occupied by nitrogen gas and the head loss increases very fast to the terminal head loss. This investigation has shown that both kinds of submerged filters are capable to serve as post-denitrification reactors to remove nitrate to the most stringent effluent standards.

scholarly journals Preparation and Characterization of High-Efficiency Magnetic Heavy Metal Capture Flocculants

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1732
Author(s):  
Yuanyuan Yu ◽  
Yongjun Sun ◽  
Jun Zhou ◽  
Aowen Chen ◽  
Kinjal J. Shah
Keyword(s):  
Heavy Metal ◽  
Reaction Time ◽  
High Efficiency ◽  
Removal Rate ◽  
Low Cost ◽  
Monomer Concentration ◽  
Synthesis Process ◽  
Response Surface Optimization ◽  
Metal Capture ◽  
Total Monomer Concentration

In this study, a high-efficiency magnetic heavy metal flocculant MF@AA was prepared based on carboxymethyl chitosan and magnetic Fe3O4. It was characterized by SEM, FTIR, XPS, XRD and VSM, and the Cu(II) removal rate was used as the evaluation basis for the preparation process. The effects of AMPS content, total monomer concentration, photoinitiator concentration and reaction time on the performance of MF@AA flocculation to remove Cu(II) were studied. The characterization results show that MF@AA has been successfully prepared and exhibits good magnetic induction characteristics. The synthesis results show that under the conditions of 10% AMPS content, 35% total monomer concentration, 0.04% photoinitiator concentration, and 1.5 h reaction time, the best yield of MF@AA is 77.69%. The best removal rate is 87.65%. In addition, the response surface optimization of the synthesis process of MF@AA was performed. The optimal synthesis ratio was finally determined as iron content 6.5%, CMFS: 29.5%, AM: 53.9%, AMPS: 10.1%. High-efficiency magnetic heavy metal flocculant MF@AA shows excellent flocculation performance in removing Cu(II). This research provides guidance and ideas for the development of efficient and low-cost flocculation technology to remove Cu(II) in wastewater.

scholarly journals Adsorption of copper ions on Magnolia officinalis residues after solid-phase fermentation with Phanerochaete chrysosporium

2019 ◽  
Vol 17 (1) ◽  
pp. 1173-1184 ◽  
Author(s):  
Fengyun Tao ◽  
Yangping Liu ◽  
Junliang Chen ◽  
Peng Wang ◽  
Qing Huo
Keyword(s):  
Chinese Medicine ◽  
Phanerochaete Chrysosporium ◽  
Solid Phase ◽  
Copper Ions ◽  
Removal Rate ◽  
Low Cost ◽  
Preparation Technique ◽  
Adsorption Enthalpy ◽  
Pseudo Second Order ◽  
Magnolia Officinalis

AbstractThe disposal of residues while manufacturing Chinese medicine has always been an issue that concerns pharmaceutical factories. Phanerochaete chrysosporium was inoculated into the residues of Magnolia officinalis for solid-phase fermentation to enzymatically hydrolyze the lignin in the residues and thus to improve the efficiency of removal of the copper ions from residues for the utilization of residues from Chinese medicine. With the increase in activities of lignin-degrading enzymes, especially during the fermentation days 6 to 9, the removal rate of copper ions using M. officinalis residues increased dramatically. The rate of removal reached the maximum on the 14th day and was 3.15 times higher than the initial value. The rate of adsorption of copper ions on the fermentation-modified M. officinalis residues followed the pseudo-second-order kinetics. The adsorption isotherms were consistent with the Freundlich models. The adsorption enthalpy was positive, indicating that it was endothermic and elevation in temperature was favorable to this adsorption process. The adsorption free energy was negative, implying the spontaneity of the process. The copper ions adsorbed could be effectively recovered using 0.2 M hydrochloric acid solution. After five successive cycles of adsorption-regeneration, the fermentation-modified M. officinalis residues exhibited a stable adsorption capacity and greater reusability. The M. officinalis residues fermented with P. chrysosporium are low-cost and environmentally friendly copper ions adsorbent, and this preparation technique realizes the optimum utilization of Chinese medicine residues.

scholarly journals Anomalous Increase in Specific Heat of Binary Molten Salt-Based Graphite Nanofluids for Thermal Energy Storage

2018 ◽  
Vol 8 (8) ◽  
pp. 1305 ◽  
Author(s):  
Hyun Kim ◽  
Byeongnam Jo
Keyword(s):  
Specific Heat ◽  
Molten Salt ◽  
Base Fluid ◽  
Solid Phase ◽  
Layer Structure ◽  
Synthesis Process ◽  
Nanoparticle Concentration ◽  
Anomalous Increase ◽  
Salt Mixtures ◽  
Graphite Nanoparticles

An anomalous increase of the specific heat was experimentally observed in molten salt nanofluids using a differential scanning calorimeter. Binary carbonate molten salt mixtures were used as a base fluid, and the base salts were doped with graphite nanoparticles. Specific heat measurements of the nanofluids were performed to examine the effects of the composition of two salts consisting of the base fluid. In addition, the effect of the nanoparticle concentration was investigated as the concentration of the graphite nanoparticles was varied from 0.025 to 1.0 wt %. Moreover, the dispersion homogeneity of the nanoparticles was explored by increasing amount of surfactant in the synthesis process of the molten salt nanofluids. The results showed that the specific heat of the nanofluid was enhanced by more than 30% in the liquid phase and by more than 36% in the solid phase at a nanoparticle concentration of 1 wt %. It was also observed that the concentration and the dispersion homogeneity of nanoparticles favorably affected the specific heat enhancement of the molten salt nanofluids. The dispersion status of graphite nanoparticles into the salt mixtures was visualized via scanning electron microscopy. The experimental results were explained according to the nanoparticle-induced compressed liquid layer structure of the molten salts.

Biological treatment characteristics of benzene and toluene in a biofilter packed with cylindrical activated carbon

2002 ◽  
Vol 46 (11-12) ◽  
pp. 51-56 ◽  
Author(s):  
G.-W. Li ◽  
H.-Y. Hu ◽  
J.-M. Hao ◽  
H.-Q. Zhang
Keyword(s):  
Carbon Dioxide ◽  
Activated Carbon ◽  
Gas Flow ◽  
Removal Rate ◽  
Carbon Dioxide Concentration ◽  
Organic Load ◽  
Filler Materials ◽  
Removal Capacity ◽  
Bacillus Spore ◽  
Maximum Removal

The biodegradation of toluene and benzene in a biofilter using cylindrical activated carbon as the filler materials was studied. Three gas flow rates, i.e. 0.25, 0.50 and 0.75 m3/h, corresponding to empty bed gas residence of 75, 37.5 and 25 s, respectively, and total organic load lower than 400 g/m3.h were tested. The biofilter proved to be highly efficient in biodegradation of toluene and benzene, and toluene was more easily degraded than benzene. When each inlet load was lower than 150 g/m3.h, removal rate increased with inlet load and reached a maximum, which was 150 and 120 g/m−3.h for toluene and benzene, respectively. For inlet load higher than the maximum removal capacity conditions, the removal rate decreased with inlet load. Carbon dioxide concentration profile through the biofilter revealed that the mass ratios of carbon dioxide produced to the toluene and benzene removed were 2.15 g(CO2)/g(toluene) and 1.67 g(CO2)/g(benzene), which furthermore, confirmed the biodegradation performance in biofilter. The observation of biotic community demonstrated that the microbes consisted of bacillus, spore bacillus and fungi, of which the spore bacillus was dominant.

scholarly journals The effect of artificial support material existence on removal of organic and nutrient in laboratory scale using plug flow reactor (PFR)

2020 ◽  
Vol 148 ◽  
pp. 01003
Author(s):  
Sarah Aphirta ◽  
Prayatni Soewondo ◽  
Nida Maisa Zakiyya ◽  
Dyah Wulandari Putri ◽  
Barti Setiani Muntalif
Keyword(s):  
Flow Reactor ◽  
Removal Rate ◽  
Plug Flow ◽  
Sem Analysis ◽  
Absorption Capacity ◽  
Organic Substrate ◽  
Laboratory Scale ◽  
Support Material ◽  
Substrate Removal ◽  
Removal Capacity

Artificial support material was examined to determine the removal capacity of organic pollutants and nutrients on laboratory scale using PFR system. The experiment was performed using artificial water with similar characteristics to Cikapayang River in three PFRs of 10.78 L. The PFRs were made of PVC pipes filled with an inert chemical substrate as an artificial support material. The process of pollutants removal in the PFR relies on a biological layer (biofilm) grown on the surface of the material support. Three type of C:N:P ratio used in this study were 30:15:1, 75:25:2, and 180:35:3. The results showed that the maximum removal efficiency of TSS, TN, TP, and COD in the preliminary tests were 85%, 87%, 71% and 79%, respectively. Moreover, the maximum water absorption capacity result was up to 30.8%. Organic substrate removal rate compared with first order and Strover-Kincannon substrate removal models prediction. The best fit model for this experiment was Stover-Kincannon model, with the average correlation coefficient up to 90% for all of the three reactors. SEM analysis shown that the microorganisms shape is coccus with the average size of 5 µm.

scholarly journals Assessing the Self-Purification Capacity of Surface Waters in Lake Baikal Watershed

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1505 ◽  
Author(s):  
Mikhail Yu. Semenov ◽  
Yuri M. Semenov ◽  
Anton V. Silaev ◽  
Larisa A. Begunova
Keyword(s):  
Lake Baikal ◽  
Water Body ◽  
Removal Rate ◽  
Water Discharge ◽  
Contaminant Removal ◽  
Removal Rates ◽  
Selenga River ◽  
Removal Capacity ◽  
Polycyclic Aromatic ◽  
The Difference

The removal of trace metals (TM), dissolved organic carbon (DOC), mineral nitrogen (Nmin.), and polycyclic aromatic hydrocarbons (PAHs) from the water of Lake Baikal and its tributaries was evaluated. The contaminant removal rate (CRR) and the contaminant removal capacity (CRC) were used as water self-purification parameters. The CRR was calculated as the difference between contaminant mass flow rates at downstream and upstream gauging stations. The CRC was calculated as the quotient of the CRR and the change in water discharge between downstream and upstream gauging stations. Whether the CRR and CRC have positive or negative values depends on whether contaminant release or removal occurs in the water body. The CRR depends on the size of the water body. The lowest and the highest CRRs observed for Baikal were equal to −15 mg/s (PAHs) to −7327 g/s (DOC), whereas the highest PAH and DOC removal rates observed for Selenga River (the major Baikal tributary) in summer were equal to −9 mg/s and −3190 g/s correspondingly. The highest PAH and DOC removal rates observed for small tributaries were equal to 0.0004 mg/s and −0.7 g/s respectively. The amplitude of annual CRR oscillations depends on contaminant abundance. The highest amplitude was typical for most abundant contaminants such as Nmin. and DOC. In unpolluted sections of the Selenga River the highest rates of N and C removal (−85 g/s and −3190 g/s, respectively) were observed in summer and the lowest rates (4 g/s and 3869 g/s, respectively) were observed in the spring. The lowest amplitude was typical for PAHs and some low-abundance TM such as V and Ni. The highest summer rates of V and Ni removal were equal to −378 mg/s and −155 mg/s respectively, whereas lowest spring rates are equal to 296 mg/s and 220 mg/s. The intermediate CRR amplitudes were typical for most abundant TM such as Sr, Al, and Fe. The spatial CRR variability depends on water chemistry and the presence of pollution sources. The lowest (up to 38 g/s) rates of Nmin. removal was observed for polluted lower Selenga sections characterized by low water mineralization and high DOC concentrations. The highest rates (−85 g/s) were observed for unpolluted upper sections. Seepage loss from the river to groundwater was also recognized as an important means of contaminant removal. The CRC values depend mostly on water residence time. The DOC removing capacity value of Baikal (−26 g/m3) were lower than those of Selenga in summer (−35 g/m3) but higher than the CRCs of all tributaries during the other seasons (from 30 mg/m3 to −10 g/m3).

scholarly journals Ultra-Highly Efficient Removal of Methylene Blue Based on Graphene Oxide/TiO2/Bentonite Sponge

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 824
Author(s):  
Yuan Liu ◽  
Luyan Wang ◽  
Ni Xue ◽  
Pengxiang Wang ◽  
Meishan Pei ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Graphene Oxide ◽  
Removal Rate ◽  
Cost Effective ◽  
Electron Hole ◽  
Efficient Treatment ◽  
Highly Efficient ◽  
Removal Capacity ◽  
Sensitivity Range

An ultra-highly efficient Graphene Oxide/TiO2/Bentonite (GO/TiO2/Bent) sponge was synthesized using an in situ hydrothermal method. GO/TiO2/Bent sponge with a GO mass concentration of 10% exhibited the highest treatment efficiency of methylene blue (MB), combining adsorption and photocatalytic degradation, and achieved a maximum removal efficiency of 100% within about 70 min. To further prove the ultra-high removal capacity of the sponge, the concentration of MB in water increased to ten times the original concentration. At so high a MB concentration, the removal rate was still as high as 80% in 90 min. The photocatalytic mechanism of GO/TiO2/Bent sponge was discussed through XPS, PL and radicals quenching experiments. Here Bent can immobilize TiO2 and react with a photo-generated hole to increase the amount of hydroxyl radical; effectively enhancing the degradation of MB.GO sponge enlarges the sensitivity range of TiO2 to visible light by increasing the charge separation of TiO2 and reducing the recombination of photo-generated electron–hole pairs. Additionally, GO sponge with an interconnected porous structure provides an effective platform to immobilize TiO2/bent and makes them be easily recovered. The as-prepared sponge develops a simple and cost-effective strategy to realize the ultra-highly efficient treatment of dyes in wastewater.

Zein bio-nanoparticles: a novel green nanopolymer as a dispersive solid-phase extraction adsorbent for separating and determining trace amounts of azorubine in different foodstuffs

RSC Advances ◽  
2016 ◽  
Vol 6 (77) ◽  
pp. 73096-73105 ◽  
Author(s):  
Behrooz Zargar ◽  
Nahid Pourreza ◽  
Elahe Bayat ◽  
Amir Hatamie
Keyword(s):  
Solid Phase Extraction ◽  
Model Compound ◽  
Solid Phase ◽  
Phase Extraction ◽  
Dispersive Solid Phase Extraction ◽  
Green Method

A new, easy, and green method using zein nanoparticles as a dispersive solid-phase extraction (DSPE) adsorbent has been used for the preconcentration of azorubine (a well-known chemical dye additive) as a model compound in foodstuffs.

Influence of dissolved oxygen concentration on the start-up of the anammox-based process: ELAN®

2015 ◽  
Vol 72 (4) ◽  
pp. 520-527 ◽  
Author(s):  
N. Morales ◽  
A. Val del Río ◽  
J. R. Vázquez-Padín ◽  
R. Gutiérrez ◽  
R. Fernández-González ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Removal Rate ◽  
Batch Reactor ◽  
Thick Layer ◽  
Average Diameter ◽  
Bulk Liquid ◽  
Anammox Bacteria ◽  
Total Biomass ◽  
Ammonia Oxidizing Bacteria ◽  
Anaerobic Digester Supernatant

The anammox-based process ELAN® was started-up in two different sequencing batch reactor (SBR) pilot plant reactors treating municipal anaerobic digester supernatant. The main difference in the operation of both reactors was the dissolved oxygen (DO) concentration in the bulk liquid. SBR-1 was started at a DO value of 0.4 mg O2/L whereas SBR-2 was started at DO values of 3.0 mg O2/L. Despite both reactors working at a nitrogen removal rate of around 0.6 g N/(L d), in SBR-1, granules represented only a small fraction of the total biomass and reached a diameter of 1.1 mm after 7 months of operation, while in SBR-2 the biomass was mainly composed of granules with an average diameter of 3.2 mm after the same operational period. Oxygen microelectrode profiling revealed that granules from SBR-2 where only fully penetrated by oxygen with DO concentrations of 8 mg O2/L while granules from SBR-1 were already oxygen penetrated at DO concentrations of 1 mg O2/L. In this way granules from SBR-2 performed better due to the thick layer of ammonia oxidizing bacteria, which accounted for up to 20% of all the microbial populations, which protected the anammox bacteria from non-suitable liquid media conditions.

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