scholarly journals Study of phosphate removal from aqueous solution by zinc oxide

2015 ◽  
Vol 13 (3) ◽  
pp. 704-713 ◽  
Author(s):  
Zhen Luo ◽  
Suiyi Zhu ◽  
Zhongmou Liu ◽  
Jiancong Liu ◽  
Mingxin Huo ◽  
...  

Zinc oxide (ZnO) was synthesized and used to investigate the mechanism of phosphate removal from aqueous solution. ZnO particles were characterized by X-ray diffraction, scanning electron microscope and Fourier transform infrared spectroscopy before and after adsorption. Batch experiments were carried out to investigate the kinetics, isotherms, effects of initial pH and co-existing anions. The adsorption process was rapid and equilibrium was almost reached within 150 min. The adsorption kinetics were described well by a pseudo-second-order equation, and the maximum phosphate adsorption capacity was 163.4 mg/g at 298 K and pH ∼6.2 ± 0.1. Thermodynamic analysis indicated the phosphate adsorption onto ZnO was endothermic and spontaneous. The point of zero charge of ZnO was around 8.4 according to the pH-drift method. Phosphate adsorption capacity reduced with the increasing initial solution pH values. The ligand exchange and Lewis acid-base interaction dominated the adsorption process in the lower and the higher pH range, respectively. Nitrate, sulfate and chloride ions had a negligible effect on phosphate removal, while carbonate displayed significant inhibition behavior.

2019 ◽  
Vol 57 (4) ◽  
pp. 492
Author(s):  
Phan Phuoc Toan ◽  
Nguyen Trung Thanh ◽  
Nguyen Nhat Huy ◽  
Le Ngoc Hang ◽  
Le Tri Thich

Amine-SiO2 material was synthesized and applied as a novel adsorbent for nitrate and phosphate removal from aqueous solution. The characterization of Amine-SiO2 were done by using TGA, FTIR, BET, and SEM analyses. Results showed that Amine-SiO2 had higher nitrate and phosphate adsorption capacity of 1.14 and 4.16 times, respectively, than commercial anion exchange resin (Akualite A420). In addition, Amine-SiO2 also had good durability with stable performance after at least 10 regeneration times, indicating that this material is very promising for commercialization in the future as an adsorbent for water treatment.


Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 816 ◽  
Author(s):  
Xuefeng Tao ◽  
Tao Huang ◽  
Bo Lv

Magnetic biochar derived from agricultural biomass has been recognized as a cost-effective biochar sorbent for phosphate removal. This study evaluated the use of novel Fe/Mg-biochar nanocomposites (WBC1x), prepared by impregnating ground walnut shell in a solution with a different molar ratio of Fe2+ to Mg2+, then pyrolyzing slowly, at a temperature of 600 °C, to remove phosphate. The results showed that MgO and Fe3O4 were loaded onto the biochar successfully through the impregnation-pyrolysis method and the composites were able to be separated easily by magnetic field. Meanwhile, a higher surface area and point of zero charge on WBC1x were observed compared to the non-magnetic biochar (WBC). Moreover, the isothermal adsorption and kinetics data further suggested the that phosphate adsorption onto WBC1x resulted from chemisorption. Additionally, the maximum phosphate adsorption capacity of WBC1x was 6.9 mg.g−1, obtained though the Langmuir–Freundlich model, which was threefold higher than WBC, where MgO addition could enhance the adsorption capacity of WBC1x markedly by improving the surface charge.


2018 ◽  
Vol 2017 (3) ◽  
pp. 686-694 ◽  
Author(s):  
Hangdao Qin ◽  
Rong Xiao ◽  
Renhui Zhang ◽  
Jing Chen

Abstract Adsorption is an efficient treatment process to remove benzoic acid from aqueous solution. In this study, nitrogen-containing surface groups were introduced onto activated carbon (AC) surface by modification with ammonium hydroxide, ammonium carbonate, melamine or urea. The nitrogen-containing AC samples were characterized using N2 adsorption-desorption, Boehm titration, determination of the pH of the point of zero charge (pHpzc) and X-ray photoelectron spectroscopy. The adsorption of benzoic acid from aqueous solution by nitrogen-containing AC has been studied. The Langmuir model fitted the experimental data of equilibrium isotherms better than the Freundlich model. At initial solution pH 2.1, the adsorption capacity was closely related with the amount of pyridinic and pyrrolic N on the AC surface, which indicated these two nitrogen-containing groups played an important part in the adsorption process. The enhancement of adsorption capacity was due to the strengthened π–π dispersion force between benzoic acid and the AC basal plane. Since the surface charge of AC as well as the existence form of benzoic acid varied with solution pH value, the adsorption capacity was found to be highest at pH 3.8 and dropped sharply at higher or lower pH values.


2012 ◽  
Vol 550-553 ◽  
pp. 2255-2258
Author(s):  
Bing Bing Liu ◽  
Hua Yong Zhang ◽  
Lu Yi Zhang

Phosphate adsorption from aqueous solution using slag was investigated as the function of pH, contact time and adsorbent dosage. The results showed that the optimum value of pH was 2. Both Langmuir isotherm and Freundlich isotherm model were fit to describe the phosphate adsorption, and the maximum adsorption capacity from Langmuir model calculated was 9.09 mg/L. The adsorption process on slag followed pseudo second-order kinetic. Due to the relatively high adsorption capacity, the slag has the potential for application to removal phosphate from wastewater.


2012 ◽  
Vol 217-219 ◽  
pp. 862-865
Author(s):  
Li Jun Wang ◽  
Hua Yong Zhang ◽  
Lu Yi Zhang

The feasibility of using honeycomb-cinder slag as an adsorbent for phosphate removal from aqueous solution was investigated in batch experiments as a function of initial pH, contact time, adsorbent dose, and solution temperature. The results indicated that the solution pH significantly influenced the phosphate adsorption; 1440 min was enough to reach equilibrium for any concentration. Langmuir isotherm model gave well fit for phosphate adsorption, and the adsorption process followed pseudo second-order model. Desorption study exhibited that the phosphate adsorption on the honeycomb-cinder slag is not completely reversible. Results showed that honeycomb-cinder slag could be used as an adsorbent to uptake phosphate from wastewater.


2017 ◽  
Vol 13 (27) ◽  
pp. 425
Author(s):  
Azeh Yakubu ◽  
Gabriel Ademola Olatunji ◽  
Folahan Amoo Adekola

This investigation was conducted to evaluate the adsorption capacity of nanoparticles of cellulose origin. Nanoparticles were synthesized by acid hydrolysis of microcrystalline cellulose/cellulose acetate using 64% H3PO4 and characterized using FTIR, XRD, TGA-DTGA, BET and SEM analysis. Adsorption kinetics of Pb (II) ions in aqueous solution was investigated and the effect of initial concentration, pH, time, adsorbent dosage and solution temperature. The results showed that adsorption increased with increasing concentration with removal efficiencies of 60% and 92.99% for Azeh2 and Azeh10 respectively for initial lead concentration of 3 mg/g. The effects of contact time showed that adsorption maximum was attained within 24h of contact time. The maximum adsorption capacity and removal efficiency were achieved at pH6. Small dose of adsorbent had better performance. The kinetics of adsorption was best described by the pseudo-second-Order model while the adsorption mechanism was chemisorption and pore diffusion based on intra-particle diffusion model. The isotherm model was Freundlich. Though, all tested isotherm models relatively showed good correlation coefficients ranging from 0.969-1.000. The adsorption process was exothermic for Azeh-TDI, with a negative value of -12.812 X 103 KJ/mol. This indicates that the adsorption process for Pb by Azeh-TDI was spontaneous. Adsorption by Azeh2 was endothermic in nature.


Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 652 ◽  
Author(s):  
Wang ◽  
Zhao ◽  
Wang ◽  
Zhang ◽  
Zhang

The selective recovery of gold from wastewater is necessary because it is widely used in various fields. In this study, a new polymeric adsorbent (TP-AFC) was prepared by modifying polyaniline with trimethyl phosphate for the selective recovery of gold from wastewater. Bath experiments were carried out to explore the adsorption capacity and mechanism. The optimum pH of adsorption is 4. The adsorption equilibrium is reached at 840 min. The maximum adsorption capacity is 881 mg/g and the adsorption was a spontaneous endothermic process. The adsorption process fitted well with pseudo second-order kinetic and the Langmuir-models. The single-layer chemisorption governed the adsorption process. In addition, the application in wastewater indicated that the interfering ions had no effect on the adsorption of gold ions. TP-AFC has good selectivity. The interaction mechanism was mainly ion exchange and complexation. In general, TP-AFC was successfully prepared and has an excellent future in practical application.


Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 890 ◽  
Author(s):  
Gabriela Kamińska ◽  
Mariusz Dudziak ◽  
Edyta Kudlek ◽  
Jolanta Bohdziewicz

Grainy Hal-CNT composites were prepared from powder halloysite nanoclay (Hal) and carbon nanotubes (CNTs). The effect of the amount and type of CNTs, as well as calcination temperature on morphology and properties of Hal-CNT composites and their adsorption capacity of anthracene (ANT), were studied. The surface topography of granules was heterogenous, with cracks and channels created during granulation of powder clay and CNTs. In FTIR, spectra were exhibited only in the bands arising from halloysite, due to its dominance in the granules. The increase in the heating temperature to 550 °C resulted in mesoporosity/macroporosity of the granules, the lowest specific surface area (SSA) and poorest adsorption potential. Overall, SSA of all Hal-CNT composites were higher than raw Hal, and by itself, heated halloysite. The larger amount of CNTs enhanced adsorption kinetics due to the more external adsorption sites. The equilibrium was established with the contact time of approximately 30 min for the sample Hal-SWCNT 85:15, while the samples with loading 96:4, it was 60–90 min. Adsorption isotherms for ANT showed L1 type, which is representative for the sorbents with limited adsorption capacity. The Langmuir model described the adsorption process, suggesting a monolayer covering. The sample Hal-SWCNT 85:15 exhibited the highest adsorption capacity of ANT, due to its highest SSA and microporous character.


2019 ◽  
Vol 9 (23) ◽  
pp. 5249 ◽  
Author(s):  
Derlin Hsu ◽  
Changyi Lu ◽  
Tairan Pang ◽  
Yuanpeng Wang ◽  
Guanhua Wang

Chemically activated biochars prepared from sorghum distillers grain using two base activators (NaOH and KOH) were investigated for their adsorption properties with respect to ammonium nitrogen from aqueous solution. Detailed characterizations, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TG), and specific surface area analyses, were carried out to offer a broad evaluation of the prepared biochars. The results showed that the NaOH- and KOH-activated biochars exhibited significantly enhanced adsorption capacity, by 2.93 and 4.74 times, respectively, in comparison with the pristine biochar. Although the NaOH-activated biochar possessed larger specific surface area (132.8 and 117.7 m2/g for the NaOH- and KOH-activated biochars, respectively), the KOH-activated biochar had higher adsorption capacity owing to its much higher content of functional groups. The adsorption kinetics and isotherms of the KOH-activated biochar at different temperatures were further studied. The biochar had a maximum adsorption capacity of 14.34 mg/g at 45 °C, which was satisfactory compared with other biochars prepared using different feedstocks. The adsorption process followed pseudo-second-order kinetics, and chemical adsorption was the rate-controlling step. The equilibrium data were consistent with the Freundlich isotherm, and the thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Consequently, this work demonstrates that chemically activated biochar from sorghum distillers grain is effective for ammonium nitrogen removal.


Author(s):  
Nguyen Thi Minh Tam ◽  
Yunguo Liu ◽  
Hassan Bashir ◽  
Zhihong Yin ◽  
Yuan He ◽  
...  

Porous graphitic biochar was synthesized by one-step treatment biomass using potassium ferrate (K2FeO4) as activator for both carbonization and graphitization processes. The modified biochar (Fe@BC) was applied for the removal of diclofenac sodium (DCF) in an aqueous solution. The as-prepared material possesses a well-developed micro/mesoporous and graphitic structure, which can strengthen its adsorption capacity towards DCF. The experimental results indicated that the maximum adsorption capacity (qmax) of Fe@BC for DCF obtained from Langmuir isotherm simulation was 123.45 mg·L−1 and it was a remarkable value of DCF adsorption in comparison with that of other biomass-based adsorbents previously reported. Thermodynamic quality and effect of ionic strength studies demonstrated that the adsorption was a endothermic process, and higher environmental temperatures may be more favorable for the uptake of DCF onto Fe@BC surface; however, the presence of NaCl in the solution slightly obstructed DCF adsorption. Adsorption capacity was found to be decreased with the increase of solution pH. Additionally, the possible mechanism of the DCF adsorption process on Fe@BC may involve chemical adsorption with the presence of H-bonding and π–π interaction. With high adsorption capacity and reusability, Fe@BC was found to be a promising absorbent for DCF removal from water as well as for water purification applications.


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