Kinetic studies of phosphate adsorption onto construction solid waste (CSW)

2014 ◽  
Vol 49 (4) ◽  
pp. 307-318 ◽  
Author(s):  
C. Liu ◽  
Y. Yang ◽  
N. Wan

Adsorption of phosphate onto construction solid waste (CSW) was investigated in a batch system. CSW as an inescapable by-product of the construction and demolition process, was used as a composite adsorbent for the removal of phosphate in this study. The adsorption kinetics was investigated under various parameters such as contact time, pH, CSW dosage, initial phosphate concentration and particle size. Greater percentage of phosphate was removed with decrease in the initial concentration and increase in the amount of CSW used. Adsorption of phosphate was pH dependent, and maximum phosphate immobilisation capacity was obtained in alkaline condition. Lagergren first-order, second-order, intra-particle diffusion and external diffusion model were used to test the experimental data. Kinetic analysis showed that the adsorption was best fitted with the pseudo-second-order kinetic model. Adsorption mechanism studies revealed that both external mass transfer and intra-particle diffusion had rate limiting effects on the removal process. These results demonstrated that the CSW could be used as a low-cost adsorbent media for phosphate removal, and the data were relevant for optimal design of wastewater treatment plants.

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1312
Author(s):  
Dereje Tadesse Mekonnen ◽  
Esayas Alemayehu ◽  
Bernd Lennartz

The contamination of surface and groundwater with phosphate originating from industrial and household wastewater remains a serious environmental issue in low-income countries. Herein, phosphate removal from aqueous solutions was studied using low-cost volcanic rocks such as pumice (VPum) and scoria (VSco), obtained from the Ethiopian Great Rift Valley. Batch adsorption experiments were conducted using phosphate solutions with concentrations of 0.5 to 25 mg·L−1 to examine the adsorption kinetic as well as equilibrium conditions. The experimental adsorption data were tested by employing various equilibrium adsorption models, and the Freundlich and Dubinin-Radushkevich (D-R) isotherms best depicted the observations. The maximum phosphate adsorption capacities of VPum and VSco were calculated and found to be 294 mg·kg−1 and 169 mg·kg−1, respectively. A pseudo-second-order kinetic model best described the experimental data with a coefficient of correlation of R2 > 0.99 for both VPum and VSco; however, VPum showed a slightly better selectivity for phosphate removal than VSco. The presence of competitive anions markedly reduced the removal efficiency of phosphate from the aqueous solution. The adsorptive removal of phosphate was affected by competitive anions in the order: HCO3− >F− > SO4−2 > NO3− > Cl− for VPum and HCO3− > F− > Cl− > SO4−2 > NO3− for VSco. The results indicate that the readily available volcanic rocks have a good adsorptive capacity for phosphate and shall be considered in future studies as test materials for phosphate removal from water in technical-scale experiments.


2020 ◽  
Vol 13 ◽  
pp. 117862212096965
Author(s):  
Yohannis Fetene ◽  
Taffere Addis

Phosphorous from municipal and industrial wastewater is the main cause of eutrophication of rivers and lakes, because effluent quality from conventional secondary wastewater treatment plants does not meet the discharge standard that demands further treatment. Therefore, we investigated pumice as a potential low-cost adsorbent for the tertiary treatment of phosphate from municipal wastewater. The phosphate adsorption process reached equilibrium after 60 minutes contact time and achieved a removal efficiency of 94.4% ± 0.7% for an adsorbent dose of 10 g/L in 3 mg/L phosphate solution. The highest phosphate removal was recorded at pH 7. The experimental data best fitted with the Redlich-Peterson isotherm and the pseudo-second-order kinetic models. The coexisting anions decreased phosphate adsorption in the order of mixture >SO42– > HCO3− > NO3− > Cl− > CO3−. Pumice removed 95% ± 0.2% of phosphate from effluents of the secondary treatment unit of a municipal wastewater treatment plant. Furthermore, effective regeneration of saturated pumice was possible with a 0.2 M NaOH solution. Therefore, pumice could be a technically workable low-cost reusable adsorbent for phosphate removal from wastewater as a tertiary treatment to curb eutrophication of surface waters. However, further column adsorption study is recommended for a continuous flow system to optimize process design variables and scale up for field applications.


2018 ◽  
Vol 250 ◽  
pp. 06013 ◽  
Author(s):  
Nur Atikah Abdul Salim ◽  
Noorul Hudai Abdullah ◽  
Muhammad Rijaluddin Khairuddin ◽  
Mohd A’ben Zulkarnain Rudie Arman ◽  
Mohd Hairul Khamidun ◽  
...  

Excessive amount of phosphate released from wastewater can cause eutrophication to the receiving waters. Adsorption technique has been used to remove phosphate from aqueous solutions. The use of waste mussel shell (WMS) to remove phosphate from aqueous solutions and application of several kinetic and isotherm models to describe the adsorption of phosphate onto WMS were conducted in batch experiments. The phosphate adsorption by the WMS was examined with respect to solute concentration, contact time and adsorbent dose. The phosphate removal efficiencies obtained were 46.7, 57.6, 64.1, 70.8 and 75.2% at 144 h contact time for WMS dosage of 2, 4, 6, 8 and 10 g, respectively. Physical and chemical properties of WMS including surface physical morphology and elemental compositions were characterized. A comparison of kinetic models applied to the phosphate adsorption onto WMS was evaluated for the pseudo-first order and pseudo-second order model. The experimental data fitted very well with the pseudo-second order kinetic model (R2 > 0.984), which indicated the adsorption process was chemisorption. In the isotherm studies, the Langmuir and Freundlich isotherm models were applied. The results indicated that the use of Freundlich equation is well described with the phosphate adsorptions onto WMS (R2 = 0.968), suggesting the heterogeneity of the adsorbent surface. The experimental results suggested the use of WMS as an excellent adsorption material for phosphate removal from aqueous solutions, giving new insights into environmental engineering practices.


2018 ◽  
Vol 78 (7) ◽  
pp. 1603-1614 ◽  
Author(s):  
Ying Wang ◽  
Hui He ◽  
Nan Zhang ◽  
Kazuya Shimizu ◽  
Zhongfang Lei ◽  
...  

Abstract In this study, akadama clay, a kind of volcano ash, was activated with sulfuric acid and then evaluated for the adsorption of phosphate from aqueous solution via batch experiments. The effects of adsorbent dose, initial pH and coexisting anions on phosphate removal by natural akadama clay and acid-activated akadama clay were investigated. Based on the pH effect, the modified adsorbent could efficiently capture phosphate over a wider pH range of 3.00–6.00 than natural akadama clay. Competitive anions showed negative effects on the phosphate adsorption, especially citrate and carbonate. The adsorption process followed the pseudo-second-order kinetic equation and the intra-particle diffusion. Langmuir isotherm model was found to fit the data better than Freundlich model, and the maximum adsorption capacities of phosphate onto the natural akadama clay and acid-activated akadama clay were 5.88 and 9.19 mg/g, respectively. Furthermore, thermodynamic studies confirmed that the adsorption of acid-activated akadama clay was a spontaneous process. The mechanisms of phosphate adsorption on the clay could be ascribed to electrostatic attraction and ligand exchange. These results suggest that after modification, acid-activated akadama clay could be used as a promising adsorbent for phosphate removal from wastewater in real application and then further used as fertilizers.


Author(s):  
Abdelkader Ouakouak ◽  
Leila Youcef ◽  
Djihad Boulanouar ◽  
Samia Achour

The objective of this work is to study the phosphate adsorption from natural waters by using a granular activated carbon (GAC). Experiments were carried out with synthetic solutions of phosphate prepared using groundwater (mineralized drinking water). Batch tests were carried out in order to study different operating parameters such as the effect of contact time, pH, initial phosphate concentration and adsorbent dosage. In addition, the adsorption kinetic data were simulated using the pseudo first order, the pseudo second-order and the intra-particle diffusion model. The sorption equilibrium was analyzed by Langmuir, Freundlich and Dubinin–Radushkevich isotherms model. Results show that the phosphate adsorption was reversible and the quantity adsorbed reached its maximum value (2.82 mg/g) after 30 min. It was also found that phosphate uptake was affected by variation of pH, initial concentration of phosphate and granular activated carbon dosage. The adsorption improved with increase in pH values, initial concentration and adsorbent dosage. The results of kinetic studies revealed that pseudo-second-order model adequately described the adsorption phosphate on GAC and the intra-particle diffusion involved in the adsorption mechanism. Also, isotherm study showed that Langmuir isotherm best fit the data and the adsorption was a physical type.


2016 ◽  
Vol 73 (8) ◽  
pp. 1891-1900 ◽  
Author(s):  
Ruzhen Xie ◽  
Yao Chen ◽  
Ting Cheng ◽  
Yuguo Lai ◽  
Wenju Jiang ◽  
...  

In this work, an effective adsorbent for removing phosphate from aqueous solution was developed from modifying industrial waste — lithium silica fume (LSF). The characterization of LSF before and after modification was investigated using an N2 adsorption–desorption technique (Brunauer–Emmett–Teller, BET), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Studies were conducted to investigate the effect of adsorbent dose, initial solution pH, contact time, phosphate concentration, and temperature on phosphate removal using this novel adsorbent. The specific surface area for modified LSF (LLSF) is 24.4024 m2/g, improved 69.8% compared with unmodified LSF. XRD result suggests that the lanthanum phosphate complex was formed on the surface of LLSF. The maximum phosphate adsorption capacity was 24.096 mg P/g for LLSF, and phosphate removal was favored in the pH range of 3–8. The kinetic data fitted pseudo-second-order kinetic equation, intra-particle diffusion was not the only rate controlling step. The adsorption isotherm results illustrated that the Langmuir model provided the best fit for the equilibrium data. The change in free energy (△G0), enthalpy (△H0) and entropy (△S0) revealed that the adsorption of phosphate on LLSF was spontaneous and endothermic. It was concluded that by modifying with lanthanum, LSF can be turned to be a highly efficient adsorbent in phosphate removal.


Author(s):  
Buhari Magaji ◽  
Aisha U. Maigari ◽  
Usman A. Abubakar ◽  
Mukhtar M. Sani ◽  
Amina U. Maigari

This study was aimed at using Balanite aegyptiaca seed coats activated carbon (BAAC) as a potential adsorbent to remove safranin dye from aqueous solution. BAAC was prepared from Balanite aegyptiaca seed coats using a one-step procedure with 67.27% yield, 3.23% ash content, 695 m2/g surface area and 203 mg/g iodine number. The FTIR spectroscopy revealed O-H, N-H, C-H, C=C, C-O-H stretching vibrations. The influences of agitation time, initial dye concentration and adsorbent dose were studied in batch experiments at room temperature. The adsorptions were rapid at the first 15 minutes of agitation, with the uptake of 2.746 mg/kg. The adsorption equilibrium was achieved at 90 minutes of agitation. Kinetic studies showed good correlation coefficient for both pseudo-first order and pseudo-second-order kinetics model but fitted well into pseudo-second order kinetic model. The adsorption data fitted well into Langmuir isotherm with correlation coefficient (R2) very close to unity and Langmuir maximum adsorption constant, qm  1.00. Thus, the fitting into Langmuir indicates monolayer coverage on the adsorbents. The results showed that BAAC has the potential to be applied as alternative low-cost adsorbents in the remediation of dye contamination in wastewater.


Author(s):  
Samuel Ng’ang’a Ndung’u ◽  
Esther Wanja Nthiga ◽  
Ruth Nduta Wanjau ◽  
James Ndiritu

Heavy metals contaminated water has detrimental health effects to human beings and animals not limited to hypertension, kidney damage, cancer and eventual death. Available water treatment methods have proved to not only function at high operation costs and ineffective but also yielded insignificant results to a local ordinary Kenyan citizens. The present study investigates the use of Jackfruit seeds wastes as a low cost adsorbent in adsorption water treatment technique. Raw and modified Jackfruit seeds adsorbent were applied to study kinetic studies of Cu2+, Cd2+ and Pb2+ ions adsorption from an aqueous solution under batch conditions. The adsorption behavior of the three metal ions onto raw and modified adsorbents was monitored spectrophotometrically and analysed with Pseudo-first-order and Pseudo-second-order kinetic models. Correlation coefficients (R2) confirmed that all experimental data fitted Pseudo-second-order with R2 > 0.984 which implied a chemisorption process. Experimental and calculated adsorption capacities was higher for modified adsorbent with Pb2+ ions registering higher values. The rate constants (k2) was higher in modified adsorbent than in raw adsorbent with Pb2+ ions registering highest value of rate of 4.54×10-1 (mg g-1min-1). Adsorption capacities was in the order of Pb2+ > Cu2+ > Cd2+. The results showed viability of the adsorbents for the removal of the heavy metals from waste solution in an economical and environmental friendly manner.


2012 ◽  
Vol 18 (4-1) ◽  
pp. 563-576 ◽  
Author(s):  
Dragana-Linda Mitic-Stojanovic ◽  
Danijela Bojic ◽  
Jelena Mitrovic ◽  
Tatjana Andjelkovic ◽  
Miljana Radovic ◽  
...  

The sorption of lead, cadmium and zinc ions from aqueous solution by Lagenaria vulgaris shell biosorbent (LVB) in batch system was investigated. The effect of relevant parameters such as contact time, biosorbent dosage and initial metal ions concentration was evaluated. The Pb(II), Cd(II) and Zn(II) sorption equilibrium (when 98% of initial metal ions were sorbed) was attained within 15, 20 and 25 min, respectively. The pseudo first, pseudo-second order, Chrastil?s and intra-particle diffusion models were used to describe the kinetic data. The experimental data fitted the pseudo-second order kinetic model and intra-particle diffusion model. Removal efficiency of lead(II), cadmium(II) and zinc(II) ions rapidly increased with increasing biosorbent dose from 0.5 to 8.0 g dm-3. Optimal biosorbent dose was set to 4.0 g dm-3. An increase in the initial metal concentration increases the sorption capacity. The sorption data of investigated metal ions are fitted to Langmuir, Freundlich and Temkin isotherm models. Langmuir model best fitted the equilibrium data (r2 > 0.99). Maximal sorption capacities of LVB for Pb(II), Cd(II) and Zn(II) at 25.0?0.5?C were 0.130, 0.103 and 0.098 mM g-1, respectively. The desorption experiments showed that the LVB could be reused for six cycles with a minimum loss of the initial sorption capacity.


In this study, the hydroxyapatite powder is investigated for both of methylene blue and thymol blue in aqueous solution. The physical and chemical properties of the adsorbent were evaluated systematically using the different techniques including Microsoft Excel programming, linear regression model and also the coefficient of determination. Batch adsorption experiments were conducted to determine the effect of contact time, solution pH, initial dye concentrations, and also the adsorbent dosage on adsorption. The adsorption kinetic parameters confirmed the better fitting of pseudo-second order kinetic model for both of methylene blue and thymol blue. The isotherm data of methylene blue and thymol blue could be well described by the Freundlich isotherm model which means the adsorption is multilayer adsorption with non-uniform distribution of adsorption heat and affinities over the heterogeneous surface. The maximum adsorption capacity (KF) of methylene blue and thymol blue is found to be 0.2736 (L/mg) and 11.18407 (L/mg) respectively. The high specific surface area and the porous structure with some acidic functional groups on the surface were obviously responsible for high dyes adsorption onto hydroxyapatite (HA). Adsorption kinetics data were modeled with the application of Pseudo first order, Pseudo second order and Intraparticle diffusion models. The results revealed that the Pseudo second order model was the best fitting model. Which means that, the adsorption mechanism followed two stages in which the first one was fast and the other was slower step. Which means the adsorption of dye molecules was limited by intra particle diffusion and film diffusion, as well as, the adsorption rate in both of adsorption system are depends only on the slower step.The Boyd plot exposed that the intra-particle diffusion was the rate controlling step of the adsorption process of both of methylene blue and thymol blue molecules by HA powder. However, the adsorption of methylene blue molecules (basic solution) using of HA as adsorbent particles is found to be extremely preferable than thymol blue molecules.


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