scholarly journals OPTIMIZATION OF EDTA ENHANCED SOIL WASHING ON MULTIPLE HEAVY METALS REMOVAL USING RESPONSE SURFACE METHODOLOGY

2018 ◽  
Vol 26 (4) ◽  
pp. 241-250 ◽  
Author(s):  
Liwei He ◽  
Bin Li ◽  
Ping Ning ◽  
Xiao Gong

This research presents the optimization of soil washing conditions in the removal of multiple heavy metals (Cu-Pb-Zn-Cd) under the using of ethylenediaminetetraacetic acid (EDTA). The optimum combination of washing parameters in a bench-scale soil washing experiments is determined by response surface methodology (RSM). Central composite design is applied after single factor experiment, EDTA concentration, solid-to-liquid ratio and washing time are evaluated variables for the removal processes, and the regression models of HMs are constructed. The results show that, EDTA concentration and solid-to-liquid ratio are significant factors for this process. Subsequently, 50% of Cu removal was set as the optimum target to optimize the combined conditions, through the building of multiple quadratic regression models, the optimal condition combination is determined that EDTA concentration is 0.0026 mol·L-1, solid-to-liquid ratio is 1:22, washing time is 3.89 h, the extraction rate of Pb, Zn, Cd is predicted to be 78%, 75% and 71%, respectively.

2020 ◽  
Vol 31 ◽  
pp. 43-47 ◽  
Author(s):  
Mohd Farhan Tajuddin ◽  
Adel Al-Gheethi ◽  
Radin Mohamed ◽  
Efaq Noman ◽  
Balkis A. Talip ◽  
...  

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
N. Sultana ◽  
S. M. Zakir Hossain ◽  
M. Ezzudin Mohammed ◽  
M. F. Irfan ◽  
B. Haq ◽  
...  

Abstract This study investigates the use of microalgae as a biosorbent to eliminate heavy metals ions from wastewater. The Chlorella kessleri microalgae species was employed to biosorb heavy metals from synthetic wastewater specimens. FTIR, and SEM/XRD analyses were utilized to characterize the microalgal biomass (the adsorbent). The experiments were conducted with several process parameters, including initial solution pH, temperature, and microalgae biomass dose. In order to secure the best experimental conditions, the optimum parameters were estimated using an integrated response surface methodology (RSM), desirability function (DF), and crow search algorithm (CSA) modeling approach. A maximum lead(II) removal efficiency of 99.54% was identified by the RSM–DF platform with the following optimal set of parameters: pH of 6.34, temperature of 27.71 °C, and biomass dosage of 1.5 g L−1. The hybrid RSM–CSA approach provided a globally optimal solution that was similar to the results obtained by the RSM–DF approach. The consistency of the model-predicted optimum conditions was confirmed by conducting experiments under those conditions. It was found that the experimental removal efficiency (97.1%) under optimum conditions was very close (less than a 5% error) to the model-predicted value. The lead(II) biosorption process was better demonstrated by the pseudo-second order kinetic model. Finally, simultaneous removal of metals from wastewater samples containing a mixture of multiple heavy metals was investigated. The removal efficiency of each heavy metal was found to be in the following order: Pb(II) > Co(II) > Cu(II) > Cd(II) > Cr(II).


2016 ◽  
Vol 19 (0) ◽  
Author(s):  
Ricardo Schmitz Ongaratto ◽  
Luiz Antonio Viotto

Summary The aim of this work was to separately evaluate the effects of pectinase and cellulase on the viscosity of pitanga juice, and determine the optimum conditions for their use employing response surface methodology. The independent variables were pectinase concentration (0-2.0 mg.g–1) and cellulase concentration (0-1.0 mg.g–1), activity time (10-110 min) and incubation temperature (23.2-56.8 °C). The use of pectinase and cellulase reduced the viscosity by about 15% and 25%, respectively. The results showed that enzyme concentration was the most important factor followed by activity time, and for the application of cellulase the incubation temperature had a significant effect too. The regression models showed correlation coefficients (R2) near to 0.90. The pectinase application conditions that led to the lowest viscosity were: concentration of 1.7 mg.g–1, incubation temperature of 37.6 °C and incubation time of 80 minutes, while for cellulase the values were: concentration of 1.0 mg.g-1, temperature range of 25 °C to 35 °C and incubation time of 110 minutes.


2016 ◽  
Vol 81 (8) ◽  
pp. 947-958 ◽  
Author(s):  
Zlate Velickovic ◽  
Negovan Ivankovic ◽  
Vanja Strikovic ◽  
Radovan Karkalic ◽  
Dalibor Jovanovic ◽  
...  

The aim of this study was to determine soil properties influence on the heavy metals sorption by vegetables which are used in the diet and possibilities for prediction of their bioaccumulation by response surface methodology (RSM). Lettuce was used as biosorbent, and cadmium (Cd) and lead (Pb) were used as contaminants. Lettuce is grown on compost (previously contaminated with different concentrations of Cd and Pb) which pH was adjusted with different amounts of NPK fertilizers. The content of heavy metals was determined by ICP-MS. Results showed that Cd content in lettuce was below the toxic values, but Pb concentration was above allowable, which indicates that limit value for Pb is not set in accordance with the food safety regulations. It was found that the heavy metals accumulation in plants depends not only on its content in the soil, but also on the plant affinity to the specific metal, and the individual or the interactive effects of different soil properties. Through the transfer factor it was found that lettuce has a much higher affinity to Cd in relation to Pb. RSM has proved to be very good for the examination of a large number of variables with a small number of experiments.


Author(s):  
Garba Uba ◽  
Motharasan Manogaran ◽  
Baskaran Gunasekaran ◽  
Mohd Izuan Effendi Halmi ◽  
Mohd Yunus Abd Shukor

Heavy metals pollution in the Straits of Malacca warrants the development of rapid, simple and sensitive assays. Enzyme-based assays are excellent preliminary screening tool with near real-time potential. The heavy-metal assay based on the protease ficin was optimized for mercury detection using Response Surface Methodology. The inhibitive assay is based on ficin action on the substrate casein and residual casein is determined using the Coomassie dye-binding assay. Heavy metals strongly inhibit the hydrolysis. A Central Composite Design (CCD) was utilized to optimize detection. The results show a marked improvement for the concentration causing 50% inhibition (IC50) for mercury, silver and copper. Compared to One-factor-at-a-time (OFAT) optimization, RSM gave an improvement of IC50 from 0.060 (95% CI, 0.0300.080) to 0.017 (95% CI, 0.0160.019), from 0.098 (95% CI, 0.0770.127) to 0.028 (95% CI, 0.0220.037) and from 0.040 (95% CI, 0.035.045) to 0.023 (95% CI, 0.0200.027), for mercury, silver and copper, respectively. A near real-time monitoring of mercury concentration in the Straits of Malacca at one location in Port Klang was carried out over a 4-h interval for a total of 24 h and validated by instrumental analysis with the result revealing an absence of mercury pollution in the sampling site.


2014 ◽  
Vol 955-959 ◽  
pp. 1466-1470 ◽  
Author(s):  
Dan Liu ◽  
Fang Yu ◽  
Wei Tan ◽  
Gui Zhen Li ◽  
Min Yang ◽  
...  

Response surface methodology based on single factors was used to optimize the process condition for extraction of nitrite nitrogen in sediment . The results indicated that the extraction amount of nitrite nitrogen was 9.5μg /g under the optimum condition of extraction time of 44min, ultrasonic power of 280W, solid-liquid ratio of 1:19,which was closed to the predicated yield of 9.3μg/g. The process can be used for the extraction of nitrite nitrogen in sediments.


2012 ◽  
Vol 161 ◽  
pp. 82-87 ◽  
Author(s):  
Yuan Heng Guo ◽  
Hua Zheng ◽  
Hong Zhang ◽  
Li Yi Ma ◽  
Juan Han ◽  
...  

For more efficient and economical extraction of cochineal dye, combined microwave-ultrasonic wave extraction was applied. It was approached 4 factors as microwave power, treated time, materials-to-liquid ratio and ultrasonic wave power. Results showed that the optimal condition individually for cochineal dye extraction was at 400W microwave power, 17min treated time, 1:8 materials-to-liquid ratio and 600W ultrasonic wave power. On the basis of single factor test, RSM optimization of the extraction was achieved at 464W microwave power, 18.48min treated time, 1:8.23 materials-to-liquid ratio and 627W ultrasonic wave power. The verification was very approximate to the predicted value from the modelling regression equation. And the best extraction grade was tesified as 4 times.


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