Batch versus column modes for the adsorption of radioactive metal onto rice husk waste: conditions optimization through response surface methodology (original) (raw)
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International Journal of Global Warming, 2018
In this work, the most common heavy metals such as Cu (II), Zn (II), and Pb (II) removal from aqueous leachate of industrial waste were investigated using pure and biochar rice husks. The influence of such parameters as pH, adsorbent dose (g L-1), and contact time (min) on the biosorption of rice and biochar rice was examined by using response surface methodology (RSM) based upon Box-Behnken surface statistical design at a leaching solution, Ci = 32.69 g L-1 as a fixed input parameter. The results show that both linear and squared terms of process variables are found significant on the response variable. The optimum conditions depending on both combinations and individual of all responses for the removal of Zn (II), Cu (II), and Pb (II) ions were determined using the optimising algorithm. To sum up, the use of biochar rice husk is found better than the use of pure rice husk according to statistical analysis. This study strongly indicated that pure and biochar rice husks are an influential alternative adsorbent for the removal of heavy metal ions by sorption. F. Aydın Temel et al.
Journal of Environmental Engineering and Landscape Management
Heavy metal removal from wastewater is a significant research area and recommends sustainable development. The heavy metals cause harmful health effects, increase environmental toxicity. Adsorption is a very effective method for heavy metal removal. A fixed bed for Cu(II) removal using rice hush, an agricultural waste, is reported in this paper. The study was carried out to determine the breakthrough curves with varying operating variables like influent concentration (10–30 mg/L), flow rate (10–40 ml/min), and bed height (4–10 cm) at pH 6. The variation of the process variables like influent concentration, flow rate, and bed height were investigated. The experimental data shows that adsorption capacity increases with the rise of influent concentration. The maximum value of adsorption capacity is 10.93 mg/g at a flow rate of 10 ml/min, bed height 4 cm, and influent concentration 30 mg/L. The applicability of the MLR and ANN modeling has also been successfully carried out. ANN has bet...
Environmental Science and Pollution Research, 2020
Rice and coffee husks (raw and chemically activated) are examined as potential biosorption materials regarding their capacity to remove U (total), 241 Am, and 137 Cs. The physical parameters evaluated were the morphological characteristics of the biomass, real and apparent density, and surface area. Contact times for the batch experiments were 0.5, 1, 2, and 4 h, and the concentrations tested ranged between 10% of the total concentration and the radioactive waste itself without any dilution. The results were evaluated by experimental sorption capacity, ternary isotherm, and kinetics models. The kinetics results showed that equilibrium was reached after 2 h for all biomass. Raw coffee husk showed the best adsorption results in terms of maximum capacity (q max) for all three radionuclides, which were 1.96, 39.4 × 10 −6 , and 46.6 × 10 −9 mg g −1 for U, Am, and Cs, respectively. The biosorption process for the raw and activated rice husks was best represented by the Langmuir ternary isotherm model with two sites. For the coffee husk, in the raw and activated states, the biosorption process was best described by the modified Jain and Snoeyink ternary model. These results suggest that biosorption with these biomaterials can be applied in the treatment of liquid organic radioactive waste containing mainly uranium and americium.
Chemical Engineering Journal, 2008
We prepared activated carbon by pyrolyzing an agro-waste, rice husk, in the presence of ZnCl 2 . The activated carbon displayed both microporous and mesoporous nature with a significant surface area of 180.50 m 2 · g -1 . Fourier transform infrared (FTIR) spectrograms of the activated carbon were recorded to determine the number and positions of the functional groups available on its surface. The adsorption of methylene blue (MB) from its aqueous solutions by rice husk activated carbon (RHAC) was studied. The removal of dye increased from (82.75 to 93.20) % with decreasing initial concentration of MB from (100 to 60) mg · L -1 . The time of equilibrium was found to be 100 min. Higher removal was obtained at higher dose of adsorbent, and the removal increased from (86.75 to 99.83) % with increasing adsorbent dose from (0.40 to 0.60) g. The removal of methylene blue increased from (93.20 to 99.16) % with increasing temperature from (30 to 50)°C at 60 mg · L -1 MB concentration, 150 rpm, and 100 µm particle size. Isotherm studies were conducted to know the capacity of the activated carbon. Langmuir and Freundlich isotherm equations were applied for the equilibrium data.
Investigation on adsorption kinetics of heavy metals by rice husk
Journal of the National Science Foundation of Sri Lanka, 2018
Removal of heavy metal ions and their derivative forms from the environment has become a priority to safeguard the quality of the ecosystem. In this context, the present study experiments reveal that Si available in rice husk in high percentage and many chemical functional groups present on-1 º of 100 º above metal ions and rice husk lead to the validity of pseudo initial rate of adsorption (h o) of metal ions varies in the order of particle diffusion model supports the data for rate constant of in initial adsorption rate measurements (h o).
Removal of Heavy Metals from Industrial Wastewater Using Rice Husks
The Open Environmental Engineering Journal, 2011
Heavy metals are widely used in textile industries and significant losses occur during the manufacture and processing of textiles, and these lost heavy metals are discharged in the effluent. Adsorption of heavy metals is a new technology for treatment of wastewater containing different types of selected heavy metals. In this study, adsorbents Carbonized Rice Husk (CRH) and Activated Rice Husk (ARH) made out of rice husks, available as agriculture waste, are investigated as viable materials for treatment of Pb, Cd, Cu, and Zn containing industrial wastewater at controlled pH. The results obtained from the batch experiments revealed a relative ability of the rice husk in removing some heavy metals at pH 7. One hand one, the CRH adsorption capacity decreases in the order of Cu > Pb > Zn > Cd in batch adsorption whereas during Rapid Small Scale Column Tests the adsorption capacity decrease as follow Cu> Zn> Pb> Cd. On the other hand, ARH adsorption capacity performance is similar to CRH. However, during Rapid Small Scale Column Tests the adsorption capacity decreases in the order Zn>Cu>Pb>Cd. The kinetic removal in batch experiment shows that the net uptake of Pb, Cd, Cu, Zn was 54.3%, 8.24%, 51.4% and 56.7%, respectively whereas using CRH, while it varied as 74.04%, 43.4%, 70.08% and 77.2% for the same dosages of ARH. Therefore, it is concluded that as regards to CRH, ARH demonstrated higher potential to remove relatively all selected heavy metals.
Application of response surface methodology in optimization of cadmium adsorption by raw rice husk
2010 International Conference on Environmental and Agriculture Engineering, ICEAE 2010, 2010
This study was aimed to model and optimize the adsorption process of cadmium from aqueous solution onto raw rice husk (RRH). The batch experiment was carried out in four factors as a function of pH (A: 5 - 9), adsorbent dosage (B: 2 - 8 g/100 ml), contact time (C: 60 - 240 minutes) and initial concentration of adsorbate (D: 70 - 110 mg/L) to response (percentage of cadmium removal). Response surface methodology (RSM) was used to analyzed and optimize the effect of four factors in cadmium adsorption. The result showed that RRH can successfully reduce cadmium from aqueous solution in removal percentage from 79.45% to 97.978%. Value of pH, dosage, contact time and initial concentration was noted significant statistically. RSM was undoubtedly used to optimize the adsorption process where the optimum condition achieved at pH 9, dosage 5 g/100 ml, contact time 240 minutes and initial cadmium concentration 90 mg/L. © 2010 IEEE. ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5560385
BioResources
Uranium adsorption was evaluated on rice straw-based carbon (RSK carbon) that had been KOH-oxidized and impregnated with ionic-liquid. Experiments were performed in fixed bed mode using 100 mg/L uranium solution at 3 different bed depths (12, 6, and 3 cm). Uranium adsorption decreased with increasing bed depth. Agreement between column and batch values was judged to be acceptable in light of inherent differences in continuous versus batch operations. Batch mode reaches equilibrium without continuous solution feeding. However, the solution in fixed bed mode was fed constantly without equilibrium. The bed depth service time (BDST) model was used to investigate uranium adsorption. BDST plots were linear, with a high correlation coefficient (R > 0.97), representing its validity when used for fixed bed of RSK carbon. The failure of the 50% breakthrough BDST curve to pass through the origin point may be due to the complex mechanism of uranium removal by RSK carbon. The calculated BDST slopes were in good agreement with the experimental values, while the values of their intercept slightly varied within certain limit of experimental error. These results support the validity of BDST model for designing a fixed bed column for uranium adsorption onto RSK carbon.
Agricultural waste has been explored as a productive adsorbent for efficient metal removal due to their lower cost. The presence of various chemical functional groups in agricultural wastes especially phenolic, amino, carbonyl, alcoholic and sulfhydryl group etc. facilitates the removal of heavy metals as they tend to form metal complexes or chelates by reacting with them. Biosorption is a process of removing metal ions using biological agents and it includes processes like chemisorption, complexation, adsorption on the surface, diffusion through pores and ion exchange etc. To enhance the adsorption ability of these adsorbents, chemical modification is required. Specific chemicals such as mineral and organic acids, bases, oxidising agents or polymeric acids are used for modification of adsorbents. The purpose of this article is to show the removal efficiency of rice husk based hydrogel as a bio-adsorbent to remove Cr ions. Characterisation of the bio-adsorbent is done using FTIR and SEM before and after adsorption in order to explore number and position of the functional groups present on the adsorbent surface for Cr(VI) binding and changes in adsorbent surface morphology.