Calcined Biomass-Modified Bentonite Clay for Removal of Aqueous Metal Ions (original) (raw)
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Preparation and characterization of adsorbents derived from bentonite and kaolin clays
Applied Water Science
The comparative study on preparation and characterization of modified bentonite and kaolin clay types is aimed at establishment of the ability of these clay types to adsorb pollutants. Its low cost, availability and recovery of clay give it added advantage of an effective adsorbent. The modified clay types were prepared by impregnation using various concentrations of either H 2 SO 4 or NaOH in w/v ratio of 1:2. The physicochemical and adsorptive properties were investigated using standard physicochemical methods like moisture content, bulk density, pH, iodine and methylene blue numbers. FTIR, XRD and SEM analyses were also conducted on these clay types. Unmodified kaolin clay exhibited lowest moisture content (1.12%) while unmodified bentonite clay type had highest value (3.98%). The peaks at 3435 cm −1 and 3410 cm −1 assigned N-H stretching frequency were obtained for 2 M H 2 SO 4 modified and unmodified bentonite clay types, respectively. The peaks at 912 cm −1 and 914 cm −1 that indicate the presence of Al-Al-OH deformation frequency were obtained for unmodified bentonite clay type and 2 M H 2 SO 4 modified bentonite clay, respectively. The physical surface morphology of the clay types revealed the presence of pores with irregular shapes, while their XRD analysis showed that the clay types are crystalline. The modified clay types exhibited better potential adsorbent for removal of small metallic or gas molecules as well as large organic molecules. Adsorbents could also remove cations or anions of pollutants since their surface charge could be positive or negative depending upon pH condition.
2020
This review dealt with environmental pollution with a number of pollutants, especially pollution with heavy elements, and because of its significant effects on the environment in general and on humans in particular, despite its presence in low quantities. How to treat it in several ways, but the most effective and least economical is adsorption technology considering that heavy elements are adsorbed materials used Bentonite clay as the adsorbent surface to remove it from aqueous solutions. Several studies also dealt with the possibility of improving the adsorption properties of bentonite clay by modifying and activating it with several experimental materials and conditions. Also, they discussed the possibility of applying the most famous kinetic models and isotherms models in addition to calculating thermodynamic functions for adsorption of heavy elements on bentonite or modified bentonite clay
Surface modification of low-cost bentonite adsorbents—A review
Particulate Science and Technology, 2018
The growth of science and technology over the world has led to the establishment of various industries which has helped the industrial, technological, and agricultural development of many nations. Environmental pollution from a variety of toxic derivatives, particularly heavy metals and minerals, aromatic molecules and dyes in wastewater posed a great danger to human, plants, and aquatic creatures. Adsorption appears to be the most widely used method among other techniques for the removal of toxic compounds from wastewater. The use of different adsorbents for heavy metal removal has become a subject of great interest, and there have been continuous efforts to develop new, low-cost, and efficient adsorbent materials. Bentonite, in natural and modified forms, has been applied in the removal of different water contaminants. This paper provides a review on recent progress of surface modifications of bentonite and their applications in the removal of organic and inorganic water pollutants. A comparison on the physicochemical characteristics and removal performance was presented. The adsorption mechanisms in relation to the bentonite properties were briefly discussed to offer readers some insight on the usefulness of this clay mineral in wastewater treatment. The challenges encountered and remarks on future prospects were highlighted.
Vandana Publications, 2020
The effect of the initial concentration of Cr, Co, Cu, Ni, and Pb metal ions from multicomponent solutions on the sorption capacity of natural and acid activated bentonite was examined in this paper. The acid activation was performed by using hydrochloric and sulfuric acid at different concentrations. The results of adsorption research have shown that bentonite can be effectively used as an adsorbent for the removal of metal ions from multicomponent solutions. Acid activation of bentonite changes the structure and content of individual oxides, increases the porosity and the number of available spots for the adsorption process. For this reason, the bentonite removal efficiency increased after acid activation for all heavy metals tested. With increased acid concentration, the degree of bentonite adsorption increased, and sulfuric acid rather than chloric acid showed better results in removal efficiency.
Organic modification of mineral clay using the monomer ethenyl acetate was performed. The exchange of inorganic interlayer clay cations was achieved using the cationic surfactant Genamine CTAC and Asepsol. Aiming to investigate the influence of organic modifications on adsorptive clay properties, dried composites of clay/ethenyl acetate, with different percentages of clay were soaked in distilled water. The influence of the temperature on the adsorptive properties of organoclays was also followed. The adsorptive properties of the obtained composites of organoclays with Luviskol, Carbopole and purine were investigated along with their capability for removing Pb 2+ from water in charged systems.
Equilibrium, kinetic and thermodynamic aspects of the adsorption of copper ions from an aqueous solution using linear alkylbenzene sulfonate (LABORA-TORIES) modified bentonite (organo-bentonite) are reported. Modification of bentonite was performed via microwave heating with a concentration of LABORA-TORIES surfactant equivalent to 1.5 times that of the cation exchange capacity (CEC) of the raw bentonite. Experimental parameters affecting the adsorption process such as pH, contact time and temperature were studied. Several adsorption equations (e.g., Langmuir, Freundlich, Sips and Toth) with temperature dependency were used to correlate the equilibrium data. These models were evaluated based on the theoretical justifications of each isotherm parameter. The Sips model had the best fit for the adsorption of copper ions onto organo-bentonite. For the kinetic data, the pseudo-second order model was superior to the pseudo-first order model. Thermodynamically, the adsorption of copper ions occurs via chemisorption and the process is endothermic (ΔH 0 >0), irreversible (ΔS 0 >0) and nonspontaneous (ΔG 0 >0).
Pamukkale University Journal of Engineering Sciences, 2020
In the present study, natural bentonite and acid-thermal co-modified bentonite were utilized for Acid Blue 25 (AB25) removal. The adsorption experiments were executed at the temperature values of 298K, 308K and 318K. According to the results, Freundlich isotherm becomes more convenient model compared with Langmuir and Temkin model. Freundlich model coefficients rise when the temperature increases. Kinetic coefficients were calculated by pseudo first order (PFO) and pseudo second order (PSO) models. Coefficients of R 2 evaluated were higher than 0.99 with experimental and obtained qe values close to each other explained that this process fits PSO kinetic model. The concentration of AB25 elevates from 30 to 80 mg/L adsorption capacity onto natural, acid-thermal co-modified bentonite increases from 8.36 to 27.00 mg/g and 9.30 to 29.09 mg/g for 298 K, respectively. Absolute values of free energy of AB25 onto natural and acid-thermal co-modified bentonite changes from 4.065 kJ/mol to 8.586 kJ/mol, respectively. Enthalpy values of AB25 onto natural and acid-thermal comodified bentonite changes from 5.483 kJ/mol to 11.249 kJ/mol and entropy values of AB25 on natural and acid-thermal co-modified bentonite changes from 4.759 J/mol K to 8.940 J/mol K, respectively. It was also found that modified bentonite has higher adsorption capacity than natural bentonite. Bu çalışmada, Asit Blue 25 (AB25) giderimi için doğal bentonit ve asittermal modifiye edilmiş bentonit kullanıldı. Adsorpsiyon deneyleri 298K, 308K ve 318K sıcaklık değerlerinde gerçekleştirildi. Sonuçlara göre Freundlich izotermi, Langmuir ve Temkin modeline göre daha uygun bir model haline geldi. Freundlich model katsayıları sıcaklık arttıkça yükseldiği görüldü. Kinetik katsayılar yalancı birinci derece (PFO) ve yalancı ikinci derece (PSO) modelleri ile hesaplandı. Değerlendirilen R 2 katsayıları 0.99'dan yüksekti ve birbirine yakın deneysel ve elde edilen qe değerleri bu sürecin PSO kinetik modeline uyduğu açıklandı. 30 ve 80 mg/L başlangıç konsantrasyonun, doğal, asit-termal modifiye edilmiş bentonit ile adsorpsiyon kapasitesinin 298 K için sırasıyla 8.36'dan 27.00 mg/g'ye ve 9.30'dan 29.09 mg/g'ye yükseldiği gözlendi. AB25'in serbest enerjisinin doğal ve asit-termal modifiye edilmiş bentonite karşı mutlak değerleri, sırasıyla 4.065 kJ/mol'den 8.586 kJ/mol'e değiştiği belirlendi. AB25'in doğal ve asit-termal modifiye edilmiş bentonit üzerindeki entalpi değerleri 5.483 kJ/mol'den 11.249 kJ/mol'e ve AB25'in doğal ve asit-termal modifiye edilmiş bentonit üzerindeki entropi değerleri 4.759 J/mol K'den 8.940 J/mol K.'ye değiştiği görüldü. Modifiye edilmiş bentonitin, doğal bentonitten daha yüksek adsorpsiyon kapasitesine sahip olduğu belirlendi.
Environmental Processes, 2020
An inexpensive and easily obtainable Egyptian bentonite was applied for the elimination of metals from aqueous solution. A simple solvothermal technique was utilized to formulate nano-bentonite to keep the method cost low. The capability of nano-bentonite particles as adsorbents to remove copper, nickel and manganese ions was scrutinized under numerous conditions in batch methods. The metal ions adsorption was reliant on initial sorbent concentration, pH, contact time and adsorbent dosage. Batch experimentations were conducted at 30°C and 300 rpm. The results showed that pH 9 for Cu 2+ and pH 7 for Mn 2+ and Ni 2+ ions were the most appropriate values, whereas the maximum adsorbent capacity was at a dosage of 0.075 g, recording sorption efficiencies of 99%, 42.18%, and 17.82% for copper, nickel, and manganese, respectively. The percent metal removal approached equilibrium within 30 min for all examined metals, with cupper recording 99%, nickel 49.92% and manganese 21.31% removal, having a trend of Cu 2+ > Ni 2+ > Mn 2+. Experimental isotherm records were analyzed by Langmuir and Freundlich models. Langmuir model showed higher R 2 values of 0.97, 0.83 and 0.98 for copper, nickel and manganese, respectively, which fitted the equilibrium adsorption process better than the Freundlich model (R 2 = 0.97, 0.65, and 0.98 for Cu 2+ , Ni 2+ and Mn 2+ ions, respectively). The monolayer adsorption capacity was 35.46 mg g −1 , 9.91 mg g −1 and 9.99 mg g −1 for Cu 2+ , Mn 2+ and Ni 2+ ions, respectively. The kinetic records for the adsorption process conformed with pseudo-second-order rate equations. The study suggests that nanobentonite can be efficiently used as an inexpensive material for metal ions elimination. Keywords Nano-bentonite. Metals. Wastewater. Adsorption. Kinetics. Isotherms contaminants, such as fertilizers, pesticides, sludge and wastewaters (Gu et al. 2019). A high degree of industrial development and suburbanization has resulted to an enormous degradation of aquatic environments through the discharge of industrial and domestic wastes. This has resulted in huge quantity of metals being deposited into aquatic and terrestrial ecosystems. It has also increased the biological cycling of toxic metals. In this context, there is an urgent need for elimination of metal contaminants (Nilanjana et al. 2008). Numerous methods have been proposed to eliminate toxic metals from water. These embrace ion exchange, chemical precipitation, adsorption and reverse osmosis (Jain and Sharma 2002). The adsorption procedure was found to be better compared to the other techniques for removal of metals, regarding its cost, flexibility, simplicity of design, ease of use, insensitivity to toxic contaminants and enhanced elimination efficiency (Amer et al. 2010). Moreover, it is highly recommended that the adsorbents utilized in the adsorption process can be used repetitively after some of the applied processes (Pan et al. 2009; Zhao et al. 2011). The adsorption procedure is leading in removal of metals from water/wastewater comparatively to other methods because of these advantages (Hua et al. 2012). Bentonite is a natural and low-cost clay (Al-Farhan 2016). It has a small particle size and porous structure with a great specific surface area, and has great efficacy for adsorption and cation exchange capacity (Rafati et al. 2016; Uddin 2017). The industrial and environmental use of bentonite has currently displayed an increased attention. Bentonite clay has been efficient in the elimination of numerous hazardous metal ions from solutions (
Removal of Pb(II), Cd(II), Cu(II), and Zn(II) from Aqueous Solutions by Adsorption on Bentonite
Journal of Colloid and Interface Science, 1997
tion. It is an inexpensive clay mineral readily available in Removal of Pb(II), Cd(II), Zn(II), and Cu(II) from aqueous Turkey. It has been extensively used in drilling processes, solutions using the adsorption process on bentonite has been invesbut few scientists have used clay minerals in water and waste tigated. In order to find out the effect of temperature on adsorpwater pollution control (7-9). In the present study, removal tion, the experiments were conducted at 20, 35, and 50ЊC. For all of Pb(II), Cd(II), Cu(II), and Zn(II) from aqueous soluthe metals, maximum adsorption was observed at 20ЊC. The rate tion by adsorption was investigated. Adsorption isotherms of attaining equilibrium of adsorption of metal ions follows the and thermodynamic parameters of the adsorption are also order Zn(II) ú Cu(II) ú Cd(II) ú Pb(II). Equilibrium modeling presented. of the adsorption showed that adsorption of Pb(II), Cd(II), and Cu(II) were fitted to a Langmuir isotherm, while the adsorption of Zn(II) was fitted to a Freundlich isotherm. Dynamic modeling EXPERIMENTAL of the adsorption showed that the first order reversible kinetic model was held for the adsorption process. The overall rate con-Bentonite, used as an adsorbent in this study, was obtained stant k, the adsorption rate constant k 1 , the desorption rate confrom MTA, Ankara, Turkey. It was dried at 110ЊC for 2 h stant k 2 , and the equilibrium constant K e for the adsorption proand used as received after sieving through a 200 mm sieve. cess were calculated. From the results of the thermodynamic anal-The chemical composition of bentonite was done according ysis, standard free energy DG 0 , standard enthalpy DH 0 , and to the methods described in literature (10). The results of standard entropy DS 0 of the adsorption process were calculated. the experiments are given in Table 1.
Separation Science and Technology, 2019
The removal of Pb 2+ , Ni 2+ , Cd 2+ , Zn 2+ , Cu 2+ , and UO 2 2+ ions from wet phosphoric acid were employed to gain the purified acid by the low-cost adsorbent that prepared by activation of natural bentonite followed by impregnation with Alizarin. The adsorbent was characterized by X-ray diffraction, scanning electron microscopyenergy dispersive X-ray spectroscopy, and Fourier transforms infrared spectroscopy techniques. The adsorption experiments were applied for the removal of studied metals ions from phosphoric acid. The best conditions for H 3 PO 4 are 5 M/L H 3 PO 4 concentrations (29% P 2 O 5), 150 mg.L −1 initial concentrations of each metal ions, and 50 mg Alizarin impregnated activated bentonite dose for 60 min contact time at room temperature. Whereas the optimum removal conditions of the studied metals ions from wet phosphoric acid (29% P 2 O 5) were 60 min contact time, 150 mg adsorbent amount, and 50 mL acid volume at room temperature. The adsorption-desorption procedures were repeated by several times, till the desorption efficiencies were reduced from 98.5 to 83.0% for Alizarin impregnated activated bentonite after five successive cycles, it was indicated that the excellent adsorption stability for removal of Pb 2+ , Ni 2+ , Cd 2+ , Zn 2+ , Cu 2+ , and UO 2 2+ on the studied adsorbent.