March 2014247 Chem. Pharm. Bull. 62(3) 247–253 (2014) Regular Article
A Study on the Adsorption of Heavy Metals by Using Raw Wheat Bran Bioadsorbent in Aqueous Solution Phase Fumihiko Ogata, Moe Kangawa, Yuka Iwata, Ayaka Ueda, Yuko Tanaka, and Naohito Kawasaki* Faculty of Pharmacy, Kinki University; 3–4–1 Kowakae, Higashi-Osaka, Osaka 577–8502, Japan. Received September 6, 2013; accepted December 25, 2013 Raw wheat bran (R-WB) was used as a biomass adsorbent. The properties of R-WB were investigated. Moreover, the adsorption of cadmium and lead ions onto R-WB was evaluated. Adsorption equilibrium of cadmium and lead ions onto R-WB was achieved within 10 h, indicating that the adsorption followed a pseudo-second-order model rather than a pseudo-first-order kinetic model. The adsorption amount increased with increasing temperature. Correlation coefficient of the Langmuir equation is 0.999 for cadmium and 0.996 for lead ions, and that of the Freundlich equation is 0.994 for cadmium and 0.993 for lead ions. The negative ΔG value implied that the adsorption of cadmium and lead ions onto R-WB is a spontaneous process. The positive ΔS value indicated an increase in randomness at the solid–liquid interface. The optimal conditions for the adsorption column experiment were investigated (space velocity (SV) 2.2 1/h, linear velocity (LV) 0.1 m/h for cadmium; SV 6.51 1/h, LV 0.23 m/h for lead ions). Further, repeated adsorption–desorption of the cadmium and lead ions could be effected by using 0.01 mol/L HCl or 0.01 mol/L HNO3 solution. Consequently, polluted water could be successfully purified by using a column filled with this bioadsorbent. Key words
wheat bran; biomass; adsorption; cadmium; lead
Heavy metal ions are often found in the environment owing to their widespread industrial use. Their ions are common contaminants in wastewater, and many of these are known to be toxic or carcinogenic.1) Heavy metal pollution has become one of the most important causes of environmental and health problems, and hence, attempts have been made to reduce their emission to or removal from the environment.2) Heavy metal ions such as cadmium and lead ions are toxic even at low concentrations.3) One of the most severe forms of chronic cadmium toxicity in human is itai-itai, a disease that is characterized by excruciating pain in the bones.4) Other health implications of cadmium in humans include renal failure, hepatic damage, and hypertension.5) Lead ions form complexes with the oxo-groups in enzymes and affect virtually all the steps involved in hemoglobin synthesis and porphyrin metabolism, thus acting as a heavy metal poison.6) Toxic levels of lead in humans have been associated with encephalopathy, seizures, and mental retardation.7) A variety of techniques such as chemical coagulation, extraction, ion exchange, membrane separation, and electrochemical techniques have been applied for the removal of heavy metal ions from wastewater. However, these techniques are cumbersome and require the use of expensive chemicals.8,9) Therefore, new techniques for removing heavy metals from wastewater are needed. Wheat is the most widely cultivated cereal in the world. Wheat bran, the inedible portion of wheat grain and classified as plant biomass, is generated during the milling process. While a part of the generated wheat bran is used as mash for cattle feed, a notable amount is wasted. Therefore, it is necessary to devise a method for the effective use of the residual wheat bran. The use of wheat bran to remove heavy metals from wastewater would be instrumental in the reduction of environmental load, purification of wastewater, and recycling of biomass. In recent years, biosorption using natural materials has emerged as a cost-effective and efficient alternative for the removal of heavy metals from wastewaters containing them The authors declare no conflict of interest.
in low concentrations.10) This novel approach is competitive, effective, cheap, scalable, and environment-friendly. In addition, bioadsorbents can eliminate heavy metal ions effectively from complex solutions containing a very low concentration of dissolved heavy metals. Agricultural by-products such as peat, wood, pine bark, banana pith, soybean and cottonseed hulls, peanut shells, hazelnut shells, rice husk, sawdust, wool, orange peel, and compost and leaves have been studied for use in heavy metal removal from water bodies.11–17) The main objective of this work was to develop a method based on the use of wheat bran as a potential bioadsorbent for the removal and determination of cadmium and/or lead ions in polluted aqueous solutions. The effects of contact time, pH of the aqueous solution, and other parameters on the efficiency of heavy metal ion removal were also investigated. Finally, the adsorption isotherms, breakthrough curves, visual bacterial counts, and mechanism of adsorption were investigated.
Experimental
Materials Raw wheat bran (R-WB) was purchased from Nisshin Pharma Inc., Tokyo, Japan. Standard cadmium (Cd(NO3)2) and lead ion (Pb(NO3)2) solutions (Wako Pure Chemical Industries, Ltd., Osaka, Japan) were used as the adsorbate. The properties of R-WB were measured by the following methods. The carbon, hydrogen, and nitrogen contents were measured by a MICRO CORDER JM-10 instrument (JSCIENCE GROUP). The specific surface area was measured by using a specific surface analyzer, NOVA4200e (Yuasa Ionics, Japan), based on nitrogen adsorption isotherms. The pH of the aqueous solutions after the addition of R-WB was measured by an activated carbon test method (JIS K 1474). The surface functional groups of R-WB were determined by using the following method.18) R-WB (0.1 g) was mixed with a 20 mL solution of 0.05 mol/L NaHCO3. (Same procedure was carried out using 0.05 mol/L Na2CO3, NaOH, and HCl, respectively.) The suspension was shaken at 100 rpm for 24 h at 25°C. The excess base or acid in 5 mL of the filtrate ob-
© 2014 The Pharmaceutical Society of Japan * To whom correspondence should be addressed. e-mail:
[email protected]
248
Vol. 62, No. 3
tained through a 0.45-µm membrane filter was titrated against 0.01 mol/L HCl or NaOH. Surface acidity or basicity was calculated on the basis of the assumption that NaHCO3 neutralizes only the carboxyl groups, Na2CO3 neutralizes only the carboxyl and lactone groups, NaOH neutralizes all the acidic groups, including carboxyl, lactone, and phenolic groups, and HCl neutralizes all the basic groups. Special-grade NaHCO3, Na2CO3, NaOH, and HCl were used (Wako Pure Chemical Industries, Ltd.). The number of acidic or basic groups on the surface is calculated from the following formula:
the number of acidic or basic groups on the surface = (0.05×V1 − 0.01×V2 ) / W
(1)
where V1 is the volume of NaHCO3, Na2CO3, NaOH, and HCl (mL), V2 is the volume of HCl or NaOH (mL), and W (g) is the weight of R-WB. Contact Time for Adsorption of Cadmium and Lead Ions by R-WB R-WB (0.05 g) was added to a 50 mL of the cadmium or lead ion solution (initial concentration of the cadmium or lead ions was 1000 µg/L and the solution pH was acidic). The suspensions were shaken at 100 rpm for 5 min to 48 h at 25°C. The sample was filtrated through a 0.45-µm membrane filter, and the filtrate was measured by an inductively coupled plasma-atomic emission spectrometer (ICP-AES, Shimadzu). The amount of cadmium and lead ions adsorbed was calculated by using Eq. 2: X = (C0 − Ce )V / M
(2)
where X is the amount adsorbed (µg/g), C0 is the concentration before the adsorption (µg/L), Ce is the concentration after the adsorption (µg/L), V is the volume of the solvent (L), and M is the mass of the adsorbent (g). The data are presented as means±S.E. of 3 experiments. We confirmed that the penetration did not affect to the interpretation from the results obtained in this study. Adsorption Isotherms of Cadmium and Lead Ions onto R-WB R-WB (0.05 g) was added to a 50 mL solution of cadmium and lead ions (initial concentration of the cadmium or lead ions was 10 µmol/L and the solution pH was acidic). The suspensions were shaken at 100 rpm for 24 h at 5, 25, and 45°C. The sample was filtrated through a 0.45-µm membrane filter, and the filtrate was measured by ICP-AES. The amount of cadmium and lead ions adsorbed was calculated by using Eq. 2. The data are presented as means±S.E. of 3 experiments. We confirmed that the penetration did not affect to the interpretation from the results obtained in this study. Breakthrough Curves of Cadmium and Lead Ions Determined Using a Column Packed with R-WB The amount of cadmium and lead ions adsorbed onto R-WB in a column (diameter×height: 1.0 cm×10.0 cm) was measured as follows. R-WB (1.2 g) was added to a level of 3.5 cm above the base of the column. The approximate conditions for the column experiment were as follows: initial concentration of cadmium and lead ions, 1000 µg/L; space velocity (SV), 4.43 1/h; linear velocity (LV), 0.15 m/h; flow rate, 0.2 mL/min (Condition 1-Cd), SV, 2.17 1/h; LV, 0.08 m/h; flow rate 0.1 mL/min (Condition 2-Cd). SV, 10.86 1/h; LV, 0.38 m/h; flow rate, 0.5 mL/ min (Condition 1-Pb), SV 6.51 1/h; LV, 0.23 m/h; flow rate,
0.3 mL/min (Condition 2-Pb). The amount of ions adsorbed was calculated by subtracting the column effluent concentration from the initial concentration. Adsorption–Desorption Capability of Cadmium and Lead Ions by R-WB R-WB (0.1 g) was added to a 100 mL solution of cadmium (initial concentration is 30 mg/L and the solution pH was acidic) and lead ion (initial concentration is 35 mg/L and the solution pH was acidic). The suspensions were shaken at 100 rpm for 24 h at 25°C. Subsequently, the suspensions were filtrated through a 0.45 µm membrane filter, and the sample solution was measured by ICP-AES. The amount of cadmium and lead ions adsorbed was calculated by using Eq. 2. The adsorbent after the adsorption was collected, dried, and then used for the desorption experiment. The collected adsorbent was added to a 100 mL solution of 0.01 mol/L HCl or 0.01 mol/L HNO3. The suspensions were shaken at 100 rpm for 24 h at 25°C. Then, the suspensions were filtrated through a 0.45-µm membrane filter, and the sample solution was measured by ICP-AES. The amount of desorbed ions was calculated by using Eq. 3. X = CeV / M
(3)
where X is the amount desorbed (µg/g), Ce is the concentration after the desorption (µg/L), V is the solvent volume (L), and M is the mass of the adsorbent (g). The data are presented as means±S.E. of 3 experiments. We confirmed that the penetration did not affect to the interpretation from the results obtained in this study. Measurement of Number of General Bacteria R-WB (0.5 g) was added to a 500 mL of sample solution (distilled water, cadmium, and lead ion solutions). The suspensions were shaken at 100 rpm in room temperature, and then, a sample solution (1 mL) was collected with elapsed time. The solution was filtrated through a 0.45-µm membrane filter, and then, the sample solution was added to an AC plate (Sumitomo 3M Limited). The plate was incubated at 35°C for 48 h, following which the bacterial counts were measured.
Results and Discussion
Properties of R-WB The carbon, hydrogen, and nitrogen contents of the R-WB were 42.31%, 5.45%, and 3.00%, respectively. The specific surface area of R-WB and pH of the aqueous solution were 3.25 m 2/g and 6.94, respectively. Moreover, the total basic and acidic functional groups in R-WB were 0.24 mmol/g and 4.65 mmol/g, respectively. The concentrations of phenolic, lactone, and carboxyl groups in R-WB were 0.00, 1.09, and 3.56 mmol/g, respectively. Effect of Contact Time for Adsorption of Cadmium and Lead Ions onto R-WB The adsorption rate of cadmium and lead ions onto R-WB in a single solution system is shown in Fig. 1. For both lead and cadmium ions, adsorption equilibrium was achieved within 10 h. The amounts of cadmium and lead ions adsorbed by R-WB were 519.1 and 869.5 µg/g, respectively. Various kinetic models have been used to describe the adsorbate-adsorbent interactions. When adsorption is preceded by diffusion through a boundary layer, in most cases, Lagergren’s pseudo-first-order rate equation is followed19): ln(qe − qt ) = ln qe − K1t
(4)
March 2014249
where qt and qe are the amounts adsorbed (µg/g) at any time and at equilibrium, respectively, t is the time taken for adsorption (h), and K1 is the rate constant of pseudo-first-order adsorption (1/h). Hence, the pseudo-first-order kinetics cannot explain the adsorption mechanism for these adsorbents. Several authors have shown that the adsorption onto solids follows pseudo-second-order kinetics20,21):
t / qt = 1/ K 2 qe2 + t / qe
(5)
where K 2 the rate constant of the pseudo-second-order adsorption (µg/g h). The pseudo-second-order kinetic model considers the rate-limiting step to be responsible for the formation of bonds in chemisorption, which involves sharing or exchange of electrons between the adsorbate and the adsorbent. The experimental data (Fig. 1) were applied to the above equations. The pseudo-first- and second-order constants are shown in Table 1. The correlation coefficients of the pseudo-first-order model are 0.980 and 0.500 for the cadmium and lead ions, respectively. On the other hand, the correlation coefficients of the pseudo-second-order model are 0.955 and 1.000 for the cadmium and lead ions, respectively. The adsorption of
cadmium and lead ions onto R-WB fits well to the pseudosecond-order model. These results suggest that chemisorption might be the rate-limiting step that controls the adsorption process.22) It is more likely to predict that the adsorption behavior may involve valences forces through sharing of electrons between heavy metal and adsorbent. The adsorption of cadmium and lead ions onto R-WB may be consist of two processes: the first process is interpreted to be the instantaneous adsorption stage or external surface adsorption. The second process is interpreted to be the gradual adsorption stage where intraparticle diffusion controls the adsorption rate until finally the metal uptake reaches equilibrium.23) Adsorption Isotherms of Cadmium and Lead Ions onto R-WB The adsorption isotherms of cadmium and lead ions onto R-WB are shown in Fig. 2. The amount adsorbed increases with increasing temperature for both cadmium and lead ions. In chemisorption, the amount of adsorption increases with increasing temperature. The equilibrium of a solute between the liquid and solid phases may be described by various models of adsorption. In order to investigate the adsorption capacity and isotherm, two equilibrium models have been used, namely, the Langmuir and Freundlich models. The Langmuir model is probably the best known and most widely applied adsorption isotherm model.14,24) This model assumes monolayer adsorption with a homogeneous distribution of adsorption sites and adsorption energies, without any interactions between the adsorbed molecules. This model is thus in good agreement with a wide variety of experimental data and may be represented as follows25): (6)
Q = qm K LCe / (1+ K LCe )
Table 1. Pseudo-First-Order and Pseudo-Second-Order Constants for Cd2+ and Pb2+ Adsorption onto R-WB Fig. 1. Adsorption Rate of Cd 2+ or Pb2+ onto R-WB in a Single Solution System Initial concentration: 1000 µg/L, sample volume: 50 mL, adsorbent: 0.05g, temperature: 25°C, contact time: 0.5–48 h, 100 rpm. ▲: Cd 2+, ■: Pb2+. The data are presented as means±S.E. of 3 experiment.
Fig. 2.
Samples 2+
Cd Pb2+
Pseudo-first-order model qe (µg/g)
K1 (1/h)
r
218.7 53.3
0.35 0.10
0.980 0.500
Pseudo-second-order model qe (µg/g) K2 (µg/g/h) 500.0 769.2
0.04 0.02
r 0.995 1.000
Adsorption Isotherms of Cd 2+ or Pb2+ onto R-WB in a Single Solution System
Initial concentration: 1–10 µg/L, sample volume: 50 mL, adsorbent: 0.05 g, temperature: 25°C, contact time: 24 h, 100 rpm. ●: 5°C , ◆: 25°C, ○: 45°C. The data are presented as means±S.E. of 3 experiment.
250
Vol. 62, No. 3
where Ce is the equilibrium concentration (µg/L), q is the amount adsorbed (µg/g), qm is the maximum amount adsorbed (µg/g), and K L is the sorption equilibrium constant. This empirical model can be applied to non-ideal sorption on heterogeneous surfaces as well as to multilayer adsorption and is expressed by Eq. 7. The Freundlich isotherm is also more widely used, but it provides no information on the monolayer adsorption capacity, in contrast to the Langmuir model.
where Ce is the equilibrium concentration (µg/L), q is the amount of adsorbed (µg/g), and K F and n are Freundlich’s adsorption constants. The experimental data for the adsorption isotherms of cadmium and lead ions onto R-WB at 25°C were applied to the above equations. The relevant Freundlich and Langmuir constants are shown in Table 2. The correlation coefficient of the Langmuir constant is 0.999 for the cadmium ions and 0.996 for the lead ions. On the other hand, the correlation coefficient of the Freundlich constant is 0.994 for the cadmium ions and 0.993 for the lead ions. These results suggest that the data obtained in this condition were well described to both equations. The K L (Langmuir constant) and K F (Freundlich constant) values for the lead ions were greater than those for the cadmium ions, which are in agreement with the adsorption isotherm data. When 1/n is in the range 0.1 to 0.5, the adsorbate becomes easily adsorbed. On the other hand, if 1/n>2, adsorption is considered difficult.26) Our results indicated that the cadmium and lead ions were easily adsorbed onto R-WB. Thermodynamic Parameters for Cadmium and Lead Table 2. Freundlich and Langmuir Constants for Cd2+ and Pb2+ Adsorption onto R-WB at 25°C Langmuir constants qm (µg/g) KL (L/µg)
2+
Cd Pb2+
Table 3.
667 1667
0.01 0.02
Freundlich constants r
1/n
KF
r
0.999 0.996
0.6 0.6
1.3 1.7
0.994 0.993
(8)
K c = Cs / Ce
(7)
log q = log K F + (1/ n) log Ce
Ion
Ion Adsorption The thermodynamic parameters—standard Gibbs free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS)—were calculated using Eqs. 8–1027,28):
ΔG = − RT ln K c
(9)
ln K c = ΔS / R − ΔH / RT
(10)
where R is the gas constant (8.314×10−3 kJ/mol/K), Kc is the equilibrium constant, Cs is the number of milligrams of adsorbate in the adsorbent after adsorption equilibrium per liter of solution in contact with the adsorbent surface (mg/L), Ce is the equilibrium concentration in the solution (mg/L), and T is the absolute temperature (K). ΔG, ΔH, and ΔS are expressed in units of kJ/mol. The thermodynamic parameters for the adsorption of cadmium and lead ions are listed in Table 3. The negative ΔG implied that the adsorption of cadmium and lead ions onto R-WB is a spontaneous process. The calculated values of ΔS were positive (except for the initial concentration of lead ions at 1 µmol/L), indicating an increase in the randomness at the solid/liquid interface. The ΔH value indicates the type of mechanisms involved in the adsorption process. An enthalpy change of less than 40 kJ/mol indicates that the physical adsorption predominates. The experimental data (Table 3) suggest the physical adsorption of cadmium and lead ions onto R-WB.29) Breakthrough Curves for Adsorption of Cadmium and Lead Ions onto R-WB The concentration of cadmium and lead ions in the effluent from a column is shown in Figs. 3 and 4. As per the results, cadmium ions in the effluent were not detected at SV 2.17 1/h and LV 0.08 m/h. This condition was very suitable for the adsorption of cadmium ions using an adsorbent column. On the other hand, cadmium ions were detected even after 20 h after the adsorption started at SV 4.43 1/h and LV 0.15 m/h. The ion concentration in the effluent increased with increasing elapsed time, and subsequently, the adsorption reached saturation at 80 h. These results suggest
Thermodynamic Parameters for Adsorption of Cd2+ and Pb2+ onto R-WB
Samples 2+
Cd
Pb2+
Initial concentration (µmol/L)
ΔH (kJ/mol)
ΔS (J/mol/K)
1 2 4 6 8 10 Mean 1 2 4 6 8 10 Mean
7.56 4.10 11.89 10.42 13.45 6.79 9.04 −16.82 16.00 18.37 11.91 7.81 16.66 8.99
34.47 22.26 46.87 40.01 48.40 24.85 36.14 −30.81 75.43 81.08 56.66 41.87 71.56 49.30
ΔG (J/mol/K) at different temperature 278.15 K
298.15 K
318.15 K
−1.57 −1.79 −1.03 −0.70 −0.10 −0.17 −0.89 −7.99 −5.06 −4.13 −3.48 −3.53 −3.22 −4.57
−3.78 −3.22 −2.35 −1.53 −0.79 −0.50 −2.03 −8.24 −6.30 −5.95 −5.82 −5.36 −4.72 −6.06
−2.81 −2.58 −2.86 −2.30 −2.06 −1.18 −2.30 −6.67 −8.10 −7.35 −5.64 −5.12 −6.08 −6.49
March 2014251
Fig. 3.
Released Concentration of Cd 2+ from R-WB with Elapsed Time
(I) Initial concentration: 1000 µg/L, SV: 4.43 1/h, LV: 0.15 m/h, flow rate: 0.2 mL/min. (II) Initial concentration: 1000 µg/L, SV: 2.17 1/h, LV: 0.08 m/h, flow rate: 0.1 mL/ min.
Fig. 4.
Released Concentration of Pb2+ from R-WB with Elapsed Time
(I) Initial concentration: 1000 mg/L, SV: 10.86 1/h, LV: 0.38 m/h, flow rate: 0.5 mL/min. (II) Initial concentration: 1000 mg/L, SV: 6.51 1/h, LV: 0.23 m/h, flow rate: 0.3 mL/min.
that increasing the contact time and contact area induces an increase in the amount adsorbed. Similar trends were observed in the adsorption of lead ions. At a SV 10.86 1/h and LV 0.38 m/h, lead ions in the effluent from a column were detected after the adsorption. The absorption reached saturation after 40 h. On the other hand, at SV 6.51 1/h and LV 0.23 m/h, no lead ions were detected in the effluent even after 50 h. These adsorption capabilities of cadmium and lead ions onto R-WB were the same as those onto other adsorbents.30) Adsorption/Desorption Capability of Cadmium and Lead Ions onto R-WB Repeated adsorption/desorption of the cadmium and lead ions onto R-WB achieved by using 0.01 mol/L HCl and 0.01 mol/L HNO3 solution is shown in Fig. 5. At first, the amount of cadmium ions adsorbed was 17.9 mg/g, and the recovery of these ions was approximately 100%. Subsequently, four cycles of adsorption/desorption of cadmium ions were possible. The amount of cadmium ions adsorbed or desorbed was 2.4–4.2 mg/g or 2.5–3.5 mg/g when using 0.01 mol/L HCl, and 3.0–4.3 mg/g or 2.5–3.3 mg/g when using 0.01 mol/L HNO3. On the other hand, the initial amount of lead ions adsorbed was 27.5 mg/g, and the recovery was ap-
proximately 56–57% (for both 0.01 mol/L HCl and 0.01 mol/L HNO3). Four cycles of repeated adsorption–desorption of lead ions were possible. Saeed et al. reported that adsorption–desorption of copper, cadmium, and zinc ions on Papaya wood could be effected by using 0.1 mol/L HCl. In this study, a similar trend is observed, and moreover, R-WB is found to be useful in the removal and recovery of these ions.31) A comparison of the maximum monolayer adsorption capacity of R-WB with the other low-cost adsorbent materials reported in literature is presented in Table 4, which clearly shows that the R-WB is a good adsorbent. Nevertheless, since R-WB is a waste biomass of no commercial value, it should have a great potential in water and wastewater treatment applications, as compared with other low-cost adsorbents.32–46) Moreover, R-WB was used for adsorption of chromium, iron, copper, and mercury ions in aqueous solution, which ionic radius was 54, 64, 96, and 110 Å, respectively.47) These results showed that R-WB could be selectivity chelation with anion (Ionic radius: 54–110 Å). Therefore, R-WB would be useful for adsorption of cadmium and lead ions. Measurement of Bacterial Counts Total viable bacterial counts in sample solutions are shown in Table 5. The viable
252
Vol. 62, No. 3
Amount of Cd 2+ or Pb2+ Adsorption or Desorption onto V-WB by Nitric Acid or Hydrochloric Acid
Fig. 5.
Initial concentration: 30 (Cd 2+) or 35 (Pb2+) mg/L, sample volume: 100 mL, adsorbent: 0.1 g, temperature: 25°C, contact time: 24 h, 100 rpm. ■: adsorption, □: desorption. The data are presented as means±S.E. of 3 experiment.
Comparison of Adsorbent of Cd2+ and Pb2+ onto Various Adsorbents
Table 4.
Cd2+
Pb2+
Adsorbent
qmax (mg/g)
References
R-WB Rice husk (modified) Papaya wood Pinus sylvestris Juniper fiber (untreated) Rice husk (raw) Peanut hulls Kazelnut shell Corncob Almond shell
17.9 20.24 17.35 9.26 9.18 8.58 5.96 5.42 5.09 3.18
Present study 32) 31) 33) 34) 32) 35) 36) 37) 36)
Table 5. Viable Bacterial Counts in Distilled Water, Cd2+ Solution, and Pb2+ Solution Treated with R-WB Time (h) 52 56 60 64 68 72 76 80 84
Cd2+
Pb2+
0 0 0 0 26 58 100 100 100
0 0 0 0 4 25 19 19 100
Distilled water 0 0 0 1 0 1 6 7 22
Initial concentration: 1000 mg/L, sample volume: 500 mL, adsorbent: 0.5 g, temperature: ambient.
bacterial counts in the cadmium and lead ion solutions increased with elapsed time. No viable bacterial counts were observed until 64 h after the adsorption. After 68 h, a viable bacterial count of 100 for the cadmium and lead ion solutions was reached within 76 h and 84 h, respectively. On the
Adsorbent R-WB Natural spider silk Peels of banana Polygonum orientale activated carbon Coconut shell activated carbon Walnut shell Almond shells Rice husk ash Bagasse fly ash Apple pomace
qmax (mg/g)
References
27.5 1.17 2.18 98.41 18.1 31.23 8.13 12.61 2.5 16.39
Present study 38) 39) 40) 41) 42) 43) 44) 45) 46)
other hand, the total viable bacterial count in distilled water was 22 at 84 h after the adsorption started. The World Health Organization (WHO) standard for water quality is less than 100 counts of total viable bacterial count in a 1 mL sample of water. Our experimental findings showed that the water quality is comparable to the WHO standards. Moreover, the above results (Table 4) suggested that R-WB was also useful purification in polluted water, and after 76 h (cadmium ion solution) or 84 h (lead ion solution), the sample solution was needed to treatment of boiling.
Conclusion
R-WB was prepared for use as a biomass adsorbent. Adsorption equilibrium of cadmium and lead ions onto R-WB was achieved within 10 h. The experimental data fitted well to the pseudo-second-order model. The amount of lead ions adsorbed was greater than that of cadmium ions. The negative ΔG implied that the adsorption of cadmium and lead ions onto R-WB is a spontaneous process. The R-WB was identified as better sorbent as compared with other adsorbent. The optimal conditions in the column experiment were as follows: SV
March 2014253
2.17 1/h and LV 0.08 m/h for cadmium ions; SV 6.51 1/h and LV 0.23 m/h for lead ions. Repeated adsorption–desorption of the cadmium and lead ions was made possible by using 0.01 mol/L HCl or 0.01 mol/L HNO3 solution. Cadmium and lead ions were effectively removed from the solutions treated by the R-WB adsorbent, after 76 h and 84 h, respectively.
21) 22) 23) 24) 25)
Acknowledgment This research was supported partly by a Grant 24710083 from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
26) 27)
References
28)
1) Rao M. M., Reddy D. H. K. K., Venkateswarlu P., Seshaiah K., J. Environ. Manage., 90, 634–643 (2009). 2) Al-Masri M. S., Amin Y., Al-Akel B., Al-Naama T., Appl. Biochem. Biotechnol., 160, 976–987 (2010). 3) Fergusson J. E., “The Heavy Metal Elements: Chemistry, Environmental Impact and Health Effects,” Pergamon Press, Oxford, United Kingdom, 1990. 4) Kasuya M., Teranishi H., Aohima K., Katoh T., Horiguchi N., Water Sci. Technol., 25, 149–156 (1992). 5) Klaassen C. D., “Heavy Metals and Heavy Metal Antagonists,” McGraw Hill, New York, 2001, pp. 1851–1875. 6) Davis T. A., Volesky B., Vieira R. H. S. F., Water Res., 34, 4270– 4278 (2000). 7) Schümann K., Z. Emahrungswiss., 29, 54–73 (1990). 8) Saygideger S., Gulnaz O., Istifli E. S., Yucel N., J. Hazard. Mater., 126, 96–104 (2005). 9) Xiangliang P., Jianlong W., Daoyong Z., Process Biochem., 40, 2799–2803 (2005). 10) Veglió F., Beolchini F., Hydrometallurgy, 44, 301–316 (1997). 11) Muraleedharan T. R., Venkobachar C., Biotechnol. Bioeng., 33, 823–831 (1990). 12) Khalid N., Rahman A., Ahmad S., Kiani S. N., Ahmed J., Radiochimica Acta, 83, 157–162 (1998). 13) Pagnanelli F., Toro L., Veglio F., Waste Manag., 22, 901–907 (2002). 14) Ahalya N., Ramachandra T. V., Kanamadi R. D., Res. J. Chem. Environ., 7, 71–79 (2003). 15) Hammaini A., González F., Ballester A., Blázquez M. L., Mañoz J. A., Minerals Engineering, 16, 723–729 (2003). 16) Keskinkan O., Goksu M. Z. L., Yuceer A., Basibuyuk M., Forster C. F., Process Biochem., 39, 179–183 (2003). 17) Norton L., Baskaran K., McKenzie T., Adv. Environ. Res., 8, 629– 635 (2004). 18) Boehm H. P., Angew. Chem. Int. Ed. Engl., 5, 533–544 (1966). 19) Singh D. B., Prasad G., Rupainwar D. C., Singh V. N., Water Air Soil Pollut., 42, 373–386 (1988). 20) Demirbas E., Kobya M., Senturk E., Ozkan T., Water SA, 30, 533– 539 (2004).
29) 30) 31) 32) 33) 34) 35) 36) 37) 38) 39) 40) 41) 42) 43) 44) 45) 46) 47)
Baral S. S., Das S. N., Rath P., Chaudhury G. R., Biochem. Eng. J., 34, 69–75 (2007). Arvand M., Pakseresht M. A., J. Chem. Technol. Biotechnol., 88, 572–578 (2013). Zhou L., Liu J., Liu Z., J. Hazard. Mater., 172, 439–446 (2009). Kim T.-Y., Park S.-K., Cho S.-Y., Kim H.-B., Kang Y., Kim S.-D., Kim S.-J., Korean J. Chem. Eng., 22, 91–98 (2005). Pino G. H., de Mesquita L. M. S., Torem M. L., Pinto G. A. S., Sep. Sci. Technol., 41, 3141–3153 (2006). Abe I., Hayashi K., Kitagawa M., Yukagaku, 25, 145–150 (1976). Jain C. K., Singhal D. C., Sharma M. K., J. Hazard. Mater., 114, 231–239 (2004). Sari A., Tuzen M., Citak D., Soylak M., J. Hazard. Mater., 149, 283–291 (2007). DiVincenzo J. P., Sparks D. L., Environ. Sci. Technol., 31, 977–983 (1997). Kabay N., Demircioðlu M., Ekinci H., Yüksel M., Saðlam M., Akçay M., Streat M., Ind. Eng. Chem. Res., 37, 2541–2547 (1998). Saeed A., Waheed A. M., Iqbal M., Sep. Purif. Tech., 45, 25–31 (2005). Iqbal M., Saeed A., Akhtar N., Bioresour. Technol., 81, 151–153 (2006). Taty-Costodes V. C., Fauduet H., Porte C., Delacroix A., J. Hazard. Mater., 105, 121–142 (2003). Min S. H., Han J. S., Shin E. W., Park J. K., Water Res., 38, 1289– 1295 (2004). Brown P., Atly Jefcoat I., Parrish D., Gill S., Graham E., Adv. Environ. Res., 4, 19–29 (2000). Bulut Y., Tez Z., J. Hazard. Mater., 149, 35–41 (2007). Leyva-Ramos R., Bernal-Jacome L. A., Acosta-Rodriguez I., Sep. Purif. Tech., 45, 41–49 (2005). Pelit L., Ertas F. N., Eroglu A. E., Shahwan T., Tural H., Bioresour. Technol., 102, 8807–8813 (2011). Anwar J., Shafique U., Waheed-uz-Zaman., Salman M., Dar A., Anwar S., Bioresour. Technol., 101, 1752–1755 (2010). Wang L., Zhang J., Zhao R., Li Y., Li C., Zhang C., Bioresour. Technol., 101, 5808–5814 (2010). Sekar M., Sakthi V., Rengaraj S., J. Colloid Interface Sci., 279, 307–313 (2004). Almasi A., Omidi M., Khodadadian M., Khamutian R., Gholivand M. B., Toxicol. Environ. Chem., 94, 660–671 (2012). Mehrasbi M. R., Farahmandkia Z., Taghibeigloo B., Taromi A., Water Air Soil Pollut., 199, 343–351 (2009). Feng Q., Lin Q., Gong F., Sugita S., Shoya M., J. Colloid Interface Sci., 278, 1–8 (2004). Gupta V. K., Ali I., J. Colloid Interface Sci., 271, 321–328 (2004). Chand P., Pakade Y. B., J. Chem., 2013, 1–8 (2013). Ogata F., Tominaga H., Kangawa M., Kawasaki N., Chem. Pharm. Bull., 59, 1400–1402 (2011).
