Printer Friendly

Facile Synthesis, Characterization and Catalytic Function of Gelatin Stabilized Gold Nanoparticles.

Byline: Zulfiqar A. Tagar, Sirajuddin, Najma Memon, Muhammad S. Kalhoro, Nazar H. Kalwar, Yasmeen Junejo and Syeda Sara Hassan

Abstract

In the present investigation, we report a new one phase, one pot method for synthesis of 3.5 +- 0.7 nm average sized gelatin capped gold nano particles (Gel-AuNPs) using strong reductant NaBH4 in aqueous system at room temperature. Size controlled Gel-AuNPs were characterized by UV- Visible, STEM, XRD, DLS and FT-IR. Spherical Gel-AuNPs showed excellent catalytic activity for reduction of three differently charged dyes eosin B (EB), methylene blue (MB) and rose bengal (RB) in the presence of NaBH4. The study revealed that 100% reduction of EB, MB and RB dyes was carried out in just 150 sec. The developed catalyst was easy to recover and capable to be reused three times. The process of reduction rate and kinetics of dyes was monitored using UV- Visible spectrophotometer. A plot of lnC Vs time (sec) showed that reaction follows the first order kinetics.

Rate constant (K) was determined for EB, MB and RB reduction at 10 IM, which was found as 2.735 x10-2 sec-1, 2.738 x 10-2 sec-1 and 2.55 x 10-2 sec-1, respectively. The study revealed that catalytic reduction of dyes by Gel-AuNPs in aqueous medium is environmental friendly in terms of recovery of catalyst, is exceptionally fast and hence extremely economical.

Keywords: Gelatin; Controlled; Catalytic activity; Dyes; Recovery.

Introduction

Nanotechnology has brought diverse disciplines together and this interdisciplinary approach is anticipated to contribute innovations that might solve many of todayis challenges in society. Noble metal nano particles (MNPs) display unique, superior and indispensable properties such as size dependent chemical, electronic and optical properties, their uniqueness arises specifically from their size, shape, higher surface to volume ratio and increased percentage of atoms that are unavailable in conventional macroscopic materials. Nevertheless, AuNPs have potential applications in different fields such as electronics, health, medicine, transportation, energy and environment [1]. There is continuous research towards synthesis of MNPs using inexpensive and nontoxic chemicals, environmentally benign solvents, clean and renewable/ biodegradable materials [2, 3]. Considering green nature of these approaches, reducing agents, capping agents and reaction medium are three key factors in synthesis and stabilization of MNPs.

AuNPs in the solution are very active and prone to coagulate due to vander waals forces and high surface energy unless they are protected. In this regard numerous capping agents and surfactants have been used to protect AuNPs from aggregation. They include cetyltrimethylammonium bromide (CTAB) [4], tetrahydrothiophene (THT) [5], 1-Phenyle- 5- thiotetrazoles [6], 11-mercaptoundecanoic acid [7], benzene and anthracene [8], ciprofloxacin [9], resorcinarene [10], polyethylene glycol [11], didodecyldimethylammonium bromide [12], aromatic thiols [13] etc. Most of these capping agents are health hazardous organic compounds. These capping agents can be replaced by environmental friendly natural polymers such as gelatin, proteins, chitosan and starch. These are biodegradable and bio absorbable with degradation products that are non-hazardous.

Gelatin is hydrolytically and thermally denatured product of collagen, the most abundant protein found in animals and has been used extensively in food, industrial, pharmaceutical and cosmetic products, as binder material and photographical applications owing to its unique functional and technological properties thatis why it is produced on a large scale at relatively low cost [14, 15]. At high temperature gelatin remains in the form of flexible, unfolded coils in the solution and can be partially re-natured to ordered, collagen-like helixes upon cooling at room temperature [16, 17]. Mostly natural collagen proteins obtained from animals are insoluble in water but gelatin is freely soluble in polar solvents such as water at ~35 0C, due to hydrogen bonding [18]. Several synthetic methods using unfolded gelatin capped Au and AgNPs have been developed at high temperature (100 0C) [19, 20, 21].

However it is reported that above 55 0C gelatin becomes denatured and looses its origin; surprisingly very little attention has been paid towards gelatin usage at low temperature. So, still there is a need to use gelatin at room temperature as capping agent. Gold is considered as inactive metal for catalysis because of its inertness [22], but when it is brought into small particle less than 10 nm, it turns out to be surprisingly active for many reactions, such as CO oxidation and propylene epoxidation at low temperatures [23]. Haruta et al. deposited very small 3-10 nm sized AuNPs on metal oxides, such as TiO2, Fe2O3, Co3O4 and NiO, which displayed surprisingly high catalytic activity for CO oxidation at low temperature (-70 0C) [24].

Mitsudome et al have synthesized Hydrotalcite- AuNPs and used them as highly efficient, selective and reusable catalyst for an aerobic oxidation of 1- phenylethanol into acetophenone [25].

Today dyes are among the most common organic industrial pollutants, such as textile, plastics, paper, food, leather, cosmetics etc. are major source of producing toxic species in the form of colored waste waters. These colored species are producing great disturbance in photosynthetic process in aquatic plants due to meager light penetration [26 n 30]. According to another report some of azo-dyes and their degradation products such as aromatic amines are highly carcinogenic [31]. Many processes have been developed for decolorization of dyes, achieved through adsorption [32], degradation [33 n 35], oxidation [36, 37] and catalytic reduction [38n41]. However, due to the reasons of energy saving, safe operation and avoiding use of organic solvents, it may be interesting and meaningful to develop process for detoxification in aqueous solution under mild condition. Also, the process could be used for treatment of wastewater which contains mainly dyes without complicated composition.

The aim of our study was to synthesize small Gel-AuNPs and investigate activity as heterogeneous, recoverable and reusable catalyst for exceptionally faster and complete reduction of EB, MB and RB dyes. To the best of our knowledge there is no easy and quick method by which Gel-AuNPs are reported for catalysis of dyes at room temperature. Therefore here we report easy quick and one step method for synthesis of well stabilized Gel-AuNPs and their catalytic activity.

Experimental Section

Chemicals and Reagents

Analytical grade HAuCl4.3H2O, NaBH4, NaOH and gelatin were purchased from Sigma- Aldrich (St. Louis, MO) HCl, methylene blue (MB), rose bengal (RB), eosin B (EB) dyes purchased from (Fluka) and used without further purification. All acidic, basic and salt solutions were prepared in milli Q water.

Instrumentation

Gel-AuNPs were characterized by UV- Visible spectrophotometer model lambda 2 of Perkin Elmer(USA). FT-IR spectra were recorded by Niclolet Avtar 5700 FT-IR spectrophotometer of thermo (USA), STEM observations were carried out using a TECNAI electrom microscope (FEI company (USA) operated at an accelerating voltage of 300 kV; zeta potential was performed by Malvern Instruments Corporation (UK) and XRD was carried out using RIGAKU RTAFLEX RAD- B of Rigaku corporation (Japan) with CU-K radiation with wavelength of 1.315 9, 40 kV, 100 mA, to scanning rate 0.005@/sec and step size 0.02 specifications.

Synthesis of Gel nAuNPs

To a 0.13 mL (0.15%) HAuCl4.3H2O solution of pH 4, was added sufficient amount of milli Q water followed by 0.1 mL of (0.1M) NaOH and 0.05 mL of freshly prepared 0.1M NaBH4 and 0.5 mL (0.5%) gelatin. The final volume was adjusted to 10 mL; this mixture was stirred vigorously with glass rod for approximately (1-2 min) until solution turned into transparent light pink color. Gelatin solution (0.5%) was prepared in milli Q water; 0.5% gelatin solution was prepared at 45 0C.

Preparation of Gel-AuNPs sample for STEM

Gel-AuNPs sample for STEM was prepared by placing 5 uL drops on carbon coated copper grid and dried at room temperature.

Preparation of Gel-AuNPs samples for XRD

According to method, a bulk solution (100 mL) with above mentioned concentration of each reagent containing synthesized Gel-AuNPs were fabricated and transferred into centrifuge cells. The process of centrifugation was carried out for 1 h at 6000 rpm. Upper portion of Gel-AuNPs was drained carefully and lower portion of approximately 1 mL was collected. With the help of micro pipette, the drop from collected portion of Gel-AuNPs was placed on glass slide, which was already put on hot plate at 100 0C.

Sample Preparation for FTIR Spectroscopy

Bulk solutions (2000 mL) containing appropriate amount of HAuCl4.3H2O solution, H2O, NaOH, NaBH4 and gelatin were mixed in similar way as mentioned above for Gel-AuNPs synthetic. Synthesized Gel-AuNPs were transferred into big petri dishes, dried at 100 0C followed by N2 treatment for 5 minutes and washed 2-3 times with methanol and water to remove any un-reacted materials. The dried sample was scratched off with clean glass slide and collected in sample holder before study.

Preparation of Gel-AuNPs as Heterogeneous

Catalyst

Gel-AuNPs were accommodated on small pieces of glass cover slips and dried under N2 for ten min. These glass pieces were weighed before and after treatment of Gel-AuNPs to find out the amount of Gel-AuNPs by difference. Gel-AuNPs in the range of 0.03 to 0.15 mg were used in catalysis experiments.

Catalytic reduction of dyes

The catalytic reduction of EB, MB and RB dyes were carried out in a standard quartz cell with 1 cm path length and about 4 mL volume containing Gel-AuNPs loaded pieces of glass. This reaction was performed in the presence of little quantity of NaBH4 alone and Gel-AuNPs. Under optimized conditions, the catalytic reaction procedure was as follows for each individual dye i.e. 0.4 mL of each individual dye was taken from 100 IM standard solution, to which was added 2.80 mL of milli Q water followed by 0.8 mL of 0.1M NaBH4. Carefully and immediately after addition of 0.12 mg, Gel-AuNPs were immobilized on pieces of glass and put in quartz cell for reduction process. The absorption spectra were monitored by a UV/Vis spectrophotometer with a time interval of 50 sec in a scanning range of 450n 750 nm at room temperature.

Results and Discussion

In order to produce very small Gel-AuNPs, various optimization studies were carried out such as pH (2-9 levels), concentration of HAuCl4, NaBH4, NaOH and gelatin. By doing so we observed that maintaining pH 4 of 0.13 mL HAuCl4 in aqueous solution in which was added 0.1 mL of (0.1M) NaOH followed by 0.05 mL (0.1M) of NaBH4 and 0.5 mL (0.5%) gelatin produced best Imax of 520 nm, indicating characteristics for formation of Gel-AuNPs [42] as shown in Fig. 1(a). Final pH of synthesized Gel- AuNPs was measured and found as 9.4. Effect of gelatin concentration on absorption band of AuNPs is shown in Fig. 1(b). A 7 nm blue shift was observed in SPR band by increasing gelatin concentration from 100 uL to 600 uL using 0.5% gelatin solution. Gelatin monomers contain amino functional group which possesses high affinity towards noble metals; they are often used to anchor MNPs on to different substrates and short wavelength was observed in the Gel-AuNPs [20].

Stability of Gel-AuNPs was tested and results show that particles are stable up to eight days.

Scanning Transmission Electron Microscope (STEM) can provide valuable and accurate information about size, shape and monodispersity of Gel-AuNPs [43]. In our experiments, STEM was used to investigate well dispersed morphology of Gel-AuNPs and their capping with gelatin network as shown in Fig. 2(a- d). Typical STEM images and a corresponding histogram for Gel-AuNPs are given in Fig. (2d).

Size of Gel-AuNPs was calculated as 3.5 +- 0.7 nm.

Narrow size distribution is obvious in STEM micrographs; however, further analysis reveals that separation among Gel-AuNPs is very remarkable. Spherical Gel-AuNPs are fairly dispersed and well separated in gelatin; because it has free amine group, which leads to protonation in acidic medium. Positive charge on amine group strongly interacts with AuNPs, maintaining triple helix tail chain which forms provides steric hindrance coagulation and acts as better stabilizer than conventional surfactants. The interaction of AuNPs with gelatin was characterized by FT-IR. FTIR of pure gelatin and Gel-AuNPs are shown (Fig. 3) in which we have observed disappearance and shifting of some peaks. The main clue from which we can get about interaction of AuNPs with gelatin, neutralization of nNH3 and in gelatin strong adsorption at 1556 cm-1 shows presence of n NH3 group [45], while in Gel-AuNPs nNH the peak is disappeared. It means that positively charged nNH + interacted with negatively charged AuNPs.

Neutrality of Gel-AuNPs also matches to results of zeta potential. In gelatin the peak at 1455 cm-1 confirms carbonate CO-3 ion, however this vibrational band is shifted at 1386 cm-1 in Gel- AuNPs. It shows the presence of sodium salt, while bands at 1069 cm-1 and 1006 cm-1 confirm C-C in gelatin as well as Gel-AuNPs.

In order to determine formation of crystal phase and atomic arrangement of Gel-AuNPs, XRD analysis was performed. XRD patterns of Gel-AuNPs were achieved at 2E scale, 38.20, 44.40, 64.80 and 77.70 that correspond to (111), (200), (220) and (311) plans of standard cubic phase of Au crystals [44] as shown (Fig. 4). These all peaks clearly indicate the presence of face centered cubic and body centered cubic patterns in Gel-AuNPs sample. Moreover broadening of XRD peaks confirms small size of Au. The average size, 3.2 +- 0.5 of Gel-AuNPs was also confirmed from width of diffraction peak using Debye-Scherrer equation. This equation can be described as d = KI/B cos E, Where d stand for particle size, K represents Scherrer constant; its value is (0.89), I indicates X-Ray wavelength (Cu Ka, 1.54056 A@), E represents the diffraction angle and B is the corrected full width at half maximum (in radian).

Catalytic reduction of dyes

To investigate catalytic efficacy of Gel- AuNPs in aqueous system, three differently charged dyes such as EB, MB and RB were selected. During working conditions, MB becomes cationic, EB is anionic and RB is neutral. SPR band of EB, MB and RB appeared at 515 nm, 663 nm and 547 nm respectively in aqueous solution. Reduction of each individual dye was observed with NaBH4 in absence of Gel-AuNPs; for half an hour, it was noticed that in the absence of catalyst, strong reducing agent NaBH4 is unable to reduce EB, MB and RB. It reduces EB, MB and RB up to small extent, 8.1%, 8.7% and 10% respectively as shown (Fig. 6 (a-c)). In agreement with previous results [46, 47], the reduction of dyes by NaBH4 did not occur to an appreciable extent in the absence of Gel-AuNPs; however, the catalytic efficiency of Gel-AuNPs can be confirmed from Fig. 7 (a-c) which shows a large decay in concentration of EB, MB and RB in the presence of Gel-AuNPs. The entire reduction process is completed in just 150 sec at 25 @C.

Interestingly, on addition of little amount of glass supported Gel-AuNPs (0.12 mg) to reaction system caused a fading and ultimate bleaching of EB, MB and RB dyes in aqueous solution. This suggests reduction of three different charged dyes by Gel-AuNPs in the presence of NaBH4 within 150 sec. To exclude possibility that reduction reaction might be activated by Gel-AuNPs, sufficient quantity of Gel-AuNPs (0.12 mg) alone was added into aqueous solution of dyes but no change was observed in the concentration of EB, MB and RB even after 30 min. This indicates that Gel-AuNPs play role of a catalyst for reduction of dyes in the presence of reducing agent. Moreover, succession of catalytic reduction of dyes can be easily monitored by change in SPR band at wavelength of the absorbance maximum (max) of dyes. (Fig. 7 (a- c)) shows evolution of UV-visible spectra of dyes during their catalytic reductions when mixture of each individual dye, the Gel-AuNPs supported on glass and NaBH4 are involved in reaction.

Evidently, the absorbance of dyes gradually decreases with reaction time, which is indication of reduction of dyes. As expected, the catalytic reduction of dyes proceeds successfully and no deactivation or poisoning of catalyst was observed.

Moreover, several optimization studies pertaining to the amount of Gel-AuNPs and NaBH4 were carried out to improve rate of reduction of dyes in which we observed that rate of reduction of dyes rapidly increased with increase in concentration of Gel-AuNPs and NaBH4. The reaction was observed at once, upon addition of Gel-AuNPs into quartz cell and each spectrum was recorded after interval of 50 sec, ultimately entire reduction process at 10 uM of dyes completes within 150 sec. It was noticed that reduction of dyes are almost linearly dependent upon quantity of Gel-AuNPs; 100% reduction of dyes was completed in just 150 sec. In this context, first-order kinetics could be used to evaluate kinetic reaction and rate of current catalytic reaction as shown (Fig. 8 (a-c)).

Plot of lnC Vs time (sec) shows that reaction is undergoing through first order kinetics; rate constant (K) was determined for EB, MB and RB reduction at 10 IM as 2.735 x10-2 sec-1, 2.738 x 10-2 sec-1 and 2.55x10-2 sec-1 respectively.

Recycling of Gel-AuNPs as Catalyst

Glass supported Gel-AuNPs (0.12mg) were removed washed susccessively and reused 3 times for catalytic reduction of three differently charged dyes at10 uM. The reducing potential of recovered and reused Gel-AuNPs for each dye was calculated, which is given (Fig. 8). It is apparent that potential of Gel-AuNPs for catalytic fading of color decreases; however the decrease in activity is still not very low. This behavior confirms that recovered Gel-AuNPs are highly active despite some possible loss during each repeated washing. The slow deactivation of catalysts (Gel-AuNPs) also confirms that poisoning of catalysts is negligible.

Conclusion

Easier, rapid and one pot synthesis with mean size 3.5 +- 0.7 nm Gel-AuNPs was performed at room temperature. Fabricated Gel-AuNPs were characterized successfully by UV-visible, STEM, XRD, DLS and FT-IR. Synthesized Gel-AuNPs proved as exceptionally efficient catalyst for reduction of EB, MB and RB dyes. The work offers cheap solution to aquatic environment in terms of time saving, use of little amount of catalytic Gel-AuNPs and is equally useful for reduction of several other organic compounds.

Acknowledgment

I am thankful to Higher Education Commission, Islamabad, Pakistan, for awarding me IRSIP scholarship to carryout a part of my PhD research work at School of Chemistry, University of Manchester UK.

References

1. S. A. Yousaf and S. Ali. J. Faculty Eng. and Technol., (2007-2008) 11.

2. P. Raveendran, J. Fu and S. L. Wallen. J. AM. CHEM. SOC., 125 (2003) 13940.

3. J. Liu, F. He, T. M. Gunn, D. Zhao and C. B. Roberts. Langmuir, 25 (2009) 7116.

4. A. K. Samal, T. S. Sreeprasad and T. Pradeep. J. Nanopart. Res., 12 (2010) 1777.

5. S. Gomez, K. Philippot, V. Colliere, B. Chaudret, F. Senocq and P. Lecante. J. ROY SOC Chem. Commun., (2000) 1945.

6. M. N. Nichick, S. V. Voitekhovich, A. Shavel, A. I. Lesnikovich and O. A. Ivashkevich, Polyhedron, 28 (2009) 3138.

7. W. Shi, Y. Sahoo and M. T. Swihart. Colloid Surface A: Physicochem. Eng., 246 (2004) 109.

8. A. Kumar, S. Mandal, S. P. Mathew, P. R. Selvakannan, A. B. Mandale, R. V. Chaudhari and M. Sastry. Langmuir, 18 (2002) 6478.

9. R. T. Tom, V. Suryanarayanan, P. G. Reddy, S. Baskaran and T. Pradeep. Langmuir, 20 (2004) 1909.

10. T. K. Misra, T. S. Chen and C. Y. Liu. J. Colloid Interf. Sci., 297 (2006) 584.

11. J. Manson, D. Kumar, B. J. Meenan and D. Dixon. Gold Bull., 8 (2011) 1.

12. L. Zhang, X. Sun, Y. Song, X. Jiang, S. Dong and E. Wang. Langmuir, 22 (2006) 2838.

13. R. M. Pattabi and M. Pattabi. Solid State Phys. AIP Conf. Proc., 1349 (2011) 369.

14. I. Yakimets, N. Wellner, A. C. Smith, R. H. Wilson and I. Farhat, J. Mitchell. Polymer, 46 (2005) 12577.

15. A. A. Karim and R. Bhat. FOOD Hydrocolloid, 23 (2009) 563.

16. D. Olsen, C. Yang, M. Bodo, R. Chang, S. Leigh, J. Baez, D. Carmichael, M. Perala, E.R. Hamalainen, M. Jarvinen and J. Polarek. Adv. Drug. Deliver. Rev., 55 (2003) 1547.

17. V. N. Izmailova, S. R. Derkach, S. M. Levachev, G. P. Yampolskaya, Z. D. Tulovskaya and B. N. Tarasevich. Colloid J., 62 (2000) 653.

18 F. S.Guerri and D. Michel. Nature, 392 (1998) 666.

19. S. Liu, Z. Zhang and M.Y. Han. Adv. Mater., 17 (2005)1862.

20. M. P. Neupane, S. J. Lee, I. S. Park, M. H. Lee, T. S. Bae, Y. Kuboki, M. Uo and F. Watari. J. Nanopart. Res., 13 (2011) 491.

21. M. Darroudi, M. B. Ahmad, R. Zamiri, A. Zak, A. H. Abdullah and N. A. Ibrahim. Int. J. Nanomed., 6 (2011) 677

22. S. Panigrahi, S. Basu, S. Praharaj, S. Pande, S. Jana, A. Pal, S. K. Ghosh and T. Pal. J. Phys. Chem. C 111, (2007) 4596.

23. M. Haruta. Cattech., 6 (2002) 102.

24. M. Haruta. Catal. Surv. Jpn., 1(1997) 61.

25. T. Mitsudome, A. Noujima, T. Mizugaki, K. Jitsukawa and K. Kaneda. Adv. Synth. Catal., 351( 2009) 1890.

26. N. Pradhan, A. Pal and T. Pal, Langmuir, 17 (2001) 1800.

27. C. Burda, X. Chen, R. Narayanan, M. A. El- Sayed. Chem. Rev., 105 (2005) 1025.

28. A. Siani, K. R. Wigel, O. S. Alexeev and M. D. Amiridis. J. Catal., 257 (2008) 5.

29. S. S. Hassan, Sirajuddin, A. R. Solangi, M. H. Agheemb, Y. Junejo, N. H. Kalwar and Z. A. Tagar. J. Hazard. Mater., 190 (2011) 1030.

30. M. B. Cortie and E. Van der Lingen, Mater. Forum., 26 (2002) 1.

31. M. A. Brown and S. C. De Vito. Crit. Rev. Environ. Sci. Technol., 23 (1993) 249.

32. I. Safarik, L. Ptackova and M. Safarikova. Eur. Cell Mater., 3 (2002) 52.

33. J. Lin, R. Zong, M. Zhou and Y. Zhu. Appl. Catal. B: Environ., 89 (2009) 425.

34. A. O. Ibhadon, G. M. Greenway and Y. Yue. Catal. Commun., 9 (2008) 153.

35. H. Lachheb, E. Puzenat, A. Houas, M. Ksibi, E. Elaloui, C. Guillard and J. M. Herrmann. Appl.Catal. B: Environ., 39 (2002) 75.

36. V. S. Ferreira-Leitao, J. G. da Silva and E. P. S. Bon. Appl. Catal. B: Environ. 42 (2003) 213.

37. N. Daneshvar, A. Aleboyeh, A. R. Khataee. Chemosphere, 59 (2005) 761.

38. N. R. Jana, Z. L. Wang and T. Pal. Langmuir, 16 (2000) 2457.

39. J. Fan, Y. Guo, J. Wang and M. Fan. J. Hazard. Mater., 166 (2009) 904.

40. T. K. Sau, A. Pal and T. Pal. J. Phys. Chem. B, 105 (2001) 9266.

41. C. F. Martin, M. Birot, H. Deleuze, A. Desforges and R. Backov, React. Funct. Polym., 67 (2007) 1072.

42. N. N. Long, L. V. Vu, C. D. Kiem, S. C. Doanh, C. T. Nguyet, P. T. Hang, N. D. Thien and L. M. Quynh. J. PHYS, 187 (2009) 1.

43. M. J. Dukes, D. B. Peckys and N. de Jonge. ACS NANO, 4 (2010) 4110.

44. Xunjun Yin, Shougang Chen and Aiguo Wu. Micro Nano Lett. 5 (2010) 270

45. L. Ding, C. Hao, Y. Xue and H. Ju. Biomacromol., 8 (2007)1341.

46. T. K. Sau, A. Pal and T. Pal. J. Phys. Chem. B, 105 (2001) 9266

47. N. R. Jana, T. K. Sau and T. Pal. J. Phys. Chem. B, 103 (1999) 115.

48. Z. J. Jiang, C. Y. Liu and L. W. Sun J. Phys. Chem. B, 109 (2005) 1730.

49. S. Kundu, D. Huitink and H. Liang J. Phys. Chem. C, 114 (2010) 7700.

National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, 76080, Pakistan, 2Institute of Physics, University of Sindh, Jamshoro, 76080, Pakistan, *Corresponding Author Email: tagarzulfiqar@gmail.com
COPYRIGHT 2012 Asianet-Pakistan
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2012 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Tagar, Zulfiqar A.; Memon, Najma; Kalhoro, Muhammad S.; Kalwar, Nazar H.; Junejo, Yasmeen; Hassan, S
Publication:Pakistan Journal of Analytical and Environmental Chemistry
Article Type:Report
Geographic Code:9PAKI
Date:Jun 30, 2012
Words:3947
Previous Article:Translocation of Aluminum to Grain Crops Grown in Different Agricultural Systems.
Next Article:Evaluation of Eleven Macro and Micro Elements Present in Various Hybrids of Millet (Pennisetum glaucum, or P. Americanum).
Topics:

Terms of use | Privacy policy | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters