Adsorptive removal of rhodamine b from aqueous solution using brewers spent grains batch and column study

ADSORPTIVE REMOVAL OF RHODAMINE B FROM AQUEOUS SOLUTION USING BREWER’S SPENT GRAINS: BATCH AND COLUMN STUDY GUO HUI (MSc, PKU) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE 2015     DECLARATION I hereby declare that this thesis is my original work and it has been written by me in its entirety I have duly acknowledged all the sources of information which have been used in the thesis This thesis has also not been submitted for any degree in any university previously 12345612345 Guo Hui 21 January 2015     ACKNOWLEDGEMENTS First and foremost, I'd like to show my deepest gratitude to my supervisor, Prof Li Fong Yau Sam, a respectable, responsible and resourceful professor who has provided me with this precious chance to study in NUS and with valuable guidance Without his enlightening instruction, impressive kindness and patience, I could not have completed my study His keen and vigorous academic observation enlightens me not only in this thesis but also in my future study I shall extend my thanks to Gan Peipei for all their kindness and help I would also like to thank all my teachers who have helped me to develop the fundamental and essential academic competence My sincere appreciation also goes to all the group members Last but not least, I'd like to thank all my friends, for their encouragement and support     i     Table of Contents ACKNOWLEDGEMENTS    i   Table of Contents    ii   List of Tables    iii   List of Figures    iv   Summary    v     Introduction    1     Materials and Chemicals    7   2.1   2.2   Preparation of BSG    7   2.3   Surface modified by HCl    7   2.4   Characterization of BSG biomass    7   2.5   Biosorption kinetics    8   2.6     Chemicals    7   Column procedure    9   Results and Discussion    10   3.1   Characterization of biosorbent    10   3.1.1   3.1.2   3.2   FT-IR spectrum    10   Scanning electron microscopy photography    11   Batch experiment    12   3.2.1   3.2.2   Effect of contact time and initial dye concentration    13   3.2.3   3.3   Effect of pH    12   Effect biosorbent dosage    15   Kinetic model    16   3.3.1   3.3.2   3.4   Pseudo-first-order model    16   Pseudo-second-order model    18   Biosorption isotherms    20   3.4.1   3.4.2   3.5   Langmuir adsorption isotherm    20   Freundlich adsorption isotherm    21   Column studies    24   3.5.1   3.5.2   Effect of flow rate    27   3.5.3   Effect of initial dye concentration    29   3.5.4     Effect of column height    26   Application of Thomas model    30   Conclusion    34   Reference    36       ii   List of Tables Table Parameters of pseudo-first-order model Table Parameters of pseudo-second-order model Table 3a Parameters of Langmuir and Fredudlich isotherm model Table 3b Parameters of Langmuir and Fredudlich isotherm model Table column data and parameters with different bed height Table column data and parameters with different flow rate Table column data and parameters with different initial dye concentration Table Thomas Model parameters for the removal of Rhodamine B by BSG   iii   List of Figures Fig Fourier transform infrared adsorption spectra of the BSG Fig SEM analysis of (a) native BSG biomass; (b) HCl treated BSG biomass Fig The effect of initial pH of dye solution Fig Effect of initial concentration and contact time on the removal of RhB Fig The effect of biosorbent dosage Fig Pseudo-first-order kinetic plot for the removal of RhB Fig Pseudo-second-order kinetic plot for the removal of RhB Fig (a) Langmuir adsorption isotherm (b) Freundlich adsorption isotherm Fig Effect of bed height on the removal of Rhodamine B in fixed bed Fig 10 Effect of flow rate on the removal of Rhodamine B in fixed bed Fig 11 Effect of initial concentration on the removal of Rhodamine B in fixed bed column Fig.12 Modified Thomas model for biosorption of Rhodamine by BSG on experimental data (a) effect of bed height (b) effect of follow rate (c) effect of initial dye concentration   iv   Summary In this study, the biosorption characteristics of brewer’s spent grain (BSG) have been analyzed For batch study, the effects of pH of dye solution, initial dye concentration, contact time, and biosorbent dosages were analyzed For biosorption mechanism research, two mostly used models (pseudo-first-order and pseudo-second-order) were applied to the experimental data to evaluate the biosorption kinetic models While for the equilibrium studies, both Langmuir and Freundlich models were applied Base on the experimental results and the modeling studies, we have gained a comprehensive understanding of adsorption processes of BSG In addition, the results showed that fixed bed column system was promising in practical application Higher adsorption capacity, ease of operation and recycle are the notable advantages of the column system Some important parameters such as flow rate, bed height and initial concentration were investigated in this study Thomas model was applied to describe the column adsorption model and to predict the breakthrough curve From the results, it was found that the column system had higher adsorption capacity for treating RhB For future work, it is noted that some experiments have been done to know about the BSG, much work is necessary (i) to modify the BSG for higher adsorption capacity, (ii) to better understand the adsorption mechanism, and (iii) to further analyze the performance of adsorption processes for dye removal from real industrial effluents   v   Introduction Synthetic dyes are important materials that are widely used in many industries such as textiles, leather, wool, printing, cosmetics, paper, pharmaceutical and food industries There are many structural varieties of dyes, such as acidic, basic, disperse, azo, diazo, anthraquinone based and metal complex dyes1 It is estimated that over 100,000 dyes are commercially available Approximately, 8×105 – 9×105 tons of dyes are produced every year, with half of them being azo dyes2 Azo dyes are artificial dyes that contain an azo functional group, which have turned out to be the most problematic dyes to the environment In industrial processes, approximately 10 – 15% dyes are wasted in effluents during dying processes3 Discharging of wastewater containing dye compounds into water sources has significantly reduced water quality Since they have a synthetic origin and complex aromatic molecular structures, azo dyes are usually inert and difficult to biodegrade in waste streams1 They also affect photosynthetic activities of aquatic lives because dyeing effluents will deplete the dissolved oxygen contents in water and inhibit sunlight from reaching to the water sources4 In addition, dye wastewater and their degradation products are usually poisonous, mutagenic, teratogenic and carcinogenic, which are certainly harmful to aquatic organisms and human beings Rhodamine B (RhB) is a dye material mostly used to dye silk, wool, cotton, leather and paper5 It can irritate eyes, skin, respiratory and gastrointestinal tract     Therefore, proper techniques and processes are necessary in industries for efficient removal of these toxic chemicals from water bodies Numerous physico-chemical processes have been proposed and applied for treatment of dye wastewater.5 Customary treatment processes including physical, chemical, biological1, comprising adsorption6, coagulation/flocculation7, advanced oxidation processes8, reverse osmosis, ion-exchange9, electrochemical, photochemical and photo-catalytic degradation However, some traditional activated sludge processes were found to be ineffective in dye wastewater treatment, since dyes are usually chemical resistant, light stable and non-biodegradable10 Some previous studies have showed that 11 of 18 dye compounds passed through sludge process practically untreated, only can be adsorbed on the activated sludge and only were biodegraded11 Moreover, the application of some physical and chemical methods are restricted because of high operating cost, excessive use of toxic chemicals or strict application conditions12 As dye wastewater cannot be efficiently treated by traditional methods, the adsorption of dyes on some specific solid materials was recommended by some researchers due to flexibilityand simplicity of design, ease of operation, insensitivity to toxic pollutants and the harmless nature of involved substances3, 11 The process of the adsorption refers to that a waste material is concentrated at a solid surface from its liquid or gaseous surroundings13 Because of the     excellent mechanical and chemical stability, high specific surface area and resistance to biodegradation, some inorganic materials have been preferentially applied in adsorption studies The carbon-based inorganic supports have been developed for removal of dyes in the industrial effluents14 Sulfonated coals have been found to have good sorption performance for synthetic dyes15 Further studies also reported that the activated carbon can efficiently remove the azo dyes Orange P and Red Px16 Similarly, it has been proved that activated carbon can also remove acid dyes17 The excellent adsorption capacity of silica was reported in the removal of textile dye Basic Blue from effluents and was employed for adsorption of Rhodamine B, Acid Red 4, and Nile Blue sulfate from aqueous solutions18 Alumina has also been used for treating wastewater containing Rhodamine B and Nile Blue sulfate19 The results shown above demonstrated that inorganic sorbents possess good adsorption capacity for considerable type of dyes However, one serious problem of these kinds of sorption materials is high energy consumption Producing adsorbent for commercial application is fairly expensive Since a large quantity of sorbent is needed in practice for the removal of dyes from large volume of wastewater, the high cost obstructs their development and application10 Due to the high cost of above mentioned adsorbents such as activated carbon, growing interests have turned to exploit and apply the low-cost, alternative, renewable, naturally-occurring, and readily available organic biosorbents in     Fig 10 Effect of flow rate on the removal of Rhodamine B in fixed bed column Table column data and parameters with different flow rate Bed Treated Breakthrough Biosorption Flow rate tb te height volume point (50%) capacity (mL/min) (min) (min) (cm) (mL) (min) (mg/g) 50 390 780 230 2.04 30 260 1040 150 2.67 20 190 1140 70 1.86 3.5.3 Effect of initial dye concentration The influence of initial dye concentration was studied between 5.0 and 10.0 mg/L in the constant bed height of cm at the flow rate of mL/min The experimental results are showed in Fig.12 and other column parameters are presented in Table The results indicated that, when the initial concentration of dye solution increased, the time of 50% breakthrough capacity decreased This can be explained that a lower concentration gradient means a lower molecular loading, which causes a slower transportation of solute This may   29   lead to a decreased diffusion coefficient (or mass transfer coefficient)42 In turn, the adsorption capacity of BSG increased from 1.86 to 2.67 mg/g with the increasing initial dye concentration The probable explanation is that when the loading concentration increased, the mass transfer and the driving force increased40a At higher concentrations, the volume of treated dye solution dereased The results are in agreement with other previous work52 Fig 11 Effect of initial concentration on the removal of Rhodamine B in fixed bed column Table column data and parameters with different initial dye concentration Bed height (cm) Initial concentration (mg/L) tb (min) te (min) Treated volume (mL) Breakthrough point (50%) (min) Biosorption capacity (mg/g) 5.0 50 410 1640 210 1.86 7.5 40 360 1440 180 2.4 10.0 30 260 1040 150 2.67 3.5.4   Application of Thomas model 30   The Thomas model53 is one of the most general and widely used models in describing the column adsorption model and predicting column breakthrough data It assumes the Langmuir kinetics of sorption – desorption and no axial dispersion, and is derived with the assumption that the rate driving force obeys second-order reversible reaction kinetics This model also assumes a constant seperation factor but it is applicable to either favorable or unfaveorable isotherms51-52 (a)   31   (b) (c) Fig.11 Modified Thomas model for biosorption of Rhodamine by BSG on experimental data (a) effect of bed height (b) effect of follow rate (c) effect of initial dye concentration   32   Table Thomas Model parameters for the removal of Rhodamine B by BSG Loading Bed height Flow rate kTh (mL/min q0 (mg/g) R2 conc.(mg/L) (cm) (mL/min) mg) × 10 10.0 0.239 25.35 0.9622 10.0 0.257 22.65 0.9712 10.0 0.243 27.53 0.97 10.0 0.327 20.14 0.9148 10.0 0.157 21.48 0.9547 7.5 0.211 24.31 0.9375 5.0 0.304 20.37 0.9385 The rate constant (kTh) charaterises the rate of dye transfer from liquid solution onto the biosorbent Fig 11 describes the modified Thomas model when fitted with the experiment data Other parameters calculated from the plotting were shown in Table The column data fitted to the Thomas model and the coefficients were obtained using linear regression analysis As the loading concentration increased the value q0 increased, while the kTh got decreased and reached lowest value at the concentration of 7.5 mg/L As it is known that the driving force for adsorption is the concentration difference between dye solution and dye on the adsorbent, there may be other machanism influencing the the adsorption processes These results showed that with the initial dye concentration of 10 mg/L, cm bed height and mL/min flow rate, the adsorption performance was the best This indicated that a higher column height, higher dye concentration and a suitable flow rate are the keys for the   33   high adsorption efficiency Conclusion The BSG was found to be one of the promising biosorbents for the uptake of RhB dye solution due to its low cost, easy availability, and possibility to treat the dye at a low concentration The utilization of BSG may be the main advantage of the present study because it is an industry waste material The RhB removal efficiencies at low concentrations (2.5-10.0 mg/L) of BSG were tested in the light of equilibrium, kinetics and isotherm parameters The solution pH, and initial dye concentration play important roles in affecting the capacity of the biosorbent When the solution is neutral or alkali, the removal efficiency is much higher than that for the acidic solution The kinetics of RhB biosorption onto BSG follows the pseudo-second-order model The biosorption pattern of RhB onto BSG was well fitted with Freundlich isotherm model The heterogeneous parameter 1/n is 0.147, the smaller 1/n, the greater heterogeneity And n (6.8) is between one and ten, showing a favorable sorption process   Fixed bed column experiments were also 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Charumathi, D.; Das, N., Packed bed column studies for the removal of synthetic dyes from textile wastewater using immobilised dead C tropicalis Desalination 2012, 285 (0), 22-30 52 Sadaf, S.; Bhatti, H N.; Ali, S.; Rehman, K.-u., Removal of Indosol Turquoise FBL dye from aqueous solution by bagasse, a low cost agricultural waste: batch and column study Desalination and Water Treatment 2013, 52 (1-3), 184-198 53 Thomas, H C., Heterogeneous ion exchange in a flowing system Journal of the American Chemical Society 1944, 66 (10), 1664-1666   43   ... of Rhodamine B in fixed bed Fig 10 Effect of flow rate on the removal of Rhodamine B in fixed bed Fig 11 Effect of initial concentration on the removal of Rhodamine B in fixed bed column Fig.12... characteristics of brewer’s spent grain (BSG) have been analyzed For batch study, the effects of pH of dye solution, initial dye concentration, contact time, and biosorbent dosages were analyzed For biosorption... reported in the removal of textile dye Basic Blue from effluents and was employed for adsorption of Rhodamine B, Acid Red 4, and Nile Blue sulfate from aqueous solutions18 Alumina has also been used