Treatment of a Selected Refinery Wastewater Compound (Benzene) by Chitin and Chitosan by Dr Maryam Mohamed

Transcription

1 Treatment of a Selected Refinery Wastewater Compound (Benzene) by Chitin and Chitosan by Dr Maryam Mohamed

2 Outline Introduction - Benzene - Treatment Methods for VOCs - Treatment Techniques of Oil Refinery Wastewater Aim and objectives Methodology - Experimental Programme - Adsorption Isotherm Models Results Conclusions Recommendations

3 Introduction Benzene is a toxic organic compound Scarce of water in GCC countries Main sources of benzene wastewaters Benzene level mg/l in refinery wastewater BAPCO Bahrain Petroleum Company

4 Benzene Regulations & Guidelines Agency Regulations and guidelines Classifications International IARC WHO National EPA Carcinogenicity classification Drinking Water Quality Guidelines Designated as hazardous substances in accordance with Section 311(b)(2)(A) of the Clean Water Act National primary drinking water standards MCLG MCL Water quality criteria for human health consumption of: Water + organism Organism only and values Group mg/l Yes Zero mg/l 2.2 μg/l 51 μg/l

5 Treatment Methods for VOCs Chemical, biological and physico-chemical treatment methods Removal by the activated carbon adsorbents Kuwait Battling Oil Spill in the Gulf (Auguest 2017).

6 Treatment Techniques of Oil Refinery Wastewater

7 Aim and objectives of the Research Aim - Potential of using chitin and chitosan as adsorbents and the development of Greener" processes Objectives - Effects of adsorbent dose, initial concentration of benzene, and contact time

8 Adsorption Isotherm Models Isotherm Model Y-axis Slope Equation Intercept X-axis Langmuir M1 ab X X M = ab C e 1 + b C e 1 Ca e Freundlich ln 1 X nm X M = KC 1/n e ln CK e Redlich Peterson Temkin Dubinin Radushkevich ln K R C e M β X 1 M = K RC e ln(a C R e ) X β 1 + a R C e B X X 1 M = B 1 ln(k T CB e 1 ) lnln(k C e T ) M X B ln M = X q d exp( B D [RT ln(1 ln( D R 2 T 2 ln(q D ))] 2 ) M C ) C e e 2

9 Kinetic Models Kinetic Model Pseudo-first order ln Y-axis Equation ln 1 U( t) 1 ( t) K t U 1 U ( t) X-axis t X X e Pseudo-second order t X 1 h t X 1 X t 2 h K2Xe e t Intraparticle diffusion X M XK tm c id t

10 (a) Experiments (b) Methodology Chitin and chitosan (a) in glass tubes and (b) after mixing with solutions. Benzene Deionized Water (50 ml) Adsorben t (0.5 g) Sample placed in a rotary shaker at 300 rpm for 24 hr. Shaker (250rpm, 24 hours) Suspended particles settle down by placing the samples in centrifuged at 3000 rpm for 20 minutes. Centrifuge (3000rpm, 20 min)

11 Experiments Methodology The supernatant was analyzed for the residual concentration of benzene using GC-MS. (a) (b) (c) (a), (b) and (c) Chromatogram and spectrum of benzene solution (temperature = 22 ± 1 C, initial concentration of benzene =100 mg/l, adsorbent dosage = 15 g/l)

12 Methodology Stock solutions for single-component benzene system was prepared 33 ml of test solutions containing different initial benzene concentrations (C 0 ) was prepared Effect of initial benzene concentration (C 0 = 5, 10, 20, 50, 100, 150 and 200 mg/l) Effect of adsorbent dose (C 0 = 50mg/l) Effect of contact time (C 0 = 5, 10, 20, 50, 100mg/l) 0.5 g± of adsorbent was added to the tubes Adsorbent dose of 0.1, 0.3, 0.5, 0.7, 0.9 g ± was added to the tubes 0.5 g± of adsorbent added to the tubes Samples were shaken at 300 rpm for 24 hrs Samples were shaken at 300 rpm for 24 hrs Samples were shaken at 300 rpm for 2, 4, 6, 8, 12, and 24 hrs Samples were centrifuged at 3000 rpm for 20 mins Supernatant was extracted and critically analysed using GC-MS

13 BBBBB BBBBB.. Methodology o-xylene, 12% p-xylene, 9% m- Xylene, 31% Benzene, 11% Toluene, 26% Ethylben zene, 11% AAAAAAAAAAAA Schematic diagram of experimental set-up of graft copolymerization of crosslinked chitosan microspheres Creating macroradicals AAAAAAAAAAAA. Structure of raw chitosan and cross-linked chitosan Schematic diagram of grafting from mechanism Reactions that may occur in chemical modification by crosslinking Adding monomer B to trunk polymer A AAAAAAAAAAAA BBBBB Graft copolymerization of methacrylic acid with chitosan

14 X/M (mg/g) M/X (g/mg) ln((k R C e M/X)-1) Benzene Uptake (mg/g) Residual Benzene Concentration (mg/l) Benzene Uptake (mg/g) Results (a) (b) (c) Initial Benzene Concentation (mg/l) Adsorbent Concentration (mg/ml) Chitin Chitosan Time (hr) The effects of (a) Initial adsorbate concentration (b) adsorbent dosage and (c) contact time, on benzene removal by chitin and chitosan (a) C e (mg/l) (b) /C e (l/mg) (a) Freundlich and (b) Langmuir isotherm models (room temperature = 22 ± 1 C; adsorbent dosage = 15 g/l) ln C e Chitin Chitoson

15 log log C 0 /(C 0 -(X/M)(m)) Benzene Uptake (mg/g) ln[(1-u(t)] t/x Results (a) Time (hr) (b) Time (hr) (c) 4 3 (d) Chitin Chitoson log t t 1/2 (hr 1/2 ) (a) Pseudo-first-order rate equation, (b) Pseudo-second-order rate equation (c) Bangham s equation and (d) Intra-particle diffusion equation, (temperature = 22 ± 1 C, initial concentration of benzene =50 mg/l, adsorbent dosage = 15 g/l).

16 Results The SEM micrograph (20 kv) of (a) chitosan (b) glutaraldehyde crosslinked with chitosan (c) chitosan modified with poly(methacrylic acid) FTIR spectra of (a) chitosan (b) glutaraldehyde cosslinked chitosan and (c) methacrylic acid grafted with cosslinked chitosan

17 Results EDX analysis of (a) chitosan (b) of glutaraldehyde crosslinked with chitosan and (c) grafted crosslinked chitosan with poly(methacrylic acid TGA analysis of chitosan, crosslinked chitosan and crosslinked chitosan grafted with poly(methacrylic acid) under nitrogen gas.

18 ln((k R C e M/X)-1) ln((k R C e M/X)-1) M/X (g/mg) M/X (g/mg) a Benzene Toluene Ethylbenzene m-xylene o-xylene p-xylene /C e (l/mg) b Benzene Toluene Ethylbenzene m-xylene o-xylene p-xylene /C e (l/mg) Langmuir isotherms for BTEX sorption by (a) chitosan and (b) modified chitosan at various initial BTEX concentrations (adsorbent dose = 0.5 g; room temperature = 22 ± 1 C) a Benzene Toluene Ethylbenzene m-xylene o-xylene p-xylene ln C e Results b Benzene Toluene Ethylbenzene m-xylene o-xylene p-xylene ln C e Redlich Peterson isotherms for BTEX sorption by (a) chitosan and (b) modified chitosan at various initial BTEX concentrations (adsorbent dose = 0.5 g; room temperature = 22 ± 1 C)

19 Conclusions Freundlich isotherm was the best model to fit the equilibrium data. Chitosan showed better removal efficiency than chitin. Chemically modified chitosan showed the best removal among other adsorbents The pseudo-second order rate model described best the adsorption kinetics of benzene for the two selected adsorbents.

20 Recommendations for Further Research Real samples of industrial effluents Effects of other competing ions Integrated processes Collaborative research with other GCC countries and UK

21 Thank You