Transilvania University of Brasov, Romania Dept. Renewable Energy Systems and Recycling

Transcription

1 Nanoclusters obtained by modified fly ash with organic additive and the adsorption performance in removing the pollutants from complex wastewater t Maria VISA, Luminita ANDRONIC, Anca DUTA Transilvania University of Brasov, Romania Dept. Renewable Energy Systems and Recycling

2 Outline The Problems The Path The solution(s): The materials The technique Conclusions

3 The objective To assess the ability of low cost fly ash in removing dyes (BB+BR) and Cu 2+ from multi-component solution by adsorption and photodegradation on FA (CPH- Brasov, Romania), modified and optimized

4 1.a. The problems WATER: very good solvent for Inorganic and Organic substances. Industries: - Electroplating and metal surface treatment processes - metallurgy, metal coating and plastics -emulsion polymerization - paint manufacture - inorganic pigments, dye finishing - cosmetics (polish, sun-care) - pharmaceuticals - leader industry - agriculture Wastewater (pollutants persistence) - heavy metals dyes, surfactants Target: - health of humans - ecosystem

5 1.b. Toxicity of heavy metals (20 HM); 1.c. Toxicity of dyes Cu (II) stable element HM can covalently bound to organic molecules can not be metabolized bio-accumulative (pas up to food chain to humans) Ions of heavy metals in aquatic systems HM are taken into the body: - inhalation - ingestion - skin absorption HM are absorbed by living organisms Cu (EPA) drinking water limit: 5 ppb Toxicity symptoms - severely irritates the stomach, leading to vomiting of blood, abdominal pain, hypotension Dyes: pollutant persistent eutrophication - disturbing the eco-balance affected water, transparency, reducing of light penetration,; -can be carcinogenic and mutagenic - FDA limits in food the colors: 15 ppm.

6 2. The path(s) More steps for treatment of each pollutant (complex installation) The conventional processes: - chemical precipitation - coagulation and flocculation l - from industrial i wastewaters t - ion-exchange - reverse osmosis - membrane nanofiltration and utrafiltration - photo-degradation using wide band gap semiconductors: TiO 21 or WO 32 choosing one or a complex solutions OR Single step process for simultaneous removal of more pollutants, HM, surfactants and dyes - (processes interference) [1] Maria Vişa, Anca Duţă, TiO2/fly ash novel substrate for simultaenous removal of heavy metals and surfactants, Chemical Engineering Journal, vol.223, (2013), [2] Visa, M., Duta, A., Tungsten oxide and fly ash mixtures for single step wastewater treatment process, J. of Optoelectron. and Adv. Mat., 2010, pp

7 Single step process for simultaneous removal of: Dyes HM cations ( Cu 2+ ) Photodegradation /adsorption Adsorption Requests for technologic process: 1. Advanced treatment efficient even at very low pollutants concentrations (but above the admissible discharge limits) 2. Upscalable process accessible technology for materials obtaining technologically feasible wastewater treatment process low cost

8 3. The solution Combined substrates, combined mechanisms Dyes, Surfactants Photodegradation Wide band gap semiconductor Water stable Highly efficient HM, dye, surfactants Adsorption High specific surface Negatively charged Low cost (modified) TiO 2 (modified) Fly Ash Powder mixture M. Visa, L. Andronic, A. Duta, Advanced treatment of waste water with Methyl Orange and heavy metals on TiO2, fly ash and their mixtures, J. Catalysis Today 144 (1) (2009) Visa, M., Bogatu, C, Duta, A, Simultaneous adsorption of dyes and heavy metals from multicomponent solutions using fly ash, J. Appl. Surf. Sci, 256, 2010, pp

9 Soil Stabilization and Amendment Construction materials Portland cement Mine Reclamation Stone Matrix Asphalt Bedding for slabs and pipes Drying agent as a Fill for abandoned means to improve storage tanks, shafts compaction Applications and dt tunnels Fly Ash Applications Embankment stabilization Composites (based on rubber and plastics Bridge abutment backfill - Adsorbent materials Cenospheres - Zeolites

10 Characterization of raw FA (CPH Brasov, RO) 1 Methods of analysis: AAS; gravimetric; i colorimetric i FA Composition major oxides [%] SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO K 2 O Na 2 O TiO 2 MnO P 2 O 5 SO 3 LOI Σ SiO 2, Al 2 O 3, Fe 2 O 3 >70% and the lime content is low thus according to the ASTM standards, the FA - type F. Raw FA Average roughness: 461 nm SiO 2 /Al 2 O 3 ratio over indicates good adsorbent properties Images AFM topography (Ntegra Spectra, NT-MDT model BL222RNTE)

11 Adsorption selectivity of substrate Charge electric surface of the substrate Type of ions ph of solution (may change charge of surface) electric negativ (adsorbent acid) adsorb Cu 2+, cations electric pozitiv (adsorbent bazic) adsorb anions FA surface modifications with: a) water (washed) efficiency (depend by type of FA) b) complexion agents efficiency <15% c) HCl efficiency <5% Why? is caused by a positive surface charge leading to repulsions between the surface ( SiOH 2+ ) and metal ions (positive)

12 Raw FA CET H 2 O The technological solution The materials FA w filtration, drying o C adsorbent NaOH 2N+ TiO 2 + HTAB 48h filtration, washing, drying o C The filtrate ph(10.2), conductivity (1.710 ms/cm) modified Fly Ash (FAA-DCS) sieved TDS (850 mg/l) Powder µm C FAA - DCS Optimisation of: 1. Heavy metal adsorption 2. Dye adsorption 3. Surfactants 3. Heavy metal + dye adsorption 4. Heavy metals + surfactants Highest adsorption efficiency i

13 Characterization of modified FA (FA W and FAA-DCS) tensity [a.u.] Int # * # #N Na 6 Al 6 Si 10 O 32 * Al 2 O 3 -SiO 2 Anatase syn " 0 Quartz syn # 0 o Rutile " Kyanite Al 2 SiO 5 * " # # 0 o (2) Fe 2 O 3 Ti 4 O (1) FAA-DCS FAw -SiO 2 (quartz), mullite (3Al 2 O 3.2SiO 5 ) γ-al 2 O 3 ), hematite (Fe 2 O 3 ), MnO 2 (ramsdellite), bixbyite (Mn 2 O 3 ) TiO 2 ( brookite, Ti 4 O 7 ) carbon (graphite) Crystallite size: anatase syn nm TiO 2 rutile nm quartz syn nm thete [degree] Crystalline degree: FAA-DCS is 63.9% The FA crystalline structure was evaluated by XRD (Bruker D8 Discover Diffractometer) The mainly processes: - most of the soluble compounds -re-precipitation p or polymorph p transformations,

14 The AFM topography and average roughness, mezo-pore size distribution The surface: Large mesopores, which are filled hydrated ions adsorption The roughness after adsorption is decreased Preferential adsorption on corners and edges. c) FAA-DCS /(BB+BR)Average Roughness: 73.18nm (d) FAA-DCS /(Cu 2+ + BB+BR)Average Roughness: 26.85nm The porosity - analysis using Autosorb-IQ-MP, Quantachrome Instruments Sample Specific surface Micropores Micropores Average pores area (BET) volume (t-plot) surface(t-plot) diameter [m 2 /g] [cm 3 /g] [m 2 /g] [nm] FAw FAA-DCS

15 SEM images FAw FAA-DCS annealing FAA-DCS

16 APPLICATIONS 1. Cu 2+ - adsorption on FAA-DCS FA - modified with NaOH 1N, 2N, 4N Why? hydroxide inclusion NaOH + FA Na a (AlO 2 ) b (SiO 2 ) c NaOH H 2 O new active site ( SiO - ) and ( AlO - ), allowing metals complexing at the surface 2( SiO - ) +M 2+ ( Si-O) 2 M 2( AlO - )+M 2+ ( Al-O) 2 M (M 2+ ) aq - cations hidrated [Cu(H 2 O) 4..5 ] 2+ Property Copper Dehydrated ionic radius [nm] Hydration number 4 5 Hydrated ionic radius [nm] 0.295

17 BB + BR removed from multi-component solution Concentration measurements: Cations: AAS (Analytic Jena ZEEnit 700) Cu = nm Dyes:Perkin Elmer Lambda 25 BB = 629 nm; BR = 501 nm BR Adsorption and photodegradation Batch experiments, stirring, at C Substrates:FAA -DCS ms : Vs= 0.5g : 50 ml BB da A/d 0,03 0,02 0,01 0,00-0,01-0,02 50 ppm BR+10 ppm BB 50 ppm BR+20 ppm BB 50 ppm BR+30 ppm BB 50 ppm BR+40 ppm BB 50 ppm BR+50 ppm BB 100 ppm BR 100 ppm BB BB, =652nm -0, Wavelength [nm] da A/d 0,03 0,02 0,01 0,00-0, ,02-0,03 BR, =444nm 10 ppm BR+50 ppm BB 20 ppm BR+50 ppm BB 30 ppm BR+50 ppm BB 40 ppm BR+50 ppm BB 50 ppm BR+50 ppm BB 100 ppm BR 100 ppm BB -0, Wavelength [nm]

18 Cu 2+ and dyes - removed from multicomponent solution on The influence of the contact time FAA-DCS ( c c ) 100 i Cu e Cu i c Cu Efficien ncy [%] Efficien ncy [%] Cu 2+ (Cu 2+ +BB+BR)/FAA-DCS (A) Cu 2+ (Cu 2+ +BB+BR)/FAA-DCS (F) Time [min] Efficiency Cu 2+ : % Contact time optimized: 90 min 120 BB(BB+BR+Cu 2+ )/FAA-DCS (F) BR(BR+BB+Cu 2+ )/FAA-DCS (F) BB(BB+BR+CuBR 2+ )/FAA-DCS (A) 100 BR(BR+BB+Cu 2+ )/FAA-DCS (A) Time [min] Efficiency BB: %(A);BR: % (A) BB: % (F); BR: % (F) Contact time optimized: 360 min Efficienc cy [%] BB(BB+BR)/FAA-DCS (A) BB(BB+BR)/FAA-DCS (F) BR(BR+BB)/FAA-DCS (A) BR(BR+BB)/FAA-DCS (F) Time [min] Efficiency BB: %(A);BR: % (A) BB: % (F); BR: % (F) Contact time optimized: 360 min

19 Efficiency [%] BB(BB+BR)/FAA-DCS (A) BB(BB+BR)/FAA-DCS (F) BR(BR+BB)/FAA-DCS (A) BR(BR+BB)/FAA-DCS (F) Time [min]

20 Removal efficiency on FAA-DCS substrate of dyes from multi-component pollutant systems Influence of H 2 O 2 H 2 O 2 + UV HO + HO ] Efficiency [% BB(BB+BR)/FAA-DCS (F) BB(BB+BR)/FAA-DCS,c 1 H 2 O 2 )(F) BB(BB+BR)/FAA-DCS,c 2 H 2 O 2 )(F) BR(BR+BB)/FAA-DCS (F) BR(BR+BB)/FAA-DCS,c 1 H 2 O 2 )(F) BR(BR+BB)/FAA-DCS,c 2 H 2 O 2 )(F) Efficiency BB: % (F); BR: % (F) +100mL H 2 O 2 BB: 86.44% (F); BR: % (F) mL H 2 O 2 BB: 98.04% (F); BR: % (F) Time [min] Contact time optimized: 360 min

21 XRD spectrum; IR - spectrum before and after contact with the (Cu 2+ + BB+BR) solution Intensity [a.u.] FAA - DCS after adsorption FAA - DCS (Na 25 CuO 2 ) 5 (SO 4 ) 45 ) Na 2 Cu(SO 4 ) theta [degree] (2) (1) Absorbance [a.u.] FAA-DCS FAA-DCS t=235 0 C FAA-DCS (BB+BR) FAA-DCS(BB+BR +Cu 2+ ) [cm -1 ] (1) (2) (3) (4) -copper oxide sulphide sulphate monocline -sodium copper sulphate indicating a possible chemical bonds FAw FAA-DCS FAA-DCS/(BB+BR) FAA-DCS/(Cu 2+ +BB+BR) Frequency: cm - 1 Si O Si or Si Al O cm -1 - attribut the hydroxyl group -Si OH, Al OH Al, Si OH Al Counts Voids distribution [ m] The particles size distribution evaluated from AFM

22 EDX spectra of FAA-DCS. Intensity of Si, Al, Cu on surface scanned after contact with the (Cu 2+ + BB+BR) BR) solution Elemen t Before adsorptio n Atom % FAA-DCS After adsorption Atom % C substrat N O Na Al Si S Ti Br Cu Total

23 Simultaneous adsorption of Cu 2+ and Dyes (BB+BR) The recommended parameters for simultaneous removal of the Cu 2+ and BB+BR: m FAA-DCS : V sol. 0.5 g : 50 ml t optimal = 90 min. Efficiency Cu 2+: % Efficiency BB;BR: >50 %

24 Kinetic parameters of the Cu 2+ and dyes adsorption and photodegradation Pseudo first-order, Lagergren equation, Langmuir-Hinshelwood Pseudo-second order kinetics developed by Ho and McKay Interparticle diffusion model n =1 n = 2 Interparticle Difusion FAA- DCS K L [min -1 ] R 2 [g mg -1 min -1 ] k 2 q e [mg/g] R 2 K id C R 2 Cu 2+ (Cu 2+ +BB+BR) Cu 2+ (BB+BR) (F) Cu 2+ (BB+BR) (A) Dyes BB(BB+BR+Cu 2+ ) BR(BR+BB+Cu 2+ ) possible chemisorption, involving valence forces between the adsorbent and the adsorbate or with dyes molecules - parallel mechanisms: first, second and interparticle diffusion - are likely for dyes and second mechanism - Cu - adsorption result of the higher copper mobility, Cu 2+ (H 2 O) 4 - adsorption studies - the efficiency follow the order: Cu 2+ >BR >BB Cu 2+

25 Adsorption process Langmuir isotherm linearization i Freundlich isotherm - linearizationi c q e cation e q 1 a max c q e cation max ln q eq Adsorption parameters of on FAA-DCS substrate ln k F 1 ln n C eq Parameters q max [mg/g] Langmuir Isotherm Freundlich Isotherm a [L/mg] R 2 n K F R 2 FAA-DCS Cu 2+ (BB+BR) (F)) Cu 2+ (BB+BR) (A) Cu 2+ : chemisorption(s) parallel mechanisms (?) active sites with significantly different affinity for the metals.

26 Conclusions The adsorption efficiencycy of Cu 2 + on FAA-DCS strongly depend of the surface area, composition, dosage, contact time, and HM concentration Cu 2+ and dyes adsorption on alkali-modified FA has convenient efficiencies after 90 min is not so strongly influenced by the dyes existent in the solution FAA-DCS substrate is recommended for simultaneous removal of Cu 2+ and dyes from wastewater resulted from textile industries The pseudo-second order kinetics describes well all the processes at medium Cu 2+ initial concentrations FAA-DCS was investigated as substrate for complex adsorption processes, involving three-component pollutant system: Cu 2+, BB and BR. The data show - if optimized fly ash can be a suitable substrate for efficient adsorption of a complex pollutants from wastewaters.

27 Acknowledgement This paper was supported by a grant of the Romanian National Authority for Scientific Research, CNCS UEFISCDI, project number PNII-RU-TE / /2013

28 What is the GENIUS Campus