PAHs for Sediment Remediation Dr. Mei Xin, Dr. Susnata Samanta, - PowerPoint PPT Presentation

Evaluation of Activated Carbons for Sequestration of PCBs and PAHs for Sediment Remediation Dr. Mei Xin, Dr. Susnata Samanta, David Flannery (Cabot Corporation, Boston, MA) Dr. Danny Reible (Texas Tech. University, Lubbock, TX) January 10, 2017

About Cabot Corporation A rich and unique history ▪ Over 130 years in operation ▪ Founded 1882 ▪ NYSE: CBT since 1968 ▪ Global specialty chemicals and performance materials company ▪ 45 manufacturing sites in 21 countries ▪ Core technical competencies in fine particles and surface modification ▪ FY2016 sales: $2.4B 2

Cabot Norit Activated Carbon ▪ World’s largest producer of activated carbon ▪ Manufacturing since 1916 ▪ 9 plants ▪ Sold globally ▪ Cabot makes activated carbon from many raw materials, including: ▪ Lignite coal ▪ Bituminous coal ▪ Coconut shell ▪ Wood ▪ Peat ▪ Products used widely in potable water and wastewater treatment 3

What is activated carbon? Characteristics • Large internal surface area • 1 teaspoon (5 g) has the same surface area as a football field (1,000m 2 /g) • Large internal pore volume (cc's/g) • Large adsorption capacity 4

Activated carbon forms POWDER GRANULAR EXTRUDATE 5

Activated Carbon for Sediment Remediation 6

Objective To provide information to help in design of caps  Freundlich sorption isotherms (Kf, 1/n) and adsorption kinetics for PCBs and PAHs required for sediment remediation design with activated carbons  Information for engineering firms to aid in design of sediment remediation caps using CAPSIM Adsorption capacity vs. kinetics 1. Relative performance of PAC vs. GAC 2. Impact of natural organic matter (NOM) on contaminant adsorption 3. Relative performance of carbons from different raw materials 4. 7

Experimental Design Topic Description • Sample prep All experiments conducted in separate batches for 1L (PAH) and 250 ml (PCB) water solutions in amber bottles • Water matrix 1L deionized water (DI) plus 350 mg of instant ocean salt and 100 mg of sodium azide • NOM loaded water: Suwannee River NOM (50 mg into 1L water solution) • Activated carbons Powdered AC (PAC), granular AC (GAC) • Raw materials: lignite, bituminous, coconut shell • Contaminants PAHs: naphthalene, phenanthrene, pyrene, benzo(a)pyrene (EPA 8270) • PCB congeners: 18, 52, 77, 101, 118, 151 (77, 118: dioxin-like) (PDMS (polydimethylsiloxane) fiber extraction / GCMS) • CAPSIM Model All modeling used CAPSIM developed by Prof. Danny Reible 8

Bench Scale Adsorption Results 9

Kinetics Study – PAC vs. GAC  At equilibrium state, PAC and GAC adsorb same amount of PAHs  PAC and GAC both show fast adsorption for low molecular weight PAHs (naphthalene MW 128)  PAC shows much faster adsorption than GAC for high molecular weight PAHs (pyrene MW 202 ) 10

Freundlich Adsorption Isotherms Lignite carbon is resilient to NOM impact · Lignite carbon was exposed to NOM 25ppm for 30 days prior to the adsorption measurement 17 OCTOBER 2017 / CABOT OVERVIEW 11 11

Compared to lignite carbon, coconut shell carbon is more sensitive to NOM impact PHENANTHRENE PCB 118 Coconut AC Lignite AC Coconut AC Lignite AC 150 /AC Capacity DI, % AC Capacity NOM AC Capacity NOM /AC Capacity DI, % 125 100 100 75 75 50 50 25 25 0 0 0 50 100 150 0 5 10 15 Phenanthrene Conc. (ug/L) PCB-118 Conc. (ng/L)  Meso and macro-pores of lignite carbon minimize NOM impact  NOM impact on lignite and coconut carbons is consistent with results from potable water and wastewater treatment plants 12

CAPSIM Model Simulations 13

CAPSIM Cap Design Model Parameters Parameter range analyzed in this project Parameter Description Low Medium High Reactive cap Sand + activated carbon Used for all scenarios (15 cm cap + 30 cm sediment) % Activated Carbon Mass % of activated carbon in cap 1% 5% 10% Upwelling rate Fresh water up-flow in sediment (cm/day) 0 1 3 PAH concentration PAH concentration in pore water (µg/l) 100 -- 3000 PCB concentration PCB concentration in pore water (ng/l) 1 -- 100 NOM Natural organic matter in pore water (ppm) 0 -- 25 Half-life rate Mass transfer rate of contaminant to AC Local 1 day 30 days equilibrium 14

CAPSIM Modeling – Naphthalene PAHs and PCBs quickly breakthrough a 100% sand cap Sand (15 cm) Upwelling Rate Upwelling Rate Sediment (30 cm) Sand cap without activated carbon at low and high upwelling rates 15

CAPSIM Modeling – Naphthalene Lignite and coconut PAC performance is similar (10% PAC, 1 cm/day upwelling, 25 ppm NOM) LIGNITE PAC COCONUT PAC    No PAH breakthrough after 100 years with either activated carbon 16

CAPSIM Modeling – PCB 101 Lignite and coconut PAC performance is similar (5% PAC, 1cm/day upwelling, 25 ppm NOM) LIGNITE PAC COCONUT PAC    No PCB breakthrough after 100 years with either activated carbon 17

CAPSIM Modeling – PCB 77 PAC is better than GAC at high upwelling rate (20%AC, 3cm/day upwelling, 25ppm NOM) PAC GAC   Carbons made from different feedstocks perform the same under both conditions 18

CAPSIM Modeling - Pyrene Need more bituminous AC to achieve the same performance as lignite AC for high MW PAHs LIGNITE PAC BITUMINOUS PAC    Conditions: 1% AC, 1 cm/day upwelling rate, no NOM  When carbon dose is 5%, there is no significant difference between lignite and bituminous carbons 19

Conclusions Investigation Conclusions • Capacity vs. Adsorption capacity is the same for PAC and GAC although GAC may absorb less due to Kinetics slower kinetics of sorption • HOCs have low solubility and migrate slowly, so kinetics is not important if low upwelling • PAC vs. GAC Adsorption rate of HOCs is much faster with PAC • PAC may be a better solution than GAC for PCBs if there is high upwelling rates because kinetics become very important • NOM at 25 mg/L reduces performance of coconut carbon by up to a factor of 5 • Impact of NOM NOM at 25 mg/L has negligible impact on performance of lignite carbon • Conclusion – consider lignite carbon rather than coconut carbon in NOM • Feedstocks All carbons perform about the same for PAHs and PCBs when there is no upwelling • All GACs perform the same (quick breakthrough) when there is very high upwelling 20

For further information, please contact: Billy Barron Regional Marketing Manager Cabot Norit Activated Carbon T +1 678 297 1549 M +1 470 281 8465 Billy.Barron@cabotcorp.com One Point Royal 4400 North Point Parkway Suite 200 Alpharetta, Georgia 30022 www.cabotcorp.com Battelle Conference Booth #431 21 17 OCTOBER 2017 / CABOT OVERVIEW 21

Acknowledgements Prof. Danny Reible, PhD PE BCEE NAE Donovan Maddox Distinguished Engineering Chair Texas Tech University Tariq Hussain Ph.D. Candidate Texas Tech University Dr. Magdalena Rakowska Postdoc Researcher Texas Tech University Xiaolong Shen Ph.D. Candidate Department of Chemical Engineering The University of Texas at Austin 22 17 OCTOBER 2017 / CABOT OVERVIEW 22

Questions? 23