SIMULTANEOUS ADSORPTION OF 11 VOLATILE ORGANIC COMPOUNDS BY AN ACTIVATED CARBON MADE FROM POLYSTYRENE SULFONIC ACID-BASED ORGANIC SALT

Introduction Carcinogenic VOCs are the first group of contaminants to be addressed under the new EPA Drinking Water Strategy. This group include 8 regulated compounds (benzene; carbon tetrachloride; 1,2-dichloroethane; 1,2- dichloropropane; dichloromethane; tetrachloroethylene; trichloroethylene; vinyl chloride) and 8 (aniline; benzyl chloride; 1,3- butadiene; 1,1-dichloroethane; nitrobenzene; oxirane methyl; 1,2,3-trichloropropane and urethane). We expect that our Polystyrende based adsorbents will be able to remove the 16 carcinogenic VOCs.

VOLATILE ORGANIC COMPOUNDS Volatile organic compounds (VOCs) become a major health issue worldwide because of their impact on human health and quality of life. Most of these chemicals are used as precursors to fabricate other chemicals. The carcinogenicity for some of these VOCs have been well determined; the remaining are suspected carcinogens Contamination of drinking water sources is often linked to liquid and solid wastes discharged into water bodies or soils.

Activated Carbon Adsorption onto activated carbon is known as one of the most effective methods for water purification. Activated carbon is a unique material that has the ability of adsorbing large amounts of impurities from liquid phase, due to its large internal surface area and a high degree of porosity Activated carbon can be made by carbonizing any material with a high carbon content such as wood, coconut shells, stones, coal, among others, and then activating it by a chemical or physical process

Batch Absorption Experiment COMPOUNDS: Carbon Tetrachloride 1,2-Dichloroethane Dichloromethane 1,1-Dichloroethane 1,2-Dichloropropane 1,2,3-Trichloropropane Tetrachloroethylene Trichloroethylene 1,3-Butadiene Benzene Benzyl Chloride

Batch Absorption Experiment POLYSTYRENE BASED AC -Carbonization at 800C of Poly (styrene sulfonic acid-co-maleic acid) Sodium Salt. -Soxhlet washing with HCl acid and distilled water. WOOD BASED AC - Commercial WV-A900

Batch Absorption Experiment SAMPLE PREPARATION: - 8mg of activated carbon -Polystyrene AC :250, 500, 1000, 2500 and 5000ppb. Duplicate -Wood AC: 100, 250, 500, 1000, 2500 and 5000ppb. Triplicate -Shacked over night, 15 hours. -5mL for GC/MS analysis -qe=(C 0 - C e )V/m

Batch Absorption Experiment

Langmuir Isotherm q e =mK L C e /(1+K L C e ) q e (mg/g): Equilibrium absorption C e (mg/L): Equilibrium concentration m (mg/g): Monolayer adsorptive capacity. K L (L/mg): Separation Factor defined by SF=1/(1+K L C 0 ) If SF>1 the isotherm is unfavorable If SF=1 it is linear If 0<SF<1 the isotherm is favorable

Langmuir Isotherm PBACWBAC Compound K L (L/mg) SF m (mg/g) R2R2 K L (L/mg) SF m (mg/g) R2R2 1,2,3trichloropropane ,2dichloropropane ,1dichloropropane TCE PCE Benzyl chloride ,3butadiene ,2dichloropropane Carbon tetrachloride Benzene Dichloromethane TOTAL

Langmuir Isotherm m: higher values for Polystyrene AC than Wood AC SF: Are between 0<SF<1, the isotherm is favorable R 2 : Over 0.90 for all compounds

1,2-Dichloromethane PCE

Carbon Tetrachlroide Benzene

TOTAL

Freundlich Isotherm q e =K F C e 1/n q e (mg/g): Equilibrium adsorption C e (L/mg): Equilibrium Concentration K F : Is an indicator of the adsorptive capacity when C e = 1mg/L. n: Related to material heterogeneity, greater its deviation from 1 then more heterogeneous.

Freundlich Isotherm Polystyrene ACWood based AC CompoundKFKF nR2R2 KFKF nR2R2 1,2,3trichloropropan ,2dichloropropane ,1dichloropropane TCE PCE Benzyl chloride ,3butadiene ,2dichloropropane Carbon tetrachloride Benzene Dichloromethane TOTAL

Freundlich Isotherm Polystyrene AC has much greater values for K F than does Wood AC. The parameter n is related to the heterogeneity of the adsorbent surface. The correlation coefficient R 2 showed values over 0.96 for most of the compounds.

1,2-Dichloroethane PCE

Carbon Tetrachloride Benzene

TOTAL

Langmuir-Freundlich Isotherm q e =mK s C e r /(1+K s C e r ) q e (mg/g): Equilibrium adsorption C e (mg/L): Equilibrium concentration m (mg/g): Related to the monolayer adsorptive capacity K s (L/mg): Affinity term r: Index of heterogeneity (0<r≤1).

Isotherm Parameters PBACWBAC m (mg/g) K s (L/mg) r R2R Langmuir-Freundlich Isotherm

Partition Coeficient 11 Compounds are considered hydrophobic with moderate to high values of Kow. It can be regarded as an indicator of the tendency of adsorption.

Pore Size Distribution AC S BET (m 2 /g) V t (cm 3 /g) V meso (cm 3 /g) V <0.7nm (cm 3 /g) V <1nm (cm 3 /g) CPS-Fe WVA

Reductive Dechlorination Experiment SAMPLE PREPARATION: 1mL from highest samples concentration of the Polystyrene Filtered and passed trough IC Calibration curve, using standards of 0.01, 0.05, 0.1, and 0.15 mMol

Reductive Dechlorination Experiment Polystyrene contained reduced iron on its surface in the form of clusters which could interact with chlorinated hydrocarbons. A mass balance was carried out to determine the percentage of the chlorinated compounds that was degraded. The total amount of chlorine in the VOCs in solution was umol. The amount of chloride detected was umol, suggesting that only around 1.5% of the chlorinated molecules were degraded.

Conclusion Batch adsorption experiments were carried out to examine the adsorption capacities of Polystyrene AC and Wood AC for VOCs. Polystyrene has almost twice the capacity than the Wood based. It turns out that the Polystyrene has well-developed micropores suitable for the adsorption of compounds with small diameters, such as the VOCs examined here. The Wood has a high mesopore volume but low micropore volume, making it less effective in capturing these VOCs.