Adsorptive Separation and Recovery of Chlorinated Phenols

Abstract

Adsorption as a process for the removal and recovery of chlorinated phenols (dichlorophenols, trichlorophenol, and 2,4-dichlorophenoxyaxceticacid) from aqueous solutions has been studied. Equilibrium adsorption studies of these compounds were carried out individually using three different commercially available polymeric resins; Amberlite XAD-4, Amberlite XAD-7, and INDION 1014 MN-2 (IMN-2) having a different surface area and polarity to compare their equilibrium loading capacities. As IMN-2 gave the highest capacity, it was used for further investigation involving column breakthrough studies. A combined approach of solubility and steric hindrance is used to compare the adsorption capacity of isomers. The effect of presence of salts (NaCl and Na 2 SO 4 ) on the adsorption capacity of 2,3-DCP and 2,4-DCP (only on IMN-2) was also studied. A Langmuir adsorption isotherm was found to correlate the equilibrium data. Column studies were also carried out to investigate the breakthrough behavior at a flow rate of 0.16 bed volume/min. LUB values were calculated to find out the column efficiency. 15-30 bed volumes of methanol accomplished the regeneration of the loaded bed.

A comparative study of 2-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol adsorption onto polymeric, commercial, and carbonaceous adsorbents

“…They used cattail fiber-based AC for adsorbing 2,4-DCP and 2,4,6-TCP derivatives that found the highest affinity to 2,4,6-TCP indicating that the uptake capacity increases with the degree of chlorination. According to Bhongade et al [15], when a compound has low solubility in water, it has a tendency to concentrate on non-polar surfaces where it has a higher affinity. Moreno-Castilla et al [52] stated that the uptake capacity improved with (i) increased hydrophobicity of the substituents and (ii) decreased water solubility of the phenolic compound.…”

“…They exhibit a perfect skeleton strength, high surface area, and also their main physico-chemical properties can be improved by modifying polymerization conditions [8]. On the other hand, commercial poly(styrene-divinylbenzene) adsorbents, such as XAD-4, XAD-12, or XAD-16 can be efficiently used for the treatment of phenolic pollutants from wastewater [14,15].…”