Efficient phenol removal of wastewater from phenolic resin plants using crosslinked cyclodextrin particles

Abstract

Removal of phenolic compounds from a raw industrial wastewater from phenolic resin processing, of which the components are phenol (8.9 wt%), m-and p-cresols (0.33 wt%), and xylenols (0.044 wt%), was carried out by using crosslinked cyclodextrin particles as a sorbent. A series of sorbents was prepared by varying the combination of cyclodextrin (CyD), β-CyD, γ -CyD, Mix-CyD (α-CyD:β-CyD:γ -CyD:dextrin = 30:10:10:50 wt/wt), the crosslinker, hexamethylene diisocyanate (HDI) or toluene-2,6-diisocyanate, and their molar ratio in the reaction batch. The removal of the phenolic compounds from raw industrial wastewater was an instantaneous process and was completed within about 5 min. The best removal efficiency was obtained by the crosslinked β-CyD with HDI in a 1:8 molar ratio or the crosslinked Mix-CyD with HDI, also in a 1:8 molar ratio. The prepared sorbents were efficiently regenerated by elution of the adsorbed phenols from the crosslinked polymers with methanol.

Preparation of crosslinked β‐cyclodextrin polymer beads and their application as a sorbent for removal of phenol from wastewater

“…In our research in a recent article, 1,2 we carried out an attempt to find a novel cyclodextrin (CyD) polymer for the removal of phenols from raw industrial wastewater discarded from phenolic resin processing, and found that the most efficient removal method was by pulverized crosslinked β-CyD with hexamethylene diisocyanate (HDI) in a 1:8 molar ratio, or pulverized crosslinked Mix-CyD (α-CyD: β-CyD: γ-CyD: dextrin = 30 : 10 : 10 : 50 wt/wt) with HDI, also in a 1:8 molar ratio, with a mean diameter of below 53 μm. However, the types of equipment that can be employed for the removal of pollutants from water are the stirred-tank, fluidized bed, and column.…”

“…With the present [β-CyD/HDI(1/8)]/HDI polymer beads, a two-stage uptake of phenol was observed, while with β-CyD/HDI(1/8) polymer powder only almost instantaneous adsorption reaching equilibrium was observed. 1,2 This behavior seems to be due to both the increase in particle size and the two-layer structures of the polymer beads resulting from the two stages of crosslinking of β-CyD, as shown in Fig. 3 (A): a hard skin layer (outer layer) of poor permeability and a soft core layer (inner layer) of good permeability.…”

“…1,2 The adsorbed phenols were removed from the adsorbent conducted by soaking it in 50cm 3 of methanol at 25 °C. After 24 h the adsorbent was filtered off and dried in vacuo.…”

Adsorption kinetics and thermodynamics of water-insoluble crosslinked β-cyclodextrin polymer for phenol in aqueous solution

“…The ingestion of such contaminated water in the human body causes protein degeneration, tissue erosion and paralysis of the central nervous system together with damage to the kidneys, liver and pancreas. 13 Water-insoluble β-CD polymer, which is synthesized by crosslinking the hydroxyl groups of β-CD with diisocyanates to form a stable crosslinked network, have already been used by investigators to remove phenol from wastewater, [14][15][16] but little is known about the adsorption kinetics and thermodynamics of the β-CD polymer for phenol.…”

β-Cyclodextrin functionalized polystyrene porous monoliths for separating phenol from wastewater

“…In recent years, many studies have been carried out on the fabrication of cross-linked ␤-cyclodextrin polymers for the adsorption of phenol (Romo, Penas, Isasi, Garcia-Zubiri, & Gonzalez-Gaitano, 2008;Yamasaki, Makihata, & Fukunaga, 2006). The chemical stability of polystyrene makes it a good support material for ␤-CD and Jiang et al (2006) prepared a novel copolymer via copolymerization of (6-O-butene diacid ester)-␤-cyclodextrin and styrene.…”