title: Pentachlorophenol removal from aqueous matrices by sorption with almond shell residues.
abstract: Sorption with activated carbon has been the technique preferred for pentachlorophenol (PCP) removal from contaminated waters, but regeneration needs and high operation costs are supporting a renewed interest in the search for alternative sorbents. Among them, almond shell, an agricultural by-product, provides interesting economical advantages, once shells account for 50% (in mass) of the whole almond. In this work, the capacity of almond shells to remove PCP from waters without previous activation was studied in batch conditions. While PCP analysis was performed solid-phase microextraction (SPME) followed by gas chromatography with electron capture detection (GC-ECD), mercury porosimetry and Fourier transform infrared spectroscopy (FTIR) provided a preliminary physical and chemical characterization of the sorbent. Almond shells were essentially a macroporous material, with an average surface area of 12.9+/-2.8 m2/g. The efficiency of PCP removal was 93+/-14%, in 24 h, with an initial concentration of 100 microg/l PCP and 5 microg PCP/g shell. Isotherm data adjusted better to Freundlich equation, where K(F) and 1/n were 0.075+/-0.081 mg(1-1/n) l(1/n) and 1.882+/-0.289, respectively. Average desorption efficiency was 7%, indicating strong adsorption capacity. Results proved that almond shells may be an excellent low-cost alternative for PCP removal from contaminated waters.
authors.affiliation: LEPAE-Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: B N
authors.initials: BN
authors.lastname: Estevinho
authors.forename: N
authors.initials: N
authors.lastname: Ratola
authors.forename: A
authors.initials: A
authors.lastname: Alves
authors.forename: L
authors.initials: L
authors.lastname: Santos
mesh_terms: D000327:Adsorption; D005240:Feasibility Studies; D009754:Nuts; D010416:Pentachlorophenol / Q000493:pharmacokinetics*; D027861:Prunus; D052617:Solid Phase Microextraction; D014867:Water
chemical_list: D014867:Water; D010416:Pentachlorophenol