title: Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on a mixed bed adsorbent (acid activated montmorillonite-silica gel) column.
abstract: A novel approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on a mixture of acid activated montmorillonite (AAM)-silica gel column. The effect of various parameters such as acidity, stability of the column, sample volume, interfering ions, etc., were studied in detail. The adsorbed complex could be easily eluted using polyethylene glycol-sulfuric acid mixture and the concentration of chromium has been determined using visible spectrophotometry. The calibration graph was linear in the range 0-1microgmL(-1) chromium(VI) with a detection limit of 6microgL(-1). A highest preconcentration factor of 25 could be obtained for 250mL sample volume using glass wool as support for the mixed bed adsorbent. Chromium(VI) could be effectively separated from other ions such as nickel, copper, zinc, chloride, sulfate, nitrate, etc., and the method has been successfully applied to study the recovery of chromium in electroplating waste water and spiked water samples.
authors.affiliation: Chemistry Group, Birla Institute of Technology and Science, Pilani 333031, India. rajesh@bits-pilani.ac.in
authors.forename: N
authors.initials: N
authors.lastname: Rajesh
authors.forename: Braja Gopal
authors.initials: BG
authors.lastname: Mishra
authors.forename: Pawan Kumar
authors.initials: PK
authors.lastname: Pareek
mesh_terms: D000143:Acids / Q000737:chemistry*; D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D004160:Diphenylcarbazide / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013464:Sulfuric Acids / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000143:Acids; D007477:Ions; D012996:Solutions; D013464:Sulfuric Acids; D014867:Water; D002857:Chromium; D001546:Bentonite; D004160:Diphenylcarbazide; D058428:Silica Gel; D012822:Silicon Dioxide; C033158:sulfuric acid