Dispersive Solid-Phase Extraction of Rhodium from Water, Street Dust, and Catalytic Converters Using a Cellulose–Graphite Oxide Composite

ABSTRACT

A cellulose–graphite oxide composite was synthesized and characterized as an adsorbent for dispersive solid-phase extraction of rhodium from various samples before atomic absorption detection. The pH, adsorbent volume, centrifugation time and rate, eluent concentration, volume and type, adsorption and elution contact time, sample volume, and matrix interferences were optimized. The developed method is simple, rapid, and inexpensive. The tolerance limits for rhodium were 10,000 mg L⁻¹ sodium, 25,000 mg L⁻¹ potassium, 10,000 mg L⁻¹ magnesium, and 20,000 mg L⁻¹ calcium. The recovery for rhodium exceeded 95%. Elution was performed with 10 mL of 2.5 mol L⁻¹ H₂SO₄. The adsorption and elution contact times were 30 and 60 s, respectively. The detection limit of the method for rhodium was 5.4 µg L⁻¹ and the precision as the relative standard deviation was 1.6%. A certified reference material 2556 (used auto catalyst pellets) and fortified samples were analyzed to evaluate the accuracy of the method. The optimized method was used for the preconcentration of rhodium from tap water, well water, wastewater, seawater, catalytic converters, and street dust.

KEYWORDS:

• Cellulose/graphite oxide composite
• dispersive solid-phase extraction
• flame atomic absorption spectrometry
• rhodium