Displacement cloud point extraction procedure for preconcentration of iron(III) in water and fruit samples prior to spectrophotometric determination

ABSTRACT. For the enrichment of iron(III) prior to spectrophotometric determination, displacement cloud point extraction (D-CPE) technique was applied depending on the difference in stability constant of metal complexes. Zinc(II) as gallic acid complex was first separated into a Triton X-100 surfactant. Then, once the aqueous phase has been removed, the sample containing Fe(III) is added, and another CPE process is performed. Because Fe-GA has a higher stability than Zn-GA, Fe(III) can displace Zn(II) from the pre-extracted Zn-GA, allowing for Fe(III) separation from the complex sample matrix and its spontaneous spectrophotometric determination at 560 nm. The effects of pH, ligand, and surfactant quantities, temperature and heating time, centrifuge processes, and interferences were all studied. At the optimal conditions, the calibration graph was linear from 0.5 to 500 µg L-1 with enrichment factor of 75.0. The LOD was 0.15 µg L-1 and the RSD was 1.3% for 60 µg L-1 of Fe(III), n = 10. Accuracy was also evaluated using the standard reference substance (SRS) and flame atomic absorption spectroscopy (FAAS) approaches. This procedure was used for separation and micro-determination of Fe(III) in water and fruit tests (banana, strawberry, lemon, orange, and peaches) with recoveries ranged from 96.5 to 105%.   KEY WORDS: Displacement cloud point extraction, Iron, Spectrophotometry, Fruit samples   Bull. Chem. Soc. Ethiop. 2023, 37(1), 1-10.                                                                       DOI: https://dx.doi.org/10.4314/bcse.v37i1.1                                                        &nbsp

Effective and Low-Cost Adsorption Procedure for Removing Chemical Oxygen Demand from Wastewater Using Chemically Activated Carbon Derived from Rice Husk

Wastewater treatment by adsorption onto activated carbon is effective because it has a variety of benefits. In this work, activated carbon prepared from rice husk by chemical activation using zinc chloride was utilized to reduce chemical oxygen demand from wastewater. The as-prepared activated carbon was characterized by scanning electron microscope, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The optimum conditions for maximum removal were achieved by studying the impact of various factors such as solution pH, sorbent dose, shaking time and temperature in batch mode. The results displayed that the optimum sorption conditions were achieved at pH of 3.0, sorbent dose of 0.1 g L−1, shaking time of 100 min and at room temperature (25 °C). Based on the effect of temperature, the adsorption process is exothermic in nature. The results also implied that the isothermal data might be exceedingly elucidated by the Langmuir model. The maximum removal of chemical oxygen demand by the activated carbon was 45.9 mg g−1. The kinetic studies showed that the adsorption process follows a pseudo-first order model. The findings suggested that activated carbon from rice husk may be used as inexpensive substitutes for commercial activated carbon in the treatment of wastewater for the removal of chemical oxygen demand