Biosorption technique using water hyacinth plant as an effective and sustainable approach for treating oil refinery waste: Vanadium element as a case study

This study aims to investigate the use of water hyacinth (Eichhornia crassipes) leaves as an adsorbent for vanadium removal from petroleum industry waste.Additionally, it seeks to identify the optimal conditions for maximizing the recovery efficiency of vanadium, a toxic heavy metal.The adsorption performance was evaluated using simulated aqueous solutions with a high concentration of vanadium, a metal released as waste from oil refineries, in a batch adsorption system.The treatment efficiency was studied at different values of acidity, temperature, agitation speed, contact time, and adsorbent dosage, and at 10 ppm concentration of vanadium.The ranges of the studied variables were 1-8, 20-50 C, 100-500 rpm, 10-150 min, 1-12 g, respectively.The obtained results indicated that the maximum percentage removal was 76.16% and the removal was inversely proportional to temperature and directly proportional to other variables.The morphological test results indicated that vanadium adsorption onto the surface of water hyacinth (Eichhornia crassipes) caused an 89% reduction in the surface area of the untreated plant.Additionally, FT-IR and EFSEM analyses revealed significant structural modifications in the adsorption surface, leading to the depletion of most active sites.Furthermore, The Langmuir model best described the obtained data, exhibiting a 99% correlation coefficient.In comparison, the Freundlich and Temkin models had correlation coefficients of 98.56% and 96.44%, respectively.Kinetically, the intra-particle diffusion and pseudo-first-order models provided the most accurate representation of the data among the tested kinetic models, with the intraparticle diffusion model having a slight edge.Based on the thermodynamic function values, the adsorption process was spontaneous, exothermic, and exhibited a decrease in randomness across all examined temperature range.