Kinetic and thermodynamic study of copper (II) IONS biosorption by Caryocar Coriaceum Wittm bark

Abstract

The improper disposal of waste containing toxic metals is a major environmental pollution problem. Among the different methodologies to deal with this problem, biosorption is considered one of the most efficient processes for the removal of toxic metals from aqueous solutions. The use of natural adsorbents, such as vegetable waste, in a process known as biosorption, stands out even more as it combines the remediation of polluted water with a reduction in the amount of solid waste. This work aimed to study the use of the bark of Caryocar Coriaceum Wittm, a fruit known as pequi, as a possible bioadsorbent for the removal of copper (II) from aqueous solutions. To this end, pequi bark was collected from a public city market, washed, dried up and crushed. The obtained material was then sieved and the 32-mesh fraction was collected, washed and dried again. The resulting material was then submitted to kinetic, isothermal and thermodynamic testing for copper (II) biosorption. We found that the copper (II) biosorption capacity is favored by increasing temperatures, ranging from 16.8 to 20.4 mg.L−1 at 5 °C and 35 °C, respectively. The kinetic model that best fits de biosorption process was the pseudo-second order model, which produced a linear regression coefficient of 0.999, while the pseudo-first order model produced a value of 0.695. The bioadsorption process was characterized by chemisorption with intra-film diffusion. The isothermal model that best represented the biosorption was Langmuir's (R2 = 0.99). In sight of the obtained results, we concluded that Caryocar Coriaceum Wittm bark is a good bioadsorbent alternative for solutions containing dissolved copper (II).