Carica Papaya Seed as a Biosorbent for Removal of Cr (VI) and Ni (II) Ions from Aqueous Solution: Thermodynamics and Kinetic Analysis of Experimental Data

Abstract

The use of Carica papaya seeds as an adsorbent for decontamination of toxic metal ions like Ni (II) and Cr (VI) in solution was investigated. The maximum biosorption capacities of Cr (VI) and Ni (II) were observed at pH 2 and pH 6 respectively. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin equations. In order to determine the best fit isotherm, five error analysis methods were used, namely the sum-of-squared errors (SSE), the composite functional error (HYBRID), the Marquardt’s percent standard deviation (MPSD), the average relative error (ARE) and the sum of absolute error (EABS). The error values demonstrated that the Langmuir isotherm model provided the best fit to the experimental data for Cr (VI) and the Freundlich model for Ni (II). Adsorption kinetics data were tested using pseudo-first-order and pseudo-second-order models. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Thermodynamic parameters such as changes of standard free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined. The maximum metal uptake of 5.85 mgg–1 for Cr (VI) and 5.58 mgg–1 for Ni (II) from Langmuir model demonstrates the ability of Carica papaya seed to absorb heavy metals. Fourier transform infrared spectroscopy analysis was used to evaluate the binding characteristics of Carica papaya seed with metals.

Efficient Sequestration of Cr(VI) from Aqueous Solution Using Biosorbent Derived from Arundo donax Stem

“…Biosorption has several important advantages over other traditional treatment methods, including minimal price, high performance, reduction of chemical and biological waste, rejuvenation of biosorbent through desorption operations, and the potential for recovery of metals [11]. Certain agricultural raw waste products have gained popularity in recent years such as cocoa shell [12], potato peel [13], rice husk [14], olive stone [15], garlic peel [16], sawdust [17], banana peel [18], Carica papaya seed [19], Anabaena and Vetiveria [20], coconut husk [21], sweet lime peels [22], date tree leaves [23], and sugarcane bagasse [24] were studied for their efficiency in eliminating metals from effluents.…”

A Review on Abatement of Nickel(II) from Aqueous Solution by Agricultural Biomass

“…Functional groups involved were determined by analyzing through FTIR. For Ni (II), ΔG o become less negative indicating less driving force and hence resulting in lesser adsorption capacity at higher temperatures [20].…”

A review on the versatility of Carica papaya seed: an agrogenic waste for the removal of organic, inorganic and microbial contaminants in water

“…66 CPS, an agricultural waste product from pawpaw, has been explored as an adsorbent (activated carbon) 50 or component of composites used either as adsorbents or photocatalysts for the removal of contaminants in water. CPS has been extensively used as an efficient adsorbent for the purification of water polluted by dyes, 50,[67][68][69][70] pharmaceuticals, [71][72][73] heavy metals [74][75][76][77] and anions. 48 Despite the abundance of research studies on the use of CPS in the remediation of environmental contaminants, there is a lack of recent comprehensive reviews on the subject.…”