Adsorption Studies of Volatile Organic Compound (Naphthalene) from Aqueous Effluents: Chemical Activation Process Using Weak Lewis Acid, Equilibrium Kinetics and Isotherm Modelling

Adeola A Akinpelu,Abu Nasser Mohd Faisal,R Saidur,Zaira Zaman Chowdhury,T M Yunus Khan,Omid Akbarzadeh,Md Al Amin,Khalisanni Khalid,Mohd Rafie Johan,Shahjalal Mohd Shibly,Sarfaraz Kamangar,Md Mahfujur Rahman,Irfan Anjum Badruddin,Suresh Sagadevan

doi:10.3390/ijms22042090

Abstract

This study deals with the preparation of activated carbon (CDSP) from date seed powder (DSP) by chemical activation to eliminate polyaromatic hydrocarbon—PAHs (naphthalene—C10H8) from synthetic wastewater. The chemical activation process was carried out using a weak Lewis acid of zinc acetate dihydrate salt (Zn(CH3CO2)2·2H2O). The equilibrium isotherm and kinetics analysis was carried out using DSP and CDSP samples, and their performances were compared for the removal of a volatile organic compound—naphthalene (C10H8)—from synthetic aqueous effluents or wastewater. The equilibrium isotherm data was analyzed using the linear regression model of the Langmuir, Freundlich and Temkin equations. The R2 values for the Langmuir isotherm were 0.93 and 0.99 for naphthalene (C10H8) adsorption using DSP and CDSP, respectively. CDSP showed a higher equilibrium sorption capacity (qe) of 379.64 µg/g. DSP had an equilibrium sorption capacity of 369.06 µg/g for C10H8. The rate of reaction was estimated for C10H8 adsorption using a pseudo-first order, pseudo-second order and Elovich kinetic equation. The reaction mechanism for both the sorbents (CDSP and DSP) was studied using the intraparticle diffusion model. The equilibrium data was well-fitted with the pseudo-second order kinetics model showing the chemisorption nature of the equilibrium system. CDSP showed a higher sorption performance than DSP due to its higher BET surface area and carbon content. Physiochemical characterizations of the DSP and CDSP samples were carried out using the BET surface area analysis, Fourier-scanning microscopic analysis (FSEM), energy-dispersive X-ray (EDX) analysis and Fourier-transform spectroscopic analysis (FTIR). A thermogravimetric and ultimate analysis was also carried out to determine the carbon content in both the sorbents (DSP and CDSP) here. This study confirms the potential of DSP and CDSP to remove C10H8 from lab-scale synthetic wastewater.

Highlights

Polycyclic aromatic hydrocarbons (PAHs) are considered highly toxic, as well as persistent, environmental contaminants
The date seeds (DSP) were collected and washed several times to remove the mesocarps of fresh date fruits and were oven-dried for 3 days at 90 ◦ C
Six grams of date seed powder was mixed with 3 g of weak Lewis acid of zinc acetate dehydrate salt (Zn(CH3 CO2 )2 ·2H2 O), where the ratio of seed powder to salt was kept constant around 2:1

Summary

Introduction

Polycyclic aromatic hydrocarbons (PAHs) are considered highly toxic, as well as persistent, environmental contaminants. These derivatives, when released into the environment without careful monitoring, can react with DNA to stimulate carcinogenic and mutagenic responses in living organisms [1,2] Due to their persistent nature, high toxicity and easy mobility, the European Environmental Protection (EEA) Agency, as well as the World Health Organization, classified it as a priority pollutant that needs to be monitored strictly in any industrial effluents and recommended a safe, tolerable limit in water for public consumption [3,4]. Naphthalene (C10 H8 ) was chosen as an adsorbate that is a representative of PAHs and is widely found in waste aqueous stream due to careless industrial discharge

Methods

Results

Conclusion