REMOVAL OF MN (II) IONS FROM AQUEOUS SOLUTION USING SILVER AND TITANIUM DIOXIDE NANOPARTICLES DERIVED FROM BACTERIAL PIGMENT: EXPERIMENTAL CHARACTERIZATION AND OPTIMIZATION
Author(s):
Akpeji Bamidele Honesty, Korode Temitayo Bukola, Adedokun John
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Abstract
The study aimed to investigate the adsorption of Mn (II) ions from aqueous solutions using silver nanoparticles (SNP) and titanium dioxide nanoparticles (TNP) derived from bacterial pigment, employing atomic absorption spectrometry. Both SNP and TNP exhibited high efficiency as adsorbents for manganese removal from aqueous solutions. The characterization of the adsorbents which are Silver Nanoparticles and Titanium Nanoparticles (SNS and TNS) involved various instrumental analyses, including UV, SEM, TEM, FTIR, BET, XRD, and EDX. UV-visible spectroscopy indicated an increase in peak intensity over reaction time, reaching maximum wavelengths of 422nm (SNS) and 399nm (TNS). SEM and TEM analyses revealed favorable adsorptive characteristics for both SNS and TNS. FTIR analysis identified functional groups (C=O, O-H, C-O, N-H, and C-H) contributing to the high adsorptive capacity (Tokeer Ahmad, 2013). BET analysis showed the highest surface area at 450.103m²/g (SNS) and 220.402m²/g (TNS), while EDX detected elements such as Ti, O, Ag, C, and Cl. Batch adsorption experiments achieved equilibrium at 50mg/L, pH 7, temperature 45°C, adsorbent dose 0.01g, and 40-60 mins for both adsorbents. Isotherm parameters indicated Freundlich > Temkin > Langmuir fit, with R² values of 0.9316, 0.9121, and 0.8761, respectively. Kinetic studies favored pseudo-second-order kinetics over the first order. Thermodynamic experiments suggested exothermic adsorption with ΔH values of +1.045 KJ/mol (SNS) and +13.047 KJ/mol (TNS), and ΔS values of +0.130 KJ/mol/K (SNS) and +0.128 KJ/mol/K (TNS). Under optimized conditions (pH 7, 0.01g/50ml dosage), SNS and TNS achieved 88.9% and 78.9% adsorptive removal of Mn (II) ions, respectively. The first-order kinetics and Largengren kinetic model were found applicable. The study underscored the significance of low-cost adsorbents in developing effective technologies for manganese ion removal from aqueous solutions.
KEYWORDS:
Adsorption, Heavy metals, Kinetics, Thermodynamics