Page 128 - AJWEP-22-6

Kuppusamy and Dhanasamy

Table 1. Characteristics of laboratory wastewater samples
Sample Metal pH TDS (mg/L) COD (mg/L) BOD (mg/L) Conductivity (mS/cm) Turbidity (NTU)
5
S1 Lead 6.8 1660 42.6 5.4 2.4 27.0
S2 Cadmium 6.6 1750 56.0 4.8 2.6 22.2
S3 Mercury 5.5 1520 60.8 4.7 2.2 45.0
S4 Iron 5.8 1620 48.5 8.0 2.4 30.8
S5 Copper 6.0 1820 50.6 6.2 2.6 40.8
Abbreviations: BOD : Biological oxygen demand (5 days); COD: Chemical oxygen demand; mS/cm: milliSiemens per centimeter;
5
NTU: Nephelometric turbidity unit; TDS: Total dissolved solids.

India), conductivity meters (Systronics, India), and amount of lead ions (Pb²⁺) adsorbed at equilibrium
TDS meters (Eutech Instruments, Singapore) were (qe, mg/g) was calculated using the mass balance
used. Turbidity was measured with a nephelometer equation (Equation I):
(HACH 2100Q, USA; supplied in India). COD ( Cs Ce ) V

and BOD were analyzed according to the standard qe (I)
5
methods provided by the American Public Health m
Association (APHA) for the examination of Where Cs is the initial concentration of Pb²⁺ (fixed
water and wastewater. Metal concentrations were at 150 mg/L),
determined using inductively coupled plasma Ce is the equilibrium concentration (mg/L),
mass spectrometry (Agilent 7900, USA). Fourier V is the volume of the solution (L),
transform infrared spectroscopy (FTIR) analysis and m is the mass of the adsorbent (g).
(PerkinElmer Spectrum Two, USA) was conducted. The derived parameters include: (1) Ce/qe for
Scanning electron microscopy (SEM) analysis (Carl linearized Langmuir isotherm fitting; (2) ln(Ce) and
Zeiss, India) was conducted. All treatments were ln(qe) for Freundlich isotherm fitting; and Ce/(Cs − Ce)
conducted in triplicate (n = 3), and the results are and Ce/[(Cs − Ce) × qe] for Brunauer-Emmett-Teller
reported as mean ± standard deviation. (BET) isotherm analysis.
All logarithmic values are natural logarithms. These
2.3. Laboratory wastewater treatment with transformations enable direct comparison with the
chemically activated powdered plantain pseudo- respective linear forms of the adsorption models and
stem (PPPS) were applied uniformly across all experimental data.
One gram of PPPS was added to 1 L screw-capped
conical flasks (Borosil, India) containing the wastewater 2.5. Statistical analysis
samples (S1–S5). The mixture was left for 24 h at room Statistical analysis was performed using one-way
temperature (25 ± 2°C) under natural pH conditions analysis of variance to assess significant differences
(5.5–6.8). After settling, the mixture was filtered to between treatment groups, with a significance
obtain filtrate-1 (F1). This was then subjected to a threshold set at p<0.05. All analyses were carried
second round of treatment with fresh PPPS (1 g), out using ORIGIN 8 Pro software (OriginLab
yielding filtrate-2 (F2). Corporation, USA).
All physicochemical parameters and heavy metal
concentrations were analyzed for both raw and 2.6. Recovery of PPPS
treated samples, following the same protocols and Following biosorption, the PPPS underwent a recovery
instrumentation as in the RPPS treatment. process to evaluate its potential for reuse in multiple
A blank control (PPPS and distilled water) and adsorption cycles. The spent biosorbent was treated
a negative control (wastewater without PPPS) were with 0.1 M hydrochloric acid, using a solid-to-liquid
processed alongside experimental samples to confirm ratio of 1 g powder to 30 mL of eluent. The suspension
treatment-specific effects. was shaken for 60 min to facilitate desorption of the
metal ions, after which it was separated by filtration.
40
2.4. Derivation of adsorption parameters The recovered biosorbent was thoroughly washed with
The experimental data in Table 2 were used to derive distilled water to remove acid residues and then dried in
parameters for adsorption isotherm modeling. The a hot air oven at 120°C for 2 h.

Volume 22 Issue 6 (2025) 122 doi: 10.36922/AJWEP025110078