Biosorption of p-chloro meta xylenol (PCMX) by bacterium-encapsulated calcium alginate beads in a novel plug flow process.

P-Chloro-Meta-Xylenol (PCMX) is a widely used disinfectant. In the current pandemic scenario, its consumption has increased largely, and as a result, wastewater is loaded heavily with PCMX as a contaminant. Remediation of this ecologically toxic phenolic compound is therefore a burning issue. This study proposes an eco-friendly biosorption-based remediation technique to remove PCMX. A novel isolated phenol-resistant gram-negative bacterium, Pandoraea sp. strain BT102, is first encapsulated in biopolymeric calcium alginate beads. These beads are packed in a long adsorption tube and the contaminated water was passed through this packed tube resembling a plug flow reactor. This unique plug-flow set-up is capable of reducing PCMX concentration from 100 mg L-1 to 2.85 µg L-1 within 4 h using only 30 g of adsorbent, resulting in 99.99% removal efficiency. Adsorption isotherms and kinetics are studied using batch experimental data. A PCMX loading capacity of the encapsulated calcium alginate beads is found to be 961.7 mg g-1, and the Freundlich isotherm results suggested the phenomenon of cooperative adsorption. A good agreement of the pseudo-second-order kinetic model along with the intra-particle diffusion model suggests a multilayer diffusion-controlled adsorption process. Biosorption of PCMX by the bacterium-modified beads was confirmed by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and Fourier-Transform Infrared spectroscopy (FT-IR) analyses. The application of multivariate model-based Response Surface Methodology (RSM) reveals flow rate to be the most important factor controlling the rate of bioremediation.

Interference-free electrocatalysis of p-chloro meta xylenol (PCMX) on uniquely designed optimized polymeric nanohybrid of P(EDOT-co-OPD) and fMWCNT modified glassy carbon electrode.

p-Chloro-meta-Xylenol (PCMX) is an environmentally hazardous phenolic compound having biocidal and antiseptic activity. Very few research publications addressed monitoring this contaminant. This paper presents a rapid sensing system to quantify it in waste water samples. The electrochemical activity of PCMX was exploited through a unique polymeric nanocomposite modified transducer for its quantification. Poly[(3,4-Ethylenedioxythiophene)-co-(o-phenylenediamine)] [P(EDOT-co-OPD)] was deposited through one-step electropolymerization technique on the glassy carbon electrode (GCE) modified by functionalized multi-wall carbon nanotubes (fMWCNTs). An optimized combination of these constituents was evaluated using response surface methodology (RSM) based Box-Behnken experimental design. This maximized the response for PCMX using differential pulse voltammetry (DPV). The sensing matrix was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The structural and morphological study of the modified film was conducted by Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), and field emission scanning electron microscope (FESEM). The anodic peak current could be read from a wide range of 0.5-225 µM calibration curve with a detection limit of 0.2545 µmol L-1. Interestingly this work did not use any biomaterial in the modification but achieved interference-free response with excellent selectivity, sensitivity (0.4668 µA µM-1 cm-2), reproducibility (RSD = 2.2%), and repeatability. The sensing platform showed good stability (85.7%) of 3 months even after 150 times repetitive use. Its applicability for real samples was established by good correlation with standard methods.