Sorptive removal of methylene blue from simulated wastewater using biochars derived from pulp and paper sludge

- Fe2O3-biochar nanocomposite from pulp and paper sludge.
- Nanocomposite used to remove methylene blue from contaminated synthetic wastewater.
- Excellent methylene blue (MB) removal achieved.
- Activation increased the MB adsorption.

Biochar (BC) and Fe2O3-biochar nanocomposite (NC) derived from pulp and paper sludge (PPS) were used to remove methylene blue (MB) dye from synthetic wastewater. Morphology characterization indicated heterogeneous adsorbent surfaces, and textural measurements showed BC and NC possessed pore size in the range 1.7-300 nm. Both these characteristics endowed the adsorbents with good sorption properties for MB. The maximum adsorption capacity of NC (50 mg/g) was higher than of BC (33 mg/g). This was attributed to the hybrid nature of NC where adsorption occurs both on the biochar matrix and Fe2O3 nanoparticles. MB adsorption data on BC and NC followed pseudo-second order (r2=0.958) and pseudo-first order kinetics (r2=1.000), respectively. Isotherm data for BC and NC followed the Freundlich (r2=0.801) and Langmuir (r2=0.948) isotherm models, respectively. Despite having lower adsorption capacities compared to other adsorbents reported in literature, the use of BC and NC for wastewater remediation is an ingenious way of reducing environmental and health risks associated with the current disposal of PPS while providing remediation of water contaminated with industrial dye effluents.