Performance evaluation of polymer-marine biomass based bionanocomposite for the adsorptive removal of malachite green from synthetic wastewater.

In this experimental investigation, feasibility and performance of a polymer hybrid bio-nano composite were evaluated to remove malachite green (MG) under controlled environment conditions. The polymer hybrid bio-nanocomposite was characterized using FTIR, SEM and EDS. The influence of operating variables, namely effect of pH (2-11), nanocomposite dosage (20-100 mg), initial MG concentration (10- 200 mg/L), contact time (10-120 min) and temperature (298-318 K) were explored. The maximum removal efficiency (RE) of 99.79% was achieved at neutral pH at the dosage level of 50 mg with the initial MG concentration of 150 mg/L in 40 min. The equilibrium results revealed that the adsorption of MG data fitted to Langmuir isotherm (R2 > 0.970) indicating monolayer adsorption. The maximum adsorption capacity of polymer hybrid nanocomposite was found to be 384.615 mg/g. Kinetic studies were performed using five kinetic models and results showed the pseudo second order model fitted very well with the MG adsorption data (R2 > 0.990). The thermodynamic results confirmed that MG adsorption onto polymer hybrid nanocomposite is feasible and (ΔS ͦ = 0.2893 kJ/mol K), spontaneous (ΔH ͦ = 81.103 kJ/mol K) and exothermic (ΔG ͦ < 0). A mechanism is also proposed for the removal of MG using the polymer nanocomposite and identified that electrostatic attraction and hydrogen bonding as the major mechanism for removal of MG. FTIR results confirmed the presence of carboxyl (-COO) and hydroxyl (-OH) groups which helped in effective binding of cationic dye. The overall results revealed that polymer nanocomposite could be used as a potential adsorbent for removing MG from aqueous solution.

Surface modified polymer-magnetic-algae nanocomposite for the removal of chromium- equilibrium and mechanism studies.

The present work explains the sorption ability of a novel nano-composite, Polypyrrole -iron oxide-seaweed (PPy - Fe3O4 - SW), for Cr(VI) removal. The influence of operating parameters, namely pH, contact time, nanocomposite dosage, initial Chromium concentration and operating temperature, on the hexavalent chromium removal was studied. The novel nano-composite was analyzed using FTIR, SEM and EDS to confirm the sorption of Cr(VI) and to understand the mechanism of sorption. PPy - Fe3O4- SW nano-composite removed 96.36% of Cr(VI) at the optimized conditions of pH = 2, temperature = 30 °C, initial Cr(VI) concentration = 50 mg/L, nanocomposite dosage = 100 mg and contact time = 30min. PPy-Fe3O4-SW nanocomposite has a maximum sorption capacity of 144.93 mg/g. The kinetic studies revealed that the metal adsorption obeys pseudo second order (PSO) model and the sorption was found to be monolayer in nature as confirmed by Langmuir isotherm (R2 > 0.9985). Electrostatic interaction and ion-exchange are identified as the fundamental mechanisms for Cr(VI) sorption on PPy-Fe3O4-SW composite.