Bulk generated textile wastewater loaded with dyes is posing a stern threat
to aquatic health, especially when dumped without prior treatment. Lignocellulosic waste based activated
carbon (AC) and Titania (TiO2) suspension can constitute the emerging technological solution.
Best lignocellulosic precursor biomass, Melia azedarach (Darek sawdust - DSD), was
selected for ortho-phosphoric acid impregnated AC production and novel AC-DSD-TiO2 nanocomposite
was developed. AC-DSD and AC-DSD-TiO2 nanocomposites were employed for reactive orange
16 (RO16) dye adsorption in batch and decoloration in photocatalytic reactors, respectively.
Materials were characterized by Scanning electron microscope (SEM), energy dispersion
X-ray (EDX) spectroscopy and Fourier transform infrared spectroscopy (FTIR). For AC-DSD production,
the raw powdered biomass of DSD impregnated (value = 2) with H3PO4 at room temperature
and after shaking, was placed in a muffle furnace at 100°C for 12 h in glass tubes and subsequently
carbonized at a high temperature of 400°C for 30 min. Batch reactor parameters for the ACDSD-
RO16 system were optimized as a function of contact time, adsorbent dose, temperature, initial
dye concentration and pH. For AC-DSD-TiO2 nanocomposite synthesis, AC-DSD and TiO2 paste
was dried in the furnace at 90°C and calcined at 300°C and stored in a desiccator.
AC-DSD exhibited RO16 adsorption capacity of 92.84 mg/g. The experimental data were
best described by Langmuir and Dubinin-Radushkevich isotherms with high R2 of 0.9995 and 0.9895
and closeness of predicted adsorption capacities of 94.15 and 88.58 mg/g respectively. This determines
the chemisorption nature for RO16 adsorption onto AC-DSD. The experimental data was well
explained by the pseudo-second order kinetic model. Thermodynamic parameters also suggest the
endothermic, chemisorption and spontaneous adsorption reaction. Photocatalytic studies of novel
AC-DSD-TiO2 revealed the higher Kc = 0.1833 value over Kad= 0.0572.
Melia azedarach AC-DSD and its novel AC-DSD-TiO2 nanocomposite prove that these
materials could provide an optimal solution for treating textile dye solutions effectively as the good
adsorbent and photocatalyst.