Response surface methodology

Nanotechnology

Organic chemistry

Process engineering

Operating system

Composite number

Adsorption

Engineering

Effluent

Composite material

Chemistry

Materials science

Computer science

Process (computing)

Chemical engineering

Chromatography

Carbon nanotube

Waste management

Central composite design

International Journal of Environmental & Analytical Chemistry

In the present study, dye(ADMI, American Dye Manufacturers' Institute) removal from raw textile wastewater was investigated by magnetic multi-walled carbon nanotubes-loaded alginate (CNT-Alg-Fe3O4). The effect of key factors i.e., pH, adsorbent dose and contact time in treatment process was modelled and optimised using response surface methodology-based central composite face-centred design (RSM-CCF). Adsorbents were characterised using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating-sample magnetometer (VSM), and energy-dispersive X-ray spectroscopy (EDS).Low value of p (7.9714e-13) and RSD (1.121) parameters, along with coefficient of determination >0.953 implied that the developed model well-fitted with experimental data. Under the optimised conditions, including pH of3, CNT-Alg-Fe3O4 dose of10 g L-1, and contact time of85.55 min, removal efficiency and ADMI adsorption capacity were obtained as 98.43% and 138.97ADMI/g, respectively. Fitting of data with the Langmuir isotherm (R2 = 1, X2 = 0.012) and Pseudo-second-order kinetics (R2 = 0.993, X2 = 0.015) showed that adsorption process is monolayer and chemical in nature. ΔH°> 0, ΔS°>0, and ∆G°< 0 indicated that dye removal was spontaneous and endothermic in nature. Reuse of the adsorbent in 10 consecutive experiments also showed that removal efficiency was reduced by about 11.94%.Adsorption mechanism can be explained by the presence of a large number of negatively charged carboxyl groups and hydroxyl groups on surface of CNT-Alg-Fe3O4, which could react with colour molecules through electrostatic interactions and π-π dispersive interactions.

Magnetic multi-walled carbon nanotubes-loaded alginate for treatment of industrial dye manufacturing effluent: adsorption modelling and process optimisation by central composite face-central design