Physics

Standard enthalpy of formation

Sorbent

Activated carbon

Tectona

Biology

Freundlich equation

Nuclear chemistry

Langmuir

Langmuir adsorption model

Adsorption

Engineering

Physical chemistry

Fourier transform infrared spectroscopy

Aqueous solution

Chemistry

Standard molar entropy

Congo red

Botany

Enthalpy

Chemical engineering

Thermodynamics

Applied Water Science

The present study investigates activated teak leaf powder (Tectona grandis) as a biosorbent for the effective removal of Congo red (CR) dye from aqueous solution. Biosorbent was characterized via Fourier transform infrared spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller and X-ray diffraction. The effect of different parameters, i.e., initial dye concentration, adsorbent dosage, contact time, pH and temperature, was studied in detail. The experimental data were interpreted and studied using Langmuir, Freundlich and Temkin isotherm, and Langmuir isotherm was observed to be best fit. The investigation shows the pseudo-second order is the prevailing kinetic mechanism during adsorption and the energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were − 5.101 kJ/mol, 246.792776 J/mol K and 69.6771398 kJ/mol, respectively. The results show that activated teak leaf powder can be a viable sorbent for the removal of CR dye from wastewater in a reasonable, economical and environmentally friendly way.

Kinetic, thermodynamics and equilibrium studies on the removal of Congo red dye using activated teak leaf powder