Aqueous solution

Chemistry

Materials science

Methyl orange

Fluorapatite

Chromatography

Composite number

Engineering

Composite material

Phosphate

Glutaraldehyde

Organic chemistry

Endothermic process

Catalysis

Mineralogy

Chitosan

Photocatalysis

Nuclear chemistry

Adsorption

Apatite

Chemical engineering

Langmuir adsorption model

Fourier transform infrared spectroscopy

Biopolymer

Polymer

International Journal of Environmental & Analytical Chemistry

In this work, chitosan, a biopolymer was cross-linked using glutaraldehyde (Gl) and modified by natural apatite. The Cs-Gl@Fap composite was used to adsorb methyl orange from an aqueous solution. The materials were characterised by SEM-EDX, FTIR, XRD and TGA-DTG analysis confirming the successful synthesis of Cs-Gl@Fap. The effects of experimental variables on adsorption efficiency were examined. Adsorption studies showed that the maximum adsorption capacity was 225.55 mg/g at an equilibration time of 120 min. The pseudo-second-order rate expression supported data best, while the Langmuir equation could satisfactorily describe isotherm data. The thermodynamic constants of the adsorption process were evaluated. The results showed that the stabilisation by contact of methyl orange on Cs-Gl@Fap was endothermic and spontaneous. Additionally, when reused, the hybrid adsorbent remains at approximately 83% of its original capacity after five adsorption cycles.

Methyl orange adsorption studies on glutaraldehyde cross-linking chitosan/fluorapatite-based natural phosphate composite