Modified waste orange peels biomass residues for sustainable and promising As(V) removal: Insights into batch and column adsorption experiments and Box-behnken Design (BBD) analysis

One of the biggest health hazards of today’s age is contamination of water due to increasing exposure of arsenic (As(V)), a carcinogenic element having no colour, taste and odor upon dissolution in water. It is still an urgent and challenging task to remove As(V) from contaminated water with suitable adsorbents. In this study, waste orange peels (OP) biomass residues, which mainly consist of amide (NH), hydroxyl (OH) and carboxyl (COOH) surface functional groups, have been modified with iron (Fe) followed by calcination for promising As(V) adsorption from aqueous environment. The batch adsorption experimental results showed that synthesized composite (OP-Fe 2 O 3 -N 2 ) showed promising As(V) adsorption capacity of more than 92 % with initial As(V) concentration of 500 μg/L under neutral pH condition at room temperature due to its large surface area, higher porosity and increased number of active adsorption sites at its surface. Langmuir isotherms model and pseudo second order kinetics model with their higher R 2 indicated that As(V) adsorption process on OP-Fe 2 O 3 -N 2 was chemisorption on a homogeneous surface with monolayer uptake. Anti-interference to common co-existing ions, regeneration ability and treatment of real like As(V) contaminated water by OP-Fe 2 O 3 -N 2 was remarkable. In addition, Box Behnken Design (BBD) analysis was conducted for optimization of As(V) adsorption by the OP-Fe 2 O 3 -N 2 . The dynamic As(V) biosorption in fixed bed column demonstrated that OP-Fe 2 O 3 -N 2 is also impressive in continuous mode. This study showed that after simple treatment of waste OP biomass residues, it can be used as promising adsorbents for As(V) removal from the aqueous solutions. • Waste orange peels (OP) biomass residues has been modified with iron and calcination . • OP-Fe 2 O 3 -N 2 is evaluated for As(V) removal in batch and column adsorption experiments. • OP-Fe 2 O 3 -N 2 demonstrated 92 % As(V) adsorption with C i = 500 μg/L at pH= 7 and 25 ℃. • OP-Fe 2 O 3 -N 2 exhibited exceptional treatment of simulated real As(V)-contaminated water. • Adsorption process was optimized with minimal number of experiments using RSM and BBD.