hexavalent chromium removal from aqueous solution using functionalized multi-walled carbon nanotube: optimization of parameters by response surface methodology

Background: chromium is one of the most commonly used heavy metals in industry. it is known as a pollutant that its discharge into the environment needs special care. objectives: the current study aimed to evaluate the functionalized multi-walled carbon nanotubes (f-mwcnts) as a novel adsorbent of chromium in aqueous solutions. materials and methods: the virgin mwcnt was protonated using sulfuric acid as a strong oxidant. the operating conditions such as initial chromium concentration, contact time, adsorbent dosage and ph were evaluated in the adsorption process. a systematic model for chromium adsorption was presented based on the experimental design. response surface method (rsm), as a mathematical technique, was used for modeling and optimizing considerable parameters. all experiments were performed according to the standard methods for the examination of water and wastewater results: according to the statistical analysis, r2 (0.998), adjusted r2 (0.996), prediction r2 (0.906), coefficient of variation (1.38%), and the mean removal efficiency (54.76%) were calculated. conclusions: the f-mwcnts can be applied as an adsorbent with excellent properties in the adsorption process. the efficiency of 61.75% was predicted by the model in the optimum conditions. in the experimental condition an adsorption percentage of 59.44% was obtained.