Optimization of Cr (VI) removal from aqueous solution with activated carbon derived from Eichhornia crassipes under response surface methodology

Abstract

Tannery industries’ effluent contains a high concentration of Cr (VI) which has the potential to affect the environment and public health. Therefore, this study aimed to investigate the optimization of Cr (VI) adsorption by activated carbon (AC) derived from Eichhornia crassipes from an aqueous solution. The adsorbent was activated with dilute sulfuric acid followed by thermal activation. AC was characterized using proximate analysis, SEM, FTIR, X-ray diffraction, and the BET method. The Cr (VI) removal optimization process was performed using a central composite design under the response surface methodology. The proximate analysis showed that the moisture content, volatile matter, ash content, and fixed carbon of the activated carbon were 5.6%, 18.2%, 14.4%, and 61.8% respectively. The surface areas of the Eichhornia crassipes before activation, after activation, and after adsorption were 60.6 g/m2, 794.2 g/m2, and 412.6 g/m2 respectively. A highly porous structure with heterogeneous and irregular shapes was observed in the SEM micrograph. In the FTIR analysis, different peaks are indicated with various functional groups. The intensity of XRD peaks decreased as 2 theta values increased, which indicates the presence of an amorphous carbon arrangement. The point of zero charge (pHpzc) of the activated carbon was found to be 5.20. A maximum Cr (VI) removal of 98.4% was achieved at pH 5, contact time 90 min, adsorbent dose 2 g, and initial Cr (VI) concentration of 2.25 mg/L. Statistically significant interactions (P < 0.05) were observed between the initial Cr (VI) concentration and adsorbent dose as well as the initial Cr (VI) concentration and contact time. Langmuir adsorption isotherm fitted the experimental data best, with an R2 value of 0.99. The separation constant (RL) indicates that the adsorption process is favorable. The kinetic experimental data were best fitted with the pseudo-second-order model with an R2 value of 0.99 whereas the adsorption rate is controlled by intraparticle and extragranular diffusion processes. Generally, the AC has the potential to be a strong adsorbent candidate for wastewater treatment at the industrial level.

Optimization of the Removal of Hexavalent Chromium Cr(VI) from Aqueous Solution by Moringa oleifera Bark-Derived Activated Carbon (MOBAC) Using Response Surface Methodology (RSM)

“…At pH 2.0, approximately 99% Cr(VI) removal was observed, and this decreases as the pH increases (Figure 3a). The decreased in Cr(VI) adsorption with an increase in pH has also been reported in other studies [47,48]. The pH of the solution affects the speciation of metal ions as well as the surface charge of the adsorbent.…”

Synthesis of Plant-Mediated Iron Oxide Nanoparticles and Optimization of Chemically Modified Activated Carbon Adsorbents for Removal of As, Pb, and Cd Ions from Wastewater

“…Percentage adsorption of selected adsorbate decreased with further increase of adsorbent dose owing to the adsorbent particle aggregation, decreasing the surface area and active sites on adsorbents for metal ion adsorption. Percentage adsorption increases with increase of adsorbent dose while adsorption capacity decreases with increase of adsorbent dose. , …”

“…Percentage adsorption increases with increase of adsorbent dose while adsorption capacity decreases with increase of adsorbent dose. 39,40 3.6.4. Study of Adsorbate Initial Concentration.…”

Investigation of the performance of activated carbon derived from ripe plantain peels for CO2 capture: Modelling and optimisation using response surface methodology

“…Utilizing biomass from agricultural waste materials such as rice husk, coconut husk, plantain peels, sawdust, bagasse, and other agricultural residues presents an economical and environmentally sustainable alternative [23,24]. These biomass-derived sources significantly reduce production costs compared to commercial counterparts and hold great potential for future commercialization [25][26][27].…”