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An adsorption study has been conducted for activated carbon obtained from grape wood wastes to assess their capability to remove methylene blue (MB) from the aqueous solutions. The properties of prepared activated carbon were characterized using FTIR, BET and SEM analyses. The effects of independent variables such as initial concentration of MB (100–500 mg L−1), initial pH of solution (3–11), adsorbent dosage (0.25–12.25 g L−1) and contact time (10–90 min) on the MB adsorption have been optimized using response surface methodology. The highest MB removal efficiency was 98% when pH, MB and adsorbent dosage were 11, 100 mg L−1 and 12.25 g L−1, respectively. The experimental data have been tested using Langmuir and Freundlich isotherm models, and the achieved data were fully fitted with the Langmuir model (R2 = 0.99), which indicates the monolayer adsorption. The adsorption kinetics well followed by the pseudo-second-order model with R2 of 0.99. This prepared activated carbon as a low-cost and eco-friendly adsorbent can be used widely for water and wastewater treatment.

The efficiency of activated carbon produced from grape waste as a low-cost, nontoxic, and available adsorbent to remove Reactive Red 2 from aqueous solution has been investigated. The prepared activated carbon has been characterized by FTIR, SEM, and BET. The results of characterization indicate the successful conversion of grape waste into mesoporous AC with desirable surface area consist of different functional groups. The results of statistical modeling displayed high R 2 value of 0.97% for dye removal that shows the developed model has acceptable accuracy. The effect of independent variables indicated that the highest adsorption (96.83%) obtained at pH 3, adsorbent dosage of 12.25 g/L, and initial dye concentration of 100 mg/L when the adsorption time was 90 min. The results of isotherms modeling showed that the data fit well with the Langmuir (type II). The kinetic studies using pseudofirst-order and pseudosecond-order models pointed out that the type (I) of pseudosecond-order kinetic model provided the best fit to the adsorption data. Parameters of thermodynamics including Gibbs energy ( Δ G ° ) and k o were calculated. The values of Δ G ° indicated that the dye adsorption of RR2 is spontaneous. The agricultural wastes due to special points such as low-cost, availability, and high ability to produce an adsorbent with high efficiency to remove dye can be proposed for water and wastewater treatment.

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