Chestnut Shell-Activated Carbon Mixed with Pyrolytic Snail Shells for Methylene Blue Adsorption

Abstract

Activated carbon has been used to treat organic dyes in water systems; however, the adsorption capacity of the samples studied was limited by the specific surface area and influenced by the pH of the aqueous solution. In this study, a hybrid adsorbent consisting of a mixture (MCS) of activated chestnut shell biochar (CN) and pyrolyzed snail shell material (SS) was developed to solve this problem, with the waste snail shell samples being processed by pyrolysis and the chestnut shell samples chemically pretreated and then pyrolyzed. The BET and SEM results revealed that the SS had a mesoporous fluffy structure with a higher specific surface (1705 m2/g) and an average pore diameter of about 4.07 nm, providing a large number of sites for adsorption. In addition, XPS and FTIR results showed that the main component of SS was calcium oxide, and it also contained a certain amount of calcium carbonate, which not only provided an alkaline environment for the adsorption of biochar but also degradation and photocatalytic capabilities. The results showed that the MCS3-1 sample, obtained when CN and SS were mixed in the ratio of 3:1, had good capacity for adsorption for methylene blue (MB), with 1145 mg/g at an initial concentration of 1300 mg/L (92% removal rate). The adsorption behaviors were fitted with the pseudo-second-order kinetic model and Freundlich isotherm model, which indicated that the adsorption was multilayer chemisorption with a saturated adsorption capacity of 1635 mg/g. The photocatalytic capacity from the SS composition was about 89 mg/g, and the sorption of MB dye onto the sorbent reached equilibrium after 300 min. The results suggested that MCS3-1 has enormous potential for removing MB from wastewater.

Efficient photodegradation of methyl red dye by kaolin clay supported zinc oxide nanoparticles with their antibacterial and antioxidant activities

“…Thus, least OH . radicals are initiated and we observe comparatively less dye degradation with an initial dye concentration increase [ 60 , 61 ].

Fig.

…”

A Critical Review of Snail Shell Material Modification for Applications in Wastewater Treatment

“…Snail shell and rice husk were combined and calcined for more than two hours at 681.1 °C to produce mixed adsorbent materials with quite high adsorption results when compared to individual materials [ 113 ]. Another study on the combination of snail shell and chestnut using a simple combination method and different ratios of snail shell and chestnut resulted in methylene blue treatment efficiency of up to 92% [ 106 ]. A combination of snail shell and pine cone powder also demonstrated high potential for heavy-metal treatment in wastewater due to the combination of cellulose in an amorphous crystalline phase and calcium carbonate compound [ 115 ].…”

“…Therefore, recent research mainly focused on modification improvements to create optimal materials that give the highest performance in wastewater treatment. Based on surface area properties, the adsorption capacity of snail shells demonstrates that shells have a high ability to treat wastes, such as heavy metals, textiles, and other wastes [ 106 ]. According to Stevens et al, the adsorption efficiency of snail shells for Pb 2+ is higher than that of oysters and periwinkles based on material properties [ 53 ].…”

“…Cationic dye adsorption is favored at higher pH levels, whereas anionic dye adsorption is favored at lower pH levels [ 51 ]. Similarly, An et al discovered that as the pH increased, the value of the zeta potential decreased, implying that more functional groups were exposed to the surface material, which facilitated the adsorption process [ 106 ].…”

“…The mixing ratio also greatly determines the adsorption efficiency, with adsorbents usually being mixed with different substances under many kinds of ratios. Research on mixing chestnut and snail shells at a ratio of 3:1 gave better results than ratios of 1:3 and 1:1, with methylene blue adsorption efficiency of up to 92% [ 106 ]. When different concentrations of NaCl, KCl, MgCl 2 , and CaCl 2 salts were used to evaluate the effect of ionic strength on the adsorption of Azure A, the influence of CaCl 2 showed higher results than the remaining salts, but this effect was not significant on the adsorption results [ 122 ].…”