Preparation of KOH and H3PO4 Modified Biochar and Its Application in Methylene Blue Removal from Aqueous Solution

Abstract

Improperly treated or directly discharged into the environment, wastewater containing dyes can destroy the quality of water bodies and pollute the ecological environment. The removal of dye wastewater is urgent and essential. In this study, corn stalk was pyrolyzed to pristine biochar (CSBC) in a limited oxygen atmosphere and modified using KOH and H 3 PO 4 (KOH-CSBC, H 3 PO 4 -CSBC, respectively). The biochars were characterized by surface area and pore size, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), as well as their behavior in adsorbing methylene blue (MB). Results indicated that the pore structure of CSBC became more developed after modification by KOH. Meanwhile, H 3 PO 4 -CSBC contained more functional groups after activation treatment. The pseudo-second-order kinetic and the Langmuir adsorption isotherm represented the adsorption process well. The maximum MB adsorption capacity of CSBC, KOH-CSBC, and H 3 PO 4 -CSBC was 43.14 mg g −1 , 406.43 mg g −1 and 230.39 mg g −1 , respectively. Chemical modification significantly enhanced the adsorption of MB onto biochar, especially for KOH-CSBC. The adsorption mechanism between MB and biochar involved physical interaction, electrostatic interaction, hydrogen bonding and π-π interaction. Hence, modified CSBC (especially KOH-CSBC) has the potential for use as an adsorbent to remove dye from textile wastewater.

Metal-free high-adsorption-capacity adsorbent derived from spent coffee grounds for methylene blue

“…Table 5 compares the MB adsorption capacities of various biowaste-derived adsorbents. 10,16,18,[39][40][41][42][43][44][45][46][47] As shown in the table, a higher adsorption capacity was measured for our carbon materials than some carbon materials reported in the literature. Chemical activators such as ZnCl 2 , KOH, FeCl 3 , K 2 CO 3 , and NaOH are widely used to prepare activated carbon materials from biowastes.…”

“…researchers have derived adsorbents for organic dyes from biowastes using non-metallic chemical activation. 18,46 The combining of non-metallic activators and other additional agents have not, however, thus far been employed in the impregnation or activation of carbon materials from coffee waste.…”

“…17 In addition, to prepare carbon materials from biowastes, chemical activation is widely utilizedchemicals such as KOH, NaOH, KCO 3 , H 3 PO 4 , and urea are oen used as activating agents. 18,19 NaOH-modied SCG has been prepared for nitrobenzene adsorption, and a removal efficiency of 98.2% was demonstrated. 20 Yun et al, reported the preparation of a porous carbon supercapacitor material from coffee waste with KOH, 21 and Ilnicka et al, prepared nitrogen-doped carbon via a urea treatment for electrochemical applications.…”

Current State of Porous Carbon for Wastewater Treatment

“…Thus, the adsorption mechanism referred to as electrostatic interactions, hydrogen bonds, π-π stacking interactions, pore filling, hydrophobic interactions, ion exchange, and also other interactions (n-π interactions, etc.) and complexation reactions can take place [30,184,187,194,197,203,205,220,[226][227][228]. The micropores and mesopores of the porous network of activated carbon contribute to the adsorption of pollutants by pore-filling mechanisms according to their total volume and the size of the pollutant molecules, and this is influenced by the affinity of the adsorbent with respect to the pollutant [229].…”

Conversion of Waste Polyethylene Terephthalate (PET) Polymer into Activated Carbon and Its Feasibility to Produce Green Fuel

“…The char produced by loading PET with 5% of Fe 2 O 3 and MgO has been found to be useful as a flame retardant, and this happens due to synergistic action of them [13]. PET char was employed to make improved epoxy resins, and the tensile strength, surface hardness and electrical characteristics of epoxy composite materials were determined [14].…”