Sulphonated date palm (Phoenix dactylifera) stone via microwave-assisted H2SO4 activation: optimisation with desirability function for methylene blue adsorption

• Published in: INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY
• Main Authors: Jawad, Ali H.; Azhar, Nuhaa Nabiihah Mohamad; Hapiz, Ahmad; Al Othman, Zeid A.; Wilson, Lee D.
• Format: Article; Early Access
• Language: English
• Published: TAYLOR & FRANCIS LTD 2024
• Subjects: Chemistry; Environmental Sciences & Ecology
• Online Access: https://www-webofscience-com.uitm.idm.oclc.org/wos/woscc/full-record/WOS:001270037000001
• ISSN: 0306-7319; 1029-0397
• DOI: 10.1080/03067319.2024.2375413

In this work, a sulphonated date palm (Phoenix dactylifera) stone (SDPS) was produced as a cost-effective and renewable adsorbent for the removal of a cationic dye called methylene blue (MB). The production process involved the use of microwave irradiation combined with H2SO4 activation under the condition of 600 W microwave radiation for 15 min. The physicochemical characteristics of SDPS were evaluated using various analytical techniques, including XRD, BET, FTIR, pH(pzc), and SEM. The Box-Behnken design (BBD) was employed to optimise key adsorption variables, including A: SDPS dosage (0.02-0.1 g/100 mL), B: pH (4-10), and C: contact time (5-25) min. According to the BBD model, the most effective removal of MB (98.4%) occurred with a dosage of 0.06 g/100 mL of SDPS, a pH of 10, and a contact time of 25 min. The rate of adsorption of the MB dye followed a pseudo second order (PSO) model, whereas the equilibrium adsorption was described by the Langmuir and Temkin models. The maximum adsorption capacity (q(max)) of SDPS for MB dye was found to be 122.3 mg/g at 25 degrees C. Several contributions to the MB dye adsorption process include electrostatic interactions, H-bonding, pore filling, and pi-pi stacking onto the SDPS adsorbent surface.