Adsorption of Neutral Red and Malachite Green onto Grapefruit Peel in Single and Binary Systems

• Published in: Water environment research 2013-05, Vol.85 (5), p.466-477
• Main Authors: Zou, Weihua, Gao, Shuaipeng, Zou, Xiuli, Bai, Hongjuan
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Applied sciences; Aqueous solutions; Binary system; Caustic soda; Chemical engineering; Citrus fruits; Citrus paradisi - chemistry; Dyes; Exact sciences and technology; Fruit - chemistry; Grapefruits; Ion exchange; Ions; Isotherms; kinetic; Kinetics; malachite green (MG); Microscopy, Electron, Scanning; NaOH‐modified grapefruit peel (MGP); neutral red (NR); Neutral Red - chemistry; Peels; Pollution; Rosaniline Dyes - chemistry; thermodynamics; Water Pollutants, Chemical - chemistry; Water Purification - methods; Water treatment and pollution
• ISSN: 1061-4303; 1554-7531
• DOI: 10.2175/106143012X13560205144696

This study characterized the properties of NaOH-modified grapefruit peel (MGP) and investigated its adsorption properties, specifically the adsorption of the synthetic dyes neutral red (NR) and malachite green (MG) onto MGP, in single and binary systems by means of batch techniques. The adsorption equilibrium data of NR onto MGP fit well with both the Langmuir and Koble-Corrigan models, while the Koble-Corrigan and Dubinin-Radushkevich models seemed to agree better with MG adsorption. The maximum equilibrium quantities of NR and MG from the Langmuir model were 640.3 and 314.9 mg/g at 298 K, respectively. The Elovich model was a better fit with the kinetic process, which suggested that ion exchange was one of the main mechanisms at work. The thermodynamic parameters of adsorption systems indicated spontaneous and endothermic processes. In the binary system experiments, NR and MG exhibited competitive adsorption. The quantity of MG adsorbed was more strongly influenced by NR, due to the higher affinity of MGP for the latter.