Document Type : Original Research Article

Authors

• Samuel N. Ndung’u ¹
• Ruth N. Wanjau ¹
• Esther W. Nthiga ²

¹ Department of Chemistry, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya

² Department of Chemistry, Dedan Kimathi University of Technology, P.O Box 657-10100, Nyeri, Kenya

Abstract

The current study utilizes Silicon Nitride (Si₃N₄) as a novel adsorbent in evaluating its adsorptive ability for Congo red dyes from an aqueous solution. The adsorbent was prepared using extracted silica from sand and coffee husk biochar in an ammonia environment. The Si₃N₄ adsorbent was characterized using a Field Emission Scanning Electron Microscope (FEI ESEM) which showed rod-like and fiber-like structures for α-Si₃N₄ and β- Si₃N₄, respectively. The SEM results also showed pores on the adsorbent surface before adsorption and a more rigid and restrained surface after adsorption. The adsorbent surface is hydroxylated in water to give important adsorption sites of silanolate ions (Si-O^-) and silazane groups (Si₂=NH₂⁺) responsible for congo red (CR) dye removal. The adsorption process was investigated by batch mode. The maximum adsorption capacity (28.87 mg/g) was obtained at an optimal pH=1.00, agitation time (50 minutes), adsorbent dosage (25 mg), and initial concentration (50 mg/L). The Langmuir isotherm model was best fitted with equilibrium data with R² > 0.9, showing that the adsorption was chemisorption in nature. The results revealed Si₃N₄ adsorbent as a potential adsorbent in textile dye wastewater treatment.

Keywords

• Silicon Nitride (Si3N4)
• Hydroxylation
• Congo Red (CR)
• Efficacy
• Kinetic
• Chemisorption

Main Subjects

• Chemistry

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