Preparation of Rice Husk Bio-Adsorbent and its Application for the Removal of Methylene Blue from Water: An Experimental Study

Water pollution caused by coloured organic compounds is an important environmental concern because dyes released from different industrial activities can affect water quality and aquatic ecosystems. Conventional adsorbents such as activated carbon are effective but may involve relatively high preparation and operating costs. Agricultural wastes provide an alternative source of low-cost and renewable adsorbent materials. Rice husk, an agricultural by-product of rice milling, contains lignocellulosic components and silica and has been investigated as a potential bio-based adsorbent for the removal of pollutants from water. The present experimental study focuses on the preparation of a simple rice husk bio-adsorbent and its application for the removal of methylene blue from aqueous solution. The study involved a simple laboratory experiment that can be undertaken by undergraduate students. The rice husk was collected, washed with water, dried, powdered and sieved to acquire a somewhat uniform adsorbent. A known concentration of methylene blue solution was then exposed to a fixed amount of the obtained rice husk bio-adsorbent. Contact time was chosen as the sole variable and samples were subjected to colorimetric analysis at various time intervals. Residual methylene blue concentration was calculated using a pre-prepared calibration curve while dye removal efficiency was estimated using the initial and final concentrations of methylene blue. This study illustrates a simple way through which an agricultural waste product can be made useful as an adsorbent for water purification process. In addition, the study gives undergraduate students exposure on how agricultural waste products can be made valuable as well as exposure on adsorption, solution preparation, colorimetric analysis and environmental chemistry among others. This experiment has significance in sustainable development because it integrates both agricultural waste utilization and a cheap method of water pollution management.