Taguchi Parametric Optimization and Cost Analysis of Hexavalent Chromium Sequestration From Aqueous Solution by NaOH-Modified Hull Particles.

The presence of chromium in industrial wastewater is unavoidable due to its large usage as part of chemical constituents used in many industries. Its removal from wastewater is imperative because it's toxic in nature. This study investigated the application of NaOH-modified hull particles (cMGK-HP) for Cr(VI) sequestration from aqueous solution. The optimization of process parameters was executed using Taguchi of Design Expert software for optimum point prediction, analysis of variance, parameters interaction and mathematical model development. A proposed model was used for the adsorption cost analysis. The predicted and experimental percentage of Cr(VI) sequestration were recorded at optimum point to be 99.02% and 98.76% with pH, adsorbent dose, contact time, initial concentration, and temperature of 2, 8 g/L, 20 minutes, 10 mg/L, and 20°C respectively. A correlation coefficient of .9937 between experimental and predicted values of percentage Cr(VI) sequestration affirmed high efficacy of the developed model. ANOVA showed the order of parameter contribution to be pH > adsorbent dose > initial concentration > contact time > temperature. A maximum adsorption capacity of 217.39 mg g was obtained for cMGK-HP. Cost analysis revealed using cMGK-HP to be cost effective for Cr(VI) sequestration with a total operational cost of 0.824 $/mole Cr(VI) ions when compared with commercial activated carbon. Adsorbent characterization revealed the presence of active functional groups enhancing the sequestration process. It could be deduced that cMGK-HP is effective to remove Cr(VI) from solution.