Sumit H. Dhawane

Defluoridation of wastewater using powdered activated carbon developed from Eichhornia crassipes stem: optimization by response surface methodology

AbstractThe present investigation describes the removal of fluoride from synthetically fluoridated water using powdered activated carbon (PAC) developed through steam activation of carbonized Eichhornia crassipes stem by series of batch sorption experiments. Process is optimized by response surface methodology and experimental matrix is developed by central composite rotatable design. Influence of five different parameters viz. pH, adsorbent dose, temperature, contact time, and revolutions per minute (RPM) were studied in the range of 2–12, 2–12 g/L, 20–60°C, 20–180 min, and 100–300, respectively. Prepared PAC was characterized to obtain physical properties and instrumentally analyzed to observe surface texture of raw PAC and spent PAC with fluoride using methods viz. SEM, EDAX, and XRD. Physical properties, such as surface area and total pore volume, obtained equal to 97.68 m2/g and 0.5185 cm3/g, respectively. From the performed experiments for fixed initial concentration of 10 mg/L, maximum fluoride rem...

Acid-catalyzed esterification of castor (Ricinus communis) oil: optimization through a central composite design approach

The present investigation emphasizes the dynamic modeling and optimization of acid esterification of non-edible castor (Ricinus communis) oil towards reduction of free fatty acid (FFA) content considering four process parameters, namely reaction time (0–4 h), reaction temperature (40–80°C), catalyst concentration (0.25–3.25 w/w) and molar ratio of methanol to oil (1:1–20:1) by the response surface methodology 24 full factorial central composite design approach. A quadratic model was developed to evaluate considerable interactive effects on FFA. Reaction temperature exhibited the most significant effect among all of the process variables. Optimal conditions during which the FFA was reduced from 4.04 to 1.08% were: 1% w/w concentrated H2SO4, 15:1 molar ratio of methanol to oil, reaction temperature 50°C and reaction time 2.09 h. Experimental verification of the predicted condition ensured an actual FFA of 1.14%. The small error (0.0634) between the predicted and actual FFA values ascertained the validity and accuracy of the model in representing the experimental data and predicting conversion at any condition within the studied range. Hence, this pre-treatment under optimized conditions could overcome the major constraint of high FFA, thereby rendering suitability for base transesterification.