Removal of aqueous nickel (II) using laterite as a low-cost adsorbent

Removal of Cu2+ and Ni2+ from Aqueous Solution using SnO2 Nanomaterial effect of: pH, Time, Temperature, interfering cations

Tin oxide, SnO₂, nanomaterial was synthesized and tested for the removal of Cu²⁺ and Ni²⁺ ions from aqueous solutions. Various parameters for the binding were investigated in batch studied, which included pH, time, temperature, and interferences. In addition, isotherm studied were performed to determine the maximum binding capacity for both Cu²⁺ and Ni²⁺ ions. The optimal binding pH determined from the effects of pH were to be at pH 5 for both the Cu²⁺ and Ni²⁺ ions. The isotherm studies were performed at temperatures of 4°C, 25 °C, and 45 °C for both the Cu²⁺ and Ni²⁺ ions and were found to follow the Langmuir isotherm model. The binding capacities for the Cu²⁺ ions were 2.63 mg/g, 2.95 mg/g and 3.27 mg/g at the aforementioned temperatures, respectively. Whereas the binding capacities for Ni²⁺ were 0.79 mg/g, 1.07 mg/g, and 1.46 mg/g at the respective temperatures. The determined thermodynamic parameters for the binding showed that the binding processes for the reactions were endothermic, as the ΔG was observed to decrease with decreasing temperatures. As well the ΔH was 28.73 kJ/mol for Cu²⁺ (III) and 13.37 kJ/mol for Ni²⁺. The ΔS was observed to be 92.65 J/mol for Cu²⁺ and 54.53 J/mol for Ni²⁺. The free energy of adsorption for the Cu²⁺ was determined to be 13.99 kJ/mol and the activation energy for the binding of Ni²⁺ was determined to be 8.09 KJ/mol. The activation energy data indicate that the reaction was occurring through chemisorption.

Comparison of treated laterite as arsenic adsorbent from different locations and performance of best filter under field conditions

Arsenic pollution in groundwater is a worldwide concern due to its chronic effects on human health. Numerous studies have been carried out to obtain cost-effective arsenic removal method. Adsorption using natural materials or its treated forms is found to be cost-effective technology. Raw laterite (RL) or its treated form (TL) is studied recently as arsenic adsorbent for aqueous system. Laterite composition varies with geographical location and extent of lateritization. The study on effects of arsenic adsorption with varying composition of laterite is not explored yet. Four laterite samples with different compositions are examined to remove arsenic from water. These laterite samples are activated using an optimized acid followed by base treatment method in order to determine the effects of RL composition on arsenic adsorption behavior of TL. Higher iron and aluminum containing RL samples show higher arsenic adsorption behavior. Similarly, TL obtained from higher iron and aluminum containing RL sample shows the higher specific surface area (130-180 m(2) g(-1)) and pore volume (0.28-0.35 mL g(-1)). Two household filters using TL are deployed in arsenic affected area of Barasat, 24 Parganas (N), West Bengal, India and their performance is monitored for about a year.