As
nitrate pollution in groundwater continues to escalate, more
is being discovered about the detrimental health implications associated
with concentrated nitrate ingestion. Thus, there is a great necessity
for the effective and sustainable remediation of nitrate from water.
The electrocatalytic reduction of nitrate (ERN) has been identified
as a promising technology with respect to selective product formation
(N
2(g) and NH3/NH4
+), adaptable instrument configurations, and compatibility
with renewable energy sources. Electrocatalysts with appreciable selectivity
for nitrate reduction to nitrogen gas are of great importance for
drinking water applications. On the other hand, ammonia-selective
catalysts are desirable for resource recovery. Traditional catalysts
for ERN applications include expensive platinum group metals, which
makes the widespread utilization of this technology economically unfavorable.
Alternatively, research within the last five years has shown cost-effective
catalytic materials such as bimetallic systems, graphitic composites,
metal oxides, and metal sulfides exhibiting substantial activity/selectivity
for ERN applications. Future ERN catalysts must not only express significant
activity/selectivity but also be capable of stable and consistent
performance under varying water chemistries. Combating electrocatalyst
aging and fouling processes will be key in material design for catalysts
capable of efficient remediation of nitrate from water under continuous
long-term operation.
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
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