Microporous and mesoporous materials for the treatment of wastewater produced by petrochemical activities

• Heavy metal and hydrocarbon adsorption of synthetic and natural material was studied.
• Ionic strength seems to depress the adsorption of heavy metals.
• A cooperation mechanism of Pb2+ and benzene seems to occur during the adsorption.
• A new model for heavy metals uptake by clinoptilolite and S910 resin was developed.
• The mesoporous materials seems to be a promising material for hydrocarbons removal.

The recovery of wastewater will be a fundamental action in the coming years to facilitate the sustainable development of the world's economies. A large portion of recoverable wastewater comes from petrochemical activities such as oil extraction and its subsequent refining processes. The most important characteristic of this water is its heavy contamination by soluble and insoluble hydrocarbons (as emulsioned hydrocarbons) and inorganic and heavy metal ions. Furthermore, the presence of refineries is directly linked to possible groundwater contamination that must be then remediated. In this context, adsorption technologies appear to be very promising for the remediation and recovery of “petrochemical” water. In this paper, we present a review of applied adsorption technologies and examine both the use of two different microporous materials, a natural zeolite called clinoptilolite and a polymeric chelating resin named Purolite® Resin S910, for the removal of dissolved heavy metals, and the use of a mesoporous siliceous material for the uptake of hydrocarbons from wastewater. Batch experiments on the kinetics and equilibrium of adsorption were carried out on all the materials by using Pb2+, Cd2+ and Ni2+ as target heavy metals and benzene and toluene as target organic pollutants. The effect of ionic strength was also investigated.The batch tests indicated a good adsorption rate and a percentage of heavy metal and hydrocarbon removal that was always greater than 90%. A new adsorption model was also developed to better describe the adsorption mechanism of heavy metals, while a model with a two-step mechanism was chosen for hydrocarbons. Increasing ionic strength appeared to decrease the adsorption performance of the microporous material and the presence of organic interfering contaminants. However, both materials seemed to maintain good adsorption capabilities.