Soil science and environmental research.

As indicated in the call for papers posted for this Special Issue, Soil Science deals with various environmental compartments, so it is closely related to Environmental Research. It is clear that synergisms and collaboration are keys to reach the most fruitful relations among different sciences and scientists, and especially in all that focused on the Environment. In this line, considering Soil Science, Environmental Research, and the multiple and complex eventual combinations involving them, could give new highly interesting works focused on any of the specific subjects covered, as well as on relations among these sciences. The main objective should be going further in positive interactions that could help in protecting the Environment, proposing solutions to face hazards that are drastically threatening our planet. In view of that, the Editors of this Special Issue invited researchers to submit high-quality manuscripts including new experimental data, as well as scientifically founded discussion and reflections on the matter. The VSI has received 171 submissions, with 27% of them being accepted after peer-review. The Editors think that the papers included in this VSI have high scientific value and provide scientific knowledge on the field. In this editorial piece the Editors include comments and reflections on the papers published in the SI.

Fenton oxidation of gallic and p-coumaric acids in water assisted by an activated carbon cloth.

The objective of this study was to investigate the effect of the presence of an activated carbon cloth (ACC) during the degradation and removal of gallic acid (GA) and p-coumaric acid (pCA) by Fenton oxidation using H2O2 and FeSO4 as catalyst. Removal of GA or pCA by Fenton oxidation was much higher than that of total organic carbon (TOC), indicating that a large proportion of GA or pCA degradation products was not mineralized. The presence of ACC increased the concentration of hydroxyl radicals generated in the FeSO4 + H2O2 system. The presence of ACC during Fenton oxidation largely increased TOC and GA removal, attributable to the adsorption of GA and its degradation products and the increased generation of OH(•) radicals that mineralize them. In the Fenton oxidation of pCA, the presence of ACC produced the same effects as for GA, but now the increased removal of pCA was due to adsorption on the activated carbon and not to the increased generation of hydroxyl radicals, due to the greater affinity of pCA for the carbon surface and its more difficult mineralization in comparison to GA.

A study of the static and dynamic adsorption of Zn(II) ions on carbon materials from aqueous solutions.

The effect of surface oxidation, solution pH, and ionic strength on the adsorption of Zn(II) ions from aqueous solution under static conditions was studied using commercial activated carbons in the form of grains and cloth. In addition, the effects of surface oxidation and the presence of dissolved natural organic matter (tannic acid) were studied under dynamic conditions using activated carbon cloth column beds. Under static conditions, surface oxidation largely increased Zn2+ uptake and two H+ ions were displaced from the oxidized carbon surface per Zn(II) ion adsorbed. It is proposed that adsorption of Zn(II) on the as-received basic carbons was due to C(pi)-cation interactions. An increase in solution pH in the range 3-6 increased Zn(II) uptake, whereas an increase in ionic strength decreased Zn(II) uptake because of the screening effect of the added salt. In the experiments carried out with carbon column beds, the oxidized activated carbon cloth was also more effective than the as-received carbon to remove Zn(II) ions. In this case, the presence of tannic acid decreased the efficiency of the oxidized activated carbon cloth bed to remove Zn(II) ions. An increase in the tannic acid initial concentration had a greater effect on the removal of tannic acid than on the removal of Zn(II) by the column bed. This may be a consequence of the greater size of tannic acid molecules and their low affinity for oxidized carbon surfaces.