###### Abstract  
This study emphasizes the importance of employing parallel batch tests with different liquid/solid (L/S) ratios to assess their dissolution mechanisms. Changes in physicochemical parameters (electrical conductivity, pH, and oxidation-reduction potential), as well as the sorption/desorption of dissolved organic carbon (DOC) and nitrate (NO\({}_{3}\)\({}^{-}\)) due to graphene addition in a calcareous sandy soil (CS) and in a siliciclastic riverine sandy soil (SS) were assessed via batch experiments at different L/S ratios. Graphene's production is growing at a great pace, so it's important to test methods to reuse graphene wastes. The results of soil batch experiments mixed with graphene were compared with classical soil improvers (compost, biochar, and zeolites). The batches were performed using the saturation soil extraction method with deionized water as a proxy of rainwater. The contact time was 48 h. At the end of the experiment, water samples were collected to be analyzed for NO\({}_{3}\)\({}^{-}\), DOC, DIC, Ca, and Mg. Graphene did not alter the physiochemical parameters of both soils. Moreover, its addition did not trigger any NO\({}_{3}\)\({}^{-}\) increase respect to control and to other improvers. Biochar increased EC and pH beyond recommended limits for most crops' growth in both soils. As expected, compost addition produced the highest NO\({}_{3}\)\({}^{-}\) release. batch experiments; sorption/desorption; engineered carbonaceous materials; dilution; leaching +
Footnote †: journal: Applied Sciences  
compounds can trigger the degradation of groundwater quality, which is strictly connected with the increase of human health risk [14]. Laboratory leaching experiments, such as batch tests, are indispensable tools to understand the potential release of contaminants on the soil-groundwater pathway [15]. [PERSON] and [PERSON] [16] summarized the four most common leaching batch experiments: German DEV S4 test, saturation soil extraction (SSE), ammonia nitrate extraction (ANE), and pH static test. They concluded that for a study focused on groundwater impact assessment, the best test is the SSE since the use of deionized water and the absence of constant agitation makes it closer to the real conditions of the soil-groundwater system. The crucial point of a batch experiment is the choice of the liquid/solid (L/S) ratio. There is currently no standardization of the L/S ratio for batch leaching experiments in groundwater risk assessment. In most literature studies the L/S ratio values vary between 2 and 10 [17; 18; 19]. Parallel batch tests can be used to determine a potential contaminant release in a soil-water system [20]. The release of chemical species, indeed, can be closely linked to the L/S ratio that can influence the solubility of a chemical species and its ability to pass in the liquid phase [21]. Therefore, it is important to perform multiple batch extraction tests on new materials that will be applied to the soil to estimate the total amount of contaminant that can be extracted from a given material [22]. It is essential to perform series of batches with different L/S since the different batch set-up could change the results and their interpretation. Indeed, multiple batches with different L/S ratios can provide useful information on the behavior of some materials under different moisture conditions, as usually happen in the field. For example, it is possible to gain insights about the conditions of maximum and minimum release of nutrients and/or contaminants. This is very important in studies focused on the release of nutrients in agricultural landscapes or in risk assessment studies tackling the potential release of contaminants. In this study, multiple leaching batch tests with different L/S ratios were carried out to assess the potential release of NO3\({}^{-}\) from graphene's application in two different soils: a calcareous sandy soil (CS) and a siliciclastic riverine sandy soil (SS).