Sorption of Natural Siderophores onto Clinoptilolite-Tuff and Its Controlled-Release Characteristics

Abstract

Iron deficiency-induced chlorosis is a widespread horti-/agricultural problem that can lead to massive crop failures, especially for plants growing on calcareous soils. The most effective agronomical practice to prevent plants from iron deficiency is to apply synthetic Fe-(chelate)-fertilizers to the soil. Because these compounds are usually not biodegradable and, therefore, may become soil contaminants, efficient and environmentally friendly solutions are needed. The present study investigates a novel approach to tackle chlorosis in plants using clinoptilolite-tuff as a carrier substrate for the natural Fe-siderophore ‘coprogen’. The combination of the two substances promises economic and ecological potential to be used as a fertilizer to prevent crop failures triggered by micro-nutritional shortages. Sorption and release experiments were performed in batch and column setups in order to understand the binding characteristics; analyses were carried out using ICP-MS, HPLC, XRD, and SEM, respectively. Results show the highest sorption capacity of coprogen (92.8%) and corresponding Fe (90.2%) on clinoptilolite-tuff at pH 4 within 30 min as well as the efficient release of coprogen at pH 8, mimicking alkaline soil conditions (88% of the sorbed coprogen is released from the tuff). The gained data suggest that coprogen is bound onto the clinoptilolite-tuff through surface-mediated sorption based on electrostatic interactions.

Purified Clinoptilolite-Tuff as an Efficient Sorbent for Food-Derived Peanut Allergens

“…The adsorption showed pH dependency ( Figure 3 ), and adsorption capacities of 40 µg/mg (≙ 80 mg in 500 mL) at pH 6.8 and 20 µg/mg (≙ 40 mg in 500 mL) at pH 1.5 could be defined ( Figure 1 and Figure 2 ). This PCT phenomenon with respect to pH dependency is already known and has been described [ 19 , 21 , 42 ]. Even minimal changes in pH towards alkalinity produced detectable results, as revealed by the adsorption of heavy metal ions to PCT.…”

“…This led to higher standard deviations with respect to cesium, thallium, and lead [ 19 ]. When using natural siderophores and clinoptilolite-tuff for sorption experiments, the highest binding capacity of coprogen and iron was detected at pH 4, but it decreased constantly to pH 10, while the most efficient release was observed at pH 8 [ 42 ]. Depending on the specific ion or protein, the pH value plays a crucial role in the process of sorption/desorption to/from PCT.…”

Clinoptilolite—An Efficient Carrier for Catalytically Active Nano Oxide Particles

“…The availability and structural features of CLI result in its widespread application in many areas, including various industrial processes, agriculture, veterinary fields, medicine and environmental protection [51][52][53][54][55][56][57].…”