Study On Surface Characteristics Of Loaded Boron Oxides And Their Sorption-Desorption Reaction With Acid Ions

Six samples were synthesized, they were goethite (denoted as G), manganite (denoted as M), adsorbed boron gothite loader (denoted as ad-B-G) and adsorbed boron manganite loader (denoted as ad-B-M) which were prepared by infusing G or M into contain-borax solution and let B be adsorbed on the surface of these oxides, occluded boron goethite loader (denoted as oc-B-G) and occluded boron manganite loader (denoted as oc-B-M) which were prepared by mixing boric acid solution with Fe³⁺ or Mn²⁺ ion to prepare goethite or manganite and let B be occluded in these oxides. We mainly discussed relationship between these oxides and acid ions like manganese ion, aluminum ion and proton which were always high in acid soils. Adsorption and desorption isotherm and kinetics of the Oxides on manganese and aluminum ions, effect of pH, temperature and electrolyte on behavior of the oxides were studied. Furthermore, we determined some surface parameters like surface acid constant, zero point of charge and surface area of the oxides which helps us to understand how boron affected chemical characteristics of the oxides. The main conclusions of this paper were listed below:1. Electrochemistry characteristics of oxides changed when boron was loaded. Surface area sequence followed this order: occluded boron oxide loader > oxide > adsorbed boron oxide loader, no matter on iron oxides or manganese oxides. Adsorbed boron oxide loaders have the largest site density and oc-B-G had the highest acid constant value. As boron loaded on goethite, ZPC declined, ZPC was G > ad-B-G > oc-B-G, but there was not too much change on three manganese oxides.2. Mn²⁺ sorption amount increased as pH increased. The oxides showed different affinity to Mn²⁺ when pH same, oc-B-G > ad-B-G > G, oc-B-M > ad-B-M > M. Mn²⁺ sorption amount on manganese oxides was several decuple of iron oxides, that might be relative with electrochemistry characteristics and their constructure.3. Mn²⁺ sorption amount increased as Mn²⁺ concentration increased in solution. The maximum Mn²⁺ sorption amount followed this order: oc-B-G > ad-B-G >Q but they desorpted same amount of Mn²⁺, this means that oc-B-G could adsorbed more Mn²⁺ than others.4. Temperature influenced Mn²⁺ sorption and desorption on iron oxides. The figure of Mn²⁺ sorption isotherm changed when temperature up to 40 degree, this means oxide had different sorption mechanism at high temperature. Enthalpy of Mn²⁺ sorption on iron oxides was positive which means that higher temperature enhanced Mn²⁺ sorption. Mn²⁺ sorption amount on M were oc-B-G > ad-B-G >G and M> ad-B-M > oc-B-M at each temperature. Isotherm was described by Langmuir equation and Freundlich equation. Constant K of Langmuir equation reflected Mn²⁺ affinity to oxide, we found oc-B-G has the biggest K and G the smallest, this proved that Mn²⁺ was more...