Hydrated phosphorus oxyacids alone and adsorbed on nanosilica

► Effects of structural characteristics of nanosilicas on the interfacial behavior of phosphorus oxyacids. ► Confined space effects on the characteristics of bound water/acid solution. ► Effects of silica on interaction of phosphorus oxyacids with water. ► The δH value as a measure of associativity of interfacial water and aqueous solution of acids.