Organic-Inorganic Hybrid Materials:Layered Double Hydroxides and Cellulose Acetate Films as Phosphate Recovery

With demand increasing for phosphate recovery,a considerable share of current research is dedicated to elaborate multifunctional materials.In this way,the objective of this work was to produce hybrid films from the combination of cellulose acetate(CA)biopolymer and magnesium and aluminium layered double hydroxides(LDHs)and investigate their performance for phosphate recovery.In this work,the following materials were prepared and characterized:LDH,calcinated LDH(LDH-c),CA film(CAF),CA film with LDH(CAF-LDH)and CA film with LDH-c(CAF-LDH-c).The produced materials were characterized by X-ray diffraction,thermogravimetric analysis coupled with differential scanning calorimetry and mass spectrometry,attenuated total reflectance Fourier transform infrared spectroscopy and scanning electronic microscopy.The thickness,H2O absorption(AH2O),stability in H2O and phosphate adsorption of the produced films were evaluated.The adsorption capacity of films was compared to LDHs in powder form.The CAF-LDH and CAF-LDH-c increased film thickness,where CAF-LDH-c was thicker than CAF-LDH.CAF-LDH-c had higher AH2O than the other films,because of its increased thickness and mainly because of the H2O sorption process of these materials.H2O stability of 98.97%for CAF-LDH and 96.81%for CAF-LDH-c suggest the produced films can maintain their structural properties even after a long contact period with aqueous solutions.For the CAF-LDH-c,the maximum adsorption capacity of phosphate,according to the Langmuir-Freundlich model,was 6.98 mg/g.The adsorption value suggests that this film can be used as an efficient phosphorus(P)adsorbent from wastewater or a eutrophicated source.

Cellulose Acetate Film and Layered Double Hydroxide as Determination Method of Available Phosphorus in the Soil

The determination of available phosphorus(P)in soil is essential to the evaluation of the current fertility status,and therefore,for recommending the required phosphate fertilizers for the cultivation of crops.The mostly used extractants around the country are Mehlich-1(M-1)and anionic resins(AR)and mixed resins(MR).However,there are still controversies in relation to the method that should be used,due to of particularities of each extractor.Therefore,the main objectives of this work was to assess the applicability of films of binary combination between cellulose acetate(CA)biopolymer and calcinated layered double hydroxide(LDH-c),named CAF-LDH-c,as a new extractor of available P in soils.For this,two experiments were set out.In the first one,sub-samples of an Oxisol layer 0-20 cm were used and submitted to increasing doses of total P(0,250,750 and 2,250 mg/dm3)in the form of monoammonium phosphate(MAP)at different incubation time(5,30,60 and 90 d).In the second experiment,samples of 20 soils from different origins and contents of available P were used with distinct chemical and physical attributes.The analysis of available P by M-1,AR,MR,Mehlich-3(M-3)and CAF-LDH-c extractants was done in both experiments.The efficiency of the extractants was evaluated by Pearson’s linear correlation.The correlation between values of P extracted from soil in the first experiment was highly significant among all extraction methods used,including for CAF-LDH-c.In the second experiment,CAF-LDH-c showed significant correlation(p<0.01)with M-1,M-3,AR and MR.Thus,the significant correlations of the extractant being tested(CAF-LDH-c)with those usually used indicates the possibility of this new method of routine laboratories for assessing the P availability of for the cultivation of crops.