Evaluation of the effects of treatment factors on the properties of bio-apatite materials

Abstract

Animal bones have been studied as a resource of low-crystalline apatite for immobilization of toxic heavy metals. Chemical and thermal treatments can be applied for selective removal of bone organic constituents. In this study, the impact of different treatment factors was determined by experimental design methodology, and comparison of the estimated effects was performed in order to optimize the treatment conditions. Fractional factorial design with five variables at two levels was applied for factors screening. The type of chemical reagent (H 2 O 2 or NaOH), its concentration (0.1 or 2 mol/L), reaction temperature (20 or 60°C), contact time (1 or 3 h) and sample annealing (without or at 400°C) were considered as process variables. Structural properties of bone sorbents, loss of ignition, point of zero charge, surface functional groups, specific surface area, chemical composition, and Cd 2? sorption efficiency, were selected as system responses. Samples significantly differed in respect to the organic phase content and composition, thus mechanisms of Cd 2? sorption were complex. Statistical analysis has revealed that, between all studied factors, temperature treatment was the most important for sorbents increased specific surface area, porosity and cation sorption. Furthermore, NaOH was more effective than H 2 O 2 , while the effects produced by variation of other factors were less pronounced. The highest proportion of bio-apatite with desired low crystallinity and high specific surface area was achieved by synergetic effects of chemical treatment with NaOH and thermal treatment at 400°C.

Synthesis and characterization of sol–gel derived calcium hydroxyapatite thin films spin-coated on silicon substrate

“…One more very important requirement for CHA coatings is porosity, because bone cells osteoblasts and osteoclasts, also proteins could flow inside pores supporting formation of new bone. The CHA coatings should have a high degree of crystallinity, correct stoichiometry and very good adhesion to the substrate [1,12,13]. Cell colonization and bone growth occur when pores are larger than 50-300 µm [2,11,[14][15][16][17].…”

Screening the Main Factors Affecting the Wear of the Scraper Conveyor Chute Using the Plackett–Burman Method

“…Design of experiment (DoE) methods allows measuring the significance of the design variables not only when they are acting alone, but also when combined effects are present [16,17]. DoE based on Plackett-Burman design (PBD) method [18,19] works at two levels and can be constructed on the basis of fractional replication of a full factorial design. It is a powerful and useful tool in searching for the key factors rapidly from a multivariable system and it can provide some important information about each factor by relatively few experiments.…”

Ni(II) immobilization by bio-apatite materials: Appraisal of chemical, thermal and combined treatments

“…Recently, the effects of various treatment conditions on bioapatite properties were compared [20]. Using experimental design methodology, the influence of five process variables was investigated.…”

“…By simultaneous variation of process variables between lower and higher level, materials with different properties were obtained. Impact of treatment factors was compared by statistical analysis, and it was concluded that annealing had predominant influence on surface properties, as well as sorption capacity towards Cd 2+ [20].…”

“…Considering the results achieved so far, this study aims to compare performances of bone sorbents obtained under conditions of chemical and thermal treatments that were found to provide the highest sorption capacities [15,[18][19][20]. In addition, synergistic effect of both treatments, applied one after the other, was tested and the results were compared with the efficiency of raw, powdered bones.…”