| 1. |
- Alenezi, Ali, et al.
(författare)
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Characteristics of 2 Different Commercially Available Implants with or without Nanotopography
- 2013
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Ingår i: International Journal of Dentistry. - : Hindawi Limited. - 1687-8736 .- 1687-8728. ; 2013:Art. no. 769768
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess histologically and histomorphometrically the early bone forming properties after 3 weeks for 2 commercially available implants, one supposedly possessing nanotopography and one without, in a rabbit femur model. Twenty-four implants divided equally into 2 groups were utilized in this study. The first group (P-I MICRO+NANO) was a titanium oxide (TiO2) microblasted and noble gas ion bombarded surface while the second group (Ospol) was anodic oxidized surface with calcium and phosphate incorporation. The implants were placed in the rabbit femur unicortically and were allowed to heal for 3 weeks. After euthanasia, the samples were subjected to histologic sectioning and bone-implant contact and bone area were evaluated histomorphometrically under an optical microscope. The histomorphometric evaluation presented that the P-I MICRO+NANO implants demonstrated significantly higher new bone formation as compared to the Ospol implants. Within the limitations of this study, the results suggested that nanostructures presented significantly higher bone formation after 3 weeks in vivo, and the effect of chemistry was limited, which is indicative that nanotopography is effective at early healing periods.
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| 2. |
- Alenezi, Ali, et al.
(författare)
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Controlled release of Clarithromycin from PLGA microspheres enhances bone regeneration in rabbit calvaria defects
- 2017
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 106:1, s. 201-208
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate the controlled release effect of Clarithromycin loaded in PLGA microspheres in a rabbit calvaria defect model. Methods: Clarithromycin-loaded PLGA microspheres (MSPs) were formulated by modified O/W single emulsion/solvent evaporation method. After characterization, in vivo animal experiment was conducted. Four critical size bone defects were created in the calvaria of New Zealand White rabbits (n=21, n=7/time point). The bone defects were randomly designated to 4 groups: Group 1: No augmentation (sham), Group 2: beta-Tricalcium phosphate (β-TCP), Group 3: beta-Tricalcium phosphate (β-TCP) with 0.12 µg clarithromycin, and Group 4: beta-Tricalcium phosphate (β-TCP) with 6.12 µg PLGA microspheres (loaded with 0.12 µg clarithromycin). After 2, 4 and 12 weeks of healing, the levels of bone regeneration were evaluated using micro- computed tomography and histology. Results: The average size of the PLGA microspheres was 26.38 μm that showed 94% encapsulation efficacy with clarithromycin. Clarithromycin release from PLGA microspheres revealed sustained release for around 4 weeks with approximately 50% release of clarithromycin during the first week. In the histological analysis, new bone formation was evident at 2 and 4 weeks of healing in all groups and bone formation increased as a function of healing time in vivo. At 12 weeks, Group 4 showed significantly higher amount of newly formed bone compared to Group 1 (p=0,002). Moreover, during the micro CT exam, Group 4 expressed significantly higher bone formation compared to Group 1 at all time points tested (p=0.00, 0.014, and 0.002 in 2, 4, and 12 weeks, respectively). Conclusions: PLGA microspheres demonstrated initial burst release of clarithromycin followed by a sustained release profile. The in vivo findings showed that β-TCP with clarithromycin-loaded microspheres can enhance bone formation in bone defects.
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| 3. |
- Alenezi, Ali, et al.
(författare)
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Development of a photon induced drug-delivery implant coating
- 2019
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Ingår i: Materials Science and Engineering C. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 98, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- A thin surface coating intended for medical devices such as implants where local drug release is enabled using near infrared light (NIR) as an external stimulus has been developed. The delivery system consists of a thin Poly (N-isopropylacrylamide)-co-acrylamide (PNIPAAm-AAm) polymer layer with incorporated gold nanorods (GNRs). The aspect ratio of the GNRs were chosen to absorb NIR light, thus fitting the biological window of low tissue absorption, to locally heat the polymeric layer to initiate a drug release. Hence, controlled drug delivery from a surface within tissue orchestrated from outside the body is achievable. Composition of the PNIPAAm-AAm co-polymer was systematically varied to find a suitable phase transition temperature for in vivo applications. Differential scanning calorimetry (DSC) analysis showed that PNIPAAm-AAm containing 10% acrylamide had an appropriate phase transition temperature of 42 °C. As visualized by scanning electron microscopy (SEM), the surface coating consisted of 200 nm uniform polymer layer. Quartz crystal microbalance with dissipation monitoring (QCM-D) analysis coupled with in situ NIR irradiation demonstrated a dramatic shift in frequency that was attributed to mass being released from the surface upon irradiation. This mass release correlated well with the drug release profile as determined using UV/VIS spectroscopy with phenol as a model drug. In addition, proof-of-concept of the drug-delivery system was demonstrated by releasing the antibiotic vancomycin to eradicate Staphylococcus epidermidis bacteria in culture.
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| 4. |
- Alenezi, Ali, et al.
(författare)
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Effects of Local Drug and Chemical Compound Delivery on Bone Regeneration Around Dental Implants in Animal Models : A Systematic Review and Meta-Analysis
- 2018
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Ingår i: International Journal of Oral & Maxillofacial Implants. - : Quintessence. - 0882-2786 .- 1942-4434. ; 33:1, s. e1-e18
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Forskningsöversikt (refereegranskat)abstract
- Purpose: One of the suggested methods for enhancing osseointegration is the local application of drug agents around implant surfaces. The aim of this review was to evaluate the methods most commonly used for local drug and chemical compound delivery to implant sites and assess their influence on osseointegration. Materials and Methods: An electronic search was undertaken in three databases (PubMed, Scopus, Embase). The search was limited to animal experiments using endosseous implants combined with local drug delivery systems. Meta-analyses were performed for the outcome bone-to-implant contact (BIC). Results: Sixty-one studies met the inclusion criteria. Calcium phosphate (CaP), bisphosphonates (BPs), and bone morphogenetic proteins (BMPs) were the most commonly used chemical compounds. There were two main methods for local drug delivery at the bone-implant interface: (1) directly from an implant surface by coating or immobilizing techniques, and (2) the local application of drugs to the implant site, using carriers. There was a statistically significant increase in BIC for both local drug delivery methods (P = .02 and P < .0001, respectively) compared with the control methods. There was a statistically significant increase in BIC when CaP (P = .0001) and BMPs (P = .02) were either coating implants or were delivered to the implant site, in comparison to when drugs were not used. The difference was not significant for the use of BPs (P = .15). Conclusion: It is suggested that the use of local chemical compound delivery systems around implants could significantly improve implant osseointegration in animal models. It is a matter of debate whether these in vivo results might have some significant effect in the human clinical setting in the long term.
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| 5. |
- Alenezi, Ali, et al.
(författare)
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Effects of the local administration of antibiotics on bone formation on implant surface in animal models : A systematic review and meta-analysis
- 2020
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Ingår i: Japanese Dental Science Review. - : Elsevier. - 1882-7616. ; 56:1, s. 177-183
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Forskningsöversikt (refereegranskat)abstract
- Purpose: This review aimed to evaluate the effects of the local delivery of antibiotics incorporated in implant surfaces on some quantitative parameters of bone formation. Materials and methods: An electronic search was undertaken in three databases (PubMed, Scopus, Embase) in addition to hand searching. The search was limited to animal experiments using endosseous implants combined with localized antibiotics release. Meta-analyses were performed for the percentages of bone volume (BV) and bone-to-implant contact (BIC). Results: Nine studies met the inclusion criteria. Several methods were identified for local delivery of antibiotics at the bone-implant interface, but the most commonly used method was by coating (incorporating the implant surface with the antibiotic agents). Different antibiotic agents were used, namely bacitracin, doxycycline, enoxacin, gentamicin, minocycline, tobramycin, and vancomycin. There was no statistically significant difference in the percentage of BIC between implants with or without localized antibiotic release (P = 0.59). The meta-analysis revealed higher BV around implants coated with antibiotics compared to control groups (without antibiotics) (P < 0.01). Conclusion: It is suggested that the local administration of antibiotics around implants did not adversely affect the percentage of direct bone contact around implants, with a tendency for a slightly better bone formation around implants when combined with local administration of antibiotics. It is a matter of debate whether these in vivo results will have the same effect in the clinical setting. However, the risk of bias of these studies may, to some extent, question the validity of these results. (C) 2020 The Author. Published by Elsevier Ltd on behalf of The Japanese Association for Dental Science.
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| 6. |
- Alenezi, Ali, et al.
(författare)
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Long-Term Survival and Complication Rates of Porcelain Laminate Veneers in Clinical Studies : A Systematic Review
- 2021
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Ingår i: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- The presented study aimed to assess the survival rate of porcelain laminate veneers (PLV) based on a systematic review of the literature. An electronic search was last updated in February 2021. Eligibility criteria included clinical series of patients rehabilitated with PLVs published in the last 25 years, with a minimum follow-up of 3 years. Survival analysis methods were applied. Twenty-five studies were included, with 6500 PLVs. The 10-year estimated cumulative survival rate (CSR) of PLVs was 95.5%. The 10-year CSR of PLVs when fracture, debonding, occurrence of secondary caries, and need of endodontic treatment were considered as isolated reasons for failure were 96.3%, 99.2%, 99.3%, and 99.0%, respectively. PLVs without incisal coverage had a higher failure rate than PLVs with incisal coverage. Non-feldspathic PLVs performed better than feldspathic PLVs. As a conclusion, the 10-year CSR of PLVs was 95.5%, when fracture, debonding, occurrence of secondary caries, and need of endodontic treatment were considered as reasons for restoration failure. Fracture seems to be most common complication of PLVs, followed by debonding, with both more commonly happening within the first years after PLV cementation. PLVs with incisal coverage and non-feldspathic PLVs presented lower failure rates than PLVs without incisal coverage and feldspathic PLVs.
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| 7. |
- Alenezi, Ali
(författare)
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On enhancement of bone formation using local drug delivery systems
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Despite that many reports have confirmed the long-term clinical success rates associated with implant treatment, implant failure to achieve and maintain osseointegration still occurs in many cases. Local and sustained drug release at the bone-implant interface is one of the strategies that have been suggested to improve the osseointegration. The local drug release could help avoiding the risks usually associated with systemic administration, such as high drug dose or the loss of drug bioavailability. Aims: To map out the most commonly used chemical compounds and drug delivery systems used in animal experiments for implant research (Study I). Furthermore, to develop a new surface coating designed for medical devices and implants, and to examine the drug release mechanism from the coating using near infrared light (NIR) as an external stimulus (Study II). In addition, we examined the release of clarithromycin from PLGA microspheres within beta-tricalcium phosphate (β-TCP), and evaluated their osteogenic effect in a calvaria defect model in vivo (Study III). In Study IV, we evaluated the local release of strontium ranelate (Sr-ranelate) from implant surface coated with mesoporous titania films, and investigated if the local release of Sr-ranelate could improve bone formation around implants in an animal model. Materials and Methods: The articles included in the present thesis consist of four different studies. For Study I, an electronic search was done in three databases (PubMed, Scopus, Embase) to map out the most commonly used methods for local drug and chemical compound delivery to implant sites, and to assess their influence on bone response. Meta-analyses were performed for the outcome of bone-to-implant contact (BIC). In Study II, PNIPAAm-AAm polymers were synthesized at different compositions. The polymers were then incorporated with gold nanorods (GNRs) since these rods at predetermined aspect ratio can absorb NIR light to generate heat within the polymeric layer to initiate a drug release. The volume-phase transition behavior for the polymers was analyzed using differential scanning calorimetry (DSC). The GNRs-incorporated PNIPAAm was characterized using scanning electron microscopy (SEM) and quartz crystal microbalance with dissipation monitoring (QCM-D). The release behavior using phenol as drug model was investigated upon NIR irradiation using UV/VIS spectroscopy. In addition, the antibacterial behavior of polymer layers loaded with vancomycin was examined against Staphylococcus epidermidis. In Study III, four bone defects (5 mm of diameter) were created in the calvaria of New Zealand White rabbits (n = 21, n= 7/time point). The defects were randomly designated to four groups. Group 1: no augmentation (sham), Group 2: β-TCP, Group 3: β-TCP with 0.12 mg clarithromycin, and Group 4: β-TCP with 6.12 mg PLGA microspheres loaded with 0.12 mg clarithromycin. After 2, 4, and 12 weeks of healing, bone regeneration was evaluated using micro-computed tomography (µCT) and histology. In Study IV, mini-screw titanium implants were coated with mesoporous TiO2 films using Pluronic (P123) with or without poly propylene glycol (PPG) to create films with two different pore sizes. The implants were then incorporated with Sr-ranelate. SEM evaluation was performed to visualize the mesoporous TiO2 films and determine the pore size. The absorption and release kinetics of Sr-ranelate from mesoporous TiO2 films were evaluated by QCM-D. For the in vivo experiment, mini-screw titanium implants with or without Sr-ranelate were inserted in rats’ tibia bone to evaluate bone formation after 2 and 6 weeks. Results: In the systematic review (Study I), sixty-one studies met the inclusion criteria. Calcium phosphate (CaP), bisphosphonates (BPs), and bone morphogenetic proteins (BMPs) were the most commonly used chemical compounds. There were two main methods for local drug delivery at the bone-implant interface: (1) directly from an implant surface by coating or immobilizing techniques, and (2) the local application of drugs to the implant site, using carriers. There was a statistically significant increase in BIC for both local drug delivery methods (p= .02 and p < .0001, respectively) when compared to controls. There was a statistically significant increase in BIC when CaP (p= .0001) and BMPs (p= .02) were either coated into implants or delivered to the implant site, in comparison to when drugs were not used. The difference was not significant for the use of BPs (p= .15). In Study II, the DSC analyses showed that PNIPAAm-AAm containing 10% acrylamide had an appropriate phase transition temperature of 42◦C. SEM images showed that the surface coating consisted of a 200 nm thick uniform polymer layer. The QCM-D analysis coupled with in situ NIR irradiation demonstrated a dramatic shift in frequency that was attributed to mass being released from the surface upon irradiation. This mass release correlated well with the drug release profile as determined using UV/VIS spectroscopy with phenol as a model drug. For Study III, clarithromycin release from PLGA microspheres revealed sustained release for around 4 weeks with 50% release during the first week. Histologically, new bone formation was evident at 2 and 4 weeks of healing in all groups and bone formation increased as a function of healing time. At 12 weeks, Group 4 (β-TCP with PLGA microspheres loaded with clarithromycin) showed significantly higher amount of newly formed bone compared to Group 1 (sham). The µCT showed that Group 4 expressed significantly higher bone formation compared to Group 1 at all time points. In Study IV, the SEM images showed TiO2 films with porous structures covering the entire surface with pore sizes determined to be 6 nm for P123 and 7.2 nm for P123-PPG. The QCM-D analysis revealed an absorption of 3300 ng/cm2 of Sr-ranelate on the 7.2 nm TiO2 films, which was about 3 times more than the observed amount on the 6 nm TiO2 films (1200 ng/cm2). The histomorphometric analyses revealed higher percentages of bone implant contact (BIC) and bone area (BA) for implants with Sr-ranelate compared to implants in the control group after 2 and 6 weeks of healing. However, these differences were found not to be significant (BIC with a p-value of 0.43 after 2 weeks and 0.172 after 6 weeks), (BA with a p-value of 0.503 after 2 weeks, and 0.088 after 6 weeks). The mean BIC and BA values within the same group showed significant increase among all groups after comparing 2 and 6 weeks. Conclusions: Most studies assessing local drug/chemical compound release systems in implants evaluated the influence of the use of BPs, CaP, and BMPs on bone healing. The use of local chemical compound delivery systems around implants could significantly improve implant osseointegration in animal models (Study I). In addition, on demand-release of the antibiotic agent vancomycin from the coating induced by NIR light resulted in a clear inhibition zone around a coated substrate in a bacteria culture test, thereby providing proof of concept of the developed drug delivery system (Study II). The in vivo findings showed that β-TCP with clarithromycin-loaded microspheres can enhance bone formation in bone defects (Study III). Meanwhile, the in vivo findings on Sr-ranelate study (Study IV) could not confirm the positive effects of Sr-ranelate on implant incorporation in bone made by other authors.
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| 8. |
- Alenezi, Ali, et al.
(författare)
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Osseointegration effects of local release of strontium ranelate from implant surfaces in rats
- 2019
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Ingår i: Journal of Materials Science: Materials in Medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 30:10, s. 116-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND : Numerous studies have reported the beneficial effects of strontium on bone growth, particularly by stimulating osteoblast proliferation and differentiation. Thus, strontium release around implants has been suggested as one possible strategy to enhance implant osseointegration. AIM : This study aimed to evaluate whether the local release of strontium ranelate (Sr-ranelate) from implants coated with mesoporous titania could improve bone formation around implants in an animal model. MATERIALS AND METHODS : Mesoporous titania (MT) thin coatings were formed utilizing the evaporation induced self-assembly (EISA) method using Pluronic (P123) with or without the addition of poly propylene glycol (PPG) to create materials with two different pore sizes. The MT was deposited on disks and mini-screws, both made of cp Ti grade IV. Scanning electron microscopy (SEM) was performed to characterize the MT using a Leo Ultra55 FEG instrument (Zeiss, Oberkochen, Germany). The MT was loaded with Sr-ranelate using soaking and the drug uptake and release kinetics to and from the surfaces were evaluated using quartz crystal microbalance with dissipation monitoring (QCM-D) utilizing a Q-sense E4 instrument. For the in vivo experiment, 24 adult rats were analyzed at two time points of implant healing (2 and 6 weeks). Titanium implants shaped as mini screws were coated with MT films and divided into two groups; supplied with Sr-ranelate (test group) and without Sr-ranelate (control group). Four implants (both test and control) were inserted in the tibia of each rat. The in vivo study was evaluated using histomorphometric analyses of the implant/bone interphase using optical microscopy. RESULTS : SEM images showed the successful formation of evenly distributed MT films covering the entire surface with pore sizes of 6 and 7.2 nm, respectively. The QCM-D analysis revealed an absorption of 3300 ng/cm2 of Sr-ranelate on the 7.2 nm MT, which was about 3 times more than the observed amount on the 6 nm MT (1200 ng/cm2). Both groups showed sustained release of Sr-ranelate from MT coated disks. The histomorphometric analysis revealed no significant differences in bone implant contact (BIC) and bone area (BA) between the implants with Sr-ranelate and implants in the control groups after 2 and 6 weeks of healing (BIC with a p-value of 0.43 after 2 weeks and 0.172 after 6 weeks; BA with a p-value of 0.503 after 2 weeks, and 0.088 after 6 weeks). The mean BIC and BA values within the same group showed significant increase among all groups between 2 and 6 weeks. CONCLUSION : This study could not confirm any positive effects of Sr-ranelate on implant osseointegration.
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| 9. |
- Bougas, Kostas, et al.
(författare)
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In vivo evaluation of a novel implant coating agent : laminin-1.
- 2014
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley Periodicals. - 1523-0899 .- 1708-8208. ; 16:5, s. 728-35
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of this study was to assess the effect of implant coating with laminin-1 on the early stages of osseointegration in vivo.MATERIALS AND METHODS: Turned titanium implants were coated with the osteoprogenitor-stimulating protein, laminin-1 (TL). Their osteogenic performance was assessed with removal torque, histomorphometry, and nanoindentation in a rabbit model after 2 and 4 weeks. The performance of the test implants was compared with turned control implants (T), alkali- and heat-treated implants (AH), and AH implants coated with laminin-1.RESULTS: After 2 weeks, TL demonstrated significantly higher removal torque as compared with T and equivalent to AH. Bone area was significantly higher for the test surface after 4 weeks, while no significant changes were detected on the micromechanical properties of the surrounding bone.CONCLUSIONS: Within the limitations of this study, our results suggest a great potential for laminin-1 as a coating agent. A turned implant surface coated with laminin-1 could enhance osseointegration comparable with a bioactive implant surface while keeping the surface smooth.
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| 10. |
- Hashim, Khalid S., et al.
(författare)
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Adsorption of fluoride on a green adsorbent derived from wastepaper: Kinetic, isotherm and characterisation study
- 2023
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Ingår i: Case Studies in Chemical and Environmental Engineering. - : Elsevier. - 2666-0164. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The excessive concentration of fluoride (F−) in water represents a grave problem for several countries, especially those that depend on groundwater as a main source of drinking water. Therefore, many treatment methods, such as chemical precipitation and membrane, were practised to remove F− from water. However, the traditional methods suffer from many limitations, such as the high cost and the slowness. Hence, many studies have been directed towards developing novel and effective water defluoridation methods. In this context, the current study investigates the development of an eco-friendly adsorbent by extracting Ca, Al, and Fe from industrial by-products, precipitating them on sand particles, and using this new adsorbent to remove F− from water. The removal experiments were commenced under different pH levels (3-10), contact times (0–240 minutes) and concentrations of F− (7.5–37.5 mg/L). X-ray fluorescence (XRF), X-ray diffraction Investigator (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) methods were used to characterise the green adsorbent. Adsorption isotherm and kinetic studies were also conducted to define the adsorption type. The results confirmed that the new adsorbent could remove as high as 86% of F− at pH, contact time, agitation speed and adsorbent dose of 10, 180 minutes, 200 rpm and 15 mg/L, respectively. The characterisation studies prove the occurrence of the sorption process and the suitability of the morphology of the adsorbent for F− removal. Adsorption kinetics follow better with a pseudo-first-order model that indicates the predominance of physisorption, which agrees with the FTIR results. The isotherm study indicated that Langmuir isotherm is more suitable for representing data with an R2 value of 0.992, which means the adsorption of F− occurs as monolayer adsorption on homogeneous sites on the surface of the new adsorbent. In summary, it can be concluded that the developed adsorbent in this study could be a promising alternative to the traditional F− removal methods.
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