Displaying publications 81 - 100 of 189 in total

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  1. Iqbal DM, Wong LS, Kong SY
    Materials (Basel), 2021 Apr 23;14(9).
    PMID: 33922871 DOI: 10.3390/ma14092175
    The rapid development of the construction sector has led to massive use of raw construction materials, which are at risk of exhaustion. The problem is aggravated by the high demand for cement as binding powder and the mass production of clay bricks for construction purposes. This scenario has led to high energy consumption and carbon emissions in their production. In this regard, bio-cementation is considered a green solution to building construction, because this technology is environmentally friendly and capable of reducing carbon emissions, thus slowing the global warming rate. Most of the previously published articles have focused on microbiologically induced calcium carbonate precipitation (MICP), with the mechanism of bio-cementation related to the occurrence of urea hydrolysis as a result of the urease enzymatic activity by the microbes that yielded ammonium and carbonate ions. These ions would then react with calcium ions under favorable conditions to precipitate calcium carbonate. MICP was investigated for crack repair and the surface treatment of various types of construction materials. Research on MICP for the production of binders in construction materials has become a recent trend in construction engineering. With the development of cutting edge MICP research, it is beneficial for this article to review the recent trend of MICP in construction engineering, so that a comprehensive understanding on microbial utilization for bio-cementation can be achieved.
    Matched MeSH terms: Urea; Urease
  2. Shamsuri AA, Daik R
    Materials (Basel), 2013 Feb 22;6(2):682-698.
    PMID: 28809334 DOI: 10.3390/ma6020682
    An ionic liquid, 1-n-butyl-3-methylimidazolium chloride (BmimCl) was blended with urea at 1:1 mole ratio to create a BmimCl/Urea mixture. The agarose/talc composite films containing the BmimCl/Urea mixture were then acquired through a gelation method. The weight ratio of agarose and talc was fixed at 4:1, while the content of BmimCl/Urea was varied from 0 to 10 wt % relative to the overall weight of the composite films. The tensile stress and modulus results showed the optimum BmimCl/Urea content in the composite film lies at 8 wt %. The talc particles are embedded in the agarose matrix and there are no pullouts for the composite films containing BmimCl/Urea as demonstrated by SEM micrographs. The addition of BmimCl/Urea increased the glass transition temperature of the composite films, however, the thermal decomposition temperature decreased drastically. FTIR and FT-Raman spectra indicated the existence of interaction between agarose and talc, which improves their interfacial adhesion. As a conclusion, a BmimCl/Urea mixture can be utilized as a coupling agent for agarose/talc composite films.
    Matched MeSH terms: Urea
  3. Thambiah CS, Samsudin IN, George E, Ranjit LK, Saat NS, Hussein Z, et al.
    MyJurnal
    Patients with diabetes have an earlier onset and increased severity of anaemia compared to those with similar degree of renal impairment from other causes. Anaemia is associated with an increased risk of vascular complications. In this study, we determined the prevalence of anaemia in T2DM patients and its association with sociodemographic, clinical and laboratory parameters in an endocrine tertiary hospital in Malaysia. This was a cross-sectional study using retrospective electronic data from January 2011 to December 2013 of 165 T2DM patients in Hospital Putrajaya. Data was analysed using IBM SPSS Statistics version 21.0 for Windows. The prevalence of anaemia was 39.4% and majority had normocytic normochromic (80%), mild (58.5%) anaemia. Majority were Malays (73.9%), aged below 60 with comparable gender percentage and long-standing, poorly-controlled DM [median fasting blood sugar (FBS) 8mmol/L; glycated haemoglobin (HbA1c) 7.9%]. Using the KDIGO chronic kidney disease (CKD) staging system, 86% of these patients were in stages 3-5. Anaemic patients had a significantly higher serum urea, creatinine and a lower FBS, estimated glomerular filtration rate (eGFR) compared to non-anaemic patients. Anaemic patients with diabetic nephropathy had a significantly lower haemoglobin (Hb) compared to those without this complication (p=0.022). The sensitivity and specificity at a cut-off eGFR value of 38.3 ml/min/1.73 m2 (maximum Youden index = 0.462) was 66.7% and 79.5%, respectively to discriminate mild from moderate anaemia. This study shows that anaemia is already present in T2DM patients in Hospital Putrajaya at initial presentation to the specialist outpatient clinic and is significantly associated with CKD. Hence, it emphasises the obligatory need for routine and follow-up full blood count monitoring in T2DM patients in primary care as well as tertiary settings in Malaysia to enable early detection and aggressive correction of anaemia in preventing further complications.

    Study site: endocrine clinic, Hospital Putrajaya
    Matched MeSH terms: Urea
  4. Omoregie AI, Ong DEL, Nissom PM
    Lett Appl Microbiol, 2019 Feb;68(2):173-181.
    PMID: 30537001 DOI: 10.1111/lam.13103
    Biocalcification through the use of ureolytic bacteria and biochemical activities has evolved in recent decades into a fervent resourceful effective technology suitable for soil stabilization, crack repair and bioremediation. Extensive studies have been carried out on numerous ureolytic bacterial species isolated from soils and sewage samples. However, very limited attention has been given to limestone caves with natural calcite formations as a possible source for isolation of ureolytic bacteria. In this study, bacterial isolates were recovered from limestone cave samples to determine their suitability for biocalcification. Twenty-seven morphologically distinct bacterial isolates were identified by partial 16S rRNA gene sequencing and their various genetic diversity was characterized according to their phylogenetic affiliations. Based on the molecular identification, Sporosarcina was the most abundant genus among all the ureolytic isolates, while the rest belonged to Pseudogracilibacillus and Bacillus genera. Analytical analysis on urease measurement showed that urease activities for the isolates ranged from 1·130 to 21·513 mol urea hydrolysed per minute, with isolate NB33 achieving the highest value and TSB4 achieving the lowest value. The estimated CaCO3 precipitates for the isolates ranged from 4·04 to 17·26 mg ml-1 , with isolate NB30 achieving the highest value and TSB20 achieving the lowest value. The findings in this study demonstrated that the ureolytic bacteria from limestone caves are promising bio-calcifying agents. SIGNIFICANCE AND IMPACT OF THE STUDY: Ureolytic bacteria continues to play an important role as microbial tools used in geotechnical engineering for soil biocalcification. Microbial strains with the ability to produce urease enzyme and induce calcium carbonate mineral are often isolated from soil, water and sludge samples. However, screening for these essential microbes from extreme regions such as caves are rarely investigated. In this study, native bacteria which were isolated from limestone cave samples are identified and characterized. The findings suggested that these ureolytic bacterial isolates have the potential to serve as suitable alternative microbial agents for soil strengthening and stabilization.
    Matched MeSH terms: Urea; Urease
  5. Hoe, Phua Choo Kwai, Khairuddin Abdul Rahim, Ahmad Nazrul Abd Wahid
    MyJurnal
    Development of biofertilizer seed treatments for okra seeds were carried out by mixing phosphate
    solubilising bacteria (AP 3) and plant growth promoter (AP 2) with adhesives. The seeds were
    coated with inoculums and four types of adhesives namely, Gum Arabic; Polyethylene Glycol
    (PEG); Sodium Alginate and Methycellulose respectively. From eight seed treatments, all seed
    treatments significantly increased seed germinations except treatment T4 (Gum Arabic and AP3).
    In general, maximum germination rates and log of viable cells were observed when treated with
    polyethylene glycol 4000 (PEG) mixed with AP2 (T7) and AP3 (T8). These results show that using
    PEG as adhesive enhanced the germination rates and log of viable cells of AP2 and AP3. Thus,
    PEG could be a good adhesive for seed treatment. In greenhouse experiment, okra seeds treatment
    with AP2 and PEG (T1) showed the highest dry weight compared to other treatments. Seeds
    treatment with AP3 and PEG (T2) showed higher contribution of N compare to seeds treatment
    (T1). There were no significant different within seed treatments and urea treatment in okra yield.
    All treatments significantly increased yields compared with control
    Matched MeSH terms: Urea
  6. Lee KW, Tan WS
    J Virol Methods, 2008 Aug;151(2):172-180.
    PMID: 18584885 DOI: 10.1016/j.jviromet.2008.05.025
    The recombinant hepatitis B virus (HBV) core antigen (HBcAg) expressed in Escherichia coli self-assembles into icosahedral capsids of about 35 nm which can be exploited as gene or drug delivery vehicles. The association and dissociation properties of the C-terminally truncated HBcAg with urea and guanidine hydrochloride (GdnHCl) were studied. Transmission electron microscopy (TEM) revealed that the dissociated HBcAg was able to re-associate into particles when the applied denaturing agents were physically removed. In order to evaluate the potential of the particles in capturing molecules, purified green fluorescent protein (GFP) was applied to the dissociated HBcAg for encapsidation. The HBcAg particles harbouring the GFP molecules were purified using sucrose density gradient ultracentrifugation and analysed using native agarose gel electrophoresis and TEM. A method for the encapsidation of GFP in HBcAg particles which has the potential to capture drugs or nucleic acids was established.
    Matched MeSH terms: Urea
  7. Amuthan A, Devi V, Shreedhara CS, Rao V, Jasphin S, Kumar N
    J Tradit Complement Med, 2021 May;11(3):279-286.
    PMID: 34012874 DOI: 10.1016/j.jtcme.2020.08.004
    Background: Traditional Siddha Medicine advises using metal-based formulations to treat cancers. In the case of any toxicities during the therapy, Siddha physicians use Vernonia cinerea (VC) whole plant kashayam (crude aqueous extract-CAE) to reverse the toxic effects.

    Aim: To evaluate the nephroprotective activity of CAE and its fractions in cisplatin-induced nephrotoxicity and to assess whether they compromise the anticancer efficacy of cisplatin.

    Materials and methods: Cisplatin-induced renal damage was induced in Ehrlich Ascites Carcinoma (EAC) bearing mice during mild phase of tumor growth. CAE and its butanol (BF) and aqueous (AF) fractions were administered orally from the 5th day for five days. Nephroprotective potential (serum urea, creatinine, renal histology) and effect of VC on cisplatin anticancer efficacy (tumor volume, viable tumor cells, percentage increase in life span (% ILS)) were calculated.

    Result: CAE and its fractions significantly reversed the cisplatin-induced renal damage. CAE and BF treated animals showed regeneration of 50%-75% of proximal tubular cells. Compared to EAC control mice, the % ILS of the cisplatin-treated group was 244% and it was further extended to 379% after CAE administration. The % ILS in the CAE treated group was 1.6 times higher than the cisplatin alone treated group. GC-MS study showed the presence of astaxanthin and betulin.

    Conclusion: CAE of VC reverses cisplatin-induced kidney damage as well as regenerates proximal tubular epithelial cells, without compromising the anticancer effect of cisplatin. When CAE was further fractionated, the nephroprotective activity was retained, but the beneficial anticancer effect of cisplatin was compromised.

    Matched MeSH terms: Blood Urea Nitrogen; Urea
  8. Muthaian R, Pakirisamy RM, Parasuraman S, Raveendran R
    J Pharmacol Pharmacother, 2017 2 7;7(4):159-164.
    PMID: 28163536 DOI: 10.4103/0976-500X.195898
    OBJECTIVE: To investigate the association of hypertension coexisting with diabetes mellitus with oxidative stress and inflammation in the kidneys of streptozotocin (STZ)-induced diabetic rats.

    MATERIALS AND METHODS: Male Wistar rats were used for the experiments. Blood glucose (BG), urea, blood pressure (BP), and heart rate (HR) were analyzed before and 48 h after STZ injection. Further, these parameters were monitored up to 3 months of diabetes induction. Subsequently, the inflammatory markers (C-reactive protein, tumor necrosis factor-alpha, and nitrate) and oxidative stress markers were estimated after 3 months of diabetes induction in the kidney homogenate. Histological analysis of renal tissue was also carried out.

    RESULTS: Linear elevation of BG, urea, mean arterial pressure (MAP), and HR was observed up to 3 months of diabetes induction. In the same manner, inflammatory and oxidative stress markers were also found to be significantly increased. Notably, the histological analysis revealed the signs of nephropathy such as increased mesangial cell number, thickness of basement membrane, and renal artery. Inflammatory and oxidative stress markers positively correlated with elevated BP and BG, but the correlation was better with BP rather than BG.

    CONCLUSION: Hypertension has a strong implication in the increased oxidative stress and inflammation of diabetic kidney at the very early stage of diabetes mellitus.

    Matched MeSH terms: Urea
  9. Al-Mulla EA, Yunus WM, Ibrahim NA, Rahman MZ
    J Oleo Sci, 2010;59(11):569-73.
    PMID: 20972356
    Fatty thiohydroxamic acids (FTAs) have been successfully synthesized from palm olein and thiohydroxamic acid by a one-step lipase catalyzed reaction. The use of immobilized lipase (Lipozyme RMIM) as the catalyst for the preparation reaction provides an easy isolation of the enzyme from the products and other components in the reaction mixture. The FTAs were characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) technique and elemental analysis. The highest conversion percentage (95 %) was obtained when the process was carried out for 30 hours using urea to palm oil ratio of 6.0: 1.0 at 40 °C. The method employed offers several advantages such as renewable and abundant of the raw material, simple reaction procedure, environmentally friendly process and high yield of the product.
    Matched MeSH terms: Urea
  10. Al-Mulla EA, Yunus WM, Ibrahim NA, Rahman MZ
    J Oleo Sci, 2010;59(3):157-60.
    PMID: 20124758
    In this study, difatty acyl urea has been successfully synthesized from corn oil using sodium ethoxide as a catalyst. Ethyl fatty ester and glycerol were produced as by-products. In this reaction, corn oil was refluxed with urea in ethanol. The highest conversion percentage (78%) was obtained when the process was carried out for 8 hours using urea to corn oil ratio of 5.6: 1.0 at 78 degrees C. Both difatty acyl urea and ethyl fatty ester have been characterized using elemental analysis, Fourier transform infrared (FTIR) spectroscopy and (1)H nuclear magnetic resonance (NMR) technique.
    Matched MeSH terms: Urea/chemical synthesis*; Urea/chemistry*
  11. Al-Mulla EA, Yunus WM, Ibrahim NA, Rahman MZ
    J Oleo Sci, 2009;58(9):467-71.
    PMID: 19654456
    N,N'-Carbonyl difatty amides (CDFAs) have been synthesized from palm oil using sodium ethoxide as catalyst. Ethyl fatty esters (EFEs) were produced as a by-product as well as glycerol. The synthesis was carried out by reflux palm oil and urea in presence of ethanol. In this process, palm oil gave 79% pure CDFAs after 8 hours and molar ratio of urea to palm oil was 6.2: 1 at 78 degrees C. Both CDFAs and EFEs have been characterized using elemental analysis, Fourier transform infrared (FTIR) spectroscopy and (1)H nuclear magnetic resonance (NMR) technique.
    Matched MeSH terms: Urea/chemistry
  12. Gonawan FN, Bakar PNMA, Kamaruddin AH
    J Oleo Sci, 2021 Oct 05;70(10):1437-1445.
    PMID: 34497176 DOI: 10.5650/jos.ess21010
    The Lipase-catalyzed synthesis of glyceryl monocaffeate (GMC) in choline chloride-urea of natural deep eutectic solvent (NADES) media is reported to provide amphiphilic character to caffeic acid (CA). The modification of CA into GMC could potentially increase its solubility and widen the application of CA's biological activities in water and oil-based systems. The high conversion was achieved when the reaction was carried out with the addition of more than 20 %v/v water, at a high molar ratio of glycerol and 40°C. It was found that the lipase-catalyzed transesterification of ethyl caffeate (EC) and glycerol in choline chloride-urea of DES media obeyed ping-pong bi-bi mechanism with Vmax = 10.9 mmol.min-1, KmEC = 126.5 mmol and KmGly = 1842.7 mmol.
    Matched MeSH terms: Urea/chemistry*
  13. Suguna S, Shankar S, Jaganathan SK, Manikandan A
    J Nanosci Nanotechnol, 2018 Feb 01;18(2):1019-1026.
    PMID: 29448527 DOI: 10.1166/jnn.2018.13960
    Ni-doped cobalt aluminate NixCo1-xAl2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) spinel nanoparticles were successfully synthesized by a simple microwave combustion method using urea as the fuel and as well as reducing agent. X-ray powder diffraction (XRD) was confirmed the formation of single phase, cubic spinel cobalt-nickel aluminate structure without any other impurities. Average crystallite sizes of the samples were found to be in the range of 18.93 nm to 21.47 nm by Scherrer's formula. Fourier transform infrared (FT-IR) spectral analysis was confirmed the corresponding functional groups of the M-O, Al-O and M-Al-O (M = Co and Ni) bonds of spinel NixCo1-xAl2O4 structure. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images was confirmed the particle like nanostructured morphology. Energy band gap (Eg) value was calculated using UV-Visible diffuse reflectance spectra (DRS) and the Eg values increased with increasing Ni2+ dopant from x = 0.2 (3.58 eV) to x = 1.0 (4.15 eV). Vibrating sample magnetometer (VSM) measurements exposed that undoped and Ni-doped CoAl2O4 samples have superparamagnetic behavior and the magnetization (Ms) values were increased with increasing Ni2+ ions. Spinel NixCo1-xAl2O4 samples has been used for the catalytic oxidation of benzyl alcohol into benzaldehyde and was found that the sample Ni0.6Co0.4Al2O4 showed higher conversion 94.37% with 100% selectivity than other samples, which may be due to the smaller particle size and higher surface area.
    Matched MeSH terms: Urea
  14. Abbasiliasi S, Tan JS, Ibrahim TAT, Ramanan RN, Kadkhodaei S, Mustafa S, et al.
    J Food Sci Technol, 2018 Apr;55(4):1270-1284.
    PMID: 29606741 DOI: 10.1007/s13197-018-3037-x
    This paper deliberates the modelling and validation of bacteriocin-like inhibitory substance (BLIS) secretion by Pediococcus acidilactici Kp10 at different agitation speeds in a stirred tank bioreactor. A range of models namely the re-parameterised logistic, Luedeking-Piret and maintenance energy were assessed to predict the culture performance of the said bacterium. Growth of P. acidilactici Kp10 was enhanced with increased agitation speed up to 600 rpm while BLIS secretion was maximum at 400 rpm but decreased at higher agitation speed. Growth of P. acidilactici aptly subscribed to the re-parameterised logistic model while BLIS secretion and lactose consumption fitted well with the Luedeking-Piret model. The models revealed a relationship between growth of the bacterium and BLIS secretion. Bacterial growth and BLIS secretion were largely affected by the agitation speed of the stirred tank bioreactor which regulated the oxygen transfer to the culture. BLIS secretion by P. acidilactici Kp10 was however enhanced in oxygen-limited culture. The study also assessed BLIS from the perspective of its stability when subjected to factors such as temperature, pH and detergents. Results showed that BLIS produced by this strain was not affected by heat (at 25-100 °C for 20 min and at 121 °C for 15 min), surfactant (Tween 40, 60 and 80 and urea), detergents (up to 1% SDS), organic solvents (50% each of acetone, methanol and ethanol) and stable in a wide range of pH (2-10). The above information are pertinent with reference to commercial applications of this bacterial product in food manufacturing which invariably involve various sterilization processes and subjected to a wide pH range.
    Matched MeSH terms: Urea
  15. Lee SM, Wong WP, Hiong KC, Loong AM, Chew SF, Ip YK
    J. Exp. Zoolog. Part A Comp. Exp. Biol., 2006 Dec 1;305(12):995-1009.
    PMID: 17068799
    This study aimed to determine effects of 6-day progressive increase in salinity from 1 per thousand to 15 per thousand on nitrogen metabolism and excretion in the soft-shelled turtle, Pelodiscus sinensis. For turtles exposed to 15 per thousand water on day 6, the plasma osmolality and concentrations of Na+, Cl- and urea increased significantly, which presumably decreased the osmotic loss of water. Simultaneously, there were significant increases in contents of urea, certain free amino acids (FAAs) and water-soluble proteins that were involved in cell volume regulation in various tissues. There was an apparent increase in proteolysis, releasing FAAs as osmolytes. In addition, there might be an increase in catabolism of certain amino acids, producing more ammonia. The excess ammonia was retained as indicated by a significant decrease in the rate of ammonia excretion on day 4 in 15 per thousand water, and a major portion of it was converted to urea. The rate of urea synthesis increased 1.4-fold during the 6-day period, although the capacity of the hepatic ornithine urea cycle remained unchanged. Urea was retained for osmoregulation because there was a significant decrease in urea excretion on day 4. Increased protein degradation and urea synthesis implies greater metabolic demands, and indeed turtles exposed to 15 per thousand water had significantly higher O2 consumption rate than the freshwater (FW) control. When turtles were returned from 15 per thousand water to FW on day 7, there were significant increases in ammonia (probably released through increased amino acid catabolism) and urea excretion, confirming that FAAs and urea were retained for osmoregulatory purposes in brackish water.
    Matched MeSH terms: Urea/metabolism
  16. Yankuzo H, Ahmed QU, Santosa RI, Akter SF, Talib NA
    J Ethnopharmacol, 2011 Apr 26;135(1):88-94.
    PMID: 21354289 DOI: 10.1016/j.jep.2011.02.020
    Murraya koenigii (Linn.) Spreng (curry leaf) is widely used as a nephroprotective agent in kidney's infirmities among diabetics by the traditional practitioners in Malaysia. However, the latter role of curry leaf has been grossly under reported and is yet to receive proper scientific evaluation.
    Matched MeSH terms: Urea/blood
  17. Adam Y, Somchit MN, Sulaiman MR, Nasaruddin AA, Zuraini A, Bustamam AA, et al.
    J Ethnopharmacol, 2009 Jul 6;124(1):154-8.
    PMID: 19375494 DOI: 10.1016/j.jep.2009.04.014
    Orthosiphon stamineus has been used in traditional medicine for centuries especially to treat diseases of the urinary system.
    Matched MeSH terms: Blood Urea Nitrogen
  18. Giribabu N, Karim K, Kilari EK, Salleh N
    J Ethnopharmacol, 2017 Jun 09;205:123-137.
    PMID: 28483637 DOI: 10.1016/j.jep.2017.05.002
    ETHNOPHARMACOLOGICAL RELEVANCE: Phylanthus niruri has been used to treat ailments related to the urogenital organs. In this study, this herb was hypothesized to help to ameliorate kidney disease in diabetes mellitus (DM).

    AIMS: To investigate P. niruri leaves aqueous extract (PN) effects on kidney functions, histopathological changes and levels of oxidative stress, inflammation, fibrosis, apoptosis and proliferation in DM.

    METHODS: PN was orally administered to streptozotocin-nicotinamide-induced male diabetic rats for 28 days. At the end of the treatment, fasting blood glucose (FBG) and kidney functions were measured. Kidney somatic index, histopathological changes and levels of RAGE, Nrf2, oxidative stress markers (TBARS, SOD, CAT and GPx), inflammatory markers (NFkβ-p65, Ikk-β, TNF-α, IL-1β and IL-6), apoptosis markers (caspase-3, caspase-9 and Bax), fibrosis markers (TGF-β1, VEGF and FGF-1) and proliferative markers (PCNA and Ki-67) were determined by biochemical assays, qPCR, Western blotting, immunohistochemistry or immunofluorescence.

    RESULTS: Administration of PN helps to maintain near normal FBG, creatinine clearance (CCr), blood urea nitrogen (BUN), BUN/Cr ratio, serum electrolytes, uric acid and urine protein levels in DM. Decreased RAGE, TBARS and increased Nrf2, SOD-1, CAT and GPx-1 were observed in PN-treated diabetic rat kidneys. Expression of inflammatory, fibrosis and apoptosis markers in the kidney reduced but expression of proliferative markers increased following PN treatment. Lesser histopathological changes were observed in the kidney of PN-treated diabetic rats.

    CONCLUSION: PN helps to preserve near normal kidney function and prevents histopathological changes via ameliorating oxidative stress, inflammation, fibrosis and apoptosis while enhancing proliferation of the kidney in DM.

    Matched MeSH terms: Blood Urea Nitrogen
  19. Ooi CH, Cheah WK, Sim YL, Pung SY, Yeoh FY
    J Environ Manage, 2017 Jul 15;197:199-205.
    PMID: 28384613 DOI: 10.1016/j.jenvman.2017.03.083
    Urea removal is an important process in household wastewater purification and hemodialysis treatment. The efficiency of the urea removal can be improved by utilizing activated carbon fiber (ACF) for effective urea adsorption. In this study, ACF was prepared from oil palm empty fruit bunch (EFB) fiber via physicochemical activation using sulfuric acid as an activating reagent. Based on the FESEM result, ACF obtained after the carbonization and activation processes demonstrated uniform macropores with thick channel wall. ACF was found better prepared in 1.5:1 acid-to-EFB fiber ratio; where the pore size of ACF was analyzed as 1.2 nm in diameter with a predominant micropore volume of 0.39 cm(3) g(-1) and a BET surface area of 869 m(2) g(-1). The reaction kinetics of urea adsorption by the ACF was found to follow a pseudo-second order kinetic model. The equilibrium amount of urea adsorbed on ACF decreased from 877.907 to 134.098 mg g(-1) as the acid-to-fiber ratio increased from 0.75 to 4. During the adsorption process, the hydroxyl (OH) groups on ACF surface were ionized and became electronegatively charged due to the weak alkalinity of urea solution, causing ionic repulsion towards partially anionic urea. The ionic repulsion force between the electronegatively charged ACF surface and urea molecules became stronger when more OH functional groups appeared on ACF prepared at higher acid impregnation ratio. The results implied that EFB fiber based ACF can be used as an efficient adsorbent for the urea removal process.
    Matched MeSH terms: Urea*
  20. Yavari S, Malakahmad A, Sapari NB, Yavari S, Khan E
    J Environ Manage, 2017 Nov 01;202(Pt 1):225-231.
    PMID: 28735207 DOI: 10.1016/j.jenvman.2017.07.030
    Application of urea manufacturing wastewater to teak (Tectona grandis) trees, a fast growing tropical timber plants, is an environmentally-friendly and cost-effective alternative for treatment of nitrogen-rich wastewater. However, the plant growth is strongly limited by lack of phosphorus (P) and potassium (K) elements when the plants are irrigated with wastewater containing high concentration of nitrogen (N). A greenhouse experiment was conducted to optimize the efficiency of teak-based remediation systems in terms of nutrient balance. Twelve test solutions consisted of 4 levels of P (95, 190, 570, 1140 mgL-1) and 3 levels of K (95, 190, 570 mgL-1) with a constant level of N (190 mgL-1) were applied to teak seedlings every four days during the study period. Evapotranspiration rate, nutrient removal percentage, leaf surface area, dry weight and nutrient contents of experimental plants were determined and compared with those grown in control solution containing only N (N:P:K = 1:0:0). Teak seedlings grown in units with 1:0.5:1 N:P:K ratio were highly effective at nutrient removal upto 47%, 48% and 49% for N, P and K, respectively. Removal efficiency of teak plants grown in other experimental units decreased with increasing P and K concentrations in test solutions. The lowest nutrient removal and plant growth were recorded in units with 1:6:0.5 N:P:K ratio which received the highest ratio of P to K. The findings indicated that teak seedlings functioned effectively as phytoremediation plants for N-rich wastewater treatment when they were being supplied with proper concentrations of P and K.
    Matched MeSH terms: Urea
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