Enhancing the decolorization of methylene blue using a low-cost super-absorbent aided by response surface methodology

The presence of organic dyes from industrial wastewater can cause pollution and exacerbate environmental problems; therefore, in the present work, activated carbon was synthesized from locally available oil palm trunk (OPT) biomass as a low-cost adsorbent to remove synthetic dye from aqueous media. The physical properties of the synthesized oil palm trunk activated carbon (OPTAC) were analyzed by SEM, FTIR-ATR, and XRD. The concurrent effects of the process variables (adsorbent dosage (g), methylene blue (MB) concentration (mg/L), and contact time (h)) on the MB removal percentage from aqueous solution were studied using a three-factor three-level Box–Behnken design (BBD) of response surface methodology (RSM), followed by the optimization of MB adsorption using OPTAC as the adsorbent. Based on the results of the analysis of variance (ANOVA) for the three parameters considered, adsorbent dosage (X1) is the most crucial parameter, with an F-value of 1857.43, followed by MB concentration (X2) and contact time (X3) with the F-values of 95.60 and 29.48, respectively. Furthermore, the highest MB removal efficiency of 97.9% was achieved at the optimum X1, X2, and X3 of 1.5 g, 200 mg/L, and 2 h, respectivel

Dental caries in primary and permanent teeth in children's worldwide, 1995 to 2019: a systematic review and meta-analysis

Background: Early childhood caries (ECC) is a type of dental caries in the teeth of infants and children that is represented as one of the most prevalent dental problems in this period. Various studies have reported different types of prevalence of dental caries in primary and permanent teeth in children worldwide. However, there has been no comprehensive study to summarize the results of these studies in general, so this study aimed to determine the prevalence of dental caries in primary and permanent teeth in children in different continents of the world during a systematic review and meta-analysis. Methods: In this review study, articles were extracted by searching in the national and international databases of SID, MagIran, IranMedex, IranDoc, Cochrane, Embase, ScienceDirect, Scopus, PubMed, and Web of Science (ISI) between 1995 and December 2019. Random effects model was used for analysis and heterogeneity of studies was evaluated by using the I2 index. Data were analyzed by using the Comprehensive Meta-Analysis (Version 2) software. Findings: In this study, a total of 164 articles (81 articles on the prevalence of dental caries in primary teeth and 83 articles on the prevalence of dental caries in permanent teeth) were entered the meta-analysis. The prevalence of dental caries in primary teeth in children in the world with a sample size of 80,405 was 46.2% (95% CI: 41.6–50.8%), and the prevalence of dental caries in permanent teeth in children in the world with a sample size of 1,454,871 was 53.8% (95% CI: 50–57.5%). Regarding the heterogeneity on the basis of meta-regression analysis, there was a significant difference in the prevalence of dental caries in primary and permanent teeth in children in different continents of the world. With increasing the sample size and the year of study, dental caries in primary teeth increased and in permanent teeth decreased. Conclusion: The results of this study showed that the prevalence of primary and permanent dental caries in children in the world was found to be high. Therefore, appropriate strategies should be implemented to improve the aforementioned situation and to troubleshoot and monitor at all levels by providing feedback to hospitals

The catalytic deacidification of acidic crude oil using Cu-doped alkaline earth metal oxide catalysts

Naphthenic acids (NAs) tend to cause operational problems that can lead to the deactivation of catalysts. To overcome the problem, catalytic deacidification was introduced utilizing an ammonia solution in ethylene glycol with the aids of alkaline earth metal catalyst with alumina as a support. The initial total acid number observed for NAs in n-dodecane was 4.21 mg KOH/g. In total, 1,000 mg/L of 0.4% NH3-EG were used as the acid removal agent. Calcium, barium, and magnesium catalysts were tested in this study. The results showed Cu/Ca/Al2O3 was found to be the best catalyst that could be used to enhance the reaction

Demetallisation of heavy metals from indian mackerel (R. kanagurta) fish

Fish especially Indian Mackerel (R. kanagurta) provides protein, essential fatty acids and essential metals that are needed in the human diet, however high concentration of essential metals will cause adverse health effect towards human. Thus, the removal of heavy metals such as lead (Pb) and copper (Cu) from R. kanagurta (Indian mackerel) by using different types of natural waste adsorbents was implemented in this study. Initial concentration of heavy metals (Pb, Cu) in Indian mackerel (R. kanagurta) fish were above the permissible limit set by World Health Organization and Malaysia Food Regulation 1985. Thus, in this study, corncob and eggshell were applied as natural waste adsorbents to enhance the demetallisation process. The result showed only the corncob able to efficiently remove all the heavy metals in Indian Mackerel (R. kanagurta) up to 78.31% compared to the eggshell, which yielded about 71.34%. Besides, this study proved that using corncob; the Cd metal found to be wholly removed from (R. kanagurta) which met the permissible limit set by WHO and MFR