An overview of equilibrium, kinetic and thermodynamic studies for the sequestration of Maxilon dyes

Maxilon dyes are a class of cationic dyes containing different aliphatic and aromatic radicals. Contamination of water by this class of dyes causes serious environmental concern to both man and other animals and plants. Adsorption as a process has been studied by various researchers for Maxilon dye uptake. This work represents a review of published literature discussing the adsorption of Maxilon dyes using various adsorbents. Adsorption operating parameters, kinetic and isotherm models, and thermodynamic models were discussed herein. In the study, it was observed that adsorption parameters such as contact time, adsorbent dosage, solution pH, and temperature affect the uptake of Maxilon dyes. The highest reported uptake of Maxilon dyes by the various adsorbents is 1830 mg/g for Maxilon blue using hydrolyzed (styrene-alt-maleic anhydride) chitosan. For the adsorption of the Maxilon dyes, the pseudo-second order kinetic model was shown to provide the best fit. The Langmuir and Freundlich isotherm models best describe the adsorption of the Maxilon dyes. There were also some proposals for the future. In conclusion, adsorption was found to be an effective approach for removing Maxilon colours from water and wastewater

An overview of equilibrium, kinetic and thermodynamic studies for the sequestration of Maxilon dyes

Maxilon dyes are a class of cationic dyes containing different aliphatic and aromatic radicals. Contamination of water by this class of dyes causes serious environmental concern to both man and other animals and plants. Adsorption as a process has been studied by various researchers for Maxilon dye uptake. This work represents a review of published literature discussing the adsorption of Maxilon dyes using various adsorbents. Adsorption operating parameters, kinetic and isotherm models, and thermodynamic models were discussed herein. In the study, it was observed that adsorption parameters such as contact time, adsorbent dosage, solution pH, and temperature affect the uptake of Maxilon dyes. The highest reported uptake of Maxilon dyes by the various adsorbents is 1830 mg/g for Maxilon blue using hydrolyzed (styrene-alt-maleic anhydride) chitosan. For the adsorption of the Maxilon dyes, the pseudo-second order kinetic model was shown to provide the best fit. The Langmuir and Freundlich isotherm models best describe the adsorption of the Maxilon dyes. There were also some proposals for the future. In conclusion, adsorption was found to be an effective approach for removing Maxilon colours from water and wastewater

Impact of acid activated Bentonites on foster swelling capacity and sorption dynamics of hydrocarbons, phenol and water

The successful protonation of the dissociable + from different organic acids (with varying alkyl chains) to supplant sodium ions in the  inter layers of bentonites resulting in increased surface area has been carried out. The resultant materials were characterized using  foster swelling and adsorption capacity techniques. Results show that the foster capacities of acid activated bentonites were greater than the un-activated bentonite (UAB) upon interaction with petroleum hydrocarbons. The bentonite activated with the organic acid having the most alkyl chain, hexanoic acid activated bentonite (HAAB) showed high affinity for all petroleum hydrocarbons. This demonstrates the hydrophilicity of UAB and upon activation, the hydrophobic properties of HAAB. The adsorption capacity result  records that bentonites and HAAB adsorbed more petroleum hydrocarbon solvents than other lower alkyl chain acid activated bentonites and UAB. This study shows that HAAB is an excellent adsorbent for the removal of hydrocarbons from industrial wastes. &nbsp

The effect of different solvent polarity on the precipitation of heavy organics from a crude oil deposit in the Niger Delta

The precipitation of heavy organics (Saturates, Aromatics, Resins and Asphaltenes) from the Niger delta (Atan crude oil residue) was studied. Two C4 organic polar solvents (ethyl acetate and butanone) were used to investigate the effect of polarity of the precipitating solvents. The heavy organics precipitated from Antan crude residue were 3.34% and 3.76% for ethyl acetate and butanone respectively. Asphaltenes were precipitated from the heavy organic precipitates using n-C5 and n-C6 alkanes. Chromatographic separation and spectroscopic analysis of the deasphalted soluble filtrate were carried out. The results identified the presence of saturates, aromatics and resins in the C4 heavy organic precipitate.Key words: Heavy Organics, Precipitates, Saturates, Aromatics, Resins, Asphaltene

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background: Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods: The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results: A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion: Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)