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Activating Agent

The increased concern by environmentalist and government on the effect of heavy metals and attempt to protect public health gave rise to a lot of research in the development of advance technology to remove heavy metals from water and waste waters. The treatment efforts involved the application of unit processes such as chemical precipitation, coagulation, adsorption, ion exchange, and membrane filtration. Several works on activation of carboneous materials showed that the specific surface area, pore structure, and surface chemical functional groups of porous carbon determined their applications. The pore structure of porous carbon could be controlled by various routes, such as, activation conditions (activation agent, temperature, and time), precursor, templates, and so forth. The surface chemical functional groups are mainly derived from activation process, precursor, heat treatment, and postchemical treatment [1].

activating agent

Yan and Viraraghavan [2] used different chemicals to study the effect of pretreatment of Mucor rouxii biomass on bioadsorption of Pb2+, Cd2+, Ni2+, and Zn2+. Pretreatment with detergent and alkali chemicals such as NaOH, Na2CO3, and NaHCO3 were found to improve or maintain the bioadsorption capacity in comparison with live M. rouxii biomass. Acid pretreatment using HCl, H2SO4, and C2H4O2 resulted in a significant reduction in the bioadsorption capacity while alkali pretreatment was found to be more effective. Ramírez Zamora et al. [3] studied the adsorption capacities of mercury and silver by activating petroleum coke with ZnCl2, NaOH, and H3PO4. The physicochemical characteristics determined for these activated carbons as well as scanning electron microscopy showed that the H3PO4 was the best activating agent. Effect of chemical activation using KOH and K2CO3 on activated carbon from Lignin from the work of Xiao et al. [4] showed that the activated carbon from Lignin activated using K2CO3 gave higher iodine number, surface area, and higher methylene blue number than those activated using KOH.

The results obtained from previous studies reviewed above showed that different carboneous materials have different reactivity to different activating agents. Bamboo, palm kernel, and coconut shell have been found to be good materials for production of activated carbon [5, 6]. The effectiveness of bamboo activated carbon to adsorbed heavy metal as not been compared with activated carbon from waste palm kernel and coconut shell. There is necessary to raise the activities of these carbons via chemical activation and compare the effectiveness of these three in adsorption of heavy metal ions from waste water streams. Therefore the objective of this study is to determine the effect of different chemical activations on the adsorption of heavy metals ions using activated carbons from waste materials such as bamboo, palm kernel shell, and coconut shell.

The following materials and apparatus were used for this work: waste Nigeria based bamboo, and waste coconut shell, waste palm kernel shell. Activating agents are hydrochloric acid, phosphoric acid, sulphuric acid, nitric acid, zinc-chloride, and sodium hydroxide. A pyrolytic reactor was used for carbonization with condenser. Other materials used are measuring cylinder, heating mantle, desiccators, crucibles, funnels, and filter papers. Two electronic weighing balance, Ohaus top loading balance (+0.01) was used to weigh the bamboo before pyrolysis, while a more sensitive electronic analytical weighing balance (+0.001, Adams AFP 360L) was used for another analysis, retort stand, thermocouple with temperature sensor, spatula, density bottle, crusher, sieves, measuring cylinders, moisture cans, and petri dish.

The effect of activation on the adsorption of lead ion (Pb++) using activated carbon from waste bamboo, palm kernel and coconut shell is presented in Figure 3. The highest percentage of lead ion (Pb2+) adsorbed was obtained from activated carbon from bamboo followed by activated carbon from waste coconut shell and then waste palm kernel shell irrespective of the activated agent used for activation carbons from bamboo, coconut, and palm kernel shells activated with HNO3 showed high adsorption for lead ions than other activating agents. It was observed that the amount of lead adsorbed by activated carbon, activated with nitric acid (HNO3), H2SO4, and HCL was significantly higher than carbons activated with ZnCl2, NaOH, and H3PO4. This shows that adsorption of Pb2+ ions requires chemisorption than physical adsorption. Activation with HNO3, H2SO4, and HCL created more reactive sites for adsorption of lead ions. Also activated carbon produced from waste coconut shell adsorbed more lead ions than palm kernel shell after activation as shown in Figure 3 than before activation in Figure 2, which shows that acid activation increased the porosity of activated carbon from coconut shell after activation.

Figure 6 shows the adsorption of different metal ions using bamboo activated with HNO3 and commercial activated carbon. Bamboo after activation adsorbed more metal ions than the commercial activated carbon, unlike the result obtained earlier in Figure 1. This shows that bamboo activated with HNO3 can effectively be used to remove metal ions from waste streams than activated carbon from coconut and palm kernel shell. HNO3 was reported by Ademiluyi et al. [12] to produce a highly reactive product known as cellulose nitrite during the adsorption of bamboo with benzene. The reaction of the cellulose in bamboo with HNO3 is shown in (1). Cellulose nitrite in turn reacts with benzene to produce an alkyl cellulose nitrate. thus forms a sigma complex with many chemicals, making HNO3 a reactive activating agent as follows:

The effect of chemical activation using different activating agents on the adsorption of heavy metals ions using activated carbons from waste materials such as bamboo, palm kernel shell, and coconut shell has been investigated. Chemical activation had a significant effect on the adsorption of metal ions and on the type of carboneous material used. The adsorption of metal ions using bamboo, coconut, and palm kernel activated with HNO3, H2SO4, and HCL was significantly higher than carbons activated with ZnCl2, NaOH, and H3PO4. The highest metal ion adsorbed was obtained from bamboo activated with HNO3. The cellulose nitrite formed during the activation of bamboo with HNO3 created more active reaction site for adsorption of different metal ions. This shows that waste bamboo activated with HNO3 can effectively be used to remove metal ions from waste streams and in different metal recovery processes than coconut and palm kernel.

Citation: Al-Awadi AMI, AlJawder AI, Mousa A, Taha S, Bakhiet M (2021) A role for the immune system-released activating agent (ISRAA) in the ontogenetic development of brain astrocytes. PLoS ONE 16(5): e0248455.

In conclusion, the preceding data provide evidence that ISRAA and IFN-γ are potentially intrinsic developmental brain astrocytes factors. Therefore, understanding the role of such inflammatory mediators as brain development regulatory agents, as well as their action networks, is essential to planning future therapies for neuroinflammatory disorders. However, one limitation on this study is the lack of in vivo data to support the presented in vitro results. But, on the other hand, a detailed in vivo study using ISRAA knockout mice that were recently generated in our laboratory [5] is currently initiated to demonstrate the in vitro effects in vivo on brain slices to further define the effects of ISRAA on astrocytes.

We also got upgraded to this automatically and were not given any way to "opt out" of it or any kind of way to test it out and then roll back if it did not meet our needs. It appears the upgrade was automated, but rollback is a chore. The new agent workspace is not helpful. We didn't want it. Didn't ask for it. Given no way to say "no thanks". The only option given was to "migrate now" or be automatically migrated later.

Abstract:The effect of chemical activators on the properties of activated carbon from sago waste was conducted in this study by using ZnCl2, H3PO4, KOH, and KMnO4 chemical solutions. The carbonized sago waste was added to each chemical solution, boiled at 85 C for 4 h, and heated at 600 C for 3 h. The porosity, microstructural, proximate, and surface chemistry analyses were carried out using nitrogen adsorption with employing the Brunauer Emmett Teller (BET) method and the Barret-Joyner-Halenda (BJH) calculation, scanning electron microscopy by using energy dispersive spectroscopy, X-ray diffractometer, simultaneous thermogravimetric analysis system, and the Fourier-transform infrared spectroscopy. The results showed that the activated carbon prepared using ZnCl2 acid had the highest specific surface area of 546.61 m2/g, while the KOH activating agent surpassed other chemicals in terms of a refined structure and morphology, with the lowest ash content of 10.90%. The surface chemistry study revealed that ZnCl2 and KOH activated carbon showed phenol and carboxylate groups. Hence, ZnCl2 acid was suggested as activating agents for micropore carbon, while KOH was favorable to producing a mesopore-activated carbon from sago waste.Keywords: sago waste activated carbon; activating agents; acid treatment; base treatment; porous properties; structural properties; thermal decomposition; surface groups

The present work attempts to convert bamboo into a high surface area activated carbon via microwave heating. Different chemical activating agents such as KOH, NaOH, K2CO3 and Na2CO3 were utilized to identify a most suitable activating agent. Among the activating agents tested KOH was found to generate carbon with the highest porosity and surface area. The effect of KOH/C ratio on the porous nature of the activated carbon has been assessed. An optimal KOH/C ratio of 4 was identified, beyond which the surface area as well as the pore volume were found to decrease. At the optimized KOH/C ratio the surface area and the pore volume were estimated to be 3,441 m2/g and 2.093 ml/g, respectively, with the significant proportion of which being microporous (62.3%). Activated carbon prepared under the optimum conditions was further characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Activated carbons with so high surface area and pore volume are very rarely reported, which could be owed to the nature of the precursor and the optimal conditions of mixture ratio adopted in the present work. 041b061a72


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