Regeneration of spent activated carbon from industrial application by NaOH solution and hot water

2016 ◽  
Vol 57 (60) ◽  
pp. 29137-29142 ◽  
Author(s):  
Su-Huan Kow ◽  
Muhammad Ridwan Fahmi ◽  
Che Zulzikrami Azner Abidin ◽  
Soon-An Ong ◽  
Naimah Ibrahim
2019 ◽  
Vol 6 (9) ◽  
pp. 191069 ◽  
Author(s):  
Wei Wang ◽  
Xin Mi ◽  
Huilan Shi ◽  
Xue Zhang ◽  
Ziming Zhou ◽  
...  

Perfluorooctane sulfonate (PFOS) was listed as a persistent organic pollutant by the Stockholm Convention. As a typical alternative to PFOS, sodium p -perfluorous nonenoxybenzene sulfonate (OBS) has recently been detected in the aquatic environment which has caused great concern. For the first time, the adsorption behaviour and mechanism of OBS on activated carbon (AC) with different physical and chemical properties were investigated. Decreasing the particle size of AC can accelerate its adsorption for OBS, while AC with too small particle size was not conducive to its adsorption capacity due to the destruction of its pore structure during the mechanical crushing process. Intra-particle diffusion had a lesser effect on the adsorption rate of AC with smaller particle size, higher hydrophilicity and larger pore size. Reactivation of AC by KOH can greatly enlarge their pore size and surface area, greatly increasing their adsorption capacities. The adsorption capacity of two kinds of R-GAC exceeded 0.35 mmol g −1 , significantly higher than that of other ACs. However, increasing the hydrophilicity of AC would decrease their adsorption capacities. Further investigation indicated that a larger pore size and smaller particle size can greatly enhance the adsorptive removal of OBS on AC in systems with other coexisting PFASs and organic matter due to the reduction of the pore-blocking effect. The spent AC can be successfully regenerated by methanol, and it can be partly regenerated by hot water and NaOH solution. The percentage of regeneration for the spent AC was 70.4% with 90°C water temperature and up to 95% when 5% NaOH was added into the regeneration solution. These findings are very important for developing efficient adsorbents for the removal of these newly emerging PFASs from wastewater and understanding their interfacial behaviour.


Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 155
Author(s):  
Régis Pamponet da Fonseca ◽  
Janaíde Cavalcante Rocha ◽  
Malik Cheriaf

The addition of natural fibers used as reinforcement has great appeal in the construction materials industry since natural fibers are cheaper, biodegradable, and easily available. In this work, we analyzed the feasibility of using the fibers of piassava, tucum palm, razor grass, and jute from the Amazon rainforest as reinforcement in mortars, exploiting the mechanical properties of compressive and flexural strength of samples with 1.5%, 3.0%, and 4.5% mass addition of the composite binder (50% Portland cement + 40% metakaolin + 10% fly ash). The mortars were reinforced with untreated (natural) and treated (hot water treatment, hornification, 8% NaOH solution, and hybridization) fibers, submitted to two types of curing (submerged in water, and inflated with CO2 in a pressurized autoclave) for 28 days. Mortars without fibers were used as a reference. For the durability study, the samples were submitted to 20 drying/wetting cycles. The fibers improved the flexural strength of the mortars and prevented the abrupt rupture of the samples, in contrast to the fragile behavior of the reference samples. The autoclave cure increased the compressive strength of the piassava and tucum palm samples with 4.5% of fibers.


Author(s):  
Hongsik Yoon ◽  
Jiho Lee ◽  
Taijin Min ◽  
Gunhee Lee ◽  
Minsub Oh

Capacitive deionization (CDI) has been highlighted as a promising electrochemical water treatment system. However, the low deionization capacity of CDI electrodes has been a major limitation for its industrial application,...


Carbon ◽  
2018 ◽  
Vol 134 ◽  
pp. 199-206 ◽  
Author(s):  
Wei Wang ◽  
Ziwen Du ◽  
Shubo Deng ◽  
Mohammadtaghi Vakili ◽  
Lu Ren ◽  
...  
Keyword(s):  

Holzforschung ◽  
1999 ◽  
Vol 53 (1) ◽  
pp. 33-38 ◽  
Author(s):  
B. Kosiková ◽  
A. Ebringerová ◽  
R. Naran

Summary Chemical analysis of Cistanche deserticola showed the presence of 7.5% of Klason lignin. Different lignin-carbohydrate fractions have been isolated from the methanol pre-extracted and depectinated Cistanche drug by sequential extractions using dioxane-water, cold and hot water, and 4% NaOH solution. 13CNMR spectroscopy in combination with sugar analysis were used to characterize the isolated fractions. The proportions of the guaiacyl-, syringyl- and p-hydroxyphenyl units in the lignin-rich fractions differ significantly from those of both hardwood and softwood lignins and resemble more those of gramineous lignins. The carbohydrate portion consists of xylan, starch, pectic polysaccharides, and cellulose in proportions which are not typical of wood tissues.


1996 ◽  
Vol 35 (12) ◽  
pp. 4619-4625 ◽  
Author(s):  
Gorazd Berčič ◽  
Albin Pintar ◽  
Janez Levec

2016 ◽  
Vol 78 (5-8) ◽  
Author(s):  
Norhafizah Ahmad Junaidi ◽  
Tohru Suwa

Solar energy is an attractive energy source among various renewable energy resources in Malaysia as relatively high solar radiation is available throughout the year. This solar energy can be utilized for air-conditioning by using solar-powered adsorption refrigeration cycle. Intermittent nature of the solar radiation leads to a challenge for continuous air-conditioning operation. In the present study, a combination of solar-powered adsorption refrigeration system and thermal storage is studied. Activated carbon-ammonia and activated carbon-methanol are the working pairs of the adsorption reaction. Analytical calculation results show that activated carbon-methanol pair indicates higher coefficient of performance (COP) than activated carbon-ammonia pair, while adsorption chiller system with hot water thermal storage has higher COP than the system with ice thermal storage. For the activated carbon-methanol case with hot water thermal storage, the COP is 0.79. Since this COP analysis is based on the ideal case with uniform temperature distribution within the reactor beds, which achieves equilibrium states at the end of the reactions. In more realistic situation, the reaction process will be terminated before reaching to the equilibrium states because of the non-uniform temperature distribution and the time required for the reaction. Transient simulation in which heat transfer and reaction equation are combined will be performed to model actual reactors.


Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 478-482 ◽  
Author(s):  
Sara A. Lisboa ◽  
Dmitry V. Evtuguin ◽  
Carlos Pascoal Neto

Abstract The amount of non-cellulosic glucans in Eucalyptus globulus wood (approx. 4.5%) was assessed by extraction of sawdust with a 0.5 M NaOH solution at 90–120°C and the structural features were elucidated in a glucan-enriched polysaccharide fraction isolated by hot water extraction (120°C, 2 h). Isolated soluble glucans were characterized by wet chemistry methods and a set of 1D and 2D NMR techniques. The major proportion of glucans consisted of amylose (20%) and amylopectin (80%), although a small proportion of β-(1→3)-glucan (<0.2% on wood weight) was also detected. Although glucans are easily removed in the initial phase of kraft pulping, notable amounts were found in unbleached pulp and it was supposed that in the final stage of kraft pulping a fraction of α-glucan is precipitated onto the fiber surface and contributes to the pulp yield.


Author(s):  
Mamata Mukhopadhyay ◽  
Palash Panja

A novel process has been developed for the recovery of phytochemicals such as, ? -HCA from kokum (Garcinia indica choisy) rinds using hot water pressurized with carbon dioxide, followed by its purification. The performance of the pressurized hot water extraction (PHWE) process has been evaluated to ascertain the optimum process parameters for maximizing the recovery of ? -HCA. A systematic parametric study has been undertaken by varying the important parameters in the ranges of 30-120 °C for temperature, 1-20 atm for pressure, 30-60 min of extraction time, 4 - 22 ml/g of water to feed ratio, 1-3 number of stages , 0-350 rpm of stirring, presence of salt, nature of feed, and grinding. Ethanol is added to the aqueous extract from kokum rinds for the removal of pectinous materials by precipitation. Quantification of ? -HCA in the product has been carried out by the titration method with 0.1N NaOH solution. The maximum recovery is obtained when PHWE is carried out at 90 °C above which the recovery decreases. Pressure does not have much effect on the recovery of ? -HCA beyond a certain pressure required to maintain the extractant in the liquid phase. More ?-HCA is recovered by 2-stage PHWE from ground dry kokum than from salty kokum rinds.


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