Papers by Keyword: Activated Carbon (AC)

Abstract: High surface area activated carbon has always fascinated researchers for its application as adsorbent, for water purification, medical and industrial. Date is the major export of Saudi Arabia, while tons of date foliar and fronds are troublesome and yet to be disposed. Transforming this waste into usable activated carbon can be a good idea for recycling, sustainable and green chemistry. In this study, date tree frond is selected to prepare activated carbon, while the effect of phosphoric acid in chemical activation is studied. Using thermogravimetry analysis, it was found that 400oC was the best temperature to convert date frond to carbon. This is supported by FTIR spectroscopy. Various concentration of phosphoric acid is used to optimize the product high surface area carbon obtained and it was found the best is at 60% phosphoric acid with the highest surface area of 1139 m2g-1. This result is also supported by FTIR spectroscopy, which indicates the similarities between commercial carbon and the carbon prepared. FESEM pictographs show chemical activation using phosphoric acid can easily open up pores and cavity of the prepared activated carbon the get the high surface area. It is thus suggested that for mass production of high surface area carbon, date palm frond is used as the source of raw material, due to its abundance and availability comes from the pruning process on the date palm tree, while chemically activated to get the high surface area.

Abstract: Textile industries usually discharge colored effluents containing various dyes. These dyes usually contain more than one aromatic structure and they are not only difficult to be degraded biologically but also toxic. UV/semiconductor procedure, with advantages including photostability, non-toxicity, affordable price, and insolubility in water, has been studied and used. This aim of this study is to develop photocatalytic reactor with higher removal efficiency. The TiO₂ thin film was prepared by Sol-Gel method and coated on the surface of activated carbon to enhance the reaction opportunity and increase pollutants removal efficiency. Taguchi method was used to optimize preparing conditions. The results indicated that the best TiO₂ photocatalytic activity can be found when tetraisopropyl orthotitanate, isopropyl alcohol and acetic acid were mixed in the molar ratio of 1：2：8 under the calcination temperature of 500°C for 90 minutes. Further analysis of TiO₂ thin film by SEM, ESCA and XRD, the results showed that grain size of TiO₂ was about 17 nm and crystal structure mainly was anatase. The photocatalytic reaction rate increased 15~20% when the ratio of PAC in catalyst increased > 4%. The results suggested that recovery of the composited catalyst become easy because its volume and subsiding increased.

Abstract: The performance of activated carbon (AC) adsorption process for the treatment of a simulated wastewater of fuchsin basic dye was investigated. The experiment revealed that under the optimum adsorption conditions (initial concentration of wastewater 250 mg L^-1 of dye, temperature 25 °C and AC dosage 4 g L^-1), the color removal efficiency was 98% after 360 min of adsorption. As for the further use of AC, the saturated AC was regenerated by heated 20 min at 600 °C in the atmosphere of N₂. Efficiency of regeneration was 99% and the regeneration loss was less than 5%. It indicated that AC was effective in the decolorization of dye wastewater.

Abstract: The waste wood dust was utilized to prepare the copper oxide loaded activated carbon for the treatment of the printing and dyeing wastewater (acid red GR wastewater). The response surface assisted with Design-Expert 7.0 software was used to optimize the process. The secondary multiple regression models for the color and COD removal rates were established and proven to be significant. The optimum process conditions determined by the software were: copper nitrate (0.5mol/L) 15mL, ratio of liquid to solid 56, activation temperature 690 °C and activation time 2.1h, under which the color and COD removal rates reached 99.8% and 88.34%, respectively.

Abstract: Br-impregnated activated carbon for gas-phase elemental mercury adsorption experiments were carried out at a fixed-bed system to get the suitable mass fraction of KBr impregnation solution. Hg removal efficiency of 1% wt KBr-ACs was 69.0%, while that of 10% wt KBr-ACs was 57.9%. Both of them were higher than that of the raw activated carbon, 42.2%. The removal efficiency of Hg⁰ was not proportional to bromine concentration. Under 80-180°C, Hg removal efficiency of 1% wt KBr-ACs were 68.3%-71.8%, and at 140°C it reached the highest due to the increasing chemical adsorption ability of the functional groups which was on the surfaces of activated carbons by impregnating. At 160°C, Hg removal efficiency was lower than that at 140°C due to desorption making physical adsorption decrease, so that the total adsorption decreased.

Abstract: Spinning effluents (SE) from dry-spun acrylic fiber manufacturing are hard to degrade due to the containing of vast dimethyl formamide (DMF). Activated carbon, ion exchange and Fenton oxidation were applied to solve this problem. Coconut-shell-based activated carbon exhibited a better performance than the coal-based and nut-shell-based ones did. At the optimal dosage of 1g/L, pH=6 and 30 °C, the removal of COD and DMF were respectively 84.39% and 66.14%. Ion exchange resins are rated as NKA-9 > D301R > D201 > 201×7 respected to the performance, and the optimum COD and DMF removal were 82.31% and 68.76% at the NKA-9 dosage of 0.22 g, pH=7 and 30°C. The most appropriate treatment process appeared to be Fenton. COD and DMF were finally reduced to 23.29 mg/L and 23.43 mg/L, with removal rates of 90.23% and 79.43% respectively. This optimum efficiency was obtained at c(H₂O₂)/c(Fe²⁺) of 14:1, pH=3, 50 °C, and an oxidation time of 3 h.

Abstract: In the paper, tetranbutyl titanate was loaded on granular active carbon using sol-gel dip-coating technique to form anatase nano-TiO₂ photocatalyst with an average diameter of 16nm doped with N, Fe, Zn ions. The morphology and crystal structure were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV–Vis spectrophotometer, respectively. The results show that the prepared photocatalyst demonstrates outstanding photodegradation efficiency and light response zone has transferred from ultraviolet light zone to UV-visible zone. Moreover, considering methylene blue (MB) as target degradation pollutant, under visible light irradiation, the photodegradation rate reached beyond 100% after 1h.

Abstract: Granular activated carbon (GAC) is extensively used to remove natural organic matter and residential chlorine in water treatment process of power plant. After being used, the spent GAC needs to be regenerated in order to save on operation costs and reduce solid waste disposal. In this study, microwave technique was tried to regenerate the field-spent GAC from a power plant. The effect of microwave power, irradiation time and hydrochloric acid pretreatment were investigated, it was found that microwave could recover the adsorption capacity of GAC within a short time and the tannic acid adsorption efficiency of regenerated GAC was 9 times greater than spent GAC; hydrochloric acid pretreatment could improve the regeneration process, it showed the highest removal efficiency and iodine number, 99.6% and 859 mg/g respectively. The results obtained from SEM-EDX showed that hydrochloric acid pretreatment could remove inorganic matter and other impurities of GAC. All these indicate that microwave technique can effectively regenerate field-spent GAC, and hydrochloric acid pretreatment is an important process before regeneration.

Abstract: In this study, a commercial activated carbon was assessed as adsorbent for post-combustion CO₂ capture. The breakthrough adsorption experiments were conducted in a fixed-bed column with simulated flue gas of 12% CO₂. The effects of feed flow rate and adsorption pressure on breakthrough time and CO₂ adsorption capacity were evaluated. The column efficiency was introduced to estimate the percentage of the utilization of the bed adsorbent capacity. At a higher flow rate, the breakthrough time, breakthrough capacity and column efficiency decreased. Conversely, increasing adsorption pressure was favorable to CO₂ adsorption by the increase in breakthrough time, CO₂ adsorption capacity and the column efficiency. During the experiments, temperature changes were detected at three positions inside the column to track the movement of breakthrough front.

Abstract: The biomass carbons were studied with ZnCl₂ as activating agent, methylene blue as index and its Hg adsorption experiment was conducted. The adsorption of soybean stem activated carbon for methylene blue was 149.84μg/g, and its adsorption capacity to Hg in flue gas in 4 hours was 14.57μg and penetration rate was 5.30% at the conditions of 600°C activation temperature, 90 min activation time and ZnCl₂ concentration 50%, and the mechanism was analyzed.