Rhodamine B dyes adsorption on palm kernel shell based activated carbons

Palm kernel shell is a promising candidate as activated carbon precursor due to its granular structure, chemical stability, high mechanical strength and local availability at almost no cost. It can be activated into high porosity carbon in a short time due to its high lignin content, low cellulose content and less fibrous structure. This paper aimed to provide a short summary of various types of palm kernel shell-based activated carbons, the preparation strategies, and the textural properties for water pollutants removal. Besides, a case study on the adsorptive performance of palm kernel shell-based activated carbon for rhodamine B removal from water was included to evaluate its feasibility in the treatment of dyes wastewater

Adsorptive characteristics and microwave dielectric properties of oil palm empty fruit bunch-based activated carbons for dye removal

The present study was aimed to evaluate the adsorptive characteristics and microwave dielectric properties of activated carbons derived from oil palm empty fruit bunch (EFB) prepared by microwave-assisted potassium hydroxide activation at 300 W and 800 W for 5 min. The resultant products were characterized for dielectric properties, BET specific surface area, surface functional groups and methylene blue adsorption. Results show that the microwave-assisted activation yields activated carbons with surface area of 695 m2/g and 1339 m2/g for heating rates (microwave irradiation power) of 300 W and 800 W, respectively and both exhibit more than 95% removal of methylene blue at concentrations higher than 100 mg/L. The dielectric properties revealed a better propensity of activated carbons towards microwave heating especially at a higher heating rate due to high surface area, and possibly high moisture content and carbon content. A greater heating rate or microwave power could turn EFB into activated carbon with a higher surface area and excellent adsorptive properties for pollution abatement

Effects of chemical activating agents on physical properties of activated carbons – a commentary

Well-developed surface areas and porous structures that render high adsorption capacity are necessary for pollutant removal from wastewater by activated carbons. Activated carbons from natural resources, and agricultural and industrial waste materials are produced using chemical agents, including KOH, H3PO4,K2CO3, ZnCl2 and NaOH. This study is intended to highlight the effects of those agents on the physical properties of the activated carbons. The operating conditions, i.e., temperature, time and ratio, show an interplay towards the physical properties at varying degree. The yield, pore size, mesoporosity and surface area of activated carbons derived using different chemical agents correlate well with the impregnation ratio. Generally, the pore size, mesoporosity and surface area increase, while the yield decreases with increasing ratio (over a given range). Higher ratio and temperature are recommended for KOH, K2CO3 and NaOH activation, to endow activated carbons with greater surface area

Twigs-derived activated carbons via H3PO4/ZnCl2 composite activation for methylene blue and congo red dyes removal

This work is aimed at evaluating the conversion of Pterocarpus indicus twigs into activated carbon via composite chemical activation for methylene blue and congo red dyes adsorption. The activated carbons were prepared by single-step chemical activation using zinc chloride and/or phosphoric acid at different mass impregnation ratios at 600 °C for 90 min. The activated carbons were characterized for textural properties and surface chemistry. The batch adsorption was investigated at different concentrations (5–1,000 mg/L), contact times (2–540 min) and temperatures (30–60 °C). Phosphoric acid-activated twigs carbon showed a high surface area of 1,445 m2/g with maximum methylene blue adsorption capacity of 438 mg/g. On the other hand, a composite-activated carbon yields a 217 mg/g of congo red removal. The adsorption data for both dyes fitted well with Langmuir and pseudo-second-order kinetics models, indicating the predominance of chemical adsorption through monolayer coverage of dye molecules on the homogenous surface of activated carbon. The thermodynamics properties of dye adsorption onto twigs-derived activated carbons indicated that the process is endothermic, spontaneous and favourable at high temperature. Overall, activated carbons derived from Pterocarpus indicus twigs could be effectively used for dye wastewater treatment

Physicochemical properties of char derived from palm fatty acid distillate

The present work was aimed to evaluate the physiochemical properties of chars derived from palm fatty acid distillate. The palm fatty acid distillate was heat-treated at 500 °C and 600 °C in a muffle furnace for 0.5 h, and the resultant products were characterized for elemental composition, surface functional groups, thermogravimetric profile and methylene blue adsorption. Results show that the char samples are rich in carbon content with unique surface functional groups that could be useful in the liquid-phase adsorption. The solid chars depict a thermally stable profile with the increase of temperature during the heat treatment. The char demonstrated the maximum removal of methylene blue of 7.6 mg/g and obeyed the monolayer-trend adsorption of Langmuir isotherm. The findings concluded that the palm fatty acid distillate-based char could be an adsorbent candidate for the removal of methylene blue

Adsorbents from the by-product of palm oil refinery for methylene blue removal

The present work was aimed at evaluating the removal of methylene blue by palm fatty acid distillate-based adsorbents. The adsorbents at different weight ratios of palm fatty acid distillate (PFAD) to palm kernel shell (PKS) were prepared at 600 °C for 2 hours. Results show that the yield of adsorbent upon heat treatment decreased with increasing weight ratio, with yield as low as 0.53% was recorded by adsorbent derived by using only PFAD. The methylene blue adsorption data show a promising performance of PFAD-based adsorbents as compared to that of PKS-adsorbent (char) with qe = 7.6 mg/g at Co = 20.8 mg/L. To conclude, PFAD is a potential candidate of dye adsorbent

Metals chloride-activated castor bean residue for methylene blue removal

This work aims to evaluate the feasibility of castor bean residue as the precursor of activated carbon by metal chloride salts as activating agent. ZnCl2, NaCl and KCl were used to activate the castor bean residue and the performance was investigated by adsorption of methylene blue and its correlation with the specific surface area. ZnCl2-activated castor bean cake with had the best adsorption result with maximum capacity of 213 mg/g and specific surface area of 643 m2/g. The adsorption of methylene blue for all metals chloride-activated castor bean residue followed Langmuir isotherm which suggests monolayer adsorption onto the homogeneous surface

Isotherm studies of methylene blue adsorption onto potassium salts-modified textile sludge

In the present work, the adsorption of methylene blue from aqueous solution by textile sludge activated with potassium salts and a composite-KI, KCl, K2SO4 and KOH+KCl-was investigated. The impregnation ratio for all activating agents was set at 1:1 and the impregnated textile sludge samples were activated at 500oC for 1h in a furnace. The specific surface area of the activated carbon (AC) was evaluated using BET analysis. The BET surface area varied from 78.8 to 321m2/g, where it decreased in the order of K2SO4-AC > KCl-AC > KI-AC > KOH+KCl-AC. Under room temperature condition and a shaking time of 72h, the batch adsorption results show that the minimum and maximum adsorption capacities were recorded as 39.1 and 85.0mg/g for textile sludge activated with KCl and KI, respectively. Langmuir isotherm model gave the best fit to adsorption equilibrium compared to Freundlich isotherm model indicating a monolayer adsorption at homogeneous sites on the adsorbent. The Langmuir mechanism yielded a maximum monolayer adsorption capacity of 90.9mg/g. Among the four prepared activated carbons, textile sludge activated with potassium iodide (KI-AC) gave the best performance on the adsorption of methylene blue

Textile sludge–sawdust chemically produced activated carbon: Equilibrium and dynamics studies of malachite green adsorption

Textile sludge–sawdust chemically produced activated carbon (SSAC) was used in equilibrium and dynamics adsorption of malachite green (MG). The effects of concentration in equilibrium, and influent flow rate (15–30 mL/min), initial concentration (20–80 mg/L) and bed height (2–6 cm) in dynamics mode were investigated. SSAC with surface area of 979 m2/g shows an outstanding maximum capacity of malachite green at 530 mg/g. In adsorption dynamics, the breakthrough time and bed capacity increased with increasing bed height, and decreasing flow rate and influent dye concentration. Bohart-Adams, Thomas, Yoon-Nelson and Clark models were applied to describe the column breakthrough, dynamics behaviour and adsorption mechanisms. The breakthrough curves were best fitted by Yoon-Nelson model at the experimental conditions. The maximum bed capacity was reported to be 565 mg/g. SSAC is an effective adsorbent for MG removal from aqueous phase

Adsorption of malachite green and congo red dyes from water: recent progress and future outlook

Global concern on dyes-laden effluent has intensified over the years. Dyes are toxic, stable to light, and hardly oxidized and bio-degraded, hence causing severe physiological effects to living organisms. In water, dye hinders the light penetration for photosynthetic activity, consequently oxygen is deficient for respiration by aquatic creatures. Adsorption has been widely recognized as the effective removal strategy to abate dye wastewater. However, the quests to improve the adsorption efficiency are continuously sought through new adsorbents with special characters, while performing the removal process at optimum operating conditions. This short review aims to summarize the recent progress in adsorption studies of two commonly used industrial dyes, namely malachite green and congo red by various adsorbents. From the quoted studies, the oxidized mesoporous carbon yields a higher adsorption capacity of malachite green at 1265 mg/g, while Fe 3 O 4 @nSiO 2 @mSiO 2 displays a greater capacity for congo red removal at 1429 mg/g. A superior adsorption relies not only on specific surface area but also the synergistic interactions of pore width and mesoporosity, surface chemistry, and operating conditions. The dyes properties and factors affecting the adsorption are also highlighted and discussed, with recommendations and future outlook