Synthesis of activated carbon from spent tea leaves for aspirin removal

Adsorption capacity of activated carbon prepared from spent tea leaves (STL-AC) for the removal of aspirin from aqueous solution was investigated in this study. Preliminary studies have shown that treatment with phosphoric acid (H3PO4) increased removal efficiency of STL-AC. Characterizations on STL-AC revealed excellent textural properties (1200 m2·g− 1, 51% mesoporosity), as well as distinctive surface chemistry (1.08 mmol·g− 1 and 0.54 mmol·g− 1 for acidic and basic oxygenated groups, pHpzc = 2.02). Maximum removal efficiency of aspirin observed was 94.28% after 60 min when the initial concentration was 100 mg·L− 1, 0.5 g of adsorbent used, pH 3 and at a temperature of 30 °C. The adsorption data were well fitted to the Freundlich isotherm model and obeyed the pseudo-second order kinetics model. The adsorption of aspirin onto STL-AC was exothermic in nature (ΔHϴ = − 13.808 kJ·mol− 1) and had a negative entropy change, ΔSϴ (− 41.444 J·mol− 1). A negative Gibbs free energy, ΔGϴ was obtained indicating feasibility and spontaneity of the adsorption process. The adsorption capacity of AC-STL (178.57 mg·g− 1) is considerably high compared to most adsorbents synthesized from various sources, due to the well-defined textural properties coupled with surface chemistry of STL-AC which favors aspirin adsorption. The results demonstrate the potential of STL-AC as aspirin adsorbent

Optimization of phenol adsorption onto biochar from oil palm empty fruit bunch (EFB)

Malaysia, as one of the leading palm oil producers in the world faces problems in disposal of oil palm empty fruit bunch (EFB), which can be converted into various value-added products, including adsorbents. This study investigated the adsorption of phenol from its solution using biochar produced from EFB through carbonization. Response Surface Methodology (RSM) with Box-Behnken design was used to investigate the effects of three parameters (temperature, time and heating rate) during carbonization on phenol removal by the biochar produced. This was followed by process optimization based on statistical analysis. The results indicated that the optimized carbonization conditions were; 500 °C for temperature, 10 °C/min of heating rate and 80 min for reaction timwhich led to 7.57% of phenol removal. SEM revealed coarse and uneven surface of the biochar surface, with small degree of pore development. Comparison between FTIR spectrum of EFB and biochar revealed the loss water and hydroxyl compounds from EFB during carbonization. The lack of oxygenated groups (especially carbonyl groups) on the adsorbent surface as well as limited number of pores were the possible reasons leading to low phenol adsorption by biochar, therefore conversion of the biochar to activated carbon was necessary for higher adsorption performance

Facile synthesis of polyethylenimine-modified sugarcane bagasse adsorbent for removal of anionic dye in aqueous solution

Many studies have reported that surface modification of various type of materials by using polyethylenimine (PEI), usually necessitate to be combined with the crosslinkers, namely glutaradehyde, sodium tripolyphosphate, etc. The sugarcane bagasse (SB) is a fibrous agricultural waste derived from sugarcane stalks residue which has rich-cellulose content that makes it amenable to surface functionalization for tailored application. Thus, it is possible for SB material to modify by using solely PEI and eliminate crosslinking step. In this study, SB was used as supporting material for modified PEI to produce polyethylenimine-modified sugarcane bagasse (PmSB) for the adsorption of Reactive Black 5 (RB5) dyes from aqueous solution. The effects of contact time (60 – 300 min), adsorbent dosage (0.05 – 0.15 g); initial dye concentration (0.01 – 0.10 g/L), pH (5 - 9) and temperature (30 – 70 °C) were varied to evaluate the performance of the PSB under different experimental conditions. The kinetics study revealed that the adsorption experimental data fitted the pseudo second order model. The equilibrium adsorption data also fitted the Langmuir model with R2 of 0.99 and maximum monolayer capacity of 25 mg/g. The thermodynamic parameters suggest that the RB5 dye adsorption by PEI modified SB was spontaneous, exothermic and exhibited chemisorption. The adsorbent can be regenerated up to 4 cycles with the percentage dye removal greater than 80%). Therefore, the PmBS adsorbent has proven that the PEI is solely sufficient as modifying agents for SB material, even without an assistance of crosslinker reagents for removal of RB5 dye in aqueous solution

Catalytic pyrolysis of plastics over maghemite-impregnated mesocellular foam using induction heating

Pyrolysis is a key technology that converts unrecyclable end-of-life plastics into value-added products. Nevertheless, the high energy consumption during plastic pyrolysis limits the economic feasibility of a scaledup process. Development of an energy-efficient plastic pyrolysis process is necessary to realise its full potential in the circular economy. Catalysts derived from mesocellular foam possess high acidity and mesoporosity, and exhibit high catalytic activity in chemical reactions. Application of such catalyst in plastic pyrolysis has never been reported. This work presents the catalytic pyrolysis of low- and high-density polyethylene and polypropylene over maghemite-impregnated mesocellular foam (Fe@AlMCF). Fe@AlMCF has a BET surface area of 629.8 m2/g and a strong Brønsted acidity (677 µmol/gcat). The catalyst contains pentagonal and hexagonal packed mesostructure. Induction heating resulted in a rapid increase in reactor temperature (at 65°C /min) and complete plastics conversion within 10 min. Catalytic pyrolysis produced gas products rich in C3 compounds. The liquid products were rich in alkenes (69.7-71.3 %) and alkanes, followed by aromatics (10.4- 12.8 %). These observations indicate that the highly acidic Fe@AlMCF catalysed hydrocarbon aromatization within a short reaction time. Thermal analysis of the spent catalysts revealed considerably high coke yields (5.78 - 6.03 %), as the higher acidity of the original catalyst promoted coke precursor formation. Based on the research findings, induction heating can rapidly and effectively convert plastics into hydrocarbon feedstocks, and Fe@AlMCF is a valuable catalyst for plastic pyrolysis

Recent advances in applications of activated carbon from biowaste for wastewater treatment: A short review

Rapid population growth and the resultant pollution of freshwater sources are expected to create water stress conditions on the world in the near future. Adsorption technique is a popular method in reducing the amount of pollutants that enter water bodies, and researchers are focusing on development of activated carbons from cheap sources to replace costly commercial activated carbons. Remediation of wastewater using activated carbon from biowaste (defined in this paper as waste material derived from living organisms or of organic origin, and capable of decomposing under anaerobic or aerobic conditions) is gaining attention among researchers, as such technology reduces the cost of activated carbon production while reducing the cost on biowaste disposal. This paper summarizes recent development and findings on application of activated carbon synthesized from biowaste in wastewater treatment. Adsorption efficiencies of newly developed activated carbons in treatment of different pollutants (including dyes, metal ions, pharmaceutical and personal care products, organic pollutants) in simulated and real wastewater are also tabulated for easy reference. The potential of activated carbons modified with magnetic materials is also discussed, followed by recent advances and challenges in applications of activated carbons derived from biowaste in wastewater treatment

Transesterification of used cooking oil (UCO) catalyzed by mesoporous calcium titanate: Kinetic and thermodynamic studies

Due to the superior catalytic property of calcium oxide in biodiesel production via transesterification, it is necessary to modify such catalyst to retain the catalytic property while overcoming the disadvantages related to the catalyst application in the process. The present study focused on the kinetic and thermodynamic studies on the transesterification of used cooking oil (UCO) catalyzed by mesoporous calcium titanate (MCT). The experiments were performed at room temperature, 65 °C, and 100 °C. Among the various models being studied, the Pseudo First order is the best model to describe the reaction kinetic. Data analysis showed that the rate constants, k, varied in the range of 0.0233–0.058 s−1, while the activation energy, Ea was determined to be 21.25 kJ·mol−1. The following parameters were also obtained: −24 kJ·mol−1 for enthalpy (ΔH), −0.16 kJ·mol−1.K−1 for entropy (ΔS) and 25.62–35.70 kJ·mol−1 for Gibb's free energy (ΔG). The results showed that the reaction was exothermic (ΔH 0). This study demonstrates the potential of MCT catalyst in promoting the conversion UCO into biodiesel with high quality fuel properties

Recent advances of feed-in tariff in Malaysia

In order to promote the growth of renewable energy sector in Malaysia, feed-in tariff (FiT) mechanism has been introduced by Malaysian government in 2011, in accordance with Renewable Energy Act 2011 and Sustainable Energy Development Authority Act 2011. The tariff was enacted to overcome the shortcomings identified in the small renewable energy power (SREP) Program from 2001 to 2010. This paper highlighted some measures adopted to rectify the shortcomings identified during SREP, and the role of Sustainable Energy Development Authority (SEDA) in achieving the above mentioned task. The paper also includes the latest progress on renewable energy projects, especially those related to solar photovoltaic system. It is predicted that solar energy will become the main source of renewable energy in Malaysia by the year 2050

Removal of aspirin from aqueous solution using phosphoric acid modified coffee waste adsorbent

Removal of pharmaceutical waste, aspirin (ASA) in an aqueous solution was investigated using activated carbon derived from coffee waste (CW). Activated carbon was prepared by using phosphoric acid as a chemical activating agent. Fourier Transform Infrared Spectroscopy (FTIR) was used to characterize the functional groups on the surface of the adsorbents. The BET technique measured the surface area of the adsorbent. The activated carbon derived from coffee waste modified by H3PO4 (AC-HCW) was observed to have a larger surface area than AC-CW. The states of the adsorption operations are controlled by the effect of initial ASA concentration, adsorbent dose, contact time, temperature, and pH adjacent to the adsorption procedure. In the batch adsorption test, the highest removal efficiency found was 98.02% in 30 min and 95% in 60 min when used AC-HCW and AC-CW, respectively. The optimum conditions for removing aspirin from aqueous solution were 1000 mg/L of initial concentration ASA, pH 4 and a temperature of 30 °C and 0.5 g of AC-HCW and 0.6 g AC-CW adsorbents. The experimental data for adsorption of aspirin were well fitted into the Langmuir isotherm model and obeyed the pseudo-second-order kinetics model. The adsorption of aspirin onto AC-HCW and AC-CW was exothermic, with enthalpy change ΔH°= −0.182 kJ/mol and −0.216 kJ/mol, ΔS° was 0.072 J/mol −0.004 J/mol, which indicates a decrease in randomness at the adsorbent surface/aspirin solution interface, respectively. In addition, a negative Gibbs free energy ΔG° was obtained, indicating the feasibility and spontaneity of the adsorption process. For this study, the coffee waste modified by H3PO4 is considered a promising adsorbent, and It could be employed as a low-cost alternative to commercial activated carbon in removing aspirin in aqueous solutions

Efficient adsorptive removal of methylene blue from synthetic dye wastewater by green alginate modified with pandan

Remediation of dye-bearing wastewater is important to preserve the water quality. This study reports the performance of new adsorbent, namely alginate polymer modified with pandan leaves (AlgiPAN), in removal of methylene blue (MB) from synthetic solution. The adsorbents in beads form demonstrated high removal percentage (61%) towards MB (0.01 g/L) at 60 min reaction time, pH 5 and adsorbent dosage of 3 g. This study demonstrates the capability of AlgiPAN in MB dye removal without involving complex synthesis processes. Such adsorbent can be easily separated after wastewater treatment, and the pandan modification increase the surface functional groups

Kinetics, thermodynamics, isotherm and regeneration analysis of chitosan modified pandan adsorbent

There has been increased interest of chitosan as a dye adsorbent. Nonetheless, the chitosan tends to form bonding between their monomer chains that result in a rigid structure which affects its capability for adsorption. This is prime reason many recent studies modified chitosan through various modifications. However, most modifications involve chemical additive agents as well as complex procedures that are conducted under strong condition. Not much research consider low-cost organic materials as modifying agent. The purpose of this work is to investigate the performance of chitosan modified with pandan leaves in the adsorption of reactive black 5 (RB5). Modified chitosan-pandan (MCP) adsorbent was synthesized by simple wet impregnation under mild conditions. The MCP was characterized using Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area analysis. Batch adsorption was conducted to study the effect of retention time (0–60 min), pH (3–11), initial dye concentration (100–1000 mg/L) and temperature (25–80 °C). Kinetics, isotherm, thermodynamics and regeneration evaluation were also performed on the adsorption data. The kinetics data obtained fitted well to the pseudo-second order model, indicating the role of chemisorption with the influence of intraparticle diffusion. For isotherm study, the data is best fitted to the Langmuir model (R2 = 0.91) with maximum adsorption of 169.49 mg/g. Thermodynamics analysis showed that the adsorption is feasible, endothermic and occurred spontaneously. MCP has been regenerated up to 5 times with percentage removal above 50% by washing with distilled water only. In conclusion, natural polyphenols from pandan leaves have been incorporated into chitosan to prepare high-efficiency adsorbent with satisfactory performance in RB5 removal from aqueous media. The MCP is a new promising biodegradable adsorbent for removal of dyes from textile wastewater