Preparation of activated carbon by microwave heating of langsat (Lansium domesticum) empty fruit bunch waste

Agricultural biomass/waste-based materials could be a potential adsorption-type remediation contributor to environmental pollution induced by pesticides-A critical review

The widespread use of pesticides that are inevitable to keep the production of food grains brings serious environmental pollution problems. Turning agricultural biomass/wastes into materials addressing the issues of pesticide contaminants is a feasible strategy to realize the reuse of wastes. Several works summarized the current applications of agricultural biomass/waste materials in the remediation of environmental pollutants. However, few studies systematically take the pesticides as an unitary target pollutant. This critical review comprehensively described the remediation effects of crop-derived waste (cereal crops, cash crops) and animal-derived waste materials on pesticide pollution. Adsorption is considered a superior and highlighted effect between pesticides and materials. The review generalized the sources, preparation, characterization, condition optimization, removal efficiency and influencing factors analysis of agricultural biomass/waste materials. Our work mainly emphasized the promising results in lab experiments, which helps to clarify the current application status of these materials in the field of pesticide remediation. In the meantime, rigorous pros and cons of the materials guide to understand the research trends more comprehensively. Overall, we hope to achieve a large-scale use of agricultural biomass/wastes.

One-step synthesis of carbonaceous adsorbent from soybean bio-residue by microwave heating: Adsorptive, antimicrobial and antifungal behavior

In this work, the transformation of soybean industrial bio-residue with limited practical applications, into a multifunctional carbonaceous adsorbent (SBAC) via one-step microwave-irradiation has been succeeded. The surface porosity, chemical compositions, functionalities and surface chemistry were featured by microscopic pore-textural analysis, elemental constitution analysis, morphological characterization and Fourier transform infra-red spectroscopy. The adsorptive performance of SBAC was evaluated in a batch experiment by adopting different classes of water pollutants, specifically methylene blue (MB), acetaminophen and 2,4-dichlorophenoxyacetic acid (2,4-D). The equilibrium uptakes were analyzed with respect to the non-linearized Langmuir, Freundlich and Temkin isotherm equations. The unique features of SBAC, specifically the antimicrobial and antifungal efficacies were examined against gram-positive/negative bacteria and fungi species. An ordered microporous-mesoporous structure of SBAC, with the BET surface area and total pore volume of 1696 m2/g and 0.94 m3/g, respectively, has been achieved. The equilibrium data of MB and acetaminophen were found to be in good agreement with the Langmuir isotherm model, with the monolayer adsorption capacities (Qo) of 434.57 mg/g and 393.31 mg/g, respectively. The adsorptive experiment of 2,4-D was best fitted to the Freundlich isotherm equation, with the Qo of 253.17 mg/g. The regeneration performance of the spent SBAC under microwave-irradiation could maintain at 69.42-79.31%, even after five (5) adsorption-regeneration cycles. SBAC exhibited excellent inhibition efficiencies against gram-positive/negative bacteria and fungi species, with the inhibition zones at 14.0-28.0 mm. This newly developed SBAC appears to be a new powerful candidate for the remediation of different classes of water contaminants, and novel antibacterial and antifungal agents against biological contaminations. The novel concept of "turn waste into wealth" in a cost-effective and energy saving manner for environmental preservation has been successfully accomplished.

Adsorption isotherms and kinetic modeling of methylene blue dye onto a carbonaceous hydrochar adsorbent derived from coffee husk waste

In this study, activated carbon in the form of carbonaceous hydrochar adsorbents with highly functionalized surface-active sites were produced from coffee husk waste via hydrothermal carbonization under low-temperature conditions (180 °C) and subsequent chemical activation. Thereafter, the hydrochars were characterized using diverse analytical techniques, and batch experiments of methylene blue (MB) adsorption were performed under various operating conditions. The results indicated that the activated hydrochar (AH) had a larger specific surface area (862.2 m² g^-1) compared to that of its carbonaceous precursor (33.7 m² g^-1). The maximum MB sorption capacity of the hydrochar activated with potassium hydroxide was extremely high (415.8 mg g^-1 at 30 °C). In addition, adsorption isotherms and kinetics were studied using experimental data fitting to further understand and describe the dynamic equilibrium, dynamic kinetics, and mechanism of MB adsorption onto the prepared hydrochars. As compared to the Freundlich isotherm model, the Langmuir isotherm model provided a better fit with the experimental data exhibiting a maximum monolayer adsorption capacity of 418.78 mg g^-1_. The linear pseudo-second-order kinetic model was found to be suitable for describing the adsorptive kinetics of the hydrochar. The results demonstrated the immense potential of coffee husk waste to produce activated carbon as an alternative green hydrochar that can be applied to dye removal from wastewater as well as improvement of waste management.

Parametric Study on Microwave-Assisted Pyrolysis Combined KOH Activation of Oil Palm Male Flowers Derived Nanoporous Carbons

Oil palm male flowers (PMFs), an abundant agricultural waste from oil palm plantation in Thailand, have been utilized as an alternative precursor to develop nanoporous carbons (NPCs) via microwave-assisted pyrolysis combined potassium hydroxide (KOH) activation. The influences of relevant processing variables, such as activating agent ratio, microwave power, and activation time on the specific pore characteristics, surface morphology, and surface chemistry of PMFs derived nanoporous carbons (PMFCs) have been investigated to explore the optimum preparation condition. The optimum condition under a microwave radiation power of 700 W, activation holding time of 6 min, and activating agent ratio of 2:1 obtained the PMFC with the highest Brunauer–Emmett–Teller (BET) surface area and total pore volume approximately of 991 m²/g and 0.49 cm³/g, composed of a carbon content of 74.56%. Meanwhile, PMFCs have a highly microporous structure of about 71.12%. Moreover, activating agent ratio and microwave radiation power indicated a significant influence on the surface characteristics of PMFCs. This study revealed the potential of oil palm male flowers for the NPCs’ production via microwave-assisted KOH activation with a short operating-time condition.

A Review of Chemicals to Produce Activated Carbon from Agricultural Waste Biomass

The choice of activating agent for the thermochemical production of high-grade activated carbon (AC) from agricultural residues and wastes, such as feedstock, requires innovative methods. Overcoming energy losses, and using the best techniques to minimise secondary contamination and improve adsorptivity, are critical. Here, we review the importance and influence of activating agents on agricultural waste: how they react and compare conventional and microwave processes. In particular, adsorbent pore characteristics, surface chemistry interactions and production modes were compared with traditional methods. It was concluded that there are no best activating agents; rather, each agent reacts uniquely with a precursor, and the optimum choice depends on the target adsorbent. Natural chemicals can also be as effective as inorganic activating agents, and offer the advantages that they are usually safe, and readily available. The use of a microwave, as an innovative pyrolysis approach, can enhance the activation process within a duration of 1–4 h and temperature of 500–1200 °C, after which the yield and efficiency decline rapidly due to molecular breakdown. This study also examines the biomass milling process requirements; the influence of the dielectric properties, along with the effect of washing; and experimental setup challenges. The microwave setup system, biomass feed rate, product delivery, inert gas flow rate, reactor design and recovery lines are all important factors in the microwave activation process, and contribute to the overall efficiency of AC preparation. However, a major issue is a lack of large-scale industrial demonstration units for microwave technology.

Remediation of anionic dye from aqueous system using bio-adsorbent prepared by microwave activation

The present study was attempted to ascertain the possible application of activated carbon as a cost-effective and eco-friendly adsorbent prepared via microwave-assisted chemical activation. The activated carbon was characterized using different techniques. The various adsorption parameters have been optimized to examine the viability of activated carbon as a plausible sorbent for the remediation of Congo red (CR) dye from the aquatic system. The equilibrium data adequately fitted to the Langmuir isotherm with better R² (0.994). The maximum adsorption capacity (q_m) of activated carbon was recorded to be 68.96 mg/g. Additionally, sorptional kinetic data were examined by reaction-based and diffusion-based models such as pseudo-first-order and pseudo-second-order equations, and Elovich, intra-particle diffusion, and Dumwald-Wagner models, respectively. The computed values of thermodynamic parameters such as free energy change (ΔG⁰), enthalpy change (ΔH⁰) and entropy change (ΔS⁰) were recorded as -3.63, 42.47 and 152.07 J/mol K, respectively, at 30°C, which accounted for a favorable, spontaneous and endothermic process. The regeneration study emphasized that the percentage uptake declined from 90.35% to 83.45% after six cycles of testing. So, our findings implied that activated carbon produced from biomass must be cost-effectively used as an adsorbent for detoxifying the CR dye from industrial effluents.

Adsorption of ciprofloxacin and norfloxacin from aqueous solution onto granular activated carbon in fixed bed column

Carbonization of Phoenix dactylifera L stones followed by microwave K₂CO₃ activation was adopted for preparation of granular activated carbon (KAC). High yield and favorable pore characteristics in terms of surface area and pore volume were reported for KAC as follows: 44%, 852m²/g, and 0.671cm³/g, respectively. The application of KAC as adsorbent for attraction of ciprofloxacin (CIP) and norfloxacin (NOR) was investigated using fixed bed systems. The effect of flow rate (0.5-1.5ml/min), bed height (15-25cm), and initial drug concentration (75-225mg/l) on the behavior of breakthrough curves was explained. The fixed bed analysis showed the better correlation of breakthrough data by both Thomas and Yoon-Nelson models. Inlet drug concentration was of greatest effect on breakthrough data compared to other fixed bed variables. Experimental and calculated breakthrough data were obtained for CIP and NOR adsorption on KAC, thus being important for design of fixed bed column.

Insights into the equilibrium, kinetic and thermodynamics of nickel removal by environmental friendly Lansium domesticum peel biosorbent

Lansium domesticum peel (LDP), a waste material generated from the fruit consumption, was evaluated as a biosorbent for nickel removal from aqueous media. The effects of dosage, contact time, initial pH, initial concentration and temperature on the biosorption process were investigated in batch experiments. Equilibrium data were fitted by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models using nonlinear regression method with the best-fit model evaluated based on coefficient of determination (R(2)) and Chi-square (χ(2)). The best-fit isotherm was found to be the Langmuir model exhibiting R(2) very close to unity (0.997-0.999), smallest χ(2) (0.0138-0.0562) and largest biosorption capacity (10.1mg/g) at 30°C. Kinetic studies showed that the initial nickel removal was rapid with the equilibrium state established within 30min. Pseudo-second-order model was the best-fit kinetic model indicating the chemisorption nature of the biosorption process. Further data analysis by the intraparticle diffusion model revealed the involvement of several rate-controlling steps such as boundary layer and intraparticle diffusion. Thermodynamically, the process was exothermic, spontaneous and feasible. Regeneration studies indicated that LDP biosorbent could be regenerated using hydrochloric acid solution with up to 85% efficiency. The present investigation proved that LDP having no economic value can be used as an alternative eco-friendly biosorbent for remediation of nickel contaminated water.

Temperature dependent, shape variant synthesis of photoluminescent and biocompatible carbon nanostructures from almond husk for applications in dye removal

The effect of the carbonization temperature on the morphology and properties of synthesized water soluble photoluminescent carbon nanostructures from almond husks have been investigated.

Experimental and theoretical studies on methylene blue and methyl orange sorption by wheat straw-derived biochar with a large surface area

MB hydrolyzes in water and the existing forms in water include both the well-accepted MB⁺ and the hydrolyzed form of MB⁺.

Adsorption of 2,4-dichlorophenoxyacetic acid by mesoporous activated carbon prepared from H3PO4-activated langsat empty fruit bunch

The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater.

Quantitative determination of methylene blue in environmental samples by solid-phase extraction and ultra-performance liquid chromatography-tandem mass spectrometry: a green approach

Industrial effluents with dyes may have appreciably high chemical oxygen demand and suspended solids, posing adverse effects to both humans and aquatic life; therefore, quantitative monitoring of these effluents is essential.

Preparation of bio-based porous carbon by microwave assisted phosphoric acid activation and its use for adsorption of Cr(VI)

Ficus carica fiber based activated carbon (FCAC) was used as a potential adsorbent for Cr(VI) removal from aqueous system. The adsorbent was prepared by carbonization of F. carica fiber followed by H3PO4 activation under microwave radiations. The activated carbon was characterized using scanning electron microscopy and Fourier transformer infrared spectroscopy. The adsorption data were well studied for adsorption isotherms, kinetics models, and thermodynamics. Adsorption of chromium ion followed the second-order kinetics and best fitted the Langmuir adsorption isotherms. The maximum adsorption capacity of Cr(VI) onto FCAC was 44.84 mg/g. The calculated values of thermodynamic parameters like enthalpy change (ΔH°), entropy change (ΔS°), and free energy change (ΔG°) were found to be 7.85 kJ/mol, 69.17 J/mol K, and -13.11 kJ/mol, respectively. Adsorption process was spontaneous and endothermic in nature.