Biomass-based Adsorbent Research Articles

Valorization of castor seed shell waste as lead adsorbent by treatment with hot phosphoric acid: Optimization and evaluation of adsorption properties

Lead is used in many industries such as refining, mining, battery manufacturing, smelting. Releases of lead from these industries is one of the major public health concerns due to widespread persistence in the environment and its resulting poisoning character. In this work, the castor seed shell (CSS) waste was exploited for preparing a beneficial bio-adsorbent for removal of Pb(II) ions from water. The raw CSS was modified with H3PO4 at different acid concentrations, impregnation ratios, activation times, and temperatures. An optimum adsorption capacity was observed for CSS modified with 2 M acid, 5 mL g−1 solid to liquid ratio, treated at 95 °C for 160 min. Exploiting acid modification, the SEM, XRD, and FTIR analyses show some alterations in functional groups and the surface morphology of the biomass. The impacts of physiochemical variables (initial lead ions concentration, pH, adsorbent dose and adsorption time) on the lead removal percentage were investigated, using response surface methodology (RSM). Maximum removal of 72.26% for raw CSS and 97.62% for modified CSS were obtained at an initial lead concentration (50 mg L−1), pH (5.7), adsorption time (123 min) and adsorbent dosage (1.1 g/100 mL). Isothermal and kinetics models were fitted to adsorption equilibrium data and kinetics data for the modified CSS and the adsorption system was evaluated thermodynamically and from the energy point of view. Isothermal scrutinization indicated the mono-layer nature of adsorption, and the kinetics experimental outcomes best fitted with the pseudo-second-order, implying that the interaction of lead ions and hot acid-treated CSS was the rate-controlling phenomenon of process. Overall, results illustrated that the hot acid-treated biomass-based adsorbent can be considered as an alternative bio-adsorbent for removing lead from water media.

Detoxification of fermentation inhibitors using a waste biomass-based adsorbent of AEPA250 to enhance bioethanol production: The adsorption analysis and microbial mechanism

Environmental pollution and energy scarcity have promoted the development of renewable alternative energy of rice straw-based bioethanol. However, the production of main fermentation inhibitors from the pretreatment of rice straw raw material reduces the bioethanol yield. In order to improve bioethanol production, a waste biomass-based adsorbent (AEPA250) was used to adsorb three main inhibitors of ferulic acid, vanillin, and furfural from the rice straw hydrolysate in this study. The adsorption percentages were calculated using the high-performance liquid chromatography method. The results showed that the adsorption percentages of three inhibitors were all above 70% in 10 min, demonstrating the efficient detoxification of AEPA250 on rice straw hydrolysate. The adsorption contributions related to the attribute features of three inhibitors and AEPA250 were evaluated for the first time. The density functional theory calculations and AEPA250 characterizations were used to obtain these attribute parameters. Analysis of the correlation heat map between adsorption efficiencies and attribute features of AEPA250 (or fermentation inhibitors) indicated that AEPA250 possessed the lower activation energy (Ea) and pre-exponential factor (A) when it was prepared, as well as fermentation inhibitors had the higher ionization constant (pKa) and lower electrophilicity index (ω), resulting in the enhancement of bioethanol production. The contribution of pKa was greater than A followed by Ea and ω for adsorption process. Meanwhile, the key metabolic pathways involved in central carbon metabolism were analyzed for AEPA250 detoxification using proteomics method. The results indicated that the up-regulation of SDH3, ACO1, CIT2 and MLS1 (or down-regulation of SCT1) genes contributed to inhibitors detoxification using AEPA250, which effectively provided more nicotinamide adenine dinucleotide (NADH) for the reduction of these inhibitors. This study explores the detoxification mechanisms at the molecular level for boosting bioethanol production in the future, which lays the foundation for the development of efficient adsorbents and resistant engineering strains.

High adsorption capacity of Pb2+ by iminodiacetic acid functionalized ramie via radiation grafting

Wastewater containing heavy metal ions discharged from industries has caused serious pollution to water. As for how to use renewable resources as the substrate, green preparation of adsorbents through eco-friendly processes and effective disposal of metal ions has become urgent. In this work, the low-cost, environmentally-friendly and easily modified natural renewable biomass ramie was used as the substrate, and glycidyl methacrylate (GMA) containing epoxy functional group was grafted onto ramie via electron beam irradiation (grafting rate up to 332.3 %). A ramie-poly-GMA-IDA (RGD) adsorbent was prepared by ring-opening reaction and grafted with iminodiacetic acid (IDA). The adsorption process was affected by pH, the RGD could effectively uptake Pb2+ when the pH = 5.0, and the adsorption equilibrium can be quickly reached within 50 min. Moreover, RGD possessed excellent uptake properties, and the Pb2+ adsorption capacity maximized to 225.71 mg/g. The adsorption procedure obeys a pseudo-2nd-order kinetic and Langmuir equation. The possible mechanisms for Pb2+ adsorption are complexation, electrostatic interaction and ion exchange. This study presents that IDA-functionalized ramie can be used as an efficient biomass-based adsorbent for Pb2+ uptake. Thus, a green, closed-loop utilization of agricultural and forestry wastes is achieved, which helps reduce heavy metal ion pollution and resource consumption and protect the environment.

Functionalization of Biomass-derived Activated Carbon and Electrochemical Reduction for the Recovery of Gold from Mobile Phone Leachate

In this age of cutting-edge technology, electronic equipment consumption, such as mobile phones, has increased tremendously. This was followed by a staggering increase in electronic waste (e-waste). However, it has been known that e-wastes contain higher amounts of precious metals than pristine sources, such as Au, which is valuable as an alternative precious metal source. Due to its various advantages, adsorption has emerged as one of the most common metal removal or recovery methods. A crucial aspect of adsorption is developing a cost-effective adsorbent for selective recovery of Au from the e-wastes. Thus, functionalized biomass-based adsorbent was developed to recover precious metals from e-waste. Functionalized activated carbon (ACIL900) has an appealing high adsorption capacity (116.2 mg g−1) performance and follows the chemisorption route, which fits with the monolayer model. The presence of IL boosts the adsorption efficiency due to its compatible interaction with the metal complexes. Remarkably, ACIL900 could quantitatively adsorb precious metals and several base metals from mobile phone leachate. The selective recovery of Au from the adsorbent was performed by sequential desorption using various solutions. Finally, Au was successfully recovered from the desorption solution using an electrochemical reduction process. ACIL900 was also found to maintain its performance for three adsorption–desorption cycles. This work reported the full recovery of Au from e-waste to its final pure product through the combination of adsorption, sequential desorption, and electrochemical reduction.

Functionalized agriculture-derived biomass-based adsorbent for the continuous recovery of gold from a simulated mobile phone leachate

Electronic waste has become a global concern, as it has been steadily increasing over the years. The lack of regulation and appropriate processing facilities has rendered these wastes an environmental hazard. However, they represent excellent alternative sources of precious metals, which are highly in demand in various industries. Adsorption has been a popular method for metal removal/recovery because of several advantages, such as ease of use and low cost. In this regard, it is crucial to develop an inexpensive and functionalized adsorbent to selectively adsorb precious metals. Thus, silica, which is derived from rice husk and is abundantly present in Indonesia, was functionalized using an ionic liquid (SiRH_Im) and used for Au(III) adsorption from a simulated mobile phone leach liquor. SiRH_Im exhibited a high adsorption capacity (232.5 mg g−1). The Au(III) adsorption kinetic suitably fitted with the pseudo-second-order kinetic model. The Au(III) adsorption followed a chemisorption route that suited the monolayer model. Thomas' and Yoon-Nelson's models were well suited for the continuous Au(III) behavior. Selective recovery of Au(III) from SiRH_Im was achieved via sequential desorption. SiRH_Im also showed excellent reusability, as indicated by a negligible decrease in adsorptive performance over three cycles. The functionalization of silica derived from rice husk using an ionic liquid led to the successful creation of a solid adsorbent with a high adsorption capacity toward precious metals present in a simulated leach solution. Our results highlight the benefit of the functionalization of biomass through the immobilization of an ionic liquid toward the enhancement of its adsorption capability.

Adsorption Recycling and High-Value Reutilization of Heavy-Metal Ions from Wastewater: As a High-Performance Anode Lithium Battery.

The dazzling adsorbent products make people overlook the harm of heavy metals adsorbed on them. Hazardous waste adsorbents cause secondary pollution. In this study, waste lignocellulose was dissolved by alkaline urea solvent and high-intensity ultrasound, then cross-linked by epichlorohydrin to make hydrogel, which was utilized to adsorb toxic heavy-metal wastewater. In situ deposition and high-temperature carbonization turn the gel that has absorbed heavy metals into carbon aerogel-loaded metal oxide energy storage materials that may be employed as anodes in lithium-ion batteries with excellent electrochemical performance. The best reversible capacity was 435.86 mAh g-1 after 100 cycles at 0.2C, indicating that the hazardous solid waste generated by the removal of heavy metals using biomass-based adsorbent has potential lithium battery applications. Thus, we provide a fresh perspective on the efficient recycling of heavy metals as well as an environmentally friendly, high-value conservation strategy for lowering the danger of heavy-metal hazardous wastes.

Fabrication of demethylated lignin-based micro-particle for efficient adsorption of malachite green from aqueous solution

Recently, the research on low-cost and renewable lignin-based adsorbent for the effective removal of organic dyes from wastewater has attracted great interest. Herein, a demethylated lignin-based micro-particle (DLMP) adsorbent with high hydroxyl content was prepared by using AlCl3 as modification reagent, which exhibited an excellent adsorption capacity for malachite green (MG). The results showed that the size distribution of DLMP was about 100–500 nm, the surface area reached 17.35 m2/g, and the phenolic hydroxyl (Ar-OH) group content was up to 5.77 mmol/g, which was much better than that of originally organosolv lignin (OL). With this DLMP as the lignin-based adsorbent, all adsorption processes fitted well with the Langmuir isothermal and the Pseudo-second-order kinetic models. The maximum adsorption capacity for MG reached 168.24 mg/g, which was higher than most of the previously published biomass-based adsorbents. Simultaneously, DLMP adsorbent could be easily regenerated, obtaining outstanding recyclability. After eight cycles, the adsorption capacity of DLMP retained at 144.59 mg/g. Finally, the investigation of the possible adsorption mechanism suggested that the synergistic interactions of electrostatic force, hydrogen bonding, π-π stacking and the superior micro-size structure significantly improved the adsorption property. In conclusion, DLMP adsorbent displays a high adsorption capacity and an excellent recyclability for the removal of MG, which might have widespread prospect in the low-cost and renewable biomass-based adsorbent.

Synthesis of biomass-based adsorbent from rice husk ash for copper ions adsorption

To solve the problems of low utilization of agricultural waste rice husk and heavy metal pollution, this investigation prepared a cheap copper ion adsorbent using rice husk ash (RA). The maximum Cu2+ adsorption capacity was 19.8 mg/g. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and surface area and porosity analyses were used to characterize the composition and structure of the material of silica-depleted rice husk ash (SDRA). The thermodynamics and kinetics of Cu2+ adsorption by SDRA were studied for their relevance to the adsorption mechanism. The adsorption of copper ions by SDRA was in accordance with the Langmuir model and the pseudo-second-order kinetic model. Furthermore, the increases in specific surface area and oxygen-containing functional groups following silica removal were primarily responsible for SDRA’s enhanced adsorption ability. And this is the first time that Cu2+ adsorbent has been prepared from the by-product of the synthesis of silane from rice husk ash. So, its synthesis cost is very low. Moreover, the preparation technique of SDRA is a revolutionary method of adsorbent creation that is both economical and environmentally benign.

Production of ultrapure biomethane from stratified bed in non-adiabatic and non-isothermal plate pressure swing adsorption

Biomethane is a renewable and clean source of energy, which can be employed to abate the greenhouse gases emissions and support the sustainable developments. Novel plate pressure swing adsorption mediated by a stratified bed containing UiO-66 followed by un-treated biomass-based adsorbent was used for production of ultrapure biomethane from biogas mixture of 30 % CO2 (balanced by CH4). Plate PSA design was proposed due to the exchangeable heat between the adsorption and desorption bed in non-isothermal/non-adiabatic conditions. Breakthrough experiments of CH4 and CO2 for individual and layered bed were conducted to understand the gases behavior in the different systems. The results were also used to determine the appropriate range of PSA operating parameters i.e., the adsorption pressure and adsorption/blowdown time. A quadratic model was built to optimize the pressure and CO2 content in the biogas feed for maximum bio-CH4 purity in the adsorption line. The results revealed that the introduction of UiO-66 layer which was positioned before the un-modified biomass adsorbent improved bio-CH4 purity to 99.99 % and recovery of 69.6 % under the adsorption pressure of 2 bar at room temperature. The optimum point to achieve the ultrapure bio-CH4 was located at pressure of 2 bar, CO2 content of up to 50 % and adsorption/blowdown time of 4 min. In this work, a new layering strategy consisting of different strata of un-treated biomass-based adsorbent and microporous UiO-66 adsorbent was introduced for bio-CH4 purification using plate PSA under non-adiabatic/non-isothermal conditions.

Performance of TSA and VSA post-combustion CO2 capture processes with a biomass waste-based adsorbent

Carbon capture in post-combustion flue gases is vital on the grounds that most of the energy requirement of the world is supplied by non-renewable energy sources. Biomass-based CO2 adsorbents are of interest due to their high potential of adsorption capacity and contribution to the sustainable circular economy. In the current study, Temperature Swing Adsorption (TSA) and Vacuum Swing Adsorption (VSA) configurations were carried out to evaluate the CO2 capture performance of a hazelnut shell-based activated carbon adsorbent from dry simulated flue gases in cyclic operation. A fixed-bed reactor with a single column is used to test the adsorption performance for CO2 concentrations of 14% and 30% and temperatures of 30 °C and 50 °C at atmospheric pressure, which resemble the conditions of industrial processes. Various TSA and VSA configurations are designed and the influence of cyclic steps on the product (CO2) purity, recovery, productivity, and specific energy consumption at different CO2 concentration and temperature are evaluated. For the VSA process, the highest purity and recovery obtained are 92% and 100%, respectively; while they are 86% and 82% for TSA process, revealing the highest TSA cycle CO2 adsorption performance of a biomass-based adsorbent reported in literature.

Development of microwave-assisted nitrogen-modified activated carbon for efficient biogas desulfurization: a practical approach.

Removal of H2S (hydrogen sulfide) from biogas is anticipated for higher energy conversion of methane (CH4), while reducing the detrimental impacts of corroding the metal parts in the plant and its hazardous effect on humans and the environment. The introduction of microwave (MW) heating and nitrogen-modification could generate superior adsorbent features, contributing to high H2S removal. Up to date, there is no work reported on the influence of physicochemical characteristics of nitrogen-modified carbon synthesized via MW and conventional heating (TH) methods and their performance in H2S removal. Palm shell activated carbon (PSAC) was functionalized with nitrogen groups via urea impregnation, followed by the synthesis of MW and TH at 950°C, 500ml/min of N2 flow rate and 30min of heating time. MW and TH heating effects on the modified PSAC adsorbent were analysed and compared towards hydrogen sulfide (H2S) removal. PSAC with nitrogen functionalization produced using MW heating (PSAC-MW) demonstrates superior performance, with an adsorption capacity of 356.94mg/g. The adsorbent sample generated using MW heating exhibited notable properties, including a large surface area and a sponge-like structure, with new pores developed within the current pores. Instead of that, there was an observation of 'hot spot' appearance during the MW heating process, which is believed to be responsible for the development of physical and chemical characteristics of the adsorbent. Thus, it is believed that MW heating was assisted in the development of the adsorbent's properties and at the same time contributed to the high removal of H2S at low adsorption temperature. The utilization of biomass-based adsorbent (PSAC) for H2S removal can address the lignocellulosic waste disposal problem, while mitigating the H2S release from the biogas production plants thus has several environmental merits. This indirectly contributed to zero-waste generation, while overcoming the adverse effects of H2S.

Adsorption-reduction of Cr(VI) onto unmodified and phytic acid-modified carob waste: Kinetic and isotherm modeling

Carob waste (CW) is an agro-biomass material abundant in nature with potential use for eco-friendly remediation. However, like many biomass-based adsorbents, it suffers from its low adsorption capacity for organic/inorganic pollutants. Therefore, modification using physical and/or chemical means is commonly applied to improve the adsorptive properties of biomass-based adsorbents. In this study, carob waste (CW) and carob waste functionalized with phytic acid (PA-CW), as an ecofriendly product, were applied for the first time for Cr(VI) elimination. Various methods were applied for the material characterization like Fourier-transform infrared spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA and DTG), X-ray photoelectron spectroscopy (XPS), specific surface area and porosity measurements. The results proved that both CW and PA-CW own appropriate features for efficient adsorption. Bach experiments revealed that the optimum parameters for Cr(VI) (100 mg/mL) removal at 25 °C were pH 2, 0.05 and 0.025 g as adsorbent dose for CW and PA-CW, respectively, over 120 min contact time. The kinetic of adsorption was well-described by the pseudo-second order model, whereas the isotherm modeling fitted well the modified Langmuir model. CW and PA-CW achieved respectively maximum adsorption capacities of 212.4 and 387.9 mg/g, which are among the highest values so far reported for biomass-based adsorbent materials. These results confirmed that CW and PA-CW could be alternative cost-effective adsorbents even for high concentrations of Cr(VI) in industrial wastewaters along with their reduction capacity.

A highly efficient biomass-based adsorbent fabricated by graft copolymerization: Kinetics, isotherms, mechanism and coadsorption investigations for cationic dye and heavy metal

Natural biomass materials are endowed with good potential for pollutant remediation due to low cost, environment friendliness and easy accessibility. In this work, an efficient biomass-based adsorbent named g-PS was fabricated by free radical graft copolymerization of peanut shell with methacrylic acid and N,N’-methylenebis(acrylamide). The structural and morphological properties of g-PS were characterized and analyzed. The effectiveness of g-PS as adsorbent to remove cationic dye and heavy metal pollutants (i.e. methylene blue (MB), basic red 46 (BR) and Cd(II)) from water was evaluated. The batch adsorption tests indicated that g-PS showed rapid removal rates for MB, BR and Cd(II), with the adsorption equilibriums achieved within 30 min. The adsorption processes of three compounds were more suitable to be described by Langmuir and pseudo-second-order models. The maximum adsorption capacities were 538.34 mg/g for MB, 687.52 mg/g for BR and 62.01 mg/g for Cd(II) at 298 K. The coadsorption experiments in the mixed system indicated that g-PS was still effective for simultaneous removal of both BR and Cd(II). Additionally, g-PS exhibited satisfactory removal performance even after seven repeated uses. The as-prepared g-PS can be used as a promising adsorbent candidate to dispose wastewater containing cationic dyes and heavy metals.

Biomass-Based Adsorbents for Removal of Dyes From Wastewater: A Review

Dyes, especially azo dyes contained in wastewaters released from textile, pigment, and leather industries, are entering into natural waterbodies. This results in environmental deterioration and serious health damages (for example carcinogenicity and mutagenesis) through food chains. Physiochemical, membrane processes, electrochemical technology, advanced oxidation processes, reverse osmosis, ion exchange, electrodialysis, electrolysis, and adsorption techniques are commonly used conventional treatment technologies. However, the limitations of most of these methods include the generation of toxic sludge, high operational and maintenance costs. Thus, technological advancements are in use to remediate dyes from effluents. Adsorption using the nonconventional biomass-based sorbents is the greatest attractive alternatives because of their low cost, sustainability, availability, and eco-friendly. We present and reviewed up-to-date publications on biomass-based sorbents used for dye removal. Conceptualization and synthesizing their state-of-the-art knowledge on their characteristics, experimental conditions used were also discussed. The merits and limitations of various biosorbents were also reflected. The maximum dye adsorption capacities of various biosorbents were reviewed and synthesized in the order of the biomass type (algae, agricultural, fungal, bacterial, activated carbon, yeast, and others). Surface chemistry, pH, initial dye concentration, temperature, contact time, and adsorbent dose as well as the ways of the preparations of materials affect the biosorption process. Based on the average dye adsorption capacity, those sorbents were arranged and prioritized. The best fit of the adsorption isotherms (for example Freundlich and Langmuir models) and basic operating parameters on the removal dyes were retrieved. Which biomass-based adsorbents have greater potential for dye removal based on their uptake nature, cost-effectiveness, bulk availability, and mono to multilayer adsorption behavior was discussed. The basic limitations including the desorption cycles of biomass-based adsorbent preparation and operation for the implementation of this technology were forwarded.

High Selectivity and Reusability of Biomass-Based Adsorbent for Chloramphenicol Removal.

Recently, biomass-based materials have attracted increasing attention because of their advantages of low cost, environment-friendly and nonpollution. Herein, the feasibility of using corn stalk biomass fiber (CF) and Fe3O4 embedded chitosan (CS) as a novel biomass-based adsorbent (CFS) to remove chloramphenicol (CAPC) from aqueous solution. Structure of CFS was characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and zeta potential techniques. The effects of solution pH, adsorption time and ion strength on the adsorption capacity were examined. Adsorption isotherms obtained from batch experiments were better fitted by Langmuir model compared with Freundlich model, Dubinin–Radushkevich model and Temkin model. Adsorption kinetic data matched well to the pseudo-second order kinetic model. CAPC adsorption was endothermic, spontaneous, and entropy-increasing nature on CFS. In addition, the CFS could be separated by an external magnetic field, recycled, and reused without any significant loss in the adsorption capacity of CAPC. Based on these excellent performances, there is potential that CFS can be considered as a proficient and economically suitable material for the CAPC removal from the water environment.

Novel dual modified alkali lignin based adsorbent for the removal of Pb2+ in water

In the present study, a dual - modified lignin (DML) adsorbent, which exhibits a high adsorption capacity for Pb2+, was prepared through the reaction of alkaline lignin with ClCH2COOH and CS2. The main objective of the present was to prepare a biomass-based adsorbent that is suitable for scavenging heavy metals from wastewater. The DML was characterized using Fourier transform-infrared Spectroscopy (FT-IR), Elemental Analysis, Conductivity titration, Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The results show that carboxyl and ‒CSS‒ components are introduced into the DML, and the corresponding concentrations were 1.3 mmol/g and 30.5 %, yielding an adsorbent with a specific surface area of 3.13 m2/g. The rough aggregated porous structure of the DML enhances the adsorption of Pb2+. An adsorption experiments reveal that the Pb2+ adsorption by the DML is adequately represented by a pseudo - second-order kinetic equation, and these produced a maximum Pb2+ adsorption capacity of 208.3 mg/g. XPS (X-ray photoelectron spectroscopy) results demonstrates that complexation and electrostatic attraction constitute the Pb2+ adsorption mechanisms associated with the DML. The adsorbent produced in the present study is valuable for protecting water quality and the environment, and provides another avenue for the utilization of lignin.

Plumeria alba (white frangipani) leaf powder as a biomass-based adsorbent for removal of methylene blue in water

ABSTRACT The present study focused on the adsorption of cationic dye, methylene blue (MB) onto Plumeria alba (White frangipani) leaf powder (WFLP) from aqueous solution in batch experiments. The effects of contact time, solution pH, adsorbent dosage, initial dye concentration, and temperature on the adsorption of MB on WFLP were investigated. The morphology of adsorbent and interactions of MB and WFLP were characterized by SEM, EDX, FTIR, TGA, and Zeta analysis, respectively. The adsorption capacity of WFLP for the removal of MB was found from the kinetic and Langmuir isotherm model. For MB solution of dye concentration, 30 mg/L, and biosorbent loading of 3.5 g/L, the maximum dye removal was 37.22% with a monolayer adsorption capacity of 45.45 mg/g. The adsorption data fitted the isotherm models of Langmuir, Freundlich, and Temkin, in line with both first- and second-order kinetics, but the second-order kinetics gave a better fit. Both ΔH° and ΔG° decreased for the adsorption process that appeared to be both exothermic and spontaneous. Thus, WFLP could be converted to a potential and promising bioadsorbent for the removal of cationic dyes like MB from wastewater solution.

Effect of pH and Contact Time on the Adsorption of Pb(II) by <i>Kapok</i> Wood (<i>Ceiba pentandra</i>) Sawdust Based Biosorbent

With rapid industrial development, the water pollution due to industrial wastewater discharge also increases. Wastewater containing heavy metals such as Lead (Pb(II)) has been one of the serious global issues. It is because lead has a high level of toxicity and very harmful to the environment as well as human body even at low level of concentration. One of the emerging methods for removal of Pb(II) from aqueous solution is called biosorption. It is adsorption process using biomass-based adsorbent or can be called biosorbent. One of biomass material that can be used for the biosorbent for removal of Pb(II) is Kapok wood sawdust. In this study, biosorbent based Kapok sawdust has been successfully prepared. The effects of pH and contact time on the adsorption performance of the biosorbent have been studied. The adsorption tests were carried out with variations in pH 4, 5, 6, and 7 and with variations in contact time of 30, 60, and 90 minutes. The amout of Pb(II) adsorbed was analyzed using Atomic Absorption Spectroscopy (AAS). The adsorption test results showed that the equilibrium contact time required for the biosorbent to absorb Pb(II) was 60 minutes, while the pH optimum was achieved at pH = 7. Furthermore, from the adsorption test results, it has also been concluded that the optimum adsorption capacity (qe) 4.83 mg/g and removal percentage (96.6%) was achieved by Adsorbent A (i.e. Kapok sawdust biosorbent activated with 0.2 M HNO3).

Facile Modification of Biochar Derived from Agricultural Straw Waste with Effective Adsorption and Removal of Phosphorus from Domestic Sewage

In recent decades, straw waste is the major byproduct around agriculture that has become one of the factors of environmental pollution. The purpose of this study is to reuse waste straw to develop a new green and highly efficient biomass-based adsorbent for phosphorus removal. To attain this aim, Mg–Al bimetallic oxide/straw fiber (Mg–Al/SF) with hierarchical structure was successfully synthesized by hydrothermal method using waste straw as the biomass carbon precursor and Mg–Al/SF was applied as adsorbent in the removal of phosphorus from wastewater. The morphology, composition and structure of the adsorbent was well supported by several characterizations. The prepared biomass-based adsorbent showed outstanding adsorption performance. Maximum adsorption capability of Mg–Al/SF towards phosphorus from the Langmuir isotherm model was fitted out to be 89.37 mg/g. The related kinetics and isotherm study for the adsorption process were explored in detail. The proposed adsorbent exhibited good reusability that the removal of phosphorus remained above 72% after 5 cycles. In addition, thermodynamic study was carried out to further investigate the phosphorus removal mechanism, which was the synergistic combination of surface adsorption and chemical adsorption. The removal of total phosphorus in actual domestic sewage (Total phosphorus, TP, 0.8–1.1 mg/L) were investigated. The results indicated that the prepared Mg–Al/SF has excellent TP adsorption and recycling performance, and the adsorption and stability performance are significantly higher than that of the commercial activated carbon. The interactions between biomass material with large surface area and metal oxide provides great potential for the real application in the water treatment. Furthermore, it also presents a feasible and efficient practical example of increasing the use of agricultural waste.

Enhancement of bioethanol production by a waste biomass-based adsorbent from enzymatic hydrolysis

Alkaline pretreatment is an efficient method to destroy the lignocellulose structure of rice straw for bioethanol production. This process generates various toxic compounds, such as ferulic acid, which could inhibit bioethanol production. In this study, a waste biomass-based adsorbent from the enzymatic hydrolysis of rice straw (AEPA250) was used for ferulic acid detoxification in the alkali-pretreated hydrolysate. The AEPA250 detoxification process was first optimized by response surface methodology to increase ferulic acid removal, while reducing glucose loss. This optimization of detoxification resulted in 99.268% ferulic acid removal coupled with 3.028% glucose loss. The fermentation processing parameters and bioethanol production for different fermentation systems were evaluated after adopting the optimal AEPA250 detoxification conditions to select the most suitable optimization method. The result revealed that optimized detoxified fermentation with AEPA250 filtration (ODF) system was more suitable for bioethanol production than optimized detoxified fermentation containing AEPA250 (ODFA) system followed by non-detoxified fermentation (NDF) system. A logistic model was applied to further compare the yeast growth kinetics of the ODF and NDF systems. The ODF system had a maximum specific growth rate (μmax) of 0.532 h−1, indicating that the ODF system possessed greater bioethanol fermentation potential. Metabonomics and transcriptomics analyses were used to identify differentially expressed metabolites and functional genes that contribute to detoxification by the ODF system. AEPA250 was produced by the enzymatic hydrolysis of biomass waste of rice straw in the bioethanol production process, and a self-sufficient bioethanol production system could be established by in-situ AEPA250 detoxification using the ODF system. These results pave the way for the realization of a cleaner bioethanol production process by reducing environmental waste production, exogenous adsorbent use, and the cost of enzymatic hydrolysis residue treatment.