Remediation of Cd2+ in aqueous systems by alkali-modified (Ca) biochar and quantitative analysis of its mechanism

Co-pyrolysis of straw and Ca(OH)₂ is a feasible modification method to improve the adsorption capacity of biochar for Cd. However, few studies have quantitatively analyzed the contribution of different adsorption mechanisms of alkali-modified biochar. In this study, the alkali-modified (Ca) biochar were prepared by co-pyrolyzing lime (Ca(OH)₂) and soybean straw (SBB) or rape straw (RSB) at 450 °C. The adsorption mechanism was investigated by a series of experiments and was provided by quantitative analysis. The maximum adsorption capacities of Cd²⁺ by Ca-SBB and Ca-RSB were calculated to be 78.49 mg g^?1 and 49.96 mg g^?1, which were 1.56 and 1.48 times higher than SBB (50.40 mg g^?1) and RSB (33.79 mg g^?1), respectively. Compared with the original biochar (SBB, RSB), alkali-modified biochar (Ca-SBB and Ca-RSB) were found to have faster adsorption kinetics and lower desorption efficiencies. The mechanism study indicated that Ca(OH)₂ modification effectively enhanced the contribution of ion exchange and decreased the contribution of functional groups complexation. After Ca(OH)₂ modification, precipitation and ion exchange mechanisms dominated Cd^2 + absorption on Ca-SBB, accounting for 49.85% and 34.94% of the total adsorption, respectively. Similarily ion exchange and precipitation were the main adsorption mechanism on Ca-RSB, accounting however for 61.91% and 18.47% of total adsorption, respectively. These results suggested that alkali-modified biochar has great potential to adsorp cadmium in wastewater.     

Evaluation of the Sorptive Capacity of Sugarcane Bagasse and Its Coal for Heavy Metals in Solution

Recycling of sugarcane bagasse and its coal as metal sorbents to capture metal ions from wastewater is the aim of this study. Thus, stability of sugarcane bagasse and its coal, in addition to the solubilities of metal ions in synthetic solution, were determined in this study at different pH values. Also, sorption of Fe, Mn, Cd, and Pb ions with different concentrations (10‐100 mg L^?1) on different grain size fractions of sugarcane bagasse (< 150 > μm) and its coal (< 80 > μm) was carried out under different pH values (2, 4 and 6), dosage (2, 6, and 10 g L^?1), time intervals (15‐300 min.) and temperature (20‐50 °C). The results indicated that the sugarcane bagasse and its coal were more stable at pH 6, and the solubilities of metal ions in the synthetic solution exhibited high values at pH 2 more than pH 4 and 6, respectively. Generally, removal of metal ions using the sorbents increased with the decreasing of grain size fractions and with increasing of pH values (6 > 4 > 2), sorbent doses (10 > 6 > 2 g L^?1) and initial concentrations of metal ions (10‐100 mg L^?1). Coal of sugarcane bagasse was more effective than the sugarcane bagasse for removal of the metal ions from solution. Positive values of ΔH° suggest the endothermic nature of sorption in all cases. The negative Gibb's free energy values indicate the feasibility of the process and spontaneous nature of sorption (Fe‐bagasse coal system), while the positive value of ΔG° suggests the non‐spontaneous character of adsorption of all metals. The negative values of entropy change ΔS° (Pb‐bagasse system) indicate the highly ordered adsorption process in this case, while the positive values of ΔS° show the increased randomness at solid/solution interface during the sorption metal ion on bagasse. The results of activation energy values indicate the order of sorption feasibility is: Pb > Fe > Cd > Mn in the case of bagasse and Fe > Pb > Cd > Mn in the case of coal. Generally, the results of this study suggest that the sugarcane bagasse and its coal might provide an economical method for the removal of metal ions from wastewater.     

Optimizing pyrolysis temperature of contaminated rice straw biochar: Heavy metal(loid) deportment,properties evolution,and Pb adsorption/immobilization

Pyrolysis of rice straw (RS), a popular method for producing biochar, effectively treats heavy metal(loid)-contaminated RS. Here, we carried out this process at different temperatures and investigated the deportment of heavy metal(loid)s and the property evolution of biochars. Also, the optimal pyrolysis temperature for Pb adsorption and immobilization was studied. We observed that increasing the temperature could volatilize the heavy metal(loid)s. Cd was the most volatile metal therein, followed by As, while Ni, Cu, and Pb were relatively refractory. More than 75% of the remaining heavy metal(loid)s were non-exchangeable fractions at 700 °C, significantly reducing the environmental risk during subsequent application. Meanwhile, higher pyrolysis temperature resulted in higher pH values, higher surface areas, and stronger Pb adsorption capacity of RS biochars. The maximum adsorption capacity (Q_m) of biochars was in the order of BC300 (77.2 mg·g^?1) < BC500 (137.2 mg·g^?1) < BC700 (222.6 mg·g^?1). Besides, high-temperature biochar could significantly reduce the vertical Pb migration. And BC700 increased the fraction of residual Pb from 39.7% to 44.0% in the soil under the acid rain leaching condition. Therefore, we propose that the heavy metal(loid)-contaminated RS biochar produced at 700 °C might be more suitable for the remediation of soil heavily polluted in the Pb-smelting area.     

Hierarchically porous tobacco midrib-based biochar prepared by a simple dual-templating approach for highly efficient Rhodamine B removal

High volatile matter contents in the feedstock could promote the development of porous structures and the reactivity of biochar. Herein, tobacco midrib with high volatile matter contents was used to prepare biochar by a dual-templating approach with mild activators (K₂C₂O₄·H₂O, CaCO₃). The characterizations of textural properties indicated that tobacco midrib-based biochar possessed numerous meso-, micro-, and macro-pores, specific surface area reached 1841.9 m² g^?1. As a dye adsorbent, the adsorption capacity of this biochar towards Rhodamine B reached 588.7 mg g^?1. After recycling 5 times, it still retained over 90% of its initial adsorption capacity. Moreover, thermodynamic parameters assessed with full vańt Hoff equation confirmed that dye molecules replace water molecules connected on biochar surface during the adsorption according to negative heat capacity change (-3.9 kJ mol^?1 K^?1), ΔH⁰ (–22.1 kJ mol^?1) and ΔS⁰ (0.3 kJ mol^?1) revealed that the adsorption process of Rh B by TMB was exothermic and the disorder of the solid–liquid interface increased. Overall, this research provides a mild and effective approach to modifying biochar from special tissue of agriculture waste and an insight into the process of dye adsorption on biochar from thermodynamics.     

Determination of monomers and oligomers in polyethylene terephthalate trays and bottles for food use by using high performance liquid chromatography-electrospray ionization-mass spectrometry

The types and contents of monomers and oligomers in polyethylene terephthalate (PET) food containers were analyzed using HPLC-ESI-MS after being extracted with 50% acetonitrile or dichloromethane using an accelerated solvent extraction unit. The types of cyclic oligomers were classified into first and second series. The first series represented a type of [TG]n composed of terephthalic acid (TPA; T) and monoethylene glycol (EG; G) at a ratio of 1:1. The second series showed a type of [TG]nG in which a single G unit was substituted by diethylene glycol (DEG; GG). The oligomer level extracted using dichloromethane was measured at 4024–11576 mg kg^?1. The first series cyclic oligomers, second series cyclic oligomers and linear oligomers constituted 83.0–90.6%, 7.8–14.7% and 1.3–2.8%, of the total extracted oligomers, respectively. The extracted amounts of TPA, monohydroxyethyl terephthalate and bishydroxyethyl terephthalate using 50% acetonitrile were 3.0–28.2 mg kg^?1, 16.8–118.2 mg kg^?1 and 3.9–26.7 mg kg^?1, respectively. The A2, A3, S2 and S3 groups as modified oligomers were detected as 42.9–221.4 mg kg^?1, 17.2–250.3 mg kg^?1, 1.1–48.1 mg kg^?1 and 1.0–19.8 mg kg^?1, respectively. The results of this study demonstrate an advanced analytical approach to determine the residual oligomers and monomers in PET products for food use and imply their potential migration to foodstuffs.     

Corncob-to-xylose residue (CCXR) derived porous biochar as an excellent adsorbent to remove organic dyes from wastewater

Biochar was prepared from corncob-to-xylose residue (CCXR) by KOH activation and anaerobic pyrolysis method. The effect of activation temperature on the microstructure of the biochar was studied. Results showed that the biochar prepared at 850°C (850NBC) possessed high specific surface area and exhibited excellent adsorption property. The maximum adsorption capacity of 2249 mg g⁻¹ was obtained when 850NBC was used for treating methylene blue (MB) solution. Adsorption isotherm fittings revealed that Langmuir and Freundlich models were applicable to 850NBC adsorption process, and the adsorption process was limited by adsorption site and the biochar surface functional groups. Furthermore, 850NBC showed good adsorption property when it was used to treat the other organic dyes of Congo red (751 mg g⁻¹), Orange II (735 mg g⁻¹), Indigo carmine (662 mg g⁻¹) and Methyl Orange (465 mg g⁻¹). Biochar 850NBC also possessed an acceptable recyclability which maintained 68.7% absorption capacity after 6 cycles when it was used to treat MB solution. These results proposed that 850NBC is expected to be a promising potential adsorbent for treating organic dyes waste water.     

Adsorption-reduction performance of tea waste and rice husk biochars for Cr(VI) elimination from wastewater

In the current study tea waste and rice husk biochars were used for the elimination of Cr(VI) from wastewater with the objectives to study the effect of pH (3–10), shaking time (0.016–24 h), sorbent dose (0.1–1.3 g L⁻¹) and initial concentration of Cr(VI) (10–250 mg L⁻¹). The Cr(VI) sorption was studied under various factors in which solution pH played a main role and at pH 5.2, maximum 99.3% and 96.8% Cr(VI) were removed by tea waste biochar (TWB) and rice husk biochar (RHB), respectively. In comparison, 197.5 mg g⁻¹ and 195.24 mg g⁻¹ Cr(VI) were sorbed by TWB and RHB, respectively with 120 mg L⁻¹ initial Cr(VI) concentration. In contact time study, after 2 h, equilibrium was achieved for both biochars which indicated that the Cr(VI) elimination from aqueous medium is a fast process. Kinetic and isotherm modeling data showed that pseudo-second order model and Langmuir (monolayer sorption) models provided the best fit for sorption of Cr(VI) onto both biochars. The –OH, COO– and –NH₂ functional groups were involved in the sorption of Cr(VI) onto biochars according to FTIR. Biochars produced from both biomass effectively removed Cr(VI) from polluted water, however in comparison sorption capacity of TWB was slightly higher than RHB. It was concluded that TWB and RHB could provide a cost-effective and viable option for elimination of Cr(VI) from wastewater.     

Single-Step Hydrothermal Synthesis of Biochar from H3PO4-Activated Lettuce Waste for Efficient Adsorption of Cd(II) in Aqueous Solution

Developing an ideal and cheap adsorbent for adsorbing heavy metals from aqueous solution has been urgently need. In this study, a novel, effective and low-cost method was developed to prepare the biochar from lettuce waste with H₃PO₄ as an acidic activation agent at a low-temperature (circa 200 °C) hydrothermal carbonization process. A batch adsorption experiment demonstrated that the biochar reaches the adsorption equilibrium within 30 min, and the optimal adsorption capacity of Cd(II) is 195.8 mg∙g⁻¹ at solution pH 6.0, which is significantly improved from circa 20.5 mg∙g⁻¹ of the original biochar without activator. The fitting results of the prepared biochar adsorption data conform to the pseudo-second-order kinetic model (PSO) and the Sips isotherm model, and the Cd(II) adsorption is a spontaneous and exothermic process. The hypothetical adsorption mechanism is mainly composed of ion exchange, electrostatic attraction, and surface complexation. This work offers a novel and low-temperature strategy to produce cheap and promising carbon-based adsorbents from organic vegetation wastes for removing heavy metals in aquatic environment efficiently.     

Nitrate removal from aqueous solution using watermelon rind derived biochar-supported ZrO2 nanomaterial: Synthesis,characterization, and mechanism

Recently, biochar has attracted tremendous research interest for environmental applications. In this study, biochar-derived watermelon rind (WM) was produced via optimal pyrolysis at 500 °C for 2 h, and then improved the adsorption capacity by Zirconium oxide nanoparticles (ZrO₂ NPs). The WM@ZrO₂ was characterized using X-ray diffraction (XRD), Scanning electron microscopic - Energy-dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infrared (FTIR). The adsorptive capacities of synthesized ZrO₂ NPs were investigated for nitrate as a function of pH, adsorbent dosage, contact time, initial adsorbate concentration, and pyrolysis temperature in the batch experiment. The results showed that a Langmuir isotherm and a pseudo-second-order kinetics model were the best-fit for experimental nitrate data in its non-linear form as correlation coefficients (R²) were 0.985 and 0.998, respectively. The maximum adsorption capacity for the Langmuir isotherm model was 15.196 mg g^?1. The proposed mechanism, including electrostatic attraction and ligand exchange, played a dominant role in nitrate adsorption. After testing with the real domestic wastewater, the removal of nitrate for WM@ZrO₂ was achieved at 78 %, which was equivalent to the adsorption capacity of 8.1 mg g^?1 of adsorbent. Overall, the WM@ZrO₂ is proposed as a promising, effective, and environmentally friendly adsorbent in removing nitrate from an aqueous solution.     

Introduction of CdO nanoparticles into graphene and graphene oxide nanosheets for increasing adsorption capacity of Cr from wastewater collected from petroleum refinery

Graphene and graphene oxide nanocomposites are promising and fascinating types of nanocomposites because of their fast kinetics, unique affinity for heavy metals, and greater specific area. Initially, in this study, a green, cost-effective and facile method was utilized to prepare G, GO, CdO, G-CdO, and CdO-GO nanocomposites by Azadirachta indica and then analyzed using UV–vis spectroscopy, Fourier-transform spectroscopy, Raman, X-ray diffraction and scanning electron microscope. The synthesized nanocomposites were explored for chromium elimination from wastewater collected from a petroleum refinery. CdO-GO, G-CdO nanocomposites showed remarkable adsorption capability of 699 and 430 mg g^?1 which was higher than G (80 mg g^?1), GO (65 mg g^?1), and CdO (400 mg g^?1). Based on the R² (correlation coefficient) values, the kinetic statistics of Cr (VI) onto the G, GO, CdO, G-CdO, and CdO-GO were effectively obeyed by pseudo-second-order than by all other models. The R² values for the five nano-bioadsorbents were extraordinarily high (R² greater than 0.990) which ensured the chemisorption. This study ensured that the adsorptive removal rate of Cr (VI) is still greater than 85 % after repeated five cycles, suggesting that the produced nanomaterials are adsorbents with strong recyclability.     

Na-alginate,polyaniline and polypyrrole composites with cellulosic biomass for the adsorptive removal of herbicide: Kinetics,equilibrium and thermodynamic studies

This study was designed to prepare the sugarcane bagasse (SB) composite with polyaniline (PAn), polypyrrole (Ppy) and sodium alginate (NaA) and employed as an adsorbent for the adsorptive removal of herbicide (2,4-dicholorophenoxyacetic acid, 2,4-D). Fabricated composites were characterized by SEM and FTIR techniques. The affecting variables, i.e., temperature, contact time, initial herbicide concentration, medium pH and adsorbent dose were studied in batch mode. Different isotherms were employed on the adsorption data and the maximum adsorption capacity of SB was recorded to be 77.75 mg/g at pH 3.0, 150 mg/L 2,4-D initial concentration at 30 °C. The models (pseudo-second-order and Freundlich) best explained the adsorption experimental data with R² values ≥ 0.90 and ≥ 0.96, respectively. The thermodynamics parameters (ΔG, ΔH, and ΔS) were computed and the herbicide adsorption onto the composites was an exothermic and spontaneous process. Results revealed that sugarcane bagasse composites with PAn, Ppy, and NaA are efficient adsorbents, which could be used for the remediation of 2,4-D in the effluents.     

Tracking Hg historical inputs by Pb-210 geochronology for the Itapessoca Estuarine Complex,Pernambuco, Brazil

The application of geochronology for tracking mercury contamination was remarkably demonstrated in the Itamaracá Estuarine Ecosystem, Pernambuco State, Brazil. Here, two sediment cores were sampled, layered and analyzed by the Gas Flow Proportional Counter technique for determining ²¹⁰Pb, radionuclide applied to geochronology. Mercury was quantified in sediment samples by Cold Vapor Atomic Absorption Spectrometry, varying from 0.17 to 1.29 mg kg^?1 in deep sediments. From ²¹⁰Pb results, the sedimentation rates of 0.84 (0.07) cm year^?1 and 1.03 (0.22) cm year^?1 confirmed Hg contamination in Itamaracá since mid-1965. Events of extreme precipitation and drought have been also related to the distribution pattern for Hg concentrations in deep sediments.

     

Optimization of cadmium adsorption from aqueous solutions by functionalized graphene and the reversible magnetic recovery of the adsorbent using response surface methodology

Novel functionalized graphene adsorbent was prepared and characterized using different techniques. The prepared adsorbent was applied for the removal of cadmium ions from aqueous solution. A response surface methodology was used to evaluate the simple and combined effects of the various parameters, including adsorbent dosage, pH, and initial concentration. Under the optimal conditions, the cadmium removal performance of 70% was achieved. A good agreement between experimental and predicted data in this study was observed. The experimental results revealed of cadmium adsorption with high linearity follow Langmuir isotherm model with maximum adsorption capacity of 502 mg g^?1, and the adsorption data fitted well into pseudo‐second order model. Thermodynamic studies showed that adsorption process has exothermic and spontaneous nature. The recommended optimum conditions are: cadmium concentration of 970 mg L^?1, adsorbent dosage of 1 g L^?1, pH of 6.18, and T = 25 °C. The magnetic recovery of the adsorbent was performed using a magnetic surfactant to form a noncovalent magnetic functionalized graphene. After magnetic recovery of the adsorbent both components (adsorbent and magnetic surfactant) were recycled by tuning the surface charges through changing the pH of the solution. Desorption behavior studied using HNO₃ solution indicated that the adsorbent had the potential for reusability.     

Elucidating dominant factors of PO43–, Cd2+ and nitrobenzene removal by biochar: A comparative investigation based on distinguishable biochars

Biochars produced from crab shell (CSB), oak sawdust (OB), Jerusalem artichoke tuber (JAB) and sorghum grain (SB) displayed distinguishable adsorption-related characteristics, such as specific surface area (SSA), ash content and acidic oxygen-containing functional groups (AFGs), which linked to the biochar adsorption mechanisms of most pollutants. Herein, PO₄^3–, Cd²⁺, and nitrobenzene (NB) were employed for adsorption by these biochars to elucidate the dominant factors for the adsorption. Adsorption performance of the three pollutants onto these four biochars varied considerably, as exemplified by the excellent adsorption of PO₄^3– and Cd²⁺ onto CSB (225.3 and 116.0 mg/g, respectively) as compared with onto the other three biochars (4.2–37.1 mg/g for PO₄^3– and 9.7–41.0 mg/g for Cd²⁺). OB displayed the best adsorption of NB (72.0 mg/g), followed by SB (39.5 mg/g), JAB (31.1 mg/g), and CSB (23.6 mg/g). The kinetics and isotherm adsorption assessments couple with material characterization suggested that the sorption of selected pollutants on biochars was attributed to the multiple mechanisms involved, including coprecipitation, chemical bonds, cation exchange, physical absorption, and complexation. Further path analysis suggested that AFGs and ash content in biochars were more important than SSA with regards to pollutant removal, especially, with ash playing a crucial role in the removal of Cd²⁺ and PO₄^3–, and AFGs being mainly responsible for NB adsorption. These findings might offer guidance on the preparation or modification of biochar with a targeted function for pollutant removal through an understanding the dominant factors.     

Tailoring biochar by PHP towards the oxygenated functional groups (OFGs)-rich surface to improve adsorption performance

In this work, a modification method of H₃PO₄ plus H₂O₂ (PHP) was introduced to targetedly form abundant oxygenated functional groups (OFGs) on biochar, and methylene blue (MB) was employed as a model pollutant for adsorption to reflect the modification performance. Results indicated that parent biochars, especially derived from lower temperatures, substantially underwent oxidative modification by PHP, and OFGs were targetedly produced. Correspondingly, approximately 21.5-fold MB adsorption capacity was achieved by PHP-modified biochar comparing with its parent biochar. To evaluate the compatibility of PHP-modification, coefficient of variation (CV) based on MB adsorption capacity by the biochar from various precursors was calculated, in which the CV of PHP-modified biochars was 0.0038 comparing to 0.64 of the corresponding parent biochars. These results suggested that the PHP method displayed the excellent feedstock compatibility on biochar modification. The maximum MB adsorption capacity was 454.1 mg/g when the H₃PO₄ and H₂O₂ fraction in PHP were 65.2% and 7.0%; the modification was further intensified by promoting temperature and duration. Besides, average 94.5% H₃PO₄ was recovered after 10-batch modification, implying 1.0 kg H₃PO₄ (85%) in PHP can maximally modify 2.37 kg biochar. Overall, this work offered a novel method to tailor biochar towards OFGs-rich surface for efficient adsorption.     

U(VI) adsorption by biochar fiber–MnO2 composites

The removal of U(VI) by biochar fibers from aqueous solutions has been investigated prior and after MnO₂ surface-deposition. The removal efficiency has been studied as a function of pH, U(VI) concentration, ionic strength, temperature and contact time. The fibers morphology and surface complexes were analyzed by SEM–EDX and FTIR, respectively. Evaluation of the experimental data indicates that the composite presents extraordinary adsorption capacity (q_max = 3.8 mmol g⁻¹, 904 mg g⁻¹), which is attributed to the formation of inner-sphere surface complexes, and that the adsorption reaction is a relatively fast, endothermic and entropy-driven process.

     

Quality variations of poultry litter biochar generated at different pyrolysis temperatures

Producing biochar and biofuels from poultry litter (PL) through slow pyrolysis is a farm-based, value-added approach to recycle the organic waste. Experiments were conducted to examine the effect of pyrolysis temperature on the quality PL biochar and to identify the optimal pyrolysis temperature for converting PL to agricultural-use biochar. As peak pyrolysis temperature increased incrementally from 300 to 600 °C, biochar yield, total N content, organic carbon (OC) content, and cation exchange capacity (CEC) decreased while pH, ash content, OC stability, and BET surface area increased. The generated biochars showed yields 45.7–60.1% of feed mass, OC 325–380 g kg⁻¹, pH 9.5–11.5, BET surface area 2.0–3.2 m² g⁻¹, and CEC 21.6–36.3 cmol_c kg⁻¹. The maximal transformation of feed OC into biochar recalcitrant OC occurred at 500 °C, yet 81.2% of the feed N was lost in volatiles at this temperature. To produce agricultural-use PL biochar, 300 °C should be selected in pyrolysis; for carbon sequestration and other environmental applications, 500 °C is recommended.     

Optimizing adsorptive removal of malachite green and methyl orange dyes from simulated wastewater by Mn‐doped CuO‐Nanoparticles loaded on activated carbon using CCD‐RSM: Mechanism,regeneration, isotherm,kinetic, and thermodynamic studies

In the present work, Mn‐doped CuO‐NPs‐AC was prepared by a simple method, characterized using various techniques such as FESEM, EDX, XRD, PSD, and pH_pzc and finally used for the adsorption of malachite green (MG) and methyl orange (MO) in a number of single and binary solutions. A series of adsorption experiments were conducted to investigate and optimize the influence of various factors (such as different pH, concentration of MG and MO, adsorbent mass, and sonication time) on the simultaneous adsorption of MG and MO using response surface methodology. Under optimal conditions of pH 10, adsorbent dose of 0.02 g, MG concentration of 30 mg L^?1, MO concentration of 30 mg L^?1, and sonication time of 4.5 min at room temperature, the maximum predicted adsorption was observed to be 100.0%, for both MG and MO, showing that there is a favorable harmony between the experimental data and model predictions. The adsorption isotherm of MO and MG by Mn‐doped CuO‐NPs‐AC could be well clarified by the Langmuir model with maximum adsorption capacity of 320.69 mg g^?1 and 290.11 mg g^?1 in the single solution and 233.02 mg g^?1 and 205.53 mg g^?1 in the binary solution by 0.005 g of adsorbent mass for MG and MO, respectively. Kinetic studies also revealed that both MG and MO adsorption were better defined by the pseudo‐second order model for both solutions. In addition, the thermodynamic constant studies disclosed that the adsorption of MG and MO was likely to be influenced by a physisorption mechanism. Eventually, the reusability of the Mn‐doped CuO‐NPs‐AC after six times showed a reduction in the adsorption percentage of MG and MO.     

Cellulases and Hemicellulases from Endophytic <Emphasis Type="Italic">Acremonium</Emphasis> Species and Its Application on Sugarcane Bagasse Hydrolysis

The aim of this work was to have cellulase activity and hemicellulase activity screenings of endophyte Acremonium species (Acremonium zeae EA0802 and Acremonium sp. EA0810). Both fungi were cultivated in submerged culture (SC) containing l-arabinose, d-xylose, oat spelt xylan, sugarcane bagasse, or corn straw as carbon source. In solid-state fermentation, it was tested as carbon source sugarcane bagasse or corn straw. The highest FPase, endoglucanase, and xylanase activities were produced by Acremonium sp. EA0810 cultivated in SC containing sugarcane bagasse as a carbon source. The highest β-glucosidase activity was produced by Acremonium sp. EA0810 cultivated in SC using d-xylose as carbon source. A. zeae EA0802 has highest α-arabinofuranosidase and α-galactosidase activities in SC using xylan as a carbon source. FPase, endoglucanase, β-glucosidase, and xylanase from Acremonium sp. EA0810 has optimum pH and temperatures of 6.0, 55 °C; 5.0, 70 °C; 4.5, 60 °C; and 6.5, 50 °C, respectively. α-Arabinofuranosidase and α-galactosidase from A. zeae EA0802 has optimum pH and temperatures of 5.0, 60 °C and 4.5, 45 °C, respectively. It was analyzed the application of Acremonium sp. EA0810 to hydrolyze sugarcane bagasse, and it was achieved 63% of conversion into reducing sugar and 42% of conversion into glucose.     

Techno-economic feasibility of biochar as biosorbent for basic dye sequestration

Biochar has a global scientific attention for its ability to remove toxic elements from wastewaters. However, due to the disparity between practical short-term agronomic benefits and aspirations of biochar as an everlasting sustainable bio sorbent for the adsorption process, economic assessments of biochar have yet to be established. In this context, the current study, an economic approach of the biochars derived from agricultural wastes (Coconut shell, Groundnut Shell and Rice husk) for the removal of Basic Red 09 from wastewaters were demonstrated. Batch adsorption experimental set up was used to carry out the adsorption process. At equilibrium batch adsorption conditions, the maximum adsorption capacity of the biochars were 10, 46.3, and 44 ​mg/g for coconut shell, groundnut shell, and rice husk based biochars, respectively. A complete cost assessment was carried out for the agro-waste biochars for their adsorption performance. The biochars derived from groundnut shell and rice husk were shown to be the most cost effective for the Basic Red 09 sequestration from wastewater. The eco-friendly characteristics of these low-cost adsorbents for industrial applications were also discussed.