Tolerance and biosorption capacity of Zn²⁺, Pb²⁺, Ni³⁺ and Cu²⁺ by filamentous fungi (Trichoderma harzianum, T. aureoviride and T. virens)

Heavy metal pollution has become a serious environmental issue in the last few decades. There is a need to develop potential technology that can remove toxic heavy metals ions found in polluted environments. This study was undertaken to determine the resistance levels of different concentrations of heavy metals using filamentous fungi of Trichoderma aureoviride, T. harzianum, and T. virens. Based on the results, the T. virens strain T128 gave the highest tolerance ability for Ni³⁺ and Pb²⁺ in a 1200 mg/L concentration. The accumulation and uptake capacity was determined by the maximum removal of Pb²⁺, Cu²⁺, and Ni³⁺ by a T. harzianum in liquid medium when compared to other fungi. The metal removal occurred at a concentration of 500 mg/L and was 13.48 g/g for Pb²⁺, 3.1254 g/g for Cu²⁺ and 0.8351 g/g for Ni³⁺. For Zn²⁺, the highest tolerance and uptake capacity of metal was recorded at 3.1789 g/g by T. virens

Tolerance and biosorption capacity of Zn<sup>2+</sup>, Pb<sup>2+</sup>, Ni<sup>3+</sup> and Cu<sup>2+</sup> by filamentous fungi (<i>Trichoderma harzianum</i>, <i>T. aureoviride</i> and <i>T. virens</i>)

Heavy metal pollution has become a serious environmental issue in the last few decades. There is a need to develop potential technology that can remove toxic heavy metals ions found in polluted environments. This study was undertaken to determine the resistance levels of different concentrations of heavy metals using filamentous fungi of Trichoderma aureoviride, T. harzianum, and T. virens. Based on the results, the T. virens strain T128 gave the highest tolerance ability for Ni³⁺ and Pb²⁺ in a 1200 mg/L concentration. The accumulation and uptake capacity was determined by the maximum removal of Pb²⁺, Cu²⁺, and Ni³⁺ by a T. harzianum in liquid medium when compared to other fungi. The metal removal occurred at a concentration of 500 mg/L and was 13.48 g/g for Pb²⁺, 3.1254 g/g for Cu²⁺ and 0.8351 g/g for Ni³⁺. For Zn²⁺, the highest tolerance and uptake capacity of metal was recorded at 3.1789 g/g by T. virens

Cost–effective microwave rapid synthesis of zeolite NaA for removal of methylene blue

In this study, microwave rapid synthesized NaA (NaAmw) was used to adsorb a methylene blue (MB) from an aqueous solution. The adsorption was optimized under four independent variables including: pH, adsorbent dosage, initial concentration, and ageing time based on central composite design (CCD) with response surface methodology (RSM). A period of 15 min was determined to be the optimum microwave ageing time for the synthesis of NaAmw, which is about sixteen times shorter than using conventional heating technique. An amount of 1.0 g L1 NaAmw demonstrated the optimum dosage for adsorption of 120 mg L1 MB, with predicted adsorption uptake of 53.5 mg g�1, at pH 7 within 1 h of contact time at room temperature. This result approximated the laboratory result, which was 50.7 mg g�1. The experimental data obtained with NaAmw best fits the Langmuir isotherm model and exhibited a maximum adsorption capacity (qmax) of 64.8 mg g�1, and the data followed the first-order kinetic equation. The intraparticle diffusion studies revealed that the adsorption rates were not controlled solely by the diffusion step. Thermodynamic studies showed that the adsorption is endothermic, non-spontaneous in nature, and favor at high temperature. These results confirm that the adsorption process of MB onto NaAmw was controlled by both physisorption and chemisorption. The reusability study shows that the NaAmw was still stable after five cycling runs. These results indicate that NaAmw efficiently adsorbed MB, and could be utilized as a cost-effective alternative adsorbent for removing cationic dyes in the treatment of wastewater

Acid-vacuo heat treated low cost banana stems fiber for efficient biosorption of Hg(II)

The potential of banana stem fiber (BSF) as a low cost biosorbent for Hg(II) removal was studied. HCl treatment increased the cellulose accessibility which led to an enhanced interaction of Hg(II) and BSF. Activation of BSF-HCl in vacuo at 373 K increased the maximum biosorption capacity from 28 to 372 mg g(-1) and altered the activation energy from 3.5 to 76.9 kJ mol(-1) showing an increase in Hg(II) chemisorption. FTIR and ESR results confirmed the large amount of structural defects on the activated BSF-HCl which led to the increase in Hg(II) uptake. Batch biosorption models showed that the kinetics follow pseudo-second-order and the equilibrium uptake fitted to all three-parameter models showing the Hg(II) biosorption behaves as a Langmuir isotherm. The non-linear regression method exhibited higher coefficient of determination values for isotherm and kinetic analyses compared to the linear method. The thermodynamic functions indicated that the nature of Hg(II) biosorption is an exothermic and non-spontaneous process

Constructing bio-templated 3D porous microtubular C-doped g-C3N4 with tunable band structure and enhanced charge carrier separation

For the first time, the bio-templated porous microtubular C-doped (BTPMC) g-C 3 N 4 with tunable band structure was successfully prepared by simple thermal condensation approach using urea as precursors and kapok fibre which provides a dual function as a bio-templates and in-situ carbon dopant. Prior to the thermal condensation process, the impregnation strategies (i.e. direct wet and hydrothermal impregnation) of urea on the treated kapok fibre (t-KF) were compared to obtained well-constructed bio-templated porous microtubular C-doped g-C 3 N 4 . The details on a physicochemical characteristic of the fabricated samples were comprehensively analyze using X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Field-emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), N 2 adsorption-desorption, Thermogravimetric (TGA), and UV-vis spectroscopy. Our finding indicated that the hydrothermal impregnation strategy resulted in well-constructed microtubular structure and more carbon substitution in sp 2 -hybridized nitrogen atoms of g-C 3 N 4 as compared to the direct wet impregnation. Also, compared to pure g-C 3 N 4 , the fabricated BTPMC g-C 3 N 4 exhibited extended photoresponse from the ultraviolet (UV) to visible and near-infrared regions and narrower bandgap. The bandgap easily tuned with the increased t-KF loading in urea precursor which responsible for in-situ carbon doping. Moreover, as compared to pristine g-C 3 N 4 dramatic suppression of charge recombination of the BTPMC g-C 3 N 4 was confirmed through photoluminescence, photocurrent response, and electrochemical impedance spectroscopy. The resultants BTPMC g-C 3 N 4 possesses more stable structure, promoted charge separation, and suitable energy levels of conduction and valence bands for photocatalysis application