Phosphorus recovery from wastewater and sludge

Wastewater and sludge are potential resource of phosphorus (P) for fertilizer production. One method of recovering phosphorus is via chemical precipitation. In the study, phosphorus was recovered from wastewater and sludge. First, hydrolysis was carried out to release the phosphorus in the sludge by the addition of 1.0M acid (sulfuric acid) or base (sodium hydroxide) solution mixed for three hours at 200 rpm. The hydrolyzed sludge was filtered, and the pH of the solution was adjusted to 9.0. Precipitation for both wastewater and hydrolyzed sludge solution was carried out using magnesium chloride hexahydrate (MgCl2•6H2O) and ammonium chloride (NH4Cl). The mixture was stirred for an hour for crystallization. Precipitates were allowed to settle for 24 hours before it was filtered and dried in an oven at 55-58oC for 24 hours. The dried sample was grinded and characterized using Fourier transform infrared spectroscopy (FTIR), x-ray fluorenscence (XRF), and scanning electron microscope with energy-dispersive x-ray spectroscopy(SEM-EDX)

A sulfur copolymers (Sdib)/polybenzoxazines (pbz) polymer blend for electrospinning of nanofibers

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This study demonstrated the processability of sulfur copolymers (SDIB) into polymer blend with polybenzoxazines (PBz) and their compatibility with the electrospinning process. Synthesis of SDIB was conducted via inverse vulcanization using elemental sulfur (S8). Polymer blends produced by simply mixing with varying concentration of SDIB (5 and 10 wt%) and fixed concentration of PBz (10 wt%) exhibited homogeneity and a single-phase structure capable of forming nanofibers. Nanofiber mats were characterized to determine the blending effect on the microstructure and final properties. Fiber diameter increased and exhibited non-uniform, broader fiber diameter distribution with increased SDIB. Microstructures of mats based on SEM images showed the occurrence of partial aggregation and conglutination with each fiber. Incorporation of SDIB were confirmed from EDX which was in agreement with the amount of SDIB relative to the sulfur peak in the spectra. Spectroscopy further confirmed that SDIB did not affect the chemistry of PBz but the presence of special interaction benefited miscibility. Two distinct glass transition temperatures of 97 °C and 280 °C indicated that new material was produced from the blend while the water contact angle of the fibers was reduced from 130° to 82° which became quite hydrophilic. Blending of SDIB with component polymer proved that its processability can be further explored for optimal spinnability of nanofibers for desired applications

A Sulfur Copolymers (SDIB)/Polybenzoxazines (PBz) Polymer Blend for Electrospinning of Nanofibers

This study demonstrated the processability of sulfur copolymers (SDIB) into polymer blend with polybenzoxazines (PBz) and their compatibility with the electrospinning process. Synthesis of SDIB was conducted via inverse vulcanization using elemental sulfur (S8). Polymer blends produced by simply mixing with varying concentration of SDIB (5 and 10 wt%) and fixed concentration of PBz (10 wt%) exhibited homogeneity and a single-phase structure capable of forming nanofibers. Nanofiber mats were characterized to determine the blending effect on the microstructure and final properties. Fiber diameter increased and exhibited non-uniform, broader fiber diameter distribution with increased SDIB. Microstructures of mats based on SEM images showed the occurrence of partial aggregation and conglutination with each fiber. Incorporation of SDIB were confirmed from EDX which was in agreement with the amount of SDIB relative to the sulfur peak in the spectra. Spectroscopy further confirmed that SDIB did not affect the chemistry of PBz but the presence of special interaction benefited miscibility. Two distinct glass transition temperatures of 97 °C and 280 °C indicated that new material was produced from the blend while the water contact angle of the fibers was reduced from 130° to 82° which became quite hydrophilic. Blending of SDIB with component polymer proved that its processability can be further explored for optimal spinnability of nanofibers for desired applications

Sulfur copolymers (SDIB) from inverse vulcanization of elemental sulfur (S8) for polymer blend

Elemental sulfur (S8) is largely available resource as by-product from petroleum refining process which is causing excess sulfur problem\u27 due to its limited usage. The utilization of sulfur as valuable material will not only address environmental concerns but provide cost-effective ways of consuming this huge amount of waste to develop new high-value, high-volume products. One facile synthetic method of utilizing sulfur directly as feedstock to produce polymeric material is inverse vulcanization. In this study, sulfur copolymers (SDIB) was synthesized via inverse vulcanization from S8 and processed into polymer blend with component polymers, polybenzoxazine (PBz) and poly(methyl methacrylate) (PMMA) to show its potential processability into polymer blend. Initially, synthesis of SDIB with varying feed ratios of sulfur to comonomer 1, 3-diisopropenylbenzene (DIB) was evaluated for its resulting properties. Spectroscopy showed copolymerization reactions occurred based on the change in characteristic absorption peaks (C=C-H, C=C, C-H) present in the spectra. Thermogravimetric analysis (TGA) indicated that SDIB is more thermally stable with the increase in onset temperature of degradation. Differential scanning calorimetry (DSC) profile exhibited new single glass transition temperature (Tg) that slightly increased with higher DIB ratio indicating evolution of microstructures of copolymers produced. The processability of SDIB into polymer blend was investigated by using SDIB (50 wt% S) with PBz and PMMA. Blending process using simple mixing technique with solvents was carried out for SDIB/PBz (10/10 wt%) and SDIB/PMMA (7.65/7.65 wt%) blend compositions. The results of this study demonstrated that polymercopolymers interactions influenced the phase structure and behaviour with polymer blend of SDIB/PBz showing higher degree of miscibility with more homogeneous and transparent blend as compared to SDIB/PMMA blend. The suitability of polymer blend in electrospinning of nanofibers could provide variety of new applications for SDIB. © 2020 IOP Publishing Ltd

Effect of a direct sulfonation reaction on the functional properties of thermally-crosslinked electrospun polybenzoxazine (PBz) nanofibers

Electrospun nanofibers of polybenzoxazines (PBzs) were fabricated using an electrospinning process and crosslinked by a sequential thermal treatment. Functionalization by the direct sulfonation process followed after the post-electrospinning modification treatment. The first stage of experiment determined the effects of varying the concentration of sulfuric acid as the sulfonating agent in the sulfonation reaction under ordinary conditions. The second stage examined the mechanism and kinetics of the sulfonation reaction using only concentrated H2SO4 at different reaction time periods of 3 h, 6 h, and 24 h. The mechanism of the sulfonation reaction with PBz nanofibers was proposed with only one sulfonic acid (-SO3H) group attached to each of the repeating units since only first type substitution in the aromatic structure occurs under this condition. The kinetics of the reaction exhibited a logarithmic correlation where the rate of change in the ion exchange capacity (IEC) with the reaction time increased rapidly and then reached a plateau at the reaction time between 18 h and 24 h. Effective sulfonation was confirmed by electron spectroscopy with a characteristic peak associated with the C-S bond owing to the sulfonate group introduced onto the surface of the nanofibers. ATR-FTIR spectroscopy also confirmed these results for varying reaction times. The SEM images showed that sulfonation has no drastic effects on the morphology and microstructure of the nanofibers but a rougher surface was evident due to the wetted fibers with sulfonate groups attached to the surface. EDX spectra exhibited sulfur peaks where the concentration of sulfonate groups present in the nanofibers is directly proportional to the reaction time. From surface wettability studies, it was found that the nanofibers retained the hydrophobicity after sulfonation but the inherent surface property of PBz nanofibers was observed by changing the pH level of water to basic, which switches its surface properties to hydrophilic. The thermal stability of the sulfonated nanofibers showed almost the same behavior compared to non-sulfonated nanofibers except for the 24 h sulfonation case, which has slightly lower onset temperature of degradation. This journal is © The Royal Society of Chemistry

Gas permeation properties and preparation of carbon membrane by PECVD method using indene as precursor

This work could demonstrate a new approach to the fabrication of gas separation membrane using indene as polymeric precursor for low pressure PECVD system. Membrane characterization was done by taking Scanning Electron Microscopy (SEM) and FTIR measurements. For membrane performance testing, permeability and selectivity of the membrane were evaluated with pure gases of H2, N2, and CO2 using a differential permeation technique. PECVD-derived polyindene membrane showed selectivities of 8.2 and 4.0 for H2/CO2 and H2/N2, respectively, at room temperature. Polyindene (PIn) membrane was successfully fabricated onto a zeolite 5A substrate via radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) at room temperature. © 2019 Published under licence by IOP Publishing Ltd

Evaluation of Ankistrodesmus falcatus for bicarbonate-based Integrated carbon capture system (BICCAPS)

This study evaluates the performance of alkaliphilic microalgae Ankistrodesmus falcatus in the Bicarbonate-based Integrated Carbon Capture and Algae Production System (BICCAPS). The system utilized bicarbonate as carbon source for microalgae production. BICCAPS parameters such as pH, algal biomass productivity and CO2 utilization (inorganic carbon conversion, Ci) were observed at different sodium bicarbonate (NaHCO3) loading concentration and type of culture media. The highest productivity was observed at 10 g/L of NaHCO3 loading in BRSP medium at 3.5539 mg/L/day. This value is 30% lower compared to the control experiment (continuously aerated bioreactor). The Ci values of the different system ranges from 1.17 x 10-4 to 1.51 x 10-4 moles/L/day. Both the pH of the BRSP and NPK media at 10 g/L and 30g/L loading of NaHCO3 increased through time. The result shows that A. falcatus has a potential in BICCAPS utilization. © The Authors, published by EDP Sciences, 2018

Evaluation of spirulina platensis in bicarbonate-based integrated carbon capture and algae production system utilizing different culture media

A method known as Bicarbonate-based Integrated Carbon Capture and Algae Production System (BICCAPS), is a growing study introduced as an alternative to current carbon capture and sequestration (CCS) methods. It is a closed-loop cycle involving inorganic carbon in the form of bicarbonates, which is consumed by microalgae for growth and utilizes the regenerated carbonates for another cycle of carbon capture. Existing literature requires more in-depth experimentation and analysis with regards to the viability of different microorganisms to the rising method. Spirulina platensis was evaluated in BICCAPS using 0.1M Na2CO3, employing three different culture media for growth, namely, modified Zarrouk’s, NPK-based, and NPK-based with A5 solution media. Biomass growth, productivity, and carbon dioxide utilization were investigated to determine the effectivity of BICCAPS as a carbon sequestration technique. At control conditions, NPK-based with A5 solution medium yielded the highest productivity with a value of 10.81 mg L-1 day-1. Likewise, using NaHCO3 as a carbon source, results show that the highest productivity was achieved also under NPK-based with A5 solution medium with a value of 6.80 mg L-1 day-1, as well as a high carbon conversion value of 2.092 day-1..© 2020, Gadjah Mada University. All rights reserved

Evaluation of bacterial cellulose-sodium alginate forward osmosis membrane for water recovery

Water resources are very important to sustain life. However, these resources have been subjected to stress due to population growth, economic and industrial growth, pollution and climate change. With these, the recovery of water from sources such as wastewater, dirty water, floodwater and seawater is a sustainable alternative. The potential of recovering water from these sources could be done by utilizing forward osmosis, a membrane process that exploits the natural osmotic pressure gradient between solutions which requires low energy operation. This study evaluated the potential of forward osmosis (FO) composite membranes fabricated from bacterial cellulose (BC) and modified with sodium alginate. The membranes were evaluated for water flux and salt rejection. The effect of alginate concentrations and impregnation temperatures were evaluated using 0.6 M sodium chloride solution as feed and 2 M glucose solution as the draw solution. The membranes were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Contact Angle Meter (CAM). The use of sodium alginate in BC membrane showed a thicker membrane (38.3 μm to 67.6 μm), denser structure (shown in the SEM images), and more hydrophilic (contact angle ranges from 28.39° to 32.97°) compared to the pristine BC membrane (thickness = 12.8 μm and contact angle = 66.13°). Furthermore, the alginate modification lowered the water flux of the BC membrane from 9.283 L/m2-h (LMH) to value ranging from 2.314 to 4.797 LMH but the improvement in salt rejection was prominent (up to 98.57%). © 2018 Penerbit UTM Press. All rights reserved

Evaluation of Ankistrodesmus falcatus for Bicarbonate-Based Integrated Carbon Capture System (BICCAPS)

This study evaluates the performance of alkaliphilic microalgae Ankistrodesmus falcatus in the Bicarbonate-based Integrated Carbon Capture and Algae Production System (BICCAPS). The system utilized bicarbonate as carbon source for microalgae production. BICCAPS parameters such as pH, algal biomass productivity and CO2 utilization (inorganic carbon conversion, Ci) were observed at different sodium bicarbonate (NaHCO3) loading concentration and type of culture media. The highest productivity was observed at 10 g/L of NaHCO3 loading in BRSP medium at 3.5539 mg/L/day. This value is 30% lower compared to the control experiment (continuously aerated bioreactor). The Ci values of the different system ranges from 1.17 x 10-4 to 1.51 x 10-4 moles/L/day. Both the pH of the BRSP and NPK media at 10 g/L and 30g/L loading of NaHCO3 increased through time. The result shows that A. falcatus has a potential in BICCAPS utilization