Photocatalytic degradation of dye wastewater

Dye wastewater is the major environmental issue of the textile and printing industries besides other minor issues like solid waste, health and safety. The use of synthetic chemical dyes in various manufacturing industrial process has increased considerably over the past decades, resulting in the release of dye-containing industrial effluents into aquatic ecosystem and soil [1]. Wastewater from printing and dyeing industries is frequently rich in color, containing residues of toxic chemicals, reactive dyes and requires proper treatment before all the effluent release into environment [2]. There are more than 8000 chemical products associated with all the dyeing, printing and finishing process listed in the color index, including some of the structural diverse of dyes, such as basic, acidic, reactive, disperse, azo, diazo, anthraquinone based and metal-complex dyes [1]. Therefore, these wastes must be genuine treated before it discharge to environment in order to comply with the environmental protection for the receiving water

Mollusk Shell Waste as Composite Photocatalyst for Methylene Blue Removal

Mollusk shell is abundant in particular areas and frequently deposited in landfills, contributing to environmental pollution. However, mollusk shell waste has been proven as an absorbent that has a high possibility of acting as a photocatalyst when integrated with metal support in composite form due to the synergistic effect. Therefore, in this study, mussel and cockle shells as agricultural wastes were selected to be innovated as support for photocatalysts. The solid-state dispersion (SSD) method was used to prepare a composite photocatalyst where mussel and cockle were integrated with titanium dioxide (TiO2) nanoparticles at a ratio of 9:1. In total, 100% of mussel and cockle were used as control samples. The prepared composite photocatalyst was evaluated with methylene blue (MB) removal in the suspension system. The result reveals that mussel/TiO2 and cockle/TiO2 composite photocatalyst show 25.92 and 24.08% for MB removal within 2 hours. It is due to the prepared composite photocatalyst particle sizes, where mussel/TiO2 and cockle/TiO2 were 259 and 268 nm, respectively. It is interesting to note that the prepared composite photocatalyst particle size should be in nanosize, where it can enhance the photocatalytic performance. Overall, agricultural waste should be utilized to ensure a clean environment for future generations

Photocatalytic performance of TiO2/Clinoptilolite: comparison study in suspension and hybrid photocatalytic membrane reactor

Comparison studies in suspension and hybrid photocatalytic membrane reactor (HPMR)system was investigated by using Reactive Black 5 (RB5)as target pollutant under UVA light irradiation. To achieve this aim, hybrid TiO2/clinoptilolite (TCP)photocatalyst powder was prepared by solid-state dispersion (SSD)methods and embedded at the outer layer of dual layer hollow fiber (DLHF)membranes fabricated via single step co-spinning process. TiO2 and CP photocatalyst were also used as control samples. The samples were characterized by Scanning Electron Microscopy (SEM), Energy Dispersion of X-ray (EDX), X-ray diffraction (XRD)and Brunauer–Emmett–Teller (BET)analyses. The result shows that TCP was actively functioned as photocatalyst in suspension system and 86% of RB5 photocatalytic degradation achieved within 60 min; however the additional step is required to separate the catalyst with treated water. In the HPMR system, even though the RB5 photocatalytic degradation exhibits lower efficiency however the rejection of RB5 was achieved up to 95% under UV irradiation due to the properties of photocatalytic membranes. The well dispersed of TCP at the outer layer of DLHF membrane have improved the surface affinity of DL-TCP membrane towards water, exhibit the highest pure water flux of 41.72 L/m2.h compared to DL-TiO2 membrane. In general, CP can help on improving photocatalytic activity of TiO2 in suspension, increased the RB5 removal and the permeability of DLHF membrane in HPMR system as well

Photocatalytic performance of TiO2/eggshell composite for wastewater treatment

The utilization of eggshells as a primary source for developing value-added materials has received significant attention recently due to its ability as an excellent adsorbent and support. This study used the solid-state dispersion method to prepare composite photocatalyst TiO2/eggshells of different ratios. TiO2 and eggshell photocatalysts were also used as control samples. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD) analyses were used to characterize the samples. Finally, the efficiency of the composite photocatalyst was evaluated in the suspension system using methylene blue (MB) solution as the target pollutant. Among three different ratios, TiO2/eggshell (1:9) is the optimum ratio that achieved the highest adsorption and 56.41% photocatalytic degradation of MB solution. Besides, pure eggshells exhibited relatively high adsorption but did not show any significance in photocatalytic degradation. It proves that the ability of eggshell as an adsorbent is very high even though it only acted as support to the TiO2 in the TiO2/eggshell composite photocatalyst. The increased surface area of the TiO2/eggshell composite photocatalyst could enhance MB solution adsorption and photocatalytic degradation, thereby increasing its effectiveness. Overall, it can be concluded that eggshell has excellent potential as support for photocatalyst and as an environmentally friendly catalyst

Investigation of heat impact behavior on exterior wall surface of building material at urban city area

This paper represents a comparative study aiming to investigate the heat impact on the vertical surfaces of buildings temperature based on their thermal behaviors. This study was carried out based on four building materials commonly used in Malaysia namely brick, concrete, granite and white concrete tiles. In order to investigate the thermal performance on the building materials, surface temperature sensors, data logging system as well as infrared thermography procedures were used, respectively. As the thermal impact to the materials was measured using infrared thermometric and thermographic, a field work of thermal value can be simply observed as a “seeing heat” effect. The results indicate that bricks had the capability to absorb and store heat greater than other materials during peak daytime event. The normalized (total heat/solar radiation) of brick materials was 0.093, which was the highest value compared to others. A brick material shows the highest impact of heat in 51% than white granite material and it releases a substantial amount of heat into the atmosphere through radiation and convection factors. The types of material used at exterior wall buildings have significant impact to the surrounding environment. The use of suitable materials contributes to the reduction of the air temperature due to heat transfer phenomena

Fabrication of dual layer hollow fibre membranes for photocatalytic degradation of organic pollutants

In recent years, the membrane photocatalytic reactor (MPR) systems have attracted much attention due to their promising function in treating organic pollutant and filtering clean water. Suspended photocatalyst titanium dioxide (TiO2) particle always become a problematic in hybrid MPR system due to membrane fouling and TiO2 loss. In the past few years, considerable attention has been paid to immobilize TiO2 nanoparticles on various materials. Since ultraviolet (UV) source and TiO2 are required for the photocatalytic reaction, thus, it is crucial to immobilize high concentration of TiO2 on the outer surface of the polymeric membrane support. By using co-extrusion approach, a dual layer hollow fibre (DLHF) membrane was fabricated. The effect of additives on the dope polymer solutions and membrane morphologies of DLHF were investigated using of scanning electron microscopy (SEM). The SEM results showed that DLHF membranes have a good adhesion between layers with no delamination

Performance evaluation of co-extruded microporous dual-layer hollow fiber membranes using a hybrid membrane photoreactor

Hybrid systems with immobilized TiO2 within dual-layer hollow fiber membranes are the most promising set-up for photocatalytic applications because they possess advantages in both the degradation and separation processes. The performance of dual-layer hollow fiber membranes may be maximized using a functional material of high performance as the selective layer. This paper reports the influence of polyethyleneglycol (PEG) as a pore forming agent on the structure and performance of dual layer hollow fiber membranes. Titanium dioxide (TiO2) was used as a photocatalyst in the outer layer of dual layer hollow fiber (DLHF) membranes. DLHF membranes were fabricated via a single step co-extrusion technique and characterized in terms of surface roughness, membrane porosity, hydrophilicity, and cross-sectional and surface morphology. Nonylphenol (NP) photocatalytic degradation and filtration were evaluated using a hybrid membrane photoreactor. The experimental results revealed that DL-PEG/TiO2 membrane increases the NP solution flux, while decreasing the incidence of membrane fouling and allowing for a smoother and more hydrophilic membrane surface. The findings show that the addition of PEG in the inner layer of DLHF membranes may enhance flux performance in the photocatalytic process

Investigation of thermal effect on exterior wall surface of building material at urban city area

This paper describes the investigation of heat impact on the vertical surfaces of buildings based on their thermal behavior. The study was performed based on four building materials that is commonly used in Malaysia; brick, concrete, granite and white concrete tiles. The thermal performances on the building materials were investigated using a surface temperature sensor, data logging system and infrared thermography. Results showed that the brick had the capability to absorb and store heat greater than other materials during the investigation period. The normalized heat (total heat/solar radiation) of the brick was 0.093 and produces high heat (51% compared to granite), confirming a substantial amount of heat being released into the atmosphere through radiation and convection. The most sensitive material that absorbs and stores heat was in the following order: brick > concrete > granite > white concrete tiles. It was concluded that the type of exterior wall material used in buildings had significant impact to the environment

Application of immobilized TiO2 on PVDF dual layer hollow fibre membrane to improve the photocatalytic removal of pharmaceuticals in different water matrices

A promising membrane configuration based on immobilized TiO2 on poly(vinylidene fluoride) (PVDF) dual layer hollow fibre membranes was prepared and successfully employed for the photocatalytic degradation of eight pharmaceuticals. Experiments were carried out in a flow reactor of 0.5 L equipped with a lamp emitting at 254 nm, treating groundwater and secondary wastewater effluent. The efficiency of the new catalyst to phototransform target micropollutants was demonstrated, being dependent on the selected compound. Only the application of photocatalysis using the supported catalyst allowed to increase the phototransformation rate of trimethoprim, metoprolol and carbamazepine treating secondary wastewater effluent (1.4–2.2 times faster than photolysis). The determination of electrical energy per order of magnitude of transformation (EEO) confirmed the lowest energy requirements to transform selected pharmaceuticals in secondary effluent employing the supported catalyst (33–58 kW h m−3 compared to 49–79 kW h m−3 applying only photolysis). The detection and identification of transformation products formed during the investigated treatments was performed by UPLC-QTOF/MS/MS. 156 transformation products were detected showing two different types of time profiles, namely a bell-shape trend or a constant increase along reaction time thus accumulating in the reaction mixture. The chemical structure for 19 out of 156 detected compounds was proposed as derived from parent compounds spiked in the secondary effluent