The rapid economic growth and technology advancement result in higher quality of human lives. However, what follow as well are various impacts on the surrounding environment. Global warming and air pollution, for instance, are the consequences of human’s over-exploitation of non-renewable energy and those of polluting human activities like large-scaled industrial manufacturing and vehicle emissions. Every year millions metric tons of hazardous wastes are generated, seriously threatening public health and the environment.
The threats suggested above are not, nevertheless, inevitable evilness appeared during the process of society development. With modern chemical technology, the impacts of such threats can virtually be minimized.
Waste treatment and reduction
With more advanced technologies and a rapidly expanding population, the volume of man-made waste has increased drastically, and the trend is expected to continue in the future. Electronic waste and synthetic polymers have attracted the most concern amongst solid waste owing to their high toxicity and persistent nature. In the meantime, industrial processes generated much wastewater that must be treated before release. To address the pollution associated with the rapid development, researchers are seeking new methods for waste treatment.
Recent research directions
Removal of surfactant on hand-washing wastewater by zeolitelink
Surfactant removal from handwashing wastewater is to improve water quality and reduce environmental pollution to prevent foaming in river streams.
Optimization of eggshell-zeolite composite as a potential surfactant adsorbent for hand-washing wastewater. A Design Expert software to optimize the composite adsorbent by varying the eggshell percentage, calcination time, and temperature. The optimized composite adsorbent had a high chemical carbon demand (COD) removal efficiency of 88%. Hence, it suggests that the use of composite adsorbents may be an effective method for removing surfactants from handwashing wastewater.
A team of plant and molecular biologists from Sri Lanka have discovered that many types of fungi that break down hardwood trees can also break down polyethylene (PE), a common kind of plastic. Fungi were isolated from species placed with PE sheets under certain conditions. They found that all of them were able to break down sheet plastic.
Shrimp waste as catalyst for hydrogen generationlink
Chitosan, a biodegradable polymer made from crustacean shells, can be used as a catalyst that releases hydrogen from alkali metal borohydride salts. The high pH and continuous release of hydrogen bubbles that this reaction creates usually destroy traditional catalysts, but the chitosan can expand during the hydrogen generation without breaking, allowing the bubbles to escape. The team found that catalysts made using chitosan could generate 40 mL of hydrogen per minute for two days in a continuous reactor.
Plastic recycling is challenging and expensive due to its complex molecular structure. Only 9% of all plastic waste is recycled, and the rest is discarded in landfills and the natural environment. New research from the lab of Giannis Mpoumpakis, suggested that pyrolysis helps plastic recycling, research tried to optimize the thermodynamic condition via density function theory where thermos-decomposition is efficient.
A new scheme for upcycling waste PET via chemical depolymerization of acetic acid has been proposed. Depolymerized waste PET achieved efficient recycling of PET into high-purity terephthalic acid. Besides, acetolysis of PET would produce ethylene glycol diacetate, which can be hydrolyzed to ethylene glycol or polymerized to form polyethylene terephthalate. This new strategy has the lowest impact on the environment and can be easily adapted to current industrial equipment.
Mercury is easily dispersed through the air and accumulates in the soil, water, and living organisms. A metal electrode absorbs the mercury, changing it from a gaseous state to a solid state and resulting in the formation of an alloy. Purifying the acid, not only prevents additional mercury emissions but also enables industries to operate more efficiently and produce a high-purity, non-toxic product.
New water treatment method can generate green energylink
A micro-motor contains a tube of silicon and manganese dioxide and is covered with laccase that accelerates the conversion of urea from polluted water into ammonia. The reaction that occurs in the tube causes the release of a gas bubble and pushes the motor. It is possible that the emission of ammonia gas can further decompose to hydrogen gas.
Titanium oxide material can remove toxic dyes from wastewaterlink
Textiles and cosmetics may carry harmful and carcinogenic dyes like rhodamine 6G and crystal violet. To separate the dyes from wastewater, research developed a titanium oxide photo-catalyst material. Once the dyes are adhered to the material under light shining, it catalyzes the decomposing of the dyes molecules into less harmful products, like carbon dioxide and water.
Reducing carbon dioxide concentration
Since the industrial revolution, the emissions of greenhouse gases, which absorb and emit infrared light to keep the Earth warm, have skyrocketed. It leads to extreme weather and the extinction of many species. To mitigate climate change, scientists are developing new technologies to reduce the concentration of carbon dioxide, which is the primary component of greenhouse gases, by providing more sustainable pathways for industrial processes, capturing carbon dioxide in the air, and converting carbon dioxide into simple organic molecules, etc.
Recent research directions
Reduction of carbon dioxide by absorption technique link
Absorption of carbon dioxide produced by vehicles was investigated. A single-cylinder engine with a water-cooled system is used to determine the absorption of carbon dioxide with different concentrations. It is observed that a maximum of 90% of carbon dioxide can be removed and even other pollutants like unburnt hydrocarbon, carbon monoxide, and nitrogen oxides showed a decrease trend in emission under this strategy.
Solar-powered microbes turn carbon dioxide into bioplastic link
To better understand their function and optimize energy conversion. The multimodal platform included multi-channel fluorescence imaging with photoelectrochemical current mapping to examine the bacterium Ralstonia eutropha. The researchers identified two types of hydrogenases, one bound to the cell's membrane and another in the cytoplasm, that help metabolize hydrogen and drive CO2 fixation and even convert to valuable products like bioplastic and biofuel.
Biomass-based carbon materials for CO2 capturelink
With the aid of physical treatment (steam/air/CO2 activation) and chemical treatment (acid/alkaline activation, metal or metal oxide impregnation, heteroatom doping), carbon materials produced by biomass pyrolysis are utilized for CO2 capture. By either physical or chemical adsorption, the adsorption capacity of carbon dioxide is worthy of study.
A new artificial catalyst, known as photocatalysis that made from copper and cobalt. When exposed to sunlight, it has the potential to generate energetic “hot” electrons that can be transferred to catalytic sites on the surface of the material. These hot electrons can then drive chemical reactions, such as the reduction of carbon dioxide to produce fuels like methane and hydrogen gas. This method is more sustainable and cost-effective way than traditional methods, such as steam methane reforming.